Monograph 26

Knee and Leg Trauma

By R. C. Schafer, DC, PhD, FICC
Manuscript Prepublication Copyright 1997

Copied by Chiro.Org with permission from   ACAPress

Background Basic Biomechanics Structural Balance   Inspecting Knees for Weight Balance and Posture Instability   External Rotation-Recurvatum Test   Anterolateral Rotary Instability Tests   Anterior-Posterior Instability Tests   Posterolateral Rotary Instability Posttraumatic Roentgenography of the Knee   Effusion   Fragmentation   Ossification   Fractures   Fatigue (Stress) Fractures   Dislocations   Lower Leg Fractures and Dislocations   Tumors Functional Anatomy of the Knee   The Knee Joint   The Patella   Knee Motion Evaluation   Kinesiology of the Knee   Flexion   Extension   Rotation Clinical Management Electives in Knee Sprain/Strain   Stage of Acute Inflammation and Active     Congestion   Stage of Passive Congestion   Stage of Consolidation and/or Formation     of Fibrinous Coagulant   Stage of Fibroblastic Activity and Potential     Fibrosis   Stage of Reconditioning Commentary   Patellar Bruises   Popliteal Aneurysm KNEE SPRAINS   Capsule Sprains   Collateral Ligament Injuries   Menisci Injury: General Considerations   Signs and Tests of Menisci Integrity   Specific Internal Semilunar Cartilage Injury   Triad of O'Donahue   Specific External Semilunar Cartilage Injury   The Crucial Ligaments   The Coronary Ligaments Miscellaneous Posttraumatic Syndromes of the Knee   Knee Joint Locking   Osteochondromatosis   Osgood-Schlatter Disease   Traumatic Arthritis   Traumatic Synovitis   Knee Pain in Athletes from Ankle Distortion   Cyst Development   Intracapsular Pinches

Acute Bursitis   Chronic Effusion   Peripheral Nerve Lesions of the Knee Area   Pellegrini Stieda   Osteochondritis Dissecans (Osteochondral     Fracture) Knee Motion Restrictions   Femorotibial Fixations   Proximal Tibiofibular Fixations TIBIAL SUBLUXATIONS   Anterior Tibia Subluxation   Posterior Tibia Subluxation   Lateral Tibia Subluxation   Medial Tibia Subluxation   Externally Rotated Tibia Subluxation   Internally Rotated Tibia Subluxation FIBULAR SUBLUXATIONS   Superior Fibula Subluxation   Inferior Fibula Subluxation   Anterolateral Fibula Subluxation   Posteromedial Fibula Subluxation   Posteroinferior Fibula Subluxation PATELLA DISORDERS   Patella Dysfunction   Patella Tendon Strain   Chrondromalacia Patellae   Sinding-Larsen-Johannson Disease   Infrapatellar Fat Pad Hypertrophy   Bipartite Patella SUBLUXATION-FIXATIONS OF THE PATELLA   Inferior Patella Subluxation   Superior Patella Subluxation   Superomedial and Superolateral Patella     Subluxations PATELLA DISLOCATIONS Miscellaneous Posttraumatic Disorders of the Leg   General Leg Bruises and Contusions   Gastrocnemius Contusions   Nerve Contusions     Seddon's General Classification of Nerve       Injury   Common Peroneal Nerve Compression LEG STRAIN: GENERAL CONSIDERATIONS   Gastrocnemius Strain (Tennis Leg)   Popliteus Tendon Rupture   Soleus Strain   Plantaris Rupture   Fascial Hernia and Tears   Shin Splints (Tibialis Anterior or Posterior     Tendinitis)   Periostitis Common Knee Rehabilitation Components CIRCULATORY AND VASCULAR DISORDERS   Screening Lower Extremity Circulatory     Insufficiencies   Compartment Syndrome   Varicosities   Mild Traumatic Phlebitis

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This paper primarily concerns the largest joint of the body: the knee. Without much soft-tissue protection, the knee is easily subject to trauma, but this same attribute offers helpful bony landmarks that are easily palpable.


BACKGROUND

Because it is a strong joint yet relatively unstable (a clinical paradox), traumatic overstress of the knee may be complicated by derangement of the intra-articular structures and precautions must be taken to carefully examine for possible displacement of the cartilages and rupture of related stabilizing ligaments. Biomechanically, the knee is far more than a simple hinge joint.

Basic Biomechanics

The knee is fairly centered between long bones above and below, thus frequently subjected to strong leverage forces. The stability of the knee is provided almost fully by its ligamentous complex, especially those straps on the medial and lateral aspects.

A knee's normal biomechanical functions are frequently altered by subluxation-fixations that may be the cause or effect of pathologic changes. Any of the three joints of the knee may be involved: the femorotibial, patellofemoral, or proximal tibiofibular joint. Injuries due to excessive stress appear especially on the short arm of a first-class-lever joint such as the knee and elbow. This is found with injury to the medial collateral ligament when valgus overstressed. During extension, force (eg, body weight) is applied at a distance from the fulcrum several times that occurring between the fulcrum and the ligament.

The knee, as with the elbow and hip, operates close to but not exactly like a first-class lever where the fulcrum is at the point of weight-bearing contact. During gait, body weight acts medially to the knee so the fulcrum of rotation is centered over the medial condyle when viewed from the A-P.

Equilibrium is maintained by the collateral ligaments, fascia lata, and tendon of the biceps femoris. As in the hip during normal gait, forces across the knee joint are from three to five times the imposed body weight. Most of the resultant joint forces are located in the medial compartment of the healthy knee. The line of action extends from the medial condyle of the distal femur through the tibia. The fibula has no weight-bearing function.

When loaded, the distal femur and proximal tibia are subjected to medial compressive forces and lateral tensile forces that tend to shift the tibia laterally relative to the femur. These forces, exaggerated during normal gait, must be counteracted by the medial ligaments of the knee. However, in a Trendelenburg gait for instance, weight is shifted to the lateral component of the knee and there is a tendency toward medial shifting of the tibia. This causes the lateral ligaments to be overstressed.

When erect, no quadriceps activity is necessary because the line of force of body weight is slightly in front of the knee's axis of rotation and the compression force at the articular surface of the knee and the shearing force of the femur on the tibia are due to the stabilizing structures at the posterior aspect of the knee.

Muscle and compression forces increase rapidly in the knee when deep knee bending is assumed. During squatting, the moment produced by body weight greatly increases, and increased muscle force is necessary to maintain equilibrium. This, in turn, increases the joint reaction force that places a greater burden of shear on the joint ligaments and compression on the menisci. Squatting exercises are thus contraindicated, even for the professional athlete.

Structural Balance

Passive nonweight-bearing flexion is essentially controlled by the hamstrings, and passive extension is primarily controlled by the quadriceps. Though these actions may appear normal, restricted rotation of the tibia on the femur during flexion-extension can produce severe dysfunction during weight-bearing.

The tibia rotates internally during knee flexion and externally during extension. These rotary movements of the tibia are governed by the ligaments and menisci of the knee and the action of the patella.

The priority considerations during physical examination where knee pain is the chief complaint are structural positioning, pain and tenderness and their localization, area warmth, motion restrictions, swelling, and ligamentous stability.

    Inspecting Knees for Weight Balance and Posture

A study has shown that angular deformity of only 10° will triple weight-bearing per unit of force in the knee. In adults, genu valgum is more common among females and genu varum is customary among males.

Genu Valgum (Valgus): Physical Signs of Knock-Knees. If there is an abnormal space between the malleoli when the knees are touching when the patient is standing with the kneecaps straight ahead, a degree of genu valgum is present that may be more marked on one side than the other. There will also be (1) excessive internal rotation of the femur and external rotation restriction, (2) excessive external rotation of the tibia and internal rotation restriction, (3) medial patella deviation due to femur rotation, and (4) foot pronation.

Valgum results in a short leg producing pelvic imbalance if the condition is unilateral. Be aware, however, that people with a large degree of joint flexibility (especially females) can hyperextend their knees along with femoral rotation to give a false appearance of structural deformity. Bilateral valgus is common in late childhood but typically corrects before the age of 8 or 9 years. Acquired causes include postural dysfunction and metabolic diseases.

Genu Varum (Varus): Physical Signs of Bowed-Leg. If the medial malleoli are touching and the knees are not when the patient is standing, the space between the knees determines the degree of genu varum. There will also be (1) excessive external rotation of the femur and internal rotation restriction, (2) excessive internal rotation of the tibia and external rotation restriction, (3) lateral patella deviation due to femur rotation, (4) anteversion of the femoral neck, and (5) an in-toeing gait.

As with genu valgum, bilateral genu varum is common in early childhood. It spontaneously corrects itself 95% of the time, states Mercier, during further growth and maturation. Nontraumatic causes include rickets, Paget's disease, scurvy, fibroid dysplasia, Blount's disease, and various other bone diseases. Other significant causes are postural dysfunction and degenerative arthritis.

Genu Recurvatum. Genu recurvatum refers to exaggerated hyperextensibility. It is usually associated with a joint disorder that produces A-P instability of the knee. Contact sports, high jumping, or any activity that may induce anterior leg trauma or strenuous "take-offs" from a locked knee would be contraindicated for severe injury is predisposed.

Tibial Rotation and Torsion. If the patient's kneecaps are facing straight ahead and the feet point distinctly outward, a positive sign of tibial lateral rotation on the femur exists. This sign is usually more pronounced on one side than the other. If the feet appear normally positioned but the patellae appear rolled medially inward, it is a positive sign of tibial torsion. Various causes have been shown to be at the root of tibial rotation or torsion. A common cause is tibial subluxation. Other causes are attributed to a congenital defect or predisposition, spastic paralysis, poliomyelitis, scurvy, or a consequence of tibial fracture.

Mikulicz's Roentgenographic Line. In the frontal view of the adult lower extremity (from hip to ankle) in the standing position, Mikulicz's line connects the middle of the inguinal ligament to the center of the talocrural joint, passing through the head of the femur and the center of the patella. If the center of the knee joint is found medial to this line, genu valgum (knock knee) exists. When the center of the knee joint is lateral to Mikulicz's line, genu varum (bowleg) presents.

Q-Angle Sign. The patient is placed in the supine position with the knees extended in a relaxed position. The quadriceps (Q) angle of the knee is then measured. The Q-angle is formed by a visualized line drawn along the long axis of the femur that is intersected by a line drawn through the center of the patella and the tibial tubercle. To record, a goniometer is centered on its side over the patella with one arm aimed at the ipsilateral ASIS and the other arm placed in line with the center of the patellar tendon. This angle is normally 10° in men and 15° in women. In external tibial rotation and/or genu varus, however, the Q-angle can be markedly increased; ie, the angle increases as the tibial tubercle is displaced laterally or when the distal femur and proximal tibia are angled toward the midline.

Management. Little can be accomplished once bone remodeling has occurred. However, much can be done in preventing further malformation by a long-term regimen of soft-tissue therapy, strengthening muscles showing weakness, stretching muscles and ligaments exhibiting shortening, maintaining fixation-free motion, nutritional concern, and assuring adequate innervation. Surgical reconstruction is rarely considered except in extreme cases.

Instability

The normal knee is provided with strong ligaments, a large joint capsule, and adjacent muscles and tendons that offer great stability. Severe sprain, especially that in hyperextension, readily leads to functional instability with chronic "giving way." A large degree of proprioception loss and loss of quadriceps power will undoubtedly be involved. In mild ligament tears, sprain symptoms are more pronounced but there is little or no instability involved. Severe tears exhibit marked laxity on stress tests.

    External Rotation-Recurvatum Test

Coupling. Because of its design, the leg cannot be fully extended without a degree of external tibial rotation on the femur. A maximal rotation of 6° lateral rotation occurs during the last 10° of extension, and the reverse occurs during the first 10° of flexion. This is called the "screw-home" mechanism. A simple test described later, the Helfet test, determines the integrity of the knee relative to the presence of this normal motion.

Technique. To screen for external rotation-recurvatum, place the patient supine. Grasp the heel with one hand, and support the calf with the other hand. Allow the knee to pass from about 10° flexion into full extension. A positive sign occurs when the knee assumes a position of slight recurvatum, the tibia rotates externally, and there is increased tibia vara. The sign indicates injury to the arcuate complex, lateral half of the posterior capsule, or posterior cruciate ligament.

    Anterolateral Rotary Instability Tests

McIntosh's Test. The patient is placed supine, the lower extremity is supported at the heel with one hand, and the other hand is placed laterally over the proximal tibia just distal to the patella. The caudad hand applies valgus stress and internally rotates the tibia as the knee is gradually moved from full extension into flexion. During knee flexion, the lateral tibial plateau can be felt to subluxate anteriorly relative to the lateral condyle. Lateral crepitation may be felt, and a slight resistance to flexion may be perceived. When the knee is flexed about 35° , the iliotibial band tightens, and the tibial plateau is suddenly reduced, often with a "clunking" sensation that can often be both felt and heard.

Houghston's Jerk Sign. This is a modification of McIntosh's test. With the patient supine, grasp the patient's foot with one hand while your other hand rests over the proximal lateral aspect of the leg just distal to the patella. The knee is flexed to 90° , and valgus stress is applied as the tibia is rotated internally. The knee is then gradually extended. The lateral tibial plateau is initially in a reduced position to the femoral condyle. However, as the knee is moved to about 35° of flexion, the lateral tibial plateau suddenly subluxates forward in relation to the femoral condyle with a jerking sensation. The lateral plateau slowly obtains its reduced position, which completes on full extension as the knee is extended.

Slocum's Test. This is another modification of McIntosh's test. The patient is placed in the lateral recumbent position with the involved knee uppermost. The under extremity is flexed at 90° at both the hip and knee. The pelvis is rotated slightly posterior about 30° , and the weight of the extremity is supported by the inner aspect of the foot and heel. This position causes valgus stress at the knee and a slight internal rotation of the leg. With the patient in this position, grip the patient's distal thigh with one hand and the proximal leg with your other hand and press back of the fibula and femoral condyle with your thumbs. The knee is then gently pushed from extension into flexion and, as the iliotibial tract passes behind the transverse axis of rotation at about 35° , the lateral tibial plateau, which has subluxated forward, is reduced with a palpable "clunk" or "giving way" sensation.

    Anterior-Posterior Instability Tests

Anterior Drawer Sign. The anterior and posterior cruciate ligaments provide A-P stability to the knee joint. These intracapsular ligaments originate from the tibia and insert onto the inner aspects of the femoral condyles. To evaluate anterior stability, place the patient supine and flex the knees to 90° so that the feet are flat on the table. Sit sideways so your hip can stabilize the patient's feet from moving during the tests. Grasp your hands around the knee being examined, with your thumbs pointing superiorly over the lateral and medial joint lines and fingers wrapped around the lateral and medial insertions of the hamstrings. In this position, pull the tibia forward. If a distinct sliding forward of the tibia from under the femur is felt, it indicates a torn anterior cruciate ligament. Slight anterior sliding, however, is often normal. A positive sign should be confirmed by repeating the maneuver with the patient's leg internally rotated 30° and again with the leg externally rotated 15° . The reason for this is that even if the anterior cruciate ligament is torn, external rotation should reduce forward movement of the tibia. If it does not, both the anterior cruciate and the anteromedial aspect of the joint capsule are likely torn. The medial collateral ligaments may also be involved in loss of A-P stability.

Posterior Drawer Sign. With the patient supine and the knees flexed, the stability of the posterior cruciate ligament is tested in the same manner as the anterior cruciate except the tibia of the flexed knee is pushed backward rather than pulled forward. Thus, both tests can be done in one continuous maneuver. When a distinct sliding backward of the tibia from under the femur is felt, a torn posterior cruciate ligament is indicated. A positive drawer sign is less common than its anterior counterpart.

Bounce-Home Test. With the patient supine, cup one hand under the patient's heel and slightly flex the patient's knee with your other hand. While the patient's heel is held, the patient's knee is allowed to passively drop gently toward the top of the table in full extension, normally with an abrupt stop. If this full extension is not achieved and passive pressure elicits a "rubbery" resistance to extension, a motion block is indicated. This lack of full extension points to a torn meniscus, intracapsular swelling, or a loose fragment within the knee joint.

Knee Hyperextension Stress Test. The patient is placed prone with the knees extended in the relaxed position. Place a fist under the distal thigh of the involved side, flex the patient's knee to about 30° with your other hand, and then allow the leg to drop without assistance when the muscles are relaxed. Most knee lesions limit extension to some degree. Thus, if extension is limited or the rebound is abnormal during this "leg drop" test (as compared to the contralateral knee), some type of knee disorder should be suspected and possibly be localized. This test, essentially, is the same as the bounce-home test except that the patient is prone.

Knee Hyperflexion Stress Test. With the patient in the supine position, place one hand on the involved knee and your other hand on the patient's ipsilateral ankle. The patient's knee is moderately flexed, the thigh is brought toward the patient's abdomen, and the patient's heel is slowly pushed toward the patient's buttock. Unless the patient is very obese, the normal knee can be flexed without pain so it closely approaches the buttock. If knee pain or severe discomfort is induced by this maneuver, a subtle localized knee lesion may be brought out.

Management. Injuries resulting in anterior or posterior instability may be treated conservatively if a complete rupture has not occurred. Initial cryotherapy and pressure support followed by a carefully supervised regimen of articular correction, interferential therapy, massage, crutch walking, guarded weight bearing with the knee in 30° flexion, other inducement's to enhance circulation and promote healing, and strengthening exercises (quadriceps after posterior cruciate injury, hamstrings after anterior cruciate injury) are often successful in returning an athlete to competition in 3 6 weeks. Many cases challenge the doctor's expertise.

    Posterolateral Rotary Instability

Posterolateral rotary instability arises from a posterior subluxation of the lateral tibial plateau, relative to the lateral femoral condyle, accompanied by abnormal external tibial rotation. This type of instability usually results from trauma on a weak (lax) arcuate complex and lateral half of the posterior capsule, and a degree of failure of the posterior cruciate ligament.

Posterolateral Rotary Instability Test. To test for posterolateral rotary instability, the external rotation-recurvatum and a posterior drawer test are performed. Excessive posterior sag of the lateral tibial plateau with external tibial rotation are noted.



POSTTRAUMATIC ROENTGENOGRAPHY OF THE KNEE

Lateral and A-P views are the standard views of the knee. Anthrography is more helpful in the diagnosis of acute ligament or meniscus injury and synovial cysts than are standard views.

Weight-bearing views, a tangential view of the patella, and a tunnel view of the intercondylar notch to show articular margin defects (eg, condyle compression fracture) are often helpful. Stress views of the knee are beneficial in gaining evidence of fracture or ligament ruptures by expressing abnormal hinging that is not evident on standard views. Local anesthesia may be required.

Effusion

The most common traumatic soft-tissue disorder of the knee area is the result of effusion at the suprapatellar joint space where adjacent fat pads are displaced. Lateral views are best for determining effusion if it can be viewed at all. Fat above the patella, anterior to the femur, and posterior to the quadriceps tendon near the superior aspect of the patella is somewhat lucent in the normal knee. If effusion exists, fatty areas are replaced by fluids matching the density of thigh muscles and normal signs of fat are obliterated.

Knee effusion may be shown in an A-P view by soft-tissue density medial to the tibia below the joint line. This is usually attributed to paratibial synovial cysts progressing posteriorly and medially that may extend via bursae connections to the popliteal space or to the posterior aspect of the upper calf. Rarely is extension to the posterior thigh.

Fragmentation

The residual epiphyseal cartilage of the distal femur should be fairly uniform in thickness. Displacement of its margins should be noted. The articular margins of the femoral condyles are normally smooth, but fragmentation will appear in osteochondritis dissecans and osteochondral fractures. Swelling at the insertion of the quadriceps tendon at the apophysis of the tibial tubercle suggests Osgood-Schlatter's disease.

Strong sudden muscle contractions may cause fracture avulsions in the lateral knee area. Small bone fragments may also be found in an A-P view at the lateral edge of the proximal tibia on iliotibial band injury.

Ossification

Signs of ossification may appear in the patellar tendon following hemorrhage produced by partial tendon tears. If dislocation has occurred, such signs may also be found in the soft tissues. After blunt trauma to a limb, soft tissues may show evidence of heterotopic bone formation. Such ossification involves not only muscle tissue but also occurs within the fascial planes. The typical history reveals trauma, muscle pain and soreness, and hemorrhage into the soft tissues. Signs of poorly defined ossification develop in 2--5 weeks.

Fractures

If knee fracture is suspected, special care must be made to avoid soft-tissue damage during movement. Supracondylar or intracondylar fractures are rare in the young and during athletics but are quite frequent in the elderly with minimal trauma. The fracture site may be stable, displaced, or comminuted. The mechanism of injury is usually a sideways blow just above the knee or a direct anterior blow when the knee is fully flexed (eg, hard-surface fall on the knee).

Football helmet "spearing" to stop a runner frequently occurs by hitting laterally and anteriorly at the junction of the fibula, tibia, and femur articulations. "This osseous impact (clip) is so traumatic that it frequently immobilizes the player --possibly to the extent of a fractured extremity, ruptured collateral ligament and meniscus, or severe contusions and hemorrhaging of infra- and supra-patellar synovial sacs and tendinous attachments." Yet, according to statistics, knee fractures are rare in sports.

Distal Femur Fractures. Comminuted lower femoral osteochondral fractures can result from jumping compression forces producing bony fragments difficult to view on film. On axial or tangential views, ossicles of the tibial tubercle may project over the femoral margins or patella and be confused with an osteochondral fracture or a loose body of bone.

Proximal Leg Fractures. After violent twisting of the knee with pain localized near the proximal fibula, fracture and/or upper fibula dislocation should be the first suspicions. Chronic subluxations and posttraumatic arthritis of the proximal tibiofibular joint are frequent complications. As in the forearm, leg fractures often involve both bones. Sometimes, however, these bones do not fracture at the same level. When an x-ray film of the leg does not include the entire length of the bones, there is a possibility that a fracture may be missed. When a fracture is seen in only one of the paired bones at a given level, one must seek other levels for fracture of the other bone. Tibial fractures rarely occur; when they do, they are usually the result of running into an obstacle (eg, a bench).

Fatigue (Stress) Fractures

With repeated, forceful contractions of leg muscles, lower leg stress fractures are sometimes seen as the result of tibia or fibula "wobble." This sign is commonly related to track and field injuries but can occur whenever a force exceeds the bone's structural strength. Progressive pain during physical activity is the primary complaint.

    Note: The phrase stress fracture is a misnomer that is common in
    use. The term fatigue fracture is more accurate biomechanically as
    all fractures are the result of overstress.

Roentgenography. An early sign, if any, is that of a linear periosteal reaction that rarely exceeds a centimeter in length, This may be associated with local bony tenderness, but tenderness is not common. In time, resorption of the fracture margin reveals a lucent linear defect on film. Fatigue fractures of the legs are usually horizontal but occasionally longitudinal. The initial signs are (1) a minute radiolucent tunneling of the cortex as a result of osteoclastic resorption, followed by cortical resorption in a fracture line of one cortex, and (2) a localized haze on the bone surface representing callus or periosteal new bone development. Within the endosteal bony surface, a line of condensation may be seen. Later, an abundant callus may be confused with a neoplasm. Soft-tissue views and bone scanning are sometimes necessary to determine fatigue fractures.

Management. Most fatigue fractures do not require splinting or casting unless extensive or if the patient is unreliable in providing the necessary rest and protection of the area involved.

Dislocations

Knee dislocations rarely occur except in vehicular accidents or falls from great heights. A few cases have been reported in football and from missteps. The diagnosis is usually obvious.

Because of the severe pain involved and the probability of associated ligament and capsule tears, popliteal artery damage, and/or peroneal nerve injury, the patient with a dislocated knee should be referred to an orthopedic surgeon immediately for reduction under anesthesia and continuous evaluation of vascular and nerve status. Vascular repair is often unsuccessful if delayed for more than 8 hours. According to orthopedists Sisto/Warren, only in rare cases will a completely dislocated knee regain normal A-P motion.

Lower Leg Fractures and Dislocations

Displacement of lower tibia or fibula fractures is usually posteromedial because of the strength of the gastrocnemius and soleus.

Lower Tibia Fracture-Dislocation. Because the tibial epiphysis does not ossify until the early twenties, epiphyseal fractures are not uncommon in adolescent contact sports. Fatigue fractures feature a dull gnawing pain following a run that increases in severity with time and weight bearing. Special care must be taken not to mistake an incomplete fracture of the distal-medial tibia (Pott's fracture) for a severely inversion-sprained ankle.

Lower Fibula Fracture-Dislocation. Most fibula injuries occur at its distal portion. Minor fractures are sometimes missed because symptoms may resemble a bruise or mild sprain. As the fibula does not carry direct body weight, a player may continue activity long after fracture occurs and thus complicate the original injury. Uncomplicated fractures infrequently require more than support followed by progressive therapeutic exercise unless the medial ligaments of the ankle or tibiofibular supports are ruptured.

Tumors

The knee is a common site of occasionally seen giant cell tumors and sarcomata. When discovered, it is usually on a film taken to confirm another suspicion.



FUNCTIONAL ANATOMY OF THE KNEE

In the normal erect relaxed posture, the support of body weight and stability of the knee joint are provided strictly through the bony design and ligaments of the joint. No muscle action is involved.

The Knee Joint

The major osseous structures of the knee joint are the lateral and medial condyles of the distal femur and the superior articular surfaces of the tibia. The head of the fibula at the upper leg can be considered a part of the knee joint complex. On rare occasions, the simple synovial joint of the tibia-fibula articulation communicates with the knee joint proper. The major ligaments of the knee are the collaterals, the cruciates, and coronarys, along with the capsule and menisci.

Collateral Ligaments. The broad medial (tibial) collateral ligament spans from the medial epicondyle of the femur to the medial aspect of the superior tibia, supporting the posterior aspect of the capsule. These fibers relax on knee flexion and tighten on extension, rotation, and lateral motions. The lateral (fibula) collateral ligament extends from the lateral epicondyle of the femur to the head of the fibula, offering no support to the capsule. These fibers relax on knee flexion and tighten on extension, rotation, and lateral movement.

Cruciate Ligaments. The cross-shaped anterior and posterior cruciate ligaments lie within the joint capsule but are separated from the joint cavity by synovial tissue. They attach between the menisci in the intercondylar valley. The anterior cruciate spans between the anterior tibial condyle and the back of the medial surface of the lateral condyle of the femur. The posterior cruciate extends from the posterior intercondylar area to the lateral side of the medial condyle of the femur. Both ligaments are tense in all positions but are especially so during extreme flexion, extension, and rotation. Their main function is to restrict shear forces across the joint.

The Coronary Ligaments. The medial and lateral coronary ligaments are extensions of the capsule. They attach the borders of the menisci to the tibia and femur.

Joint Capsule. The synovial joint capsule of the knee is supported laterally to the patella by the inferior fibers of the fascia lata and quadriceps. The posterior capsule is supported by the semimembranosus tendon and the oblique popliteal ligament. The popliteus muscle pierces the capsule but is separated from the cavity by a synovial membrane.

The Menisci. The two wedged-shaped internal and external menisci communicate only anteriorly. These articular crescents deepen the joint, cushion axial forces between the femur and tibia, and help to smooth the distribution of synovial fluid.

The Patella

The triangular knee cap has its apex directed caudally. Its posterior surface is smooth for articulation with the femur. The patella is the largest sesamoid bone in the body. It lies within the tendon of the quadriceps, tending to hold the tendon anterior from the femur. This improves quadriceps extension ability about 30%. In this sense, the patella can be compared with a movable pulley.

Knee Motion Evaluation

Basic knee movements are flexion, extension, internal rotation, and external rotation. See Table 1. Flexion and extension occur essentially between the femur and tibia. Rotation during slight flexion, internal and external, occurs between the tibia and femur and from menisci shifting.

Table 1. Knee Motion

Joint Motion	Prime Movers	Accessories
Flexion	Hamstrings	Sartorius
	Semimembranosus	Gracilis
	Semitendinosus	Gastrocnemius
	Biceps femoris	Plantaris
		Popliteus
Extension	Quadriceps
	Rectus femoris
	Vastus lateralis
	Vastus medialis
	Vastus intermedius
External rotation	Biceps femoris	Tensor fascia latae
Internal rotation	Semimembranosus
	Semitendinosus
	Gracilis
	Popliteus
	Sartorius

Flexion-Extension Screening. Test active flexion (135° ) by having the youthful patient carefully squat in a painless knee-bent position. Active extension (0° ) is tested by having the patient arise from this position to the standing position. Note dominance of one knee over the other and the smoothness of movement, especially of the last 10° of extension. Test flexion and extension passively if necessary with the patient prone. Stabilize the popliteal space with one hand, and grasp the patient's ankle with the other hand. Flex the leg as far as possible on the femur, noting the distance from the heel to the buttock. The leg should normally extend to 0° in a smooth arc.

Lateral Stability Screening. To test sideward stability, place the patient supine and flex the knee just enough to free it from extension. To test the integrity of the medial ligament, apply valgus stress to open the knee joint on the medial side. Test the lateral ligament by applying pressure to open the knee joint on the lateral side. In these maneuvers, secure the ankle with one hand, place the other hand on the opposite side of the knee of the ligament being tested, and apply pressure toward the ligament being tested. More knowledge can be gained, however, if you lock the patient's ankle between your arm and chest and use this hand to palpate the ligaments in question and the underlying joint gap during the test.

Internal and External Rotation Screening. To test active knee rotation, the patient is asked to slightly flex the knee and rotate the foot laterally and medially. About 10° either way is normal. Passive rotation is tested with the patient supine. Place a stabilizing hand just above the patient's knee, and rotate the tibia internally and externally with your active hand. It is helpful to have your stabilizing hand simultaneously palpate the tibial tubercle to note the amount of movement.


Kinesiology of the Knee

The muscles of the knee, their major functions, and the spinal segment of their nerve supply are shown in Table 2.

Table 2. Muscles of the Knee

Muscle	Major Functions	Spinal Segment
Gastrocnemius	Flexion	S1--S2
Gracilis	Flexion, medial rotation	L2--L3
Hamstrings	Flexion, rotation	L5--S2
Biceps femoris	Flexion, external rotation (long head)	S1--S2
Semimembranosus	Flexion, medial rotation	L5--S1
Semitendinosus	Flexion, medial rotation	L5--S2
Plantaris	Flexion	L5--S1
Popliteus	Flexion, medial rotation	L4--S1
Quadratus femoris	Extension	L4--S1
Rectus femoris	Extension	L2--L4
Sartorius	Flexion, medial rotation	L2--L3
Tensor fasciae latae	External rotation	L4--S1
Vastus muscles	Extension	L2--L4

Note: Spinal innervation varies somewhat in different people. The spinal nerves listed here are averages and may differ in a particular patient; thus, an allowance of a segment above and below those listed should be considered.

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Flexion

Knee flexion is under the control of the hamstring group (semitendinosis, semimembranosus, and biceps femoris) supplied by the sciatic nerve (L5--S2). Help is provided by the sartorius, gracilis, gastrocnemius, plantaris, and popliteus. To evaluate strength with the patient supine, test the group by stabilizing the thigh above the knee. Grasp the patient's leg above the ankle with the other hand, and offer increasing resistance as the patient attempts to flex the knee. If the patient rotates his leg externally during the test, more work is forced on the biceps femoris. Greater stress is placed on the semitendinosus and semimembranosus when the leg is rotated internally.

Extension

Knee extension is provided essentially by the rectus femoris (L2--L4) and quadratus femoris (L4--S1), with help from the vastus group (L2--L4). To test strength with the patient sitting, place your stabilizing hand above the knee and fix the femur. Then apply increasing resistance on the patient's tibia above the ankle as the patient attempts to extend his knee. It is helpful to palpate the prime movers with the fingers of the stabilizing hand during the test.

Rotation

During internal rotation, power is provided medially by the reciprocal action of the semitendinosus, semimembranosus, sartorius, popliteus, and gracilis. The biceps femoris controls external rotation.



CLINICAL MANAGEMENT ELECTIVES IN KNEE SPRAIN/STRAIN

1. Stage of Acute Inflammation and Active Congestion

The major goals are to control pain and reduce swelling by vasoconstriction, compression, and elevation; to prevent further irritation, inflammation, and secondary infection by disinfection, protection, and rest; and to enhance healing mechanisms. Common electives include:


Disinfection of open skin (eg, scratches, abrasions, etc)
Cryotherapy
Cold packs
Ice massage
Vapocoolant spray
Compression
Pressure bandage
Aircast
Protection (padding)
Elevation
Indirect therapy (reflex therapy)
Iontophoresis/phonophoresis
Auriculotherapy
Meridian therapy
Spondylotherapy
Mild pulsed ultrasound
Mild pulsed alternating current
Rest
Bedrest
Cane
Crutches
Foam/padded appliance
Immobilization
Brace
Rigid appliance
Strap
Plaster cast
Indicated diet modification and nutritional supplementation.


2. Stage of Passive Congestion

The major goals are to control residual pain and swelling, provide rest and protection, prevent stasis, disperse coagulates and gels, enhance circulation and drainage, maintain muscle tone, and discourage adhesion formation. Common electives include:

Indirect articular therapy (reflex therapy)
Alternating superficial heat and cold
Pressure bandage
Protect lesion (padding)
Light nonpercussion vibrotherapy
Passive exercise of adjacent joints
Mild surging alternating current
Mild pulsed ultrasound
Phonophoresis
Cryokinetics (passive exercise)
Meridian therapy
Spondylotherapy
Rest
Bedrest
Cane
Crutches
Foam/padded appliance
Immobilization
Brace
Rigid appliance
Strap
Plaster cast
Indicated diet modification and nutritional supplementation.


3. Stage of Consolidation and/or Formation of Fibrinous Coagulant

The major goals are the same as in Stage 2 plus enhancing muscle tone and involved tissue integrity and stimulating healing processes. Common electives include:

Mild articular adjustment technics
Moist superficial heat
Thermowraps
Spray-and-stretch
Cryokinetics (active exercise)
Moderate active range-of-motion exercises
Meridian therapy
Sinusoidal current
Ultrasound, continuous
Phonophoresis
Vibromassage
Stretching distraction
High-volt therapy
Interferential current
Spondylotherapy
Mild transverse friction massage
Mild proprioceptive neuromuscular facilitation techniques
Rest
Bedrest
Cane
Crutches
Foam/padded appliance
Immobilization
Brace
Semirigid appliance
Indicated diet modification and nutritional supplementation.


4. Stage of Fibroblastic Activity and Potential Fibrosis

At this stage, causes for pain should be corrected but some local tenderness likely remains. The major goals are to defeat any tendency for the formation of adhesions, taut scar tissue, and area fibrosis and to prevent atrophy. Common electives are:

Deep heat
Articular adjustment technics
Spondylotherapy
Local vigorous vibromassage
Transverse friction massage
Spray-and-stretch
Active range-of-motion exercises without weight bearing
Negative galvanism
Ultrasound, continuous
Phonophoresis
Sinusoidal and pulsed muscle stimulation
High-volt therapy
Interferential current
Meridian therapy
Proprioceptive neuromuscular facilitation techniques
Rest
Bedrest
Cane
Crutches
Foam/padded appliance
Immobilization
Semirigid appliance
Support
Indicated diet modification and nutritional supplementation.


5. Stage of Reconditioning

Direct articular therapy for chronic fixations
Progressive remedial exercise
Passive stretching
Isometric static resistance
Isotonics with static resistance
Isotonics with varied resistance
Plyometrics
Aerobics
Indicated diet modification and nutritional supplementation.



COMMENTARY

Knee injuries in football have the highest injury incidence (60%). Field physicians should remember that just because a player can walk off the field after injury is no sign that severe injury has not occurred. Athletes are drilled to be stoic.

Skiing also has a high incidence of knee sprains, fractures (usually of the medial collateral ligament), and ankle injuries, but the incidence has lowered with the popularity of release-type bindings. The common fracture in skiing has changed from that of the ankle to that of the lower third of the tibia.

Patellar Bruises

A blow to the prepatellar bursa may quickly lead to a ballooning hemorrhage, which may extend several inches above the patella. This can be quite alarming to the inexperienced physician. Intricate examination must be made to differentiate the effects of contusion about the knee from a low quadriceps strain with suprapatellar bursal hemorrhage. Bone bruises are not difficult to differentiate as there is no effusion, motion restriction, joint instability, locking, ligament tenderness, or joint line tenderness.

Popliteal Aneurysm

When direct trauma affects major vessels and hematoma develops, aneurysmal dilation or a fistula may be produced as a complication. These are most often seen in the popliteal region following injury. The lesion must be differentiated from a pulsating hematoma, which is not a true aneurysm. A pulsating hematoma is fed by a ruptured arteriole and requires the skill of a vascular surgeon for correction. Discomfort behind the knee or upper calf on forced dorsiflexion of the foot is often a sign of thrombosis in the leg (Homan's sign).

KNEE SPRAINS

When examining joint motion in the knee, special care must be taken that normal motion is not confused with the exaggerated motion resulting from joint instability.

Capsule Sprains

As the knee is a superficial joint and the largest joint in the body, symptoms after severe trauma are readily apparent. Any forced movement beyond the normal range of movement can produce symptoms and signs. Tenderness may be immediate, but effusion and stiffness are usually slow in development. Fluctuation and ballotement of the patella from joint distention may occur, and hemarthrosis may be associated. Pain and motion limitation are constant.

Management. After mild injuries, cold, corrective manipulation, and strapping may be sufficient. When effusion into the joint is extremely severe, referral for aspiration may be necessary that is followed by compression bandages. Physiotherapy should be employed daily, and a knee support is advisable until full functional power is achieved. During the acute stage, structural alignment, cold, compression, positive galvanism, and possibly elevation are indicated. Ultrasound is especially effective. Hyaluronidase is helpful to reduce tissue swelling and edema if it is "driven in" with iontophoresis or phonophoresis. Complete rest is usually contraindicated in mild or moderate sprains; thus, use of a cane or crutch may be helpful. Therapy must consider rapid quadriceps atrophy, especially that of the vastus medialis.

After 48 hours, passive congestion can be managed by contrast baths, sinusoidal stimulation, ultrasound, light massage, gentle passive manipulation, and a mild range of active exercise. During the stage of consolidation, local moderate heat, moderate active exercise, moderate range of motion manipulation, and ultrasound are beneficial. Supplementation with 140 mg of manganese glycerophosphate six times daily throughout care appears to speed healing. In the stage of fibroblastic activity, deep heat and massage, carefully monitored active exercise, negative galvanism, ultrasound, and active joint manipulation speed recovery and inhibit postinjury effects.

Vapocoolant Technique in Grade I Knee Sprains. Place the patient supine with a pillow under the involved knee. Spray the painful and tender areas, and gently assist and resist the patient in knee flexion-extension, with emphasis on extension. As the pain shifts position, spray the affected area. Have the patient attempt to walk. Youthful patients may be asked to carefully semisquat and kneel. Spray any painful area. If possible, have the patient stand on his toes and bend forward with his heels on the floor. Once relief is obtained, strap the joint, and instruct the patient in home exercises for 1 or 2 minutes each half hour during the waking hours. Full weight bearing should be restricted until the quadriceps indicate adequate strength. Begin resistance, stretching, and weight-bearing exercises as soon as logical.

Collateral Ligament Injuries

The collateral ligaments provide critical medial and lateral stability to the knee joint. Tears are caused by violent adduction or abduction and sometimes are associated with knee dislocation.

Background. Minor sprains usually have a history of a sudden or unexpected movement, especially when the knee is in valgus position from an internally rotated thigh, a pronated or flat foot, or abduction during foot strike in gait. The mechanism is usually a combination of partial flexion, varus position, and sudden internal rotation overstress such as produced during stumbling, misstepping off a curb or stair, stepping into a hole, or onto a small object. Such sprains are common to cross-country runners, joggers, and jumpers who land with the knee in a valgus position.

Severe rupture of the lateral ligaments is produced by trauma where the internal lateral ligament is ruptured by overabduction of the leg or the external ligament is torn by overadduction. Excessive lateral motion during complete extension indicates laceration of lateral ligaments. Thus, the internal lateral ligament is impaired if abduction is excessive; the external ligament, if adduction is excessive.

Clinical Features. Collateral ligament sprain presents with the same symptoms of localized pain, tenderness, and swelling as does capsule sprain. In minor lateral-ligament sprains, signs of effusion are not common. Stress tests help in differentiation. Pain is progressively severe and aggravated by the motion of injury, swelling is localized, point tenderness is demonstrable, muscles are spastic, and hemarthrosis may be present. Drawer signs are negative. Postinjury x-ray films may show elongated amorphous shadows near the affected femoral condyle, evidence of hematoma resolution, and possible displacement of the fibula or tibia.

Testing Collateral Ligament Stability. The medial and lateral ligaments provide stability to the knee joint. To examine sideward stability, place the patient supine and flex the knee just enough to free it from extension. To test the integrity of the medial ligament, apply valgus stress to open the joint on the medial side. Test the lateral ligament by applying pressure to open the joint on the lateral side. In these maneuvers, secure the ankle with one hand, place the other hand on the opposite side of the knee of the ligaments being tested, and apply pressure toward the ligaments being tested. More knowledge can be gained, however, if the examiner locks the patient's ankle between his arm and chest and uses this hand to palpate the ligaments in question and the underlying joint gap during the test.

Medial (Tibial) Collateral Ligament Sprain. Twisting overstress with the valgus knee in partial flexion often produces partial tearing of the long anterior fibers. Complete rupture may occur from violent abduction while the knee is extended or in external rotation and abduction while the knee is partially flexed. Hematoma usually develops, especially if the mechanism of injury is a severe blow. In minor sprains, effusion is slight and rapidly disappears during rehabilitation. In severe sprains, pain and swelling are severe and the meniscus will undoubtedly be involved. Adhesive taping will rarely be strong enough to prevent irritation during weight bearing. An early brace is helpful.

Lateral (Fibular) Collateral Ligament Sprain. These ligament tears are caused by violent adduction, often associated with knee dislocation. The mechanism of injury is usually partial flexion in a varus position with internal rotation overstress. In minor lateral-ligament sprains, signs of effusion are rare.

Management. The knee should be strapped in complete extension and treated as a severe sprain. Hirata warns that early aspiration or local anesthesia is contraindicated as they both obscure important signs of progress. Straight-leg lifts should be started 36 hours after injury. Effusion developing the first day after injury that subsides 50% or more the second day is an encouraging sign. However, if the swelling reduces and then returns on ambulation, a related meniscus tear should be suspected.

Early ligament or cartilage tenderness is often obscured by effusion. Once tenderness subsides, graduated resistance exercises may be begun. Once strapping is removed, a brace may be applied that allows flexion but limits lateral motion and full extension. In severe rupture, referral for surgery is usually required, but there are few miracles in knee surgery.

Taping Technique. The patient should stand with a 1-1/2 to 2-inch wedge under the heel. Shave the knee, and spray with pretaping adherent or apply underwrap. (1) Using 3-inch tape, start the first strip at about midcalf on the medial aspect of the leg, bringing it around the back of the calf so that it angles upward on the inside of the leg and crosses the shin just below the patella. Extend it up the medial side of the leg about 10 inches. The second strip is applied on the same angle, overlapping the first strip by a third. (2) The third strip starts at the same point as the first two but runs upward on the leg and above the top of the patella to end on the lateral side of the leg. The fourth strip begins on the lateral aspect of the calf and angles under the patella to the medial side of the thigh. The fifth strip begins at the same spot as the first three but angles across the shin at the bottom of the patella, ending on the lateral thigh. Strips one, three, four, and five are then repeated, with the new strips overlapping the original strips by about a third. (3) To anchor, a continuous 3-inch-wide strip can then be applied, again leaving the patella free and being sure that the tape is not applied too tightly around the leg to restrict circulation. This is done by pulling the tape to its full elastic extension and then laying it in place. (4) A piece of 3-inch tape about 10 inches long (unstretched) is applied to the popliteal space. If the fossa is not covered by underwrap, pre-cover with cotton or gauze padding. Split the free ends of the tape, and carry the tails above and below the patella. (5) The final strip is applied over the first strip in the same manner. These last two strips, states Christensen, further stabilize the knee and help to prevent cartilage slippage.

Menisci Injury: General Considerations

The design of the knee joint predisposes it to attacks of impingement or instability. Many pathologic factors can produce mechanical derangement within a joint, but none exceeds the incidence of trauma. Symptoms of a meniscus injury closely resemble knee sprain such as sudden localized pain aggravated by motion, disability, and swelling. However, swelling develops gradually in contrast to that of knee sprain and locking is common in meniscus injury and absent in pure sprain. Injury to either semilunar cartilage may occur in either gender at any age but because trauma received during contact sports is the common cause, males are more frequently affected than females.

Menisci Malpositions. Dislocation of the anterior horn is the most common menisci injury because this part of the meniscus is loosely bound to the internal lateral ligament. After displacement, the anterior border is caught between the articulations and may be rolled posteriorly within the joint to cause further displacement or tear. The posterior horn may be dislodged and nipped between the back part of the articular surfaces in flexion, thus preventing full flexion of the knee. The central portion of the cartilage may be pulled into the joint when its peripheral attachments are torn. In rare situations, the whole cartilage may be detached and avulsed within the joint.

Menisci Fractures. Knee cartilage fractures may be longitudinal, transverse, oblique, or irregular. Bifurcation of the cartilage's anterior border makes this portion particularly easy to split. When the anterior horn is ripped loose and retracted within the joint, the transverse ligament locks the outer edge of the meniscus while traction on the displaced horn tears the cartilage. The central portion of the meniscus may be jammed between the articulations causing a longitudinal split and displacement of the inner half of the cartilage within the joint (buckethandle type). A similar tear of the posterior horn (posterior tag) may be caused by the same mechanism as dislocation. Transverse fractures are common where the anterior third of the meniscus joins with the posterior two-thirds. A horizontal "T" or oblique fracture may occur at this point by the cartilage bending without detachment.

Almost any sprain involving forced rotation will injure the menisci and one or both central cruciate ligaments. However, studies show that the majority of knee injuries do not involve severe cartilage damage as once supposed. Fractured menisci can be helped by conservative treatment, but recurrent locking is common. Surgery is the alternative, but it too is not always successful. Prognosis must always be carefully guarded.

Signs and Tests of Menisci Integrity

Steinmann's Sign. In meniscus disorders, tenderness moves posteriorly when the knee is flexed and anteriorly when the knee is extended. This displacement of tenderness is not generally thought to occur in degenerative osteoarthrosis.

Payr's Sign. The patient is asked to sit flat with the legs crossed and folded inward so that the femurs are internally rotated. The involved knee is flexed and abducted, and the foot is plantar flexed. If pain occurs on the medial side of a knee when downward (valgus) pressure is applied on the knee, a lesion at the posterior horn of the medial meniscus is suggested.

Apley's Compression Test. The patient is placed prone with one leg flexed to 90° . Stabilize the patient's thigh with a knee and grasp the patient's foot. Apply downward pressure to the patient's foot to compress the medial and lateral menisci between the tibia and femur. Next, rotate the tibia internally and externally on the femur, holding downward pressure. Pain during this maneuver indicates probable meniscal or collateral damage. Medial knee pain suggests medial meniscus damage; lateral pain, lateral meniscus injury.

Apley's Distraction Test. Apley designed this test to follow the compression test as an aid in differentiating meniscal from ligamentous knee problems. With the patient and the examiner in the same position as in the compression test, apply traction (rather than compression) while the leg is rotated internally and externally. This maneuver reduces pressure on the menisci but stretches the medial and lateral ligaments of the knee.

McMurray's Test. In this two-part test, the patient is placed supine with the thigh and leg flexed until the heel approaches the buttock. Place one hand on the patient's knee, the other hand on the patient's ankle. Internally rotate the patient's leg, then slowly extend the leg. Next, externally rotate the leg and slowly extend the leg. The test is positive if at some point in the arc a painful click or snap is heard, which is significant of meniscus injury. The point in the arc where the snap is heard locates the site of injury in the meniscus. If noted with internal rotation, for example, the lateral meniscus will be involved. The higher the leg is raised when the snap is heard, the more posterior the lesion is in the meniscus. If noted with external rotation, the medial meniscus will be involved. Unfortunately, false positive and false negative signs are not uncommon with this test.

Childress' Test. This is a two-phase test for the young: (1) The patient is asked to stand with the feet separated about 12--18 inches apart, assume a "knock-kneed" position by rotating the thighs inward, and then attempt to carefully squat as low as possible. Pain, joint restriction, or a clicking sensation suggests a lesion of the medial meniscus. (2) The test is then conducted with the patient assuming a "bowed-leg" position by rotating the thighs outward before squatting. Pain, joint restriction, or a clicking sensation when attempting to squat suggests a lesion of the lateral meniscus.

Specific Internal Semilunar Cartilage Injury

Cartilage damage medially is most often seen in young adults. Various pathologic factors can produce mechanical derangement within a joint, but trauma is the most common causes.

Incidence. The internal semilunar cartilage is injured 15 times more frequently than the external meniscus. This is because the internal semilunar cartilage is longer than the external, crescentic in shape, and bifurcates, with the anterior portion of the bifurcation passing across to attach to the external semilunar cartilage. The coronary ligaments holding the meniscus to the tibia are much shorter medially than those of its lateral mate and do not permit free play.

Injury Forces and Effects. The mechanism of injury causing internal semilunar stress is more common than that for injury to the external cartilage --a sudden inward twist of the femur on the fixed tibia. This produces severe tension and torsion on the anterior border of the meniscus, which may be ruptured or stretched. Tibial abduction is often associated with torsion and, when present, the mid part of the cartilage may be sucked outward and caught between the femur's inner condyle and tibial tuberosity. Also, abduction widens the medial aspect of the articulation, allowing nipping of the internal meniscus. The posterior border of the internal cartilage may be pinched between the articular surfaces by outward rotation of the femur when the tibia is fixed in extreme flexion (eg, the squatting position). During injury, the meniscus may be contused, subluxated, dislocated, or fractured. Fractures and luxations may be combined during the initial injury or occur after cartilage impingement.

Other Clinical Features. Symptoms usually reflect the amount of damage and impingement. The joint may be locked, swollen, and extremely painful. There is frequently inability to fully extend the knee, indicating joint locking. The infrapatellar fat pad may be hot and enlarged. Either or both side strapings may be stretched or ruptured. Sometimes swelling does not develop for several hours, upon which tenderness increases over the involved ligaments. Diagnosis is arrived at by the history along with physical and roentgenographic findings to differentiate arthritis, anomalies, and other causes for the internal derangement and clinical picture.

Recurring Displacements. After recurrent dislocation, the picture is not so acute except on rare occasions. A low-grade inflammatory process is related to recurrent displacements and associated with proliferative changes in the synovial membrane. The common protective mechanisms can be expected.

Reduction. If impingement is mild, first flex the knee over your fist placed in the patient's popliteal fossa for counterleverage. Rock the limb gently in this position to loosen the jammed meniscus. The leg is then grasped at the ankle, and the tibia is laterally rocked on the femur to widen the space between the medial condyle of the femur and the tibia's articular surface, thus further freeing the cartilage. The leg is then rotated inwardly while the patient actively kicks his leg forward and upward. Severe force should never be used. An audible snap is usually heard as the meniscus is repositioned.

The test for reduction is the patient's ability to completely extend the knee without assistance. Reduction must be made within 24 hours after injury; if not, effusion produces a loss in meniscus elasticity preventing it from springing back to its normal seat.

Management. After reduction, treat the injury as a severe sprain. Painless full weight bearing should be allowed as soon as possible, but excessive motion should be restricted by strapping. The taping procedure is the same as for collateral ligaments. Later, a brace with lateral stays may be applied that allows flexion but not rotation. A sole lift is helpful for several weeks until full strength and stability returns. Competitive activity should never be resumed until all symptoms have subsided and quadriceps strength and tone have returned to normal. Management should also consider strengthening the rotators of the knee.

Triad of O'Donahue

This is a clinical complex consisting of injury to the medial meniscus, medial collateral sprain, and anterior cruciate sprain. All signs and symptoms pertinent to these three injuries will be positive. This complex is also called the "unhappy triad" by many professional athletes.

Specific External Semilunar Cartilage Injury

The external semilunar cartilage is more circular and thicker than the internal. It is strapped to the tibia by coronary ligaments, as is the internal, but lateral fibers are much longer and permit more free play than allowed for the internal cartilage. The external cartilage conforms to the articular surface of the tibia when the knee is extended. The internal meniscus does not fit snugly in any joint position.

Injury Forces and Effects. The mechanism of injury to the external semilunar cartilage is the reverse of that producing internal cartilage damage. In this type of injury, the foot has usually been fixed on the ground by body weight, the femur is rotated outwardly on the tibia, and the knee is simultaneously adducted. The posterior border of the lateral meniscus ruptures, and the cartilage is avulsed within the anterior compartment. The external lateral ligament may also be stretched or torn. The same type of lesions common to internal malpositions are found, but here the whole cartilage is usually displaced because it is thicker and heavier than its medial counterpart.

Other Clinical Features. Symptoms are similar to but usually milder than those of medial injury except they are located at the lateral aspect; viz, locking, local tenderness, and inability to make full extension. Sometimes pain and tenderness are referred medially if the lateral ligament is severely stretched.

Reduction. The reduction maneuver is the opposite of that used for internal meniscus impingement. The knee is acutely flexed, adducted to open the joint laterally, and the leg is rotated outwardly while the patient quickly extends the knee. Again, the test for reposition is active full extension of the knee. Postadjustment management is similar to that for internal meniscus damage.

The Crucial Ligaments

Sprain of the cruciates is often involved in "the unhappy triad" (cruciates and miniscus) because the straps may be ruptured by the same mechanisms producing meniscus displacement. The anterior cruciate restricts backward shifting of the femur and hyperextension. The posterior cruciate ligament restricts forward displacement of the femur or backward displacement of the tibia. Both the anterior and the posterior crucial ligaments may be torn. Because knee twisting disrupts the meniscus, the coincidence of meniscus and anterior ligament sprain is often seen.

Injury Forces and Effects. Pure A-P shearing overstress of the cruciates is rare. The anterior cruciate ligament is commonly disrupted when internal rotation of the femur with the knee slightly flexed produces a relaxation of the cruciate ligaments as they untwist. The cruciates re-tense with forced external rotation of the femur, and the anterior cruciate gives way because it is weaker than the posterior. Laxity of the anterior cruciate is especially common, but it is unimportant if functional stability is to be maintained. There will be no lateral instability unless the collateral ligaments are also functional.

Posterior tears are caused by sudden external rotation of the femur with the foot fixed while the knee is forced into abduction, flexion, or by forceful displacement of the tibia backward on the femur with the knee flexed. Another mechanism is a fall on the knee with the force received on the proximal tibia.

Lachman's Test. With the patient supine, the examiner slightly flexes the involved knee (about 20° ), cups a palm against the proximal calf, and attempts to pull the tibia forward. Excessive anterior translation of the tibia from the femur (anterior drawer sign) and lack of a definite end point suggest a rupture of the anterior cruciate ligament. If the anterior crucial ligament is torn, the tibia can be glided forward on the femur (drawer sign) and the knee can be hyperextended. Again, this sign must be elicited early before reflex hamstring spasm obscures a possibly positive sign. If the posterior crucial ligament is torn, the tibia can be glided posteriorly on the femur.

Other Clinical Features. After rupture of either portion, the subject is apprehensive and insecure. The history reveals the knee "giving way" with slight locking, similar to that seen with stretching of a lateral ligament. In full rupture, severe avulsion or fracture of the bony attachment is usually associated. Stress films reveal excessive joint motion.

Classes of Injury. (1) Mild: pain is elicited by passive stress, and point tenderness and local swelling develop. The joint is stable, and there is no locking or effusion. (2) Moderate: there is local swelling, some effusion, constant pain aggravated by passive stress, and locking if a meniscus rupture is related. There may be hemarthrosis. (3) Severe: With complete tear with or without avulsion, there is overt disability, instability, extensive swelling, agonizing pain, protective spasm, locking if a meniscus is involved, and probable hemarthrosis. Referral for surgery must be decided within 24 hours.

Taping Procedure for Moderate Sprain. (1) The heel should sit on a 2-inch wedge to place the knee in approximately 20° flexion. Apply underwrap, leaving the patella free. (2) Apply 2-inch-wide strips in a diagonal basketweave fashion from midcalf to midthigh. Extension is restricted by placing three vertical strips from the posterior thigh to the calf. Pad the popliteal space. (3) Strapping is anchored by 3-inch-wide strips to cover the entire basketweave but not covering the patella. This technique can be combined with that described for collateral ligament sprain to give additional support.

Management. In mild cases, treat by activity restriction, cold packs, compression, elevation, support, and muscle therapy. Heat is helpful in the late stages. In moderate to severe cases, the limb should be elevated and cold packs applied for 36--72 hours. When effusion completely subsides, mild heat may be applied. The knee is often pressure-dressed, casted in extension and treated as a severe sprain until the ruptured ligament(s) is repaired by fibrosis. Early weight bearing should be limited, and ultimately a program of muscle re-education can be initiated. A brace may be applied that allows flexion but firmly inhibits lateral motion. Rehabilitation must emphasize strengthening the extensors in the last 10° --15° . Management should also consider strengthening the rotators of the knee. In severe rupture, referral for surgery may be required, especially if there is evidence of bone damage.

The Coronary Ligaments

It is not difficult to confuse meniscus tear with an excessively mobile meniscus that results from lax coronary ligaments. The coronary ligaments (a part of the capsule) attach the convex margins of the menisci to the upper end of the tibia just below the articular margin. The symptoms of coronary sprain mimic mild meniscus sprain with the exceptions that there is no joint locking and point tenderness at the joint line may be more acute. Typically, a negative McMurray's sign and an Apley's compression sign are found.



MISCELLANEOUS POSTTRAUMATIC SYNDROMES OF THE KNEE

Knee Joint Locking

While meniscus tears and lax coronary ligaments may be exhibited in joint locking, there can be other causes such as free bodies within the joint that produce a motion block. Transient locking is often the result of recurrent nipping of the alar folds to produce pedunculated tags that are easily caught. Hemarthrosis is typically associated.

It was described earlier that because of its design, the leg cannot be extended without a degree of external tibial rotation on the femur. A maximal rotation of 6° of lateral rotation occurs during the last 10° of extension and the reverse during the first 10° of flexion. This is called the "screw-home" mechanism. Helfet's test determines the integrity of the knee relative to the presence of this normal motion.

Helfet's Test. This test is designed to detect the presence of an intra-articular "loose body" disturbing the normal biomechanics of the joint. To test normal knee locking, a dot is made with a skin pencil in the center of the patella and another is made over the tibial tubercle when the knee is flexed. The knee is then passively extended, and the motion of the dot relative to the patella is observed. A positive sign occurs when there is lack of full lateral movement of the dot.

Palpation of the tibial tubercle during this test allows for subtle determination of disturbed joint mechanics. Apart from intra-articular bodies, a lack of rotational joint play at the tibiofemoral articulation and imbalance in the tone of the internal and external rotators of the tibia could promote the pathomechanics observed during the test. It should also be noted that all but two of these muscles find their origin in the pelvis.

Osteochondromatosis

Osteochondromatosis is a noninflammatory condition in which pedunculated or loose bodies form from the synovial membrane within the joint cavity or within bursae and/or tendon sheaths. Traumatic, infectious, and neoplastic etiologies have been put forth. The exact cause is controversial, but the facts tend toward trauma being the primary precipitating agent.

Pathology. The disorder features villous hypertrophy of the synovial membrane with bony or fibrous bodies forming in the villi. One large cauliflower-like displaced body or several hundred small round or kidney-shaped bodies, closely packed, may be revealed floating free within the joint on x-ray examination. There is some progressive growth after development. Each body contains a cancellous core with fat cells surrounded by a hyaline-like exterior. With time and pressure, large bodies may develop smooth convex facets.

Associated False Locking. While true joint locking can occur from a displaced fragmented cartilage, a false locking may occur where there is stiffening on extension that gives way with persistence. It is more like a painful arc than a true block.

Osgood-Schlatter Disease

The most likely form of osteochondrosis met with in young athletics is that of the tibial tubercle. It is seen quite frequently in young male football backs and runners of either sex. The disorder is misnamed, however, in that it is not a disease. The exact cause is unknown, but it is thought to be a form of osteochondrosis with intrinsic trauma as the inciting factor; eg, sudden contractions of quadriceps femoris concentrated on a portion of an incompletely developed tibial tubercle resulting in an avulsion fracture. The disorder is not usually severely disabling and is milder in girls than boys. The disorder can be bilateral.

Roentgenography. Findings of the A-P view are usually negative. In a lateral film, the epiphysis of the tibia is seen fragmented and irregular in outline and density during the advanced stage. The patellar ligament becomes thickened at its insertion early. This is usually evident before osseous changes occur. Williams/Sperryn believe the anterior tibial tubercle becomes infarcted because of excessive pull from the patella tendon. The primary trauma is followed by numerous lesser injuries that constantly give rise to new interruptions of continuity during the growth period.

Clinical Features. Symptoms depend on the extent of involvement of the synovial membrane and the mechanical interference of the loose bodies. The typical complaint is pain at the anterior knee, inferior to the patella, especially when the knee is flexed. Repeated attacks of "catching" are common. A hot, red, tender swelling develops over the tibial tubercle when the disorder is active. The patient reports pain during activity and the inability to kneel. There is also pain on running and climbing stairs. An enlarged tubercle may be palpable. While joint motion may be only slightly affected, crepitation on active and passive motion is typical. Pain is increased by any activity that produces active knee extension against resistance.

Management. Immediate rest of the part is indicated. Normalize any vertebral motion-unit abnormality if possible, especially those found in the hip, lumbar, or sacroiliac areas. Normalize muscle tone in the lower back, pelvis, and thigh. A plaster cast, brace, or other means to restrict joint flexion may be necessary to allow the tubercle to fuse. Some authorities say this should always be done, others say it is never necessary. Ultrasonic therapy helps in increasing vascularization at the appropriate stage. Weight-bearing is permitted after the acute stage, but knee flexion is restricted until overt symptoms subside. Afterwards, weakened muscles must be strengthened. Never overlook a possible aggravating balance defect in the foot or pelvis. Patients responding poorly to conservative measures or who are subject to frequent attacks should be referred for surgical appraisal.

Traumatic Arthritis

Osteoarthritis of the knee is not always a sequel of aging degeneration; it is sometimes seen in the young athlete. Trauma usually initiates symptoms that began, often subclinically, after earlier trauma that was improperly managed or neglected (eg, inadequate mobilization and/or muscle re-education). Heavy weight bearing superimposed on a joint with microcirculation impairment, possibly of a reflex nature, and congenital defects are two other common predisposing factors. When seen in the elderly very obese patient, the articular cartilages may be too far destroyed to offer much help.

Traumatic Synovitis

Even mild trauma can produce extensive knee swelling if the alar folds of the synovial fringes are pinched between the tibial and femoral condyles. Movement quickly becomes limited and maintained in about 20° flexion (position of rest), pain is severe, and tenderness is acute. Swelling is less severe in complete rupture because the fluid is able to escape through the tear. Uncommon tears of the posterior capsule, characterized by extension instability, may produce painful swelling and bleeding into the popliteal fossa.

Knee Pain in Athletes from Ankle Distortion

Runners with a hyperpronated ankle (ipsilateral or bilateral) frequently report nonspecific medial knee pain. Weight bearing medially shifts the pronated foot, and these stresses transmit up the leg medially to the knee. Thus, internal tibial rotation is commonly associated with both hyperpronation and medial knee pain.

In contrast, lateral knee pain may result from iliotibial band or popliteal tendinitis. Ankle hyperpronation may predispose runners to these conditions. Internal tibial rotation related to overpronation excessively stretches involved fiber attachments. The result is iliotibial band tendinitis, popliteal tendinitis, or both. In addition, ankle hyperpronation often leads to a valgus deformity of the knee. This angulation results in an increased lateral pull of the patella during quadriceps contraction.

Cyst Development

Synovial cysts are frequent complications of knee trauma and various arthritides (especially rheumatoid). Long-standing posttraumatic effusion may be great enough to distend the semimembranosus gastrocnemius bursal complex in the popliteal area to produce Baker's cyst. A firm, mildly tender meniscal cyst may also occur, usually occurring on the anterolateral aspect of the knee and is nonfluctuating.

Intracapsular Pinches

Intracapsular pinches are common in sports than cartilage injuries. Sudden joint stress, usually rotational, may cause some soft tissue to be pinched within articular structures during jumping, defensive running, kicking, etc. This is frequently seen in the knee where the infrapatellar fat pad is nipped, resulting in some effusion and possibly hemorrhage.

Clinical Features. Diagnosis is essentially by exclusion. There is no history of external trauma, nor are there signs of joint line tenderness or instability. Discomfort is felt directly behind the patella. A slight effusion may be found that is associated with a slight loss in full extension. The sides of the patella and its tendon will feel thick and firm. This mass will be tender, and it will be the sole site of tenderness if ligament and fibrocartilage involvement are excluded.

Management. Treatment is the same as that for sprain, but active movement is slightly delayed because injured fat is slow to heal. In forming a prognosis, keep in mind that damaged fat is frequently replaced by inelastic fibrous tissue that is readily irritated by further stress. Cold packs, compression, and elevation should be continued as long as there is palpable thickening near the patella and any degree of extension restriction. Despite patient objections, no forceful activity should be permitted for 6--10 days.

Referral for surgery may be necessary if the superior portion of the tibia severs a large portion of the infrapatellar pad or if a tag later becomes calcified and causes trouble. Surgery is mandated in cases where a pedunculated part may become strangled by adhesions resulting in joint locking, hemarthrosis, and torsion gangrene.

Acute Bursitis

The term "housemaid's knee" refers to prepatellar bursitis. Fluctuation, with or without heat and tenderness, limited to the prepatellar space is usually diagnostic. Management of an acutely swollen bursa is not difficult if undertaken immediately. Cold packs, rest, some elevation, and a pressure bandage are usually adequate. On rare occasions, referral for aspiration and steroids may be necessary if swelling does not begin to subside within 24 hours. Graduated activity may start as soon as the acute phase has resolved.

Knee Effusion Test. If a joint is greatly swollen from major effusion, place the patient in a relaxed supine position. With the limb relaxed, slowly extend the involved knee. The patella is then pushed into the trochlear groove and released quickly. This forces fluid under the patella to the sides of the joint and then to return under the patella. This rebound effect is referred to as a ballottable patella. Minimal effusion, however, will not ballot the patella. In cases of mild effusion, it is necessary to "milk" the fluid from the suprapatellar pouch and lateral side to the medial side of the joint. Once the fluid has been moved medially, tapping over the fluid will return it to the lateral side. This is confirmatory.

Chronic Effusion

In chronic "water on the knee," the original trauma may not be remembered. The effect is from an inflamed synovial membrane of the knee with escape of fluid into a synovial sac. Causes include sharp trauma, repeated minor blunt or intrinsic trauma, lymphatic congestion, and atherosclerosis that may be associated with flat feet and/or genu valgum. The cause can sometimes be traced to psoas dysfunction from an anterior pelvic tilt and everted feet producing an increased torque at the knee. This disorder is not as common today as it was in past years when people scubbed floors or did other chores when on their knees.

Clinical Features. The presenting picture consists of prepatellar or infrapatellar bursitis with a locally inflamed knee. There is little pain except on motion, mild-to-extensive swelling, and obvious low quadriceps atrophy. Knee instability tests may not be strongly positive. There may be signs of inhibitions of the neuromuscular mechanisms of the knee and features of recurrent subluxation of the patella over the lateral condyle

Management. Standard regimens for chronic strain/sprain management and muscle re-education are usually sufficient. If not, referral for aspiration of fluid, steroids, and possibly antibiotics may be advisable. In competitive sports, there is no absolute cure as reaggravation can be anticipated. Swimming is beneficial during recuperation. Protection and compression must be provided during competitive activity until healing is secure. The duration is approximately one month. For the hypersensitive knee, standard padding is usually inadequate in contact sports.

Peripheral Nerve Lesions of the Knee Area

Peroneal Nerve Contusion. The peroneal nerve, a terminal branch of the sciatic nerve, is exposed to injury at the knee especially as it winds about the neck of the fibula. In addition to laceration, it is frequently injured in fracture of the neck of the fibula and occasionally by pressure of poorly padded athletic supports. A typical "foot drop" results.

Lust's Sign. When the external branch of the sciatic nerve (the peroneus communis) is struck with a percussion hammer, the reflex produces dorsal flexion and abduction of the foot. This is best accomplished by following the nerve below the bifurcation of the great sciatic nerve, especially in an oblique position outwardly along the outer portion of the popliteal space. This pathologic reflex indicates peroneal spasmophilia.

Pellegrini Stieda

Pellegrini stieda is a chronic disorder characterized by posttraumatic calcification and ossification of the medial collateral ligament of the knee. The physical features mimic chronic ligament overstress; eg, severe pain localized on the medial aspect of the knee, tenderness over the medial condyle of the distal femur, mild swelling, restricted range of knee motion, and difficulty ascending stairs.

Osteochondritis Dissecans (Osteochondral Fracture)

A bony defect of the articular margin of the femur at the lateral aspect of the medial condyle is called osteochondritis dissecans. This is, however, a misnomer in that it represents a form of compression fracture rather than a dissecting inflammatory lesion. It is frequently related to a history of sports-related trauma. It is essentially an affection of adolescence and young adults, rarely seen in middle age, and almost unknown in later life. It occurs frequently between the ages of 12 and 25, and males are more often affected than females in a ratio of 15:1. Usually one joint is affected, sometimes bilaterally; and 90% of the time it occurs in the knee. Elbow involvement is next in frequency.

Etiology. Osteochondritis dissecans occurs in the knee (or elbow) at the point of greatest impact; ie, the lateral portion of the surface of the internal condyle adjacent to the intercondylar notch. The exact cause is unknown, but there are many theories: traumatic, embolic, and constitutional. Most authorities feel that trauma is at least a predisposing agent if not the cause. Knee trauma may occur in three ways: (1) by direct force at the point of greatest contact; (2) by direct pull on the anterior attachment of the posterior ligament; and (3) by injury to the arterial supply. Fat embolism or bacterial embolism may also be involved. Aseptic necrosis due to embolism, low-grade bacterial infection, and congenital predisposition of the femoral epiphysis are other factors to be weighed.

Symptoms. The chief complaint is intermittent mild joint disability. There is usually a low-grade inflammatory process associated with slight effusion, swelling, and joint clicking or locking. Before fragment separation, the associated pain is dull and aching.

Wilson's Sign. The patient is placed supine with the legs in an extended, relaxed position. The knee of the involved side is flexed to a right angle, the leg is firmly rotated internally, and then the knee is slowly extended while maintaining the leg in internal rotation. If osteochondritis of the knee exists, the patient will complain of pain in front of the medial condyle of the distal femur. If the leg is then externally rotated, the pain will subside.

Roentgenography. Routine A-P and lateral films plus a tunnel-view projection are recommended. Whatever the cause, a somewhat crater-like, rarefied, and conical-shaped depression on the border of the condyle involving subchondral bone is characteristic. This may require months or years to develop. Giammarino reports the most frequent site of the lesion is in the medial femoral condyle near the intercondylar notch. On the surface of the condyle, a punched-out irregular triangular notch of varying size appears. The loose body or sequestra may be seen in the crater or within the joint space. If the body is not completely detached, it may be seen lying in the cavity and separated from the underlying bone by a clear line of demarcation. If detached, it appears as an oval shadow in the joint. If it is cartilaginous, it may not be visible. As a line of cleavage is formed, the cavity and loose body are covered with fibrocartilage, becoming rough and irregular. It later releases and falls into the joint cavity where it is ground into small fragments by body weight. The fragments may be small or large, round, oval, or irregular, and each fragment usually continues to increase in size.

Management. Mild mobilizing manipulation, traction, and various forms of physiotherapy to improve circulation, reduce pain and swelling, and enhance healing will usually ameliorate the symptoms. Mechanical traumatic arthrosis may result if a joint "mouse" repeatedly sets up irritation. As in Perthe's disease, revascularization of an undisplaced fragment in osteochondrosis dissecans of the knee in children appears to progress with reasonable rapidity in some cases provided the joint is protected from bearing injurious weight for about 6 months.

If a fragment is caught and unable to be dislodged or if a loose body is within the joint, surgical consultation should be considered. In spite of symptom absence, some authorities advise surgery to prevent osteoarthritis. Surgery is normally reserved only for those cases in which clinical and roentgenographic improvement cannot be demonstrated or if displacement occurs repeatedly.



KNEE MOTION RESTRICTIONS

Femorotibial Fixations

Releasing Restricted Distraction (Joint Separation). With the patient prone, stand perpendicular to the involved knee. Flex the patient's knee to a right angle, place your cephalad knee gently in the patient's popliteal space to stabilize the patient's femur, grasp the patient's leg distally (above the ankle) with both hands, and apply a short, sharp upward pulling force directed through the vertical axis of the tibia.

Evaluating A-P Glide. To judge A-P motion glide of the knee, sit at the foot of the table obliquely facing the supine patient, flex the involved knee to approximately 45° , grasp the proximal aspect of the patient's leg with both hands (thumbs pointing upward and fingers interlocking at the posterior), and apply pressure posteriorly and anteriorly in a rocking motion. This is the same position used to elicit a drawer sign. It usually helps to stabilize the patient's leg by placing the toes of the foot of the involved limb slightly under your cephalad thigh. Normal joint play will be perceived as a slight but distinct motion (about 1/8 inch) and is best felt when the knee is in midflexion. Weak or torn tissues should be suspected if A-P glide is felt during full flexion or extension.

Releasing Restricted Posterior Glide. If the posterior glide of the femur on the tibia is restricted, place the patient supine. Insert about 2 inches of toweling under the distal aspect of the patient's femur. On the side of involvement, stand perpendicular to the patient's knee, grasp the anterior surface of the patient's thigh just above the patella with your cephalad hand, place the heel of your caudad (active) hand on the anterior surface of the patient's tibia (just below the patella), apply pressure, and administer a short moderate thrust.

Releasing Restricted Anterior Glide. With the patient supine, flex the involved hip and knee so the plantar surface of the foot rests firmly on the table. Sit on the table, obliquely facing the patient, so your cephalad thigh rests lightly against the patient's foot for stabilization. Grasp the patient's knee (proximal tibia and fibula) with both hands as to elicit a drawer sign, apply a pulling force directed toward your sternum, hold the traction for several seconds, and conclude by administering a short dynamic pull.

Another method to release anterior glide restriction is the reverse of the technic described above to release posterior glide restrictions. With the patient prone, insert about 2 inches of toweling under the distal aspect of the patient's femur. On the side of involvement, stand perpendicular to the patient's knee, grasp the posterior surface of the patient's thigh just above the popliteal space with your cephalad hand, place the heel of your caudad (active) hand on the posterior surface of the patient's tibia (just below the popliteal space), apply pressure and administer a short moderate thrust.

A common home therapy is to have the sitting or supine patient bring the involved flexed knee toward the abdomen after inserting a rolled towel against the popliteal space, grasp the anterior surface of the leg distally with both hands, and apply firm painless pressure (directed toward the buttock) several times.

Evaluating Restricted Rotation. To appraise the rotory ability of the knee, place the patient supine, stand perpendicular to the involved limb, and flex the patient's knee and hip to approximately 45° . Grasp the patient's knee with your cephalad (stabilizing) hand and just above the patient's ankle with your caudad (active) hand. In this position with the patient fully relaxed, rotate the patient's leg clockwise and counterclockwise with your active hand by supinating and pronating your forearm. Slight motion should be felt that will normally be absent in full knee flexion or extension if the integrity of the ligaments of the knee and tendons of the quadriceps is intact.

Releasing Restricted Rotation. With the doctor-patient positions the same as during evaluation, apply clockwise or counterclockwise pressure (according to the restriction), hold the pressure for several seconds, and conclude with a firm shallow twist to free the motion.

Evaluating Restricted Lateral Tilt. To test lateral tilt (outside opening) of the knee, the doctor-patient positions remain the same as described above but pressure of the contact hand is applied from the medial to the lateral to open the lateral aspect of the femorotibial joint. If joint motion is restricted at its lateral aspect, normal lateral tilt will be lost. If the lateral ligaments are torn, exaggerated motion will be perceived. It will also be felt when the knee is fully extended.

Releasing Restricted Lateral Tilt. Place the patient supine, stand on the side of involvement obliquely facing the patient so that you can flex the patient's hip and knee to a right angle. Place your stabilizing cephalad hand on the patient's flexed knee, and reach around and under the patient's leg so your caudad palm can support the proximal aspect of the patient's leg. The patient's leg should rest on your caudad forearm and hip. While holding the patient's leg distally by elbow pressure, slowly adduct the patient's leg by shifting your trunk medially over the table. This will place a lateral stretch on the patient's knee. Once tension is achieved, apply a shallow thrust with your caudad hand directed laterally. The application of a temporary wedge (1/8--1/4 inch) to the patient's shoe medially may be helpful in stretching chronic lateral restrictions.

Evaluating Restricted Medial Tilt. To evaluate medial tilt (inside opening) of the knee, stand perpendicular on the side of involvement of the supine patient. Grasp the anterior surface of the patient's leg distally on the involved side for stabilization with your caudad hand, and place the supinated heel of your cephalad hand against the lateral aspect of the patient's knee, just above the joint line (over the lateral femoral condyle). The fingers of your active hand (cephalad) should be curled under the knee against the popliteal space. As there is almost no perceptible femorotibial sideward tilt or rotational joint play when the knee is fully extended (locked) and the ligaments are intact, flex the patient's knee slightly by raising it 3--4 inches with your contact hand, and apply lateral to medial pressure. This should elicit slight opening (about 1/8 inch) of the medial aspect of the femorotibial joint. If joint motion is restricted medially, medial tilt will be nonexistent. If the medial ligaments are torn or the vastus medialis muscle is extremely weak, exaggerated motion will be perceived. This will also be felt when the knee is fully extended. Atrophy of the vastus medialis is an early sign in many knee disorders and articular derangements.

Releasing Restricted Medial Tilt. Place the patient supine, stand on the side of involvement obliquely facing the patient so that you can flex the patient's hip and knee to a right angle. Place your stabilizing cephalad hand on the patient's flexed knee, and reach around and under the patient's leg so your caudad palm can support the proximal aspect of the patient's leg. The patient's leg should rest on your caudad forearm and hip. While holding the patient's leg distally by elbow pressure, slowly abduct the patient's leg by shifting your trunk laterally away from the table. This will place a medial stretch upon the patient's knee. Once tension is achieved, apply a shallow thrust with your caudad hand directed medially. The application of a temporary wedge (1/8--1/4 inch) to the patient's shoe laterally may be helpful in stretching medial restriction.

Proximal Tibiofibular Fixations

Mennell states that the only joint-play movement at the tibiofibular joint is A-P glide: maximum at knee midflexion, minimal at full knee extension. Gillet reported that superior tibiofibular fixation is quite common. The joint between the proximal heads of the tibia and fibula normally opens slightly when the foot is inverted. This gap can be palpated just inferolateral to the patellar tendon. In addition, the head of the fibula will shift slightly cephalad when the foot is actively dorsiflexed. These movements will not be felt if the joint is locked. Gillet believed fixation at this joint is often linked to an L5 or sacral subluxation.

Evaluating Tibiofibular A-P Glide. To judge this motion, sit at the foot of the table obliquely facing the supine patient as if you were to evaluate A-P glide of the femorotibial joint. With your lateral active hand, grasp the head of the patient's fibula between your thumb anteriorly and the tips of your index and middle fingers posteriorly. Your medial hand can be used to stabilize the proximal aspect of the patient's tibia. In this position, use your active hand contact to pull the head of the patient's fibula forward and then push it backward to appraise A-P glide motion.

Releasing Restricted Tibiofibular A-P Glide. With doctor and patient remaining in the examination position, mobilization is made by applying pressure for several seconds and then a slight thrust against the resistance.


TIBIAL SUBLUXATIONS

All signs of tibial and fibular subluxations are usually subtle. They require a trained kinesthetic sense during dynamic and static palpation to determine.

When a subluxation exists between the distal femur and the proximal tibia, the malpositioning may be attributed to either the femur or the tibia. The tibia has been elected in the following descriptions, but the reader should realize that this has been an arbitrary decision. Thus, a listing for an externally rotated tibia may be described by another writer as an internally rotated femur, for example. A lateral tibia subluxation may be rightfully described as a medial femur subluxation. Keep in mind that bones do not subluxate, articulations do.

Because the articulation between the femur and tibia is so complex, an array of subluxation possibilities exists. The tibia may be translated solely in one direction; eg, medially, laterally, posteriorly, anteriorly, or diagonally relative to the femur. In addition, rotary instability may produce a displacement in the anteromedial, anterolateral, posteromedial, or posterolateral direction. Therefore, astute evaluation of these displacement possibilities and the integrity of the associated soft tissues must be made before an efficient corrective adjustment can be applied.

Anterior Tibia Subluxation

The major features of anterior tibial subluxation include patellar tendon tenderness, an anterior drawer sign, anterior cruciate tenderness, patellar tendon hypertonicity or tendinitis, and restricted posterior tibial motion. The history often reveals a blow to the back of the upper leg or falling backward over a low obstacle.

Adjustment. Place the patient supine, and stand on the side of involvement. Apply contact with your cephalad hand against the proximal anterior aspect of the patient's tibia. Place your caudad hand under the patient's calf to support the weight of the leg and to apply traction during the adjustment. As traction is applied, simultaneously make a short A-P thrust to correct the malposition.

Posterior Tibia Subluxation

Physical indications include popliteal fossa tenderness, posterior cruciate ligament tenderness, posterior drawer sign, patella tendon hypotonicity and depression, and restricted anterior tibia motion. A history of high anterior tibial trauma is usually involved.

Adjustment. Place the patient prone with the involved knee flexed 70° . Squat at the end of the table, and place the patient's involved leg against your medial shoulder. Interlock both hands on the posterior aspect of the tibial condyles. Apply traction and simultaneously deliver a fairly strong thrust directed to bring the tibia anteriorly, correcting the malposition.

Lateral Tibia Subluxation

Lateral tibia subluxation is often consequent to lateral collateral ligament sprain with restricted medial motion. A history of trauma to the medial aspect of the upper tibia is frequently associated.

Adjustment. Place the patient supine with the involved knee extended and the ipsilateral hip flexed about 40° . Stand on the side of involvement, and place your cephalad contact palm against the upper-lateral aspect of the patient's tibia. A pisiform contact is applied against the lateral aspect of the tibial condyle. Wrap your caudad hand under the patient's calf to support the weight of the patient's leg. Slightly flex the patient's knee, apply traction to the leg, and simultaneously make a short thrust directed from the lateral to the medial to correct the malposition.

Medial Tibia Subluxation

Medial tibial subluxation is frequently consequent to medial collateral ligament sprain with restricted lateral motion. A history of trauma to the lateral upper aspect of the tibia is usually reported.

Adjustment. Place the patient supine with the involved knee extended and the ipsilateral hip flexed about 45° . Stand on the side opposite to involvement, and place your cephalad contact palm against the upper medial aspect of the patient's tibia. A pisiform contact is applied against the medial aspect of the tibial condyle. Wrap your caudad hand under the patient's calf to support the weight of the patient's leg. Slightly flex the patient's knee, apply traction to the leg, and simultaneously make a short thrust directed from the medial to the lateral to correct the malposition.

Externally Rotated Tibia Subluxation

The physical features of an externally rotated tibia are medial capsular pain and tenderness, genu valgum, a prominent medial tibial condyle and plateau, tightness of the pes anserine tendons, chondromalacia patellae, and restricted internal tibial rotation.

Patient Prone Adjustmen t. Place the patient prone with the involved knee flexed about 70° . Stand at the side of the involved tibia, and set your cephalad knee on the distal aspect of the patient's femur to stabilize the patient's knee against the table. Grasp the patient's distal tibia and fibula with your fingers interlocking on the anterior aspect. Apply upward traction to the leg, and then make a firm but gentle internal rotation maneuver of the leg to correct the malposition.

Patient Supine Adjustment. Place the patient supine, and stand on the side of involvement facing the patient. Place your medial foot upon the table. It sometimes helps to place your knee against a pad in the patient's popliteal space for countertraction. Next, place the patient's leg against your hip for stabilization. Your medial hand grasps the anterior surface of the patient's leg just above the ankle, and your lateral hand is moved under the patient's leg so you can grasp your medial forearm. The patient's leg rests within your cubital fossa for support. Apply traction to the leg while simultaneously manipulating the leg into internal rotation to correct the malposition.

Alternative Patient Supine Adjustment Procedure. Stand on the side of involvement of the supine patient. The patient's hip should be flexed about 60° with the knee flexed about 110° . Grasp the patient's lower leg with your medial contact hand, and place your lateral hand on the patient's knee to stabilize the patella. The adjustment is made in this position by flexing and internally rotating the patient's leg to correct the malposition.

Internally Rotated Tibia Subluxation

The typical physical features of an internally rotated tibia are lateral capsular pain and tenderness, genu varum, a prominent lateral tibial condyle and plateau, tightness of the iliotibial band and lateral hamstring tendons, chondromalacia patellae, and restricted external tibial rotation.

Patient Prone Adjustment Procedure. Place the patient prone with the involved knee flexed about 70° . Stand facing away from the patient at the side of the table, opposite to the involved tibia, and place your medial knee on the distal aspect of the patient's involved femur for stabilization. Grasp the distal aspect of the patient's tibia and fibula, with your fingers interlocking on the anterior aspect. Apply upward traction to the leg, and make the adjustment by externally rotating the patient's leg to correct the malposition.

Patient Supine Adjustment Procedure. Place the patient supine, and stand on the side of involvement facing the patient. Place your medial foot on the table, and put the patient's ankle in your axilla. Your lateral hand should grasp the anterior surface of the patient's leg just above the ankle. Your medial hand is moved under the patient's leg so you can grasp your arm laterally. The patient's leg rests within your cubital fossa medially for support. Apply traction to the leg while simultaneously manipulating the leg into external rotation to correct the malposition.


FIBULAR SUBLUXATIONS

Superior Fibula Subluxation

A superior fibula subluxation often follows eversion sprain of the ankle. Typical features include tenderness about the fibular collateral ligament due to jamming, restricted inferior fibula joint play, and possibly a slight foot-drop sign.

Adjustment. Place the patient supine with knee extended and hip flexed at about 45° . Stand at the end of the table with the patient's foot placed on the anterior aspect of your thigh. Grasp the patient's ankle with your lateral hand, and take a web or capitate contact at the proximal aspect of the lateral malleolus. With your medial hand, overlap the wrist of your contact hand for stability. Apply traction, and simultaneously make a short inferiorly directed thrust to correct the malposition.

Inferior Fibula Subluxation

An inferior fibula subluxation can be the result of inversion ankle sprain and is often associated with tenderness about the collateral ligament of the fibula and restricted superior fibula joint play.

Adjustment. Place the patient in the lateral recumbent position with the affected side upward and the medial aspect of the affected foot resting relaxed on the table. Stand at the foot of the table in line with the longitudinal axis of the patient's affected leg. Apply a capitate contact with your medial hand against the inferior aspect of the lateral malleolus, with your lateral hand grasping your contact wrist for stability. Apply pressure, and simultaneously make a short thrust directed superiorly along the vertical axis of the fibula to correct the malposition.

Anterolateral Fibula Subluxation

An anterolateral fibula subluxation is often the result of lateral hamstring strain, eversion ankle sprain, or trauma to the posterolateral aspect of the knee. It is characterized by lateral hamstring tendon tenderness, genu varum, excessive ankle pronation, and restricted posteromedial fibula motion.

Adjustment. Place the patient prone with the involved knee flexed. Squat at the end of the table (facing the patient) so that the patient's leg can rest on your shoulder for stability. Grasp the involved leg and interlace your fingers around the posterior aspect of the patient's leg proximally. Direct a pisiform contact with your cephalad hand against the anterolateral aspect of the fibular head. Apply traction, and simultaneously rotate the fibula posteromedially to correct the malposition.

Posteromedial Fibula Subluxation

A posteromedial subluxation of the fibula often follows inversion ankle sprain, violent hamstring pull, trauma to the anterolateral knee, and genu valgum. Abnormal anterolateral fibula joint play is usually associated.

Adjustment. Place the patient prone with the involved leg flexed. Squat at the end of the table (facing the patient) so that the patient's leg rests on your shoulder for stability. Grasp the involved leg and interlace your fingers around the posterior aspect of the patient's leg proximally. Apply a specific pisiform contact with your lateral hand against the medial aspect of the involved fibular head. Apply traction, and simultaneously rotate the fibula impulsively anterolaterally to correct the malposition.

Posteroinferior Fibula Subluxation

The typical physical features of a posteroinferior subluxation of the fibula include pain at the fibula head, lateral collateral ligament pain at the ankle, lateral hamstring complaints, and restricted anterosuperior fibula joint play. This subluxation is often the result of inversion ankle sprain.

Adjustment. Place the patient supine with the affected knee flexed. Stand lateral to the involved limb with your cephalad hand within the popliteal fossa. Apply a thenar-pad contact against the fibular head. For leverage, grasp the anterior aspect of the patient's lower leg with your caudad hand. Apply oblique pressure with your stabilizing hand to flex the knee and push the leg superiorly, while simultaneously briskly lifting the fibular head anteriorly with your contact hand to make the correction.

PATELLA DISORDERS

Patella Dysfunction

Rupture or inflammation of the patella tendon, quadriceps rupture or tendinitis, and fatigue fracture of the tibia have a high incidence of injury. In tendinitis, the pain may be perceived either during and shortly after activity or be chronic. Forceful jumping may result in an avulsion fracture of the patella.

Patella Apprehension Sign. The patella normally displaces laterally with vigorous quadriceps contraction. When a person strongly extends the knee with the leg externally rotated, the patella may dislocate and lock if its attachments are weak. In testing, place the patient in the relaxed neutral supine position and apply increasing pressure against the patella. If a chronic weakness exists, the patient will become increasingly apprehensive as the patella begins to dislocate.

Dreyer's Sign. Place the patient supine with the legs extended in the relaxed position, then ask the patient to raise the involved thigh while keeping the knee extended. If the patient is unable to do this, grasp the large quadriceps tendon just above the knee to anchor it against the femur and ask the patient to try to lift the limb again. If the patient is able to lift the limb when the quadriceps tendon is stabilized, a fractured patella should be suspected because the rectus femoris (a primary hip flexor) tendon attaches to the patella.

Patella Tendon S