Adolescent Idiopathic Scoliosis

Adolescent Idiopathic Scoliosis

This section is compiled by Frank M. Painter, D.C.
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By Dr. Diane Benizzi DiMarco

Due to the close association of spinal maturity with lateral spinal curve progression, adolescent idiopathic scoliosis represents a sensitive topic for those treating females who have entered menarche or will be soon.

A lateral bending of the spine, adolescent idiopathic scoliosis can present with a lateral and rotary deformity. Spinal curvatures can be the result of varied factors including; muscle diseases or spasms, neurological disease, diseases of the CNS or PNS, congenital vertebral deformities, leg length inequalities, tumors, pain, injury and degenerative spinal arthrosis. The most common cause of scoliosis, adolescent idiopathic scoliosis, accounts for approximately 80% of all diagnosed scoliosis cases. [1] Females are affected at a rate of 9:1. Idiopathic scoliosis, juvenile and adolescent affect females ages three to ten years of age and ten years to skeletal maturity, respectively. [2,3]

Theorists have included several possible causes and risk associated factors that may predispose females to adolescent idiopathic scoliosis. Possible explanations include genetic predisposition, leg length inequalities, curve type, menarche, and the slenderness of the female spine, and skeletal maturity.

The true pathogenesis of adolescent idiopathic scoliosis is vague. Speculations exist, pronouncing discogenic complications not only as a cause for further insult to curve deformities, but some have actually speculated on it as the culprit. [4] Disruptions in the disc material could solidify the development of a structural scoliosis from a functional scoliosis remain.[4] Some authors attribute scoliosis deformations to abnormal, chronic and continue forces on the intervertebral disc and its components as the true cause of scoliosis development. Taylor et al. and Tueta purport this theory. Taylor et al concluded that the nucleus pulposus of a rabbit disc is the transitional zone as in a growth plate, and that it too is subject to physical forces altering its natural growth. [4,5] Disc material, as analyzed through dissection and tissue analysis, has shown alterations in its collagen and glycosaminoglycans in a scoliotic spine. Fibrocartilage matrixes have been identified in tendonous tissue when exposed to compressive forces. [4] Aspegren and Cox propose a similar phenomenon within the disc. This would account for the increase collagen formation in the nucleus pulposus found in-patients with adolescent idiopathic scoliosis.[4,6] Noted changes identified where most pronounced at the apex of the curve and lessened outwardly.[4] Pedrini et al identified decreases in chodroitant-6-sulfate, Chondroitant-4-sulfate, and glycosaminoglycans with the nucleus pulposus of those patients with idiopathic adolescent scoliosis. [6]

The intervertebral disc, as reported by Taylor et al, consists of three separate but intimately related portions of connective tissue; the nucleus polpolsus, the annulus fibrosus and the cartilaginous endplates. The combination of which is unique and essential for normal spinal growth. Taylor and his associate, Colletti included unpublished findings identifying the transition zone of the intervertebral disc as an ill-defined junction between the nucleus pulposus and the annulus fibrosus, which behaves as a growth plate. Unlike the epiphyseal growth plate, it is sensitive to physical forces, chemical and hormonal substances during growth. [5]

Alterations of the intervertebral disc composition causes it to weaken, thereby predisposing it to compositional breakdown. The ability of the disc to withstand torsion and compressive forces becomes compromised eventuating the inevitable breakdown of tissue integrity. Patients with lateral and rotary deviated spines have an obvious disparity in weight distribution. Excessive and prolonged axial compression along the concavity occurs, while continued the disc material along the convexity endures stretching. Eventually the disc integrity is compromised, as is its ability to appropriate proper biomechanical function, and lateral deformation increases. [1,4,5,7]

Risk Factors for Developing AIS

The most widely known and accepted risk factors for adolescent idiopathic scoliosis are gender, skeletal maturity and heredity. [2-4,8,9]. Female incidence registers at 9:1, [2,9] with those who are pre-menarche at an even higher risk. In his review of literature, Emans documented data reported by Clarisse, which declared that risk progression in adolescent idiopathic scoliosis is much greater in premenarche girls. [3] Typically found with the onset of adolescent idiopathic scoliosis is the appearance of a small curve (most commonly right thoracic or right thoraco-lumbar) around the time of puberty. As menarche indicates the transition into adulthood it too represents the gradually slowing of growth. Adolescent women, who have attained menarche, soon thereafter report developmental maturity. Associated with this is skeletal maturity. Beyond menarche, skeletal growth is severely slowed, then stopped. Once menarche is reached, progression of a scoliotic curve becomes more predictable as menarche greatly influences the course of the curve. Some theorists have even used the cornerstone of menarche as a safeguard indicator to progression.

Identifying curves that are at a higher risk aids in formulating a treatment protocol. Emans declares that some patients that have reached puberty and have been diagnosed with a mild curve, have not progressed. Conversely those patients who are premerchal remain at high risk for progression. [3] It should be noted that though this population represents a group that needs to be closely monitored, there have been reports of spontaneous remission. [1] Premenarchal females retain risk of progression if diagnosed with curves beyond ten degrees and definitely beyond twenty degrees. Mild curves, those less than twenty degrees, have a greater chance of not progressing or slowed progression once skeletal maturity is reached. Skeletal maturity, identified radiographically, occurs post-menarche. Curves that measure between thirty and up to fifty degrees are those that pose the most threat for progression and development of cardiovascular and cardiopulmonary problems.

Adolescent females who have a family history of scoliosis are much more vulnerable to developing lateral spinal deformities. Familial predisposition reaches beyond the maternal and paternal bonds. Persons with kinship within the family line retain the risk associated with hereditary development of scoliosis though, reports do indicate an inverse relationship with a family member who is further removed. [1,3,9] Danbert reported data indicating a 25-33% recurrence among relatives, stating that the first-degree relatives are 3-4 times that for those whose parents were not affected by scoliosis. Authors also indicate up to a 40% occurrence when both parents are affected. [9]

Anatomical leg length inequalities that go uncorrected impart biomechanical aberrations throughout the spine. Through the righting reflex the body attempts to remain visually balanced. To attain this with an anatomical leg inequality, compensatory lateral deformities develop in the spine. Though the concept of leg inequality remains speculative in the contribution of adolescent idiopathic scoliosis, Specht and De Boer reported data supporting the association between leg length inequality and scoliosis. [10]. Participants of the study were radiographically analyzed. Subjects who measured a leg length inequality of 6mm or more on reontrogram often had scoliosis and/or abnormal lordodic curves. Authors concluded that evidence predominately supported spinal adaptation occurring relative to unequal anatomic leg lengths. Specht and De Boer also reported findings from Friberg that concluded a significant correlation between scoliosis spinal deformities and leg length inequality. [10]

Several authors do confer that spinal adaptations are inevitable with unequal leg lengths. The major adaptations are reported to occur are pelvic obliquity, scoliosis and hyper or hypolordosis. [10]. Nykoliation et al suggested that clinical evaluation assessing leg length inequality be done as a mandatory part of postural assessment. [1]

Diagnosis and Curve Monitoring

Diagnosis of adolescent idiopathic scoliosis can be accomplished through parents who may accidentally notice a spinal deviation, school mandated screenings, chiropractors and osteopaths, and orthopedic doctors. Radiographs provide an invaluable diagnostic tool once a spinal deviation is identified. Confirmation of a spinal deviation on radiographs will illuminate the spinal curve and its’ curve angle. This assists the clinician in accurately defining the curve angle and its’ progression on subsequent exams.

Thorough examinations for adolescent idiopathic scoliosis should include a postural analysis. Plumbline analysis can aid in determining scoliosis. During the plumbline analysis, in addition to evaluating for spinal curvature, the clinician should check for scapula height, rib humping, and iliac crest heights. Before concluding the exam it is recommended to have the patient perform the Adams test. The patient, who initially stands erect as the spine is examined, then forward flex. A patient who demonstrates a spinal deviation while standing that does not remiss is deemed to have a structural scoliosis. Rib humping can be identified at this time.

The screening process for adolescent idiopathic scoliosis has since 1999 been the primary forum for initial evaluation. Mandated in twenty-six states it has proven to be a valuable source. School based screening, usually performed by a school nurse, is a fortifiable process for mass screening. Their training in biomechanics, kinesiology and posture analysis is limited. Due to their extensive training, chiropractors offer patients a reliable resource for adolescent women to receive a thorough, private exam. School based screenings may perpetuate a young woman’s’ fears of self-consciousness. Adolescence is a very sensitive time for most young women. As puberty imparts hormonal changes the body begins to transform into a more female physique. Breast development and menarche can cause an adolescent female to be very sensitive about her out-ward appearance. In office scoliosis exams are strongly recommended for this patient group.

Radiographs for Diagnosis and Monitoring

Diagnosis and future monitoring help appropriate treatment interventions. Radiographic diagnostic imaging augments the ability to define the initial curve value and assess its progress accurately. Radiographic exam has been described as the single most important and definitive tool for diagnosis, assessment, and management of scoliosis. [2-4,11,12] Radiographs provide information regarding etiology, region and severity and magnitude of both the primary and secondary (if one is present) curve, it helps assess the flexibility of the curve, monitor the progression or regression and therefore treatment protocol. Skeletal maturity is also assessed through radiographic evaluation. This too provides direction for appropriate treatment protocols.

Radiographic evaluations are implemented through the course of treatment in determining developmental complications resulting from spinal deformations. Chest views provide cardiac and pulmonary information; contrast exams, for example, a myelography, is used to evaluate spinal cord integrity. Special views, such as flexion-extension views, assist the clinician in determining saggital mobility of the curve; supine radiographs aid in evaluation of spinal flexibility. [1-4,11,12,]

Mensuration of the lateral and rotary components of the curve are essential for initial and subsequent radiological evaluations. Several methods are available to assess the lateral curve angle with the Cobb technique being the most accepted due to its ease in reproducibility between practitioners and its ease of application. [2] A caveat to the evaluating doctor is to be consistent regarding measuring techniques. The method used on initial evaluation should be the method throughout.

The Cobb-Lippman method and Risser-Ferguson method are the primary techniques. As mentioned previously Cobb angles are the most frequently used. [2] Other measurements essential in determining the severity of the scoliosis include the Spinous Method and the Pedicle Method. Both are used to asses rotation, and lateral bending to determine the flexibility of the scoliosis. Continuity in assessment technique is paramount. It provides increased accuracy in reporting necessary for monitoring curve progression. Cobb method of mensuration requires that the most superior and inferior vertebrae of the curve be identified. Subsequent measurements require that the same vertebrae be used. The Risser-Ferguson technique requires that each end vertebrae be located as well as locating the apical vertebrae. [2]

Measurement values are then compartmentalized into the appropriate numerical category. Each category aids in determining the appropriate method of treatment intervention and to evaluate curve progression status. Cobb angle values are compartmentalized into seven categories called groups. Group 1 is for angles measured at 0 to 20degrees; Group 2, 21 to 30 degrees; Group 3, 31-50 degrees; Group 4, 51 to 75 degrees; Group 5, 76 to 100 degrees: Group 6, 101 to 125 degrees; and Group 7, 126 degrees and above. Values for the groups are taken directly from Yochum and Rowe, Essential of Skeletal Radiology. [2]

Vertebral rotation, according to Yochum and Rowe is " invariably present in scoliosis and is intimately associated with the degree of external cosmetic deformity…" The degree of rotational deviation is primarily evaluated based on pedicular position. The Pedicle method assesses the pedicle position of the apical vertebra on the convex side of the curve. Movement is graded on a scale of 0 to 4, whereby 0 represents no rotation and 4 represents maximal rotation. [2]

Flexibility of the scoliotic curve is another means by which to evaluate the severity of the curve, potential for progression, and treatment intervention. Yochum and Rowe suggest that the evaluation process commence with a radiological exam of patient supine and laterally flexed into the convex side of the deformity. The Cobb method is used to obtain a value. A direct relationship exists between Cobb values for flexibility and risk progression. This measurement may also indicate the probability of spinal fusion. Risser comments that as the patient gets older, flexibility normally decreases, possibly ankylosing can result. Risser also suggests that the deformity present on reontrogram between standing and recumbent gradually conform to where the recumbent deformity appears equal to that of the standing deformity. [11]

Evaluating Skeletal Maturity

Evaluating skeletal maturity or immaturity represents the probability for predicting progression or arrest of the scoliosis development. The pathogenesis of scoliosis increases in its’ progression during the years of skeletal growth and premenarche. [1-4,11]

Studies conclude that the most rapid progression occurs between the ages of twelve and sixteen years. [1-4,11] Emans declares that "…Risk of progression in adolescent idiopathic scoliosis is much greater in premenarche girls and in curves over twenty degrees. Slow progression of the curve occurs until the rapid acceleration of growth just prior to the onset of menses. The average cessation of spinal growth in girls is approximately sixteen or three years after the onset of menses but varies among individuals…At the end of skeletal growth the tendency for rapid progression of adolescent idiopathic scoliosis stops." [3]

Methods for evaluating skeletal maturity declare proper diagnosis, prognosis and treatment approaches for AIS patients. Three accepted methods for observation include radiographs of the iliac epiphysis, the vertebral ring epiphysis and comparison of the left hand to the Greulich and Pyle atlas. Risser purports the iliac crest epiphysis as the most accurate and reliable method in determining skeletal growth. [11]

Closure of the iliac crest and vertebral ring epiphysis indicate skeletal maturity has been reached. Prior to closure, these two epiphyseal growth plates are monitored through stages, until closure is complete. Each stage correlates to the skeletal growth that has been achieved and is yet to be achieved. Yochum and Rowe declare the vertebral ring epiphysis as the strongest indicator for skeletal maturity. Though Risser denotes an almost simultaneous development between the iliac apophysis and the vertebral growth plates, Risser declares that the completed ossification of the iliac apophysis as determinant of closure of the vertebral ring epiphysis. Risser cautions that observation of closure of the line between the apophysis and the ilium should not be deemed conclusive, that in fact, focus should directed on the lateral and anterior iliac crest. Risser points out that growth begins at the anterior and lateral iliac crest and continues, medially and posteriorly, and is deemed complete once ossification is visualized at the junction of the sacrum. [11] The average age for iliac apophysis fusion for females is approximately fourteen years. Risser views the iliac apophysis as the most reliable indicator for growth completion due to the difficulty in evaluating the vertebral growth plate on reontrogram.

Once spinal maturation has been achieved, risk of curve progression declines dramatically. Structural changes eminent with scoliosis can then create irreversible changes. Scoliotic deformities cause aberrant distributions of biokineomatic movements and weight distributions. Motion and pressure of the spinal segment become compromised. The Heuter- Volkmann epiphyseal rule states that excessive pressure on the bone retards bone growth, when pressure is diminished, bone growth accelerates. [2-4,11] Application of this principle to lateral spinal deformities perpetuates and further exacerbates structural changes to the spine. Since the principle applies to the epiphyseal growth centers, irreversible vertebral deformities can occur. Vertebral bodies on the convex side of the curve no longer remain parallel to those on the concavity. [2,11]

The vertebral bodies located at the apex of the curve become wedged permanently. These secondary changes eventually lead to painful degenerative spinal arthrosis during adult years. Although lateral and rotary changes customary to scoliosis are frequently asymptomatic in the early stages, progressive and destructive adaptations eventually present in chronic back pain. Myalgia from paraspinal muscles that have become fatigued and exposed to microtrauma, exacerbate an already painful condition.

Non-surgical treatment protocols are primarily focused on risk of curve progression, and limiting curve progression. Curve values, as measured based on Cobbs’ method are the primary indicators for treatment intervention. Standard treatment for patients with curves measuring less than twenty degrees usually requires no immediate intervention. These patients should be monitored closely for slow progression. Patients with five degress or more within a three month period, bracing is recommended. [2,3,11]. Patients who are skeletally mature can anticipate no further curve progression. [3] Degenerative changes are not considered at the evaluative stage. Curves with Cobb values of 20-40 degrees should be evaluated for bracing. Other findings that strongly support brace therapy include; those skeletally immature, curves displaying flexibility, a curve exhibiting signs of rapid progression. [1-4,11] Authors also suggest bracing for curves displaying rib humping on the convex side of the curve and for those curves positive for rotation. The Milwlkee brace appears to be the standard brace used at this time.Yochum and Rowe recommend gradual weaning of patients who have attained skeletal maturity of the brace. Curves of 40 degrees or more require more aggressive intervention. Surgery may be necessary at this junction but at a minimum is recommended to be concidered. The Dwyer procedure of wires and screws and the Harrington rods are the most common types of surgical intervention used.

Non traditional healing methods are emphatically encourage for all patients diagnosed with scoliosis. Therapies such as electric stimulation, manipulative and adjustive procedures and an exercise program can help attain the most comprehensive clinical outcomes. Recommendations for counseling can also be implemented. Ideally patients who corral all therapies into their treatment protocol may experience less deformity, improved psychological health, decreased pain and a decrease in degenerative changes.


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