Arthrokinematics
Basic Functional Anatomy of the Thumb and Fingers
The Thumb
The Fingers
Thumb and Finger Motion
Thumb Motion
Thumb Kinesiology and Strength
Finger Motion
Finger Kinesiology and Strength
Finger Biomechanics
Commentary
Contusions and Lacerations
Fistfighter's Knuckle
Karate Lump
Aneurysms of the Hand
Tests for Damaged Tendons
Finger and Thumb Strains
Contractures
Dupuytren's Contracture
Volkmann's Ischemic Contracture
of the Hand
Finger Sprains
Metacarpophalangeal and Inter-
phalangeal Sprains
Boutonniere Deformity
Mallet (Baseball) Finger
Tenosynovitis
Tenosynovitis of the Extensor
Carpi Radialis
Suppurative Tenosynovitis
De Quervain's Disease
Trigger Finger
Thumb Sprains
Video Thumb
Bowler's Thumb
Skier's Thumb
Management
Articular Therapy
Subluxations and Simple Articular Displacements
Significant Features
General Management Direction
Adjustment Technics
Metacarpal Base Posterior Subluxation
Thumb Dislocations
Structural Fixations in the Hands
Posttraumatic Exercise
The hand is the least protected and most active part of the upper
extremity. Thus, it is easily injured. Aside from vulnerability to trauma, the
hand often discloses important clues to remote and systemic disorders.
Extension. Thumb extension is provided essentially by
the extensor
pollicis brevis (C7-C8) at the metacarpophalangeal joint and the
extensor pollicis longus (C7-C8) at the interphalangeal joint. Test
strength by stabilizing the patient's wrist and having the patient extend the
thumb as far as possible. Apply increasing flexion resistance and record
degree. The major muscles of the thumb are shown in Table 3.
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 in most
text tables should be considered.
Flexion. Thumb flexion is controlled by the medial (C8,
ulnar) and lateral
(C6-C7, median) flexor pollicis brevis at the metacarpophalangeal
joint and by
the flexor pollicis longus (C8-T1) at the interphalangeal joint.
Strength is
tested by having the patient touch the tip of the thumb firmly
against the pad
below the little finger. Note the power it takes to pull the
patient's thumb
from flexion.
Abduction. Thumb abduction is provided by the abductor
pollicis
longus (C6-C7, radial) and abductor pollicis brevis (C8-T1,
median). Strength
is tested by stabilizing the patient wrist, especially on the
ulnar side. The
patient fully abducts the thumb, and, at the end of motion, the
examiner
increasingly applies reverse pressure.
Adduction. Adduction of the thumb is controlled by the
adductor
pollicis (C8-T1, ulnar). Strength is tested by stabilizing the
patient's wrist
along the ulnar border and having the patient adduct the thumb
against the
examiner's increasing resistance.
Finger Motion.
Gross movements of the fingers are regulated by the extrinsic
muscles of
the hand, while the intrinsics control the finer movements and
tend to
counterbalance the extrinsics. Finger extension is associated
with finger
spreading, and flexion tends to draw the fingers together. See
Table 4.
Finger motion involves flexion and extension at the
metacarpophalangeal and interphalangeal joints. Abduction and
adduction occur at the
metacarpophalangeal joints. Active metacarpophalangeal motion is
tested by
stabilizing the patient's wrist and having him extend and flex
with the digits
straight. Active proximal interphalangeal motion is checked by
stabilizing the
metacarpophalangeal joints and having the patient extend and flex
the proximal
interphalangeal joints.
Active distal interphalangeal movement is judged by
stabilizing the
proximal interphalangeal joints and having the patient extend and
flex the
distal interphalangeal joints. Observe finger abduction and
adduction by
having the patient place the hand flat and spread the fingers
apart and then
tight. Individual joint-motion restriction should be noted when
occurring in
any direction. Also test passively if necessary.
Table 3. Major Muscles of the Thumb
Muscle
Major Function
Spinal Segment
Abductor pollicis brevis
Thumb metacarpophalangeal
flexion,
abduction
C8-T1
Abductor pollicis
longus
Thumb abduction and
metacarpophalangeal
extension
C6-C7
Adductor pollicis
Thumb adduction
C8-T1
Extensor pollicis brevis
Thumb metacarpophalangeal
extension
C7-C8
Extensor pollicis longus
Thumb metacarpophalangeal and
interphalangeal
extension
C7-C8
Flexor pollicis brevis
Thumb adduction,
metacarpophalangeal
flexion
C8-T1
Flexor pollicis longus
Thumb metacarpophalangeal and
interphalangeal
flexion, abduction
C8-T1
Opponens digiti minimi
Opposition
C8-T1
Opponens pollicis
Opposition
C6-C7
Table 4. Finger Motion
Joint Motion
Prime Movers
Accessories
Metacarpophalangeal
flexion
Interossei, dorsal
Flexor digit.
Profundus
Interossei, volar
Flexor digit.
superfic.
Lumbricales
Flexor digiti minimi
Proximal interphalangeal
flexion
Flexor digitorum
superficialis
Flexor digit.
profundus
Distal interphalangeal
flexion
Flexor digitorum
profundus
Extension
Extensor digitorum
Extensor digiti minimi
Extensor indicis
Lumbricales
Interossei, dorsal and
volar
Abduction
Interossei, dorsal
Abductor digiti minimi
Adduction
Interossei, volar
Finger Kinesiology and Strength
During contraction of the flexor digiti group, for example,
the tendons
move proximally, and this exerts a pull on the attached
phalanges. The degree
of tendon excursion decreases distally with each joint from about
1-1/2 inches
at the wrist to less than half an inch at the metacarpophalangeal
joint, thus
determining the movement of the joint involved. The major muscles
of the
fingers are shown in Table 5.
Table 5. Major Muscles of the Fingers
Muscle
Major Function
Spinal Segment
Abductor digiti
minimi
Abduction, flexion
C8-T1
Dorsal interossei
Abduction, flex proximal, extend
middle and
distal phalanges
C8-T1
Extensor digiti
minimi
Extension
C6-C8
Extensor
digitorum
Extension
C6-C8
Extensor indicis
Extension
C7-C8
Flexor digiti
minimi
Flex metacarpophalangeal joint
C8-T1
Flexor digiti
profundus
Flex metacarpophalangeal,
proximal, and distal
interphalangeal joints
C8-T1
Flexor digiti super-
ficialis
Flex metacarpophalangeal and
proximal
interphalangeal joints
C7-T1
Lumbricales
Flex metacarpophalangeal joints,
extend middle
and distal phalanges
C7-C8
Palmar interossei
Adduction, flex proximal, extend
middle and
distal phalanges
C8-T1
Flexion. Finger flexion is essentially controlled by the
lateral (C7,
median) and medial (C8, ulnar) lumbricals for the
metacarpophalangeal joint,
the flexor digiti superficialis (C7-T1) for the proximal
interphalangeal
joint, and the flexor digiti profundus (C8-T1) for the distal
interphalangeal
joint. To test flexion strength as a whole, the patient tightly
flexes the
fingers with the wrist pronated while the examiner stabilizes the
patient's
wrist with one hand and with the active supinated hand curls his
fingertips
under those of the patient's. The patient's fingers are then
grasped in the
palm, and increasing extension pressure is applied.
Extension. Primary finger extension is provided by the
extensor
digitorum (C6-C8), extensor indicis (C7-C8), and extensor digiti
minimi (C8-
T1). Strength is tested by stabilizing the wrist in the neutral
position and
having the patient extend the metacarpophalangeal joints while
flexing the
proximal interphalangeal joints. The examiner then places the
active hand on
the back of the patient's proximal phalanges and increasingly
applies flexion
pressure.
Abduction. Finger abduction is produced by the dorsal
interossei
(C8-T1) and the abductor digiti minimi (C8-T1). Strength is
tested by having
the patient extend and fan the fingers. The examiner, using his
thumb and
first finger, applies increasing pressure to force any two
fingers together
that are being measured.
Adduction. Adduction of the fingers is controlled by
the palmar
interossei (C8-T1). Strength is evaluated by having the patient
extend the
fingers, keeping them together. The examiner slips a sheet of
paper between
any two fingers being tested, has the patient apply maximum
pressure, and then
pulls the slip of paper and notes resistance.
Bilateral grip strength is commonly tested with a dynamometer
and pinch
strength by a pinch meter if objective records are necessary.
Finger Biomechanics
Finger motion is less difficult to appreciate when the
proximal bone of the
joint is stabilized while the distal bone moves about it. For
example, the
axis of flexion for an interphalangeal joint is considered to be
at that point
not moving in relation to either involved digit.
Leverage. A digit's flexor tendon lies close to the
axis when that
finger is extended, but it moves further from the axis during
flexion. This
creates better mechanical advantage because of the longer moment
arm produced.
Each tendon exerts tension on the end of a lever whose vector
extends from the
joint axis perpendicular to the tendon.
Pulleys. Each tendon is held in a sling of fibrous
tissue to create
a series of pulleys parallel along the finger bones. If these
pulleys were
absent, the tendons would bowstring between the joints during
flexion and
fingertip control would be lost. Another important effect of
these pulleys is
that when the tendon changes direction across a pulley, there is
an equal and
opposite reaction force at the pulley that establishes a state of
equilibrium;
ie, the plus and minus factors total zero.
Viscoelastic Forces. Black/Dumbleton point out that
there is a
distinct relationship between finger joint position and the
position of more
proximal joints; ie, joint motion is the effect of involuntary
viscoelastic
forces in addition to normal active contraction. Active wrist
flexion, for
example, increases the viscoelastic forces on the posterior of
the digit. The
result is finger extension even without active contraction of the
finger
extensors. Likewise, active wrist extension affects finger
flexion.
CLINICAL MANAGEMENT ELECTIVES OF DIGIT STRAIN/SPRAIN
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
Cold immersions
Ice massage
Vapocoolant spray
Pressure bandage
Protection (padding)
Elevation
Indirect therapy (reflex therapy)
Auriculotherapy
Meridian therapy
Spondylotherapy
Pulsed ultrasound in water
Rest
Immobilization
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:
Alternating warm and cool hydrotherapy
Pressure bandage
Protect lesion (padding)
Indirect therapy (reflex therapy)
Passive exercise of adjacent joints
Pulsed ultrasound in water
Cryokinetics (passive exercise)
Meridian therapy
Spondylotherapy
Rest
Immobilization
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 related trigger points
Cryokinetics (active exercise)
Moderate active range-of-motion exercises
Meridian therapy
Gentle alternating stretching
Sinusoidal current
Ultrasound in water
Vibromassage
Spondylotherapy
Mild transverse friction massage
Mild proprioceptive neuromuscular facilitation techniques
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 exists. 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
Spray-and-stretch related trigger points
Active range-of-motion exercises without weight bearing
Negative galvanism
Ultrasound in water
Meridian therapy
Proprioceptive neuromuscular facilitation techniques
Protective strap
Indicated diet modification and nutritional supplementation.
5. Stage of Reconditioning
Direct articular therapy for chronic fixations
Progressive remedial exercise
Passive stretching
Isometric static resistance
Isotonic with static resistance
Isotonic with varied resistance
Plyometric
Aerobic
Indicated diet modification and nutritional supplementation.