Poliomyelitis: Splints for the Upper Extremity
C.E. Irwin M.D. *
The splints to be discussed in this presentation are designed and used for therapeutic reasons only. They are in no sense recommended as permanent assistive or supportive equipment. The author through experience has learned that a patient with upper extremity involvement will develop ingenious substitution patterns and will of his own accord discard the equipment. It is conspicuous and often a hindrance rather than a help to him in carrying out the necessary every-day activities. We, as orthopedic surgeons, should thoroughly evaluate these individuals and carry out the necessary operative procedures to make them as independent and dextrous as possible without the need of any apparatus.
A therapeutic splint may be classed as supportive, assistive and corrective. A single splint may fulfill one or a combination of two or more of these basic needs. A splint used pre-operatively may be used for support and assistance postoperatively as the need for assistance and support remains the same as it was prior to surgery.
Splints may be static or dynamic in use and design. Dynamic splinting should be used when possible. This principle provides both support and assistance for a weakened muscle or a weakened segment and allows motion and use of a weakened or transferred muscle in a manner approaching that for which it was normally intended. The splint should be simple in design, light in weight and constructed so that it can be easily applied and removed for necessary physical therapy. Rigid supports or plaster casts worn twenty-four hours a day are definitely contraindicated, particularly for the hand.
This discussion will be concerned with splints for the thumb, for the intrinsics of the digits other than the thumb, the long finger extensors and flexors, the wrist, the elbow and the shoulder.
The Thumb
In the presence of weakness or paralysis of the thenar intrinsic musculature, the thumb will assume a position of adduction, hyperextension and external rotation or supination (
Fig. 1
). Unless the thumb is properly splinted during convalescence, the following deformities will result: It will become contracted in adduction and external rotation or supination. Second, prolonged hyperextension of the thumb metacarpal will result in attenuation of the palmar portion of the capsule of the carpometacarpal joint. This important joint becomes unstable (
Fig. 2
). Third, in the adducted and externally rotated thumb the long extensor will gradually migrate into the web space between the thumb and index metacarpal, resulting in ulnar deviation of the phalanges on the metacarpal. The patient uses the long extensor as an adductor and not as a true extensor of the distal phalanx (
Fig. 3
,
Fig. 4
,
Fig. 5
,
Fig. 6
,
Fig. 7
,
Fig. 8
).
Intrinsic Musculature of the Digits Other Than the Thumb
The important intrinsic muscles provide both an extensor and a flexor component for the fingers. (The abduction component will be discussed with the index finger.) (
Fig. 9
)
For the purpose of discussing splints, one may say that the intrinsic muscles initiate and are the chief extensors of the distal two phalanges. The extrinsic flexor profundi and sublimi are the moderators of this component. For the same reason one may say that the intrinsic muscles initiate and are the chief flexors of the proximal phalanges. The extrinsic common extensors are the moderators of this component (
Fig. 10
).
The extrinsic extensors are not the primary extensors of the distal phalanges, nor are the extrinsic profundi and sublimi the primary flexors of the proximal phalanges.
Skilled function of the fingers depends on proper balance between these two moderated groups of muscles. Appropriate dynamic splinting is important for these muscles both during the convalescent stage of the disease and for postoperative support and assistance following certain muscle transfers (
Fig. 11
,
Fig. 12
,
Fig. 13
,
Fig. 14
,
Fig. 15
).
Instinsic Musculature of the Index Finger
The function of the intrinsic muscles of the index finger differs from that of the other digits (
Fig. 16
,
Fig. 17
). The abductor function of the first dorsal interosseus muscle is highly developed and plays an important part in increasing the horizontal inter-tip space between the index and fifth fingers. Unlike the other intrinsics, it inserts chiefly into bone rather than into the lateral band.
It does not ordinarily aid in extending the distal phalanges but is a strong abductor, a flexor, and an important stabilizer of the metacarpophalangeal joint, important for effective pinch.
Supportive and assistive splinting for this finger should be dynamic (
Fig. 18
).
Long Finger Extensor
When the wrist is extended 180 degrees or more, the common extensor extends only the proximal phalanges (
Fig. 19
,
Fig. 20
). The distal phalanges are extended by the intrinsics when the wrist is in this position. When the wrist is flexed or dropped, the long extensor can extend the distal phalanges by tenodesis action through the central slips.
Long Finger Flexors
The flexor profundi and sublimi are flexors of the distal phalanges and augment the flexor component of the intrinsics on the proximal phalanges (
Fig. 21
,
Fig. 22
,
Fig. 23
). Grasp is strongest when the wrist is extended or slightly hyperextended.
Fixed Deformities of the Digits
Weak intrinsic muscles which have been neglected as regards proper splinting will develop fixed flexion contractures of the distal phalanges and hyperextension contracture of the proximal phalanges-fixed claw hand (
Fig. 24
). These contractures must be overcome prior to intrinsic transfers. Continuous corrective force by a rigid plaster cast cannot be tolerated due to painful pressure on the palmar surfaces of the distal phalanges. The following figures demonstrate an effective corrective splint attached to the basic opponens splint (
Fig. 25
,
Fig. 26
,
Fig. 27
). It can be easily removed for periods of rest, manual stretching, and other physical therapy measures.
The Wrist
Splints for the wrist present no problem and nothing of particular interest (
Fig. 28
). Dropped wrist is fairly common and may be associated with radial or ulnar deviation, depending on the distribution of muscle weakness. A static splint for support only is ordinarily used for convalescent care in our clinic and is shown in the following figures (
Fig. 29
,
Fig. 30
,
Fig. 31
,
Fig. 32
).
The Elbow
Inability to flex the forearm on the arm constitutes a real handicap, particularly for the patients with bilateral involvement (
Fig. 33
). These individuals may be able to use the hands on flat table surfaces for most anything they wish, but, being unable to get their bands to their face level, they cannot feed themselves, brush their teeth, shave, and comb their hair, and are deprived of many other functions ordinarily taken for granted.
The following figures show a very efficient assistive piece of apparatus which enables the patient to get his hand to the face level although he has no muscles to flex the forearm on the arm. With the apparatus the forearm can be flexed by depressing the shoulder or shifting the body weight toward the involved side. The principle may be used on a flat table surface or as a part of an assistive overhead sling (
Fig. 34
,
Fig. 35
).
Some of these patients may be freed of apparatus by a Bunnell modification of the Steindler flexorplasty.
The Shoulder
Splinting of the shoulder weakened by poliomyelitis is a controversial subject.
Three possible component disabilities of a weakened shoulder must be considered. These components are: (1) the abductors, (2) the rotator cuff, and (3) the shoulder depressors. If one keeps in mind the above three possible component disabilities and will accept the premise that a weakened muscle is done no harm if it is supported at a point of its maximum resting length, then the time-honored use of abduction or airplane splints for all weakened shoulders is not always applicable (
Fig. 36
,
Fig. 37
).
* The majority of this material and photographs was previously published in the American Academy of Orthopaedic Surgeons, Instructional Course Lectures, Vol. IX, Ann Arbor, J. W. Edwards, 1952, under the title "Apparatus for the Upper Extremity Disabled by Poliomyelitis," by C. E. Irwin, M.D. This is being reproduced with the permission of the American Academy of Orthopaedic Surgeons and J. W. Edwards, Inc.
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