Amputation and Congenital Deficiency in the Upper Extremity. D.W. Lamb. To appear in Proceedings of the Conference on Priorities in Prosthetic and Orthotic Practise, Dundee. Scotland, 1969. George Murdoch, editor.
Dr. Lamb highlights surgical, prosthetic, training, and psychological considerations for children with upper-limb deficiencies, particularly those of congenital origin.
Terminal Deficiency. Congenital absence of the end of the arm, usually at the wrist or proximal forearm, is almost invariably unilateral, unassociated with other anomalies. The more proximal the deficiency, the more important is prosthetic replacement for bimanual function. Formerly the child was fitted just prior to school, after he and his parents had become oriented to one-handed function. Current practice calls for fitting at four to six months of age. The below-elbow amputee has a simple, lightweight, rigid prosthesis to accustom him to its feel and appearance, and to aid his crawling. A split hook applied at one year of age is worked passively to familiarize him with holding so that he can manipulate with the other hand. By the age of 18 months he can operate the hook with cable control. The child should be seen every three months to correct any prosthetic inadequacies and to institute a smooth pattern of prosthetic acceptance and use.
Until the above-elbow amputee is five or six, his elbow lock is manipulated by his other hand or by another person. Very short above-elbow and shoulder-disarticulation amputees are the only unilateral types where external power has a place at this time.
Partial hand deficiencies may require prostheses for function or cosmesis. A carpal remnant permits loose bimanual holding against the sound hand. A prosthesis with a split hook provides the best prehension, but covers the stump to deprive the wearer of sensory feedback. An open socket allows tactile sensation. The child grasps by a hook on the dorsal surface, a volar plate, or by stump movement. A plastic one-piece forearm socket with hand is cosmetic.
Present artificial hands do not duplicate normal appearance or function. The Bock, Sierra, and Hosmer hands have three-jaw-chuck prehension, the index and middle fingers moving to oppose the thumb. A similar grip is utilized in the Russian and Bottomley hands operated by myoelectric signals. Prehensile hands are of less value than split hooks. Dorrance hooks overcome certain design limitations of the wider range of English devices serving varying functions. The cosmetic appeal of a skillfully used hook is greater than that of a cadaverous-looking glove.
Multiple Congenital Upper-Limb Deficiency. Short deformed limbs may be so useful that the child should have cosmetic prostheses only when he is older. Other deficiencies benefit from the Krukenberg procedure, which creates split prehensile forearms with intact sensation.
Thalidomide accounted for many severe bilateral symmetrical anomalies: amelia, digital appendage (valuable to control powered prostheses), phoeomelia, and radial paraxial hemimelia. Children with high deficiencies benefit most from gas power with built-in servomechanisms. The older child has severe disadvantages in reaching. Radial hemimelia is the most common: usually the elbow is stiffly extended with absence of the radius and that side of the carpus and hand. Surgery may improve function and appearance considerably. Ulnar hemimelia may be associated with marked elbow flexion which hinders prosthetic and surgical correction.
Acquired Amputations of the Upper Limb. Most upper-limb amputees are young adults who sustained trauma. Past failure to achieve bimanual function has been due to delayed fitting, inadequate prostheses, and insufficient training.
Amputation surgery, in principle, is the same for upper as for lower limbs, aiming for the expeditious achievement of well-healed stumps. Long below-elbow stumps provide the advantage of active pronation and supination not available in any present table-controlled prosthesis. A very long above-elbow stump, however, is not an obvious advantage, because excellent elbow mechanisms are available. A pneumatic tourniquet and myoplasty are used routinely. Immediate fitting is very important. The stump is enclosed in plaster with a split hook and shoulder harness. The patient learns bimanual functions. Plaster and stitches are removed at two weeks and a second cast is applied. Usually by six weeks the patient is fitted with a definitive prosthesis.
Most sockets are of plastic and are accurately fitted. The long below-elbow prosthesis is suspended with a figure-eight harness without restriction of elbow movement. The short below-elbow has rigid elbow hinges, or a closely fitting Munster socket. The above-elbow amputee also has a figure-eight harness: the shorter the stump, the more the socket encroaches on the upper aspects of the shoulder. A ring-type suspension harness is effective for the below-elbow amputee, but less so for the above-elbow amputee, for whom the harness acts as both a suspension and a control point.
Prosthetic components include elbow joint mechanisms, a turntable for passive rotation above the elbow to compensate for lack of shoulder rotation, a passively operated wrist-rotation unit to compensate for lack of pronation and supination, and a wrist- disconnect mechanism. Artificial hands have little value in body-powered prostheses. External power permits better control of the fingers. The most valuable terminal device is the all-purpose split hook; voluntary-opening hooks are more effective and less tiring. Body movement, with leather, nylon, or Bowden cable attached to the harness, gives excellent and effortless control for long stumps. There is no evidence to show that the most successful cineplasty procedures are any better than conventional body power. External power by electricity or gas, or by voltages induced by muscle contraction, requires considerable refinement.
Abstracted by Joan E. Edektein. R.P.T.