The indications for amputation of upper extremities are much different from those of lower extremities because advanced atherosclerosis is unusual in the upper extremity. Upper extremity amputations are most often performed for severe trauma or malignant tumors. Conditions causing arterial ischemia in upper extremities that may require amputation include thromboangiitis obliterans, connective tissue disorders, accidental intra-arterial injection of drugs, and diabetic patients with long-standing end-stage renal disease.
Microsurgical techniques now allow previously hopeless cases of traumatic amputation to be treated by replantation. Function following replantation of the thumb and other digits is good; after replantation of the palm, wrist, or forearm, function is less satisfactory, but an attempt at limb salvage is warranted in selected cases, especially in children. The advantages and disadvantages of amputation and replantation must be weighed: with amputation, there is a cosmetic defect but a relatively short period of rehabilitation; with replantation, there is normal appearance but a long, costly rehabilitation period.
It is advisable to preserve as much length as possible when performing amputations in the upper extremity. Good skin coverage must be obtained, but length should not be sacrificed for the sake of skin closure; split-thickness skin grafts, musculocutaneous flaps, and skin traction can all help in complex situations. In the hand, maintenance of length should be based on functional considerations.
Usefulness of the upper extremity prosthesis is limited by diminished sensory and proprioceptive feedback; thus, auditory and visual control of the prosthesis is required. Limited “gadget tolerance” and high costs due to low demand reduce the availability of electric-powered prostheses. Prostheses with elbow joints and terminal devices activated by body power are generally more acceptable to amputees.
Traumatic amputations do not have to be treated definitively at the initial debridement. Expectant management will permit questionably viable tissues to demarcate and thereby allow maximal preservation of length. When deciding whether to amputate an injured extremity, the physician should assess the status of five structures: skin, tendons, nerves, bones, and joints. If three or more are compromised, amputation is usually favored over attempts at preserving the part.
After amputation below the elbow, only about 50% of the ability to perform pronation and supination can be transmitted to a prosthesis, because of the bulk of the proximal forearm and the length of the remaining radius and ulna. The more proximal the amputation, the less pronation and supination is possible. Amputations through the wrist permit the most pronation and supination and provide for better prosthetic control than higher amputations do.
Even if only a short residual limb can be achieved, forearm amputation is preferable to above-elbow amputation. As much muscle function as possible should be preserved to maximize control of a prosthesis. Several innovative reconstructive procedures are available that allow upper arm muscles to assist in controlling a prosthesis when a very short residual limb precludes pronation and supination by forearm muscles.
Every effort should be made to preserve length. Even if a very high amputation is necessary, the head of the humerus should be spared, since it serves as a support for a prosthesis and maintains shoulder width.
Malignant tumor is the usual indication for forequarter amputation. The operation is easiest if done from a posterior approach, but the location and size of the mass may require an anterior approach. A thoracotomy or partial neck dissection may be necessary to resect the tumor completely. After the wound has healed, a Silastic foam shoulder cap held in place with straps provides a cosmetically acceptable shoulder.