Amputation of an upper limb is a catastrophic event primarily performed as the result of high-energy trauma,^1,2 with approximately 90% of upper limb amputations resulting from trauma³ (Figure 1). The surgeon’s goal in selecting a definitive amputation level after traumatic amputation is to ensure that the residual limb has maximal length and soft-tissue coverage so that a highly functional prosthetic limb can be painlessly accepted (Figure 2). The amputation itself is only the first step in the patient’s rehabilitation from injury and should not be considered a treatment failure. Consideration should be made toward improving prosthesis wear in amputees who reject standard prostheses through potential osseointegration at the transhumeral level.

As much limb length as possible should be preserved to maximize the patient’s options for later prosthetic fitting. In addition, having a relatively long residual limb is useful for allowing the patient to interact with the environment when the prosthesis is not being worn.⁴ The caveat in maintaining maximal limb length is that the soft tissues must be able to support the residual limb to achieve comfortable use of a prosthesis. The zone of injury is the most important factor in choosing the final limb length. Usually the most durable coverage is achieved with local skin flaps. The ultimate size, shape, durability, and appearance of the residual limb will affect a patient’s satisfaction and should be considered in surgical decision-making.⁴

Distraction osteogenesis and microvascular techniques can be used to allow successful soft-tissue closure during an initial proximal transhumeral amputation.^5,6 Free tissue transfer may be indicated for preserving the shoulder joint (allowing a forequarter or shoulder disarticulation to be converted to a transhumeral amputation), the elbow joint, or bone length of more than 7 cm below the shoulder or elbow (to improve prosthetic fit and performance).⁷

Although a transhumeral amputation proximal to the deltoid insertion functions as a shoulder disarticulation, it has advantages over shoulder disarticulation. Retaining the proximal humerus preserves the contour of the shoulder, thus improving the fit of the prosthesis and cosmesis. There is greater controversy as to whether a long transhumeral amputation or an elbow disarticulation is preferable. The disarticulation offers enhanced prosthetic suspension and rotational control because the medial and lateral flares of the distal humerus are preserved. However, preserving the full length of the humerus may preclude the use of a prosthetic elbow by limiting the space available for a prosthesis; at a minimum, a bulky, nonanatomic elbow component is required. The available external hinge elbow mechanisms can be cosmetically displeasing, particularly if the patient has an unaffected contralateral upper limb. An angulation osteotomy of the distal humerus or humeral shortening proximal to the elbow can be used to improve rotational control and avoid
limiting prosthetic elbow options.^3,8 On average, 7.6 cm of space above the center of rotation of the elbow is required so that the prosthetic elbow center is at the level of the intact elbow.⁹

Regardless of the final amputation level, proper management of the nerves and muscles of the residual limb is of paramount importance. Adequate padding of the residual bone end and prevention of postoperative neuritic pain substantially affect prosthetic wear comfort. Therefore, myoplasty or myodesis should be done to pad any bony prominence about the residual limb. One suggested consideration for dealing with the muscles that has recently begun investigation is the agonist-antagonist myoneural interface, which allows for innervated muscles that are linked together to reform normal muscle tendon agonist-antagonist relationships that have the potential to augment control of a prosthesis, preserve proprioception, and prevent limb atrophy.¹⁰ When dealing with the peripheral nerves, historically, traction neurectomies were advocated. The armamentarium of the surgeon currently dealing with peripheral nerves in amputations, however, is substantially greater. Strong consideration should be given to addressing nerves with options that provide the nerve with direction, such as targeted muscle reinnervation or regenerative peripheral nerve interfaces, as well as improving terminal device control. In the author’s experience a combination of these two techniques is frequently used.

Modern prosthetic techniques allow comfortable fitting and function in patients who have undergone amputation at almost any humeral level. However, despite improved suspension techniques and advances in bioprosthetic interfaces for myoelectric prostheses, the rejection rate of upper limb prostheses is more than 30%.^11,12 A prosthetic limb cannot replace the sensibility or dexterity of the natural hand, and, as the amputation level progresses proximally, the relative function of the prosthesis decreases. The result can be diminished wear or use by the patient. To improve the bioprosthetic interface and function of myoelectric prostheses, research efforts have focused on improving suspension, durability, degrees of freedom at the terminal device, and myoelectric control at additional intuitive input sites. In addition, reducing the weight of the prosthesis and extending its battery life are being studied.^13,14,15