Upper Extremity Arterial Disease: Amputation

Etiology

The majority of upper extremity amputations are the result of trauma (80%–90%), and thus these patients are generally younger (average age 20–40 years old) and predominately male. ^, However, other etiologies exist and include vascular disease and tumors, representing 7% and 0.6% of upper extremity amputations, respectively. Other less frequent causes include infection, congenital anomalies, and iatrogenic complications from catheterization, vasopressor administration, or vascular access. ^, This overall distribution differs from lower extremity amputation, where vascular disease is the inciting etiology in nearly 80% of cases ^, (see Ch. 114 , Lower Extremity Amputations: Epidemiology, Procedure Selection, and Rehabilitation Outcome).

Ischemia as the cause of upper extremity amputation usually results from trauma. Atherosclerosis is less common in the arteries of the arm and is a rare form of peripheral arterial disease. Even in more chronic scenarios, the most frequent reason for upper extremity revascularization is traumatic injury, followed by embolization from more proximal atherosclerotic or cardiac origins as opposed to chronic occlusive disease. Such trauma may include vibration-induced white finger, hypothenar hammer syndrome, and athletic-associated conditions such as quadrilateral space syndrome and arterial thoracic outlet compression resulting in subclavian aneurysm. Arterial trauma or embolization related to drug use may also be responsible. Apart from atherosclerosis, a variety of arterial disorders leading to extremity arterial insufficiency may affect the arm, including vasospastic disorders (e.g., Raynaud disease), vasculitides, small-vessel diseases (e.g., Buerger disease), and radiation-induced arteritis.

Initial Management

Amputations secondary to trauma are generally managed in a staged fashion to preserve as much of the arm as possible, based on principles dating back to the care of battlefield injuries during World War II. As opposed to the lower extremity, which requires only adequate soft tissue coverage in anticipation of a functional prosthesis, an upper extremity amputation must be both functional and cosmetically acceptable, and thus definitive decisions on the level and length of amputation should not be made in the acute setting. Sequential stepwise debridement and later definitive closure are key to ensuring technical and functional success. In recent years, advancements in wound care and wound bed preparation prior to definitive closure, including the use of negative pressure therapy to promote tissue granulation, has allowed for this staged approach to become the mainstay of therapy, even in the modern battlefield. Additionally, emotional and functional rehabilitation has dramatically improved, with advancements in prosthesis design and functionality allowing these patients to return to meaningful positions in today’s society. Factors that play major roles in individualizing the surgical strategy for upper extremity amputation include etiology, age, handedness, occupation, associated injuries and physiologic state, accessibility to state-of-the-art occupational and physical therapies, and cultural settings.

Arterial Assessment

For all indications, the level of upper extremity amputation depends on adequate arterial perfusion. The use of physical examination in conjunction with noninvasive studies, such as duplex ultrasound, segmental pressure measurement, pulse volume recording, infrared photoplethysmography, laser Doppler techniques, transcutaneous oxygen tension (tcP o ₂ ) measurement, and arteriography can ensure that no ischemic component of the injury will prevent healing. Although the use of these tools in selecting the appropriate level in upper extremity amputations is less well described than for lower extremity amputation, the same principles can be applied. Generally, healing will occur at the hand level when digital pressure exceeds 40 mm Hg and wrist Doppler pressure exceeds 60 mm Hg, while healing is unlikely for digit pressures less than 20 mm Hg. At the forearm and arm levels, healing will almost always occur when wrist or brachial pressure exceeds 60 mm Hg, or when tcP o ₂ is 40 mm Hg or greater. Healing is less predictable when tcP o ₂ is between 20 and 40 mm Hg, and wrist or brachial Doppler pressure is less than 50 mm Hg. Pulse volume recordings may provide evidence of collateralization and suggest a higher likelihood of success, although they remain nonspecific when blunted. Once the level for amputation is chosen, simple ligation of blood vessels during the procedure is usually sufficient, provided that tissue coverage of these structures can be obtained.

Preservation of Length

Although preservation of length is a fundamental principle of amputation surgery, length does not always correlate directly with function, depending on the type of prosthetic application contemplated. However, in general, it is important to retain and salvage as much residual stump as possible to maximize the ultimate functional outcome. To this end, several reconstructive techniques have been described to salvage stump length, including plastic and orthopedic surgery techniques such as bone and free tissue transfer. These techniques have been applied selectively and may be helpful in certain instances, particularly in elective procedures. Moreover, selective reimplantation methods and even hand transplantation have been suggested in an attempt to maintain viable, functional tissue and length for the upper extremity, and should be given consideration in certain circumstances. ^{, ,} Length preservation techniques may have a more limited role when vascular insufficiency raises concern for viability of grafted tissue, with longer length correlating with poorer healing. The level of the acute amputation must balance the chance of healing with function, as shorter lengths result in decreased function. In addition, the elbow joint should be retained, if at all possible, to facilitate later prosthetic function.

Soft Tissue Coverage

Historically, length depended on local soft tissue coverage, and if tissue coverage was not adequate, one merely shortened the extremity until closure could be achieved. Skin grafts, free flaps, and composite tissue transfer have, however, dramatically changed this approach. Skin grafts are applicable when the underlying soft tissue bed is acceptable, but one must be sensitive to the ultimate functional needs of the amputation site; in some cases, skin grafts may not be durable enough to tolerate therapy and the use of prostheses. Local flaps are also an option for providing soft-tissue coverage (see below), but their applicability is limited by the anatomy at more proximal amputation sites. Pedicled flaps (regional or distal) have a long, productive history in hand surgery; however, they have been increasingly replaced by free tissue transfers. This change is based on: (1) better matching of the tissue transferred (in terms of thickness and ultimate functional performance); (2) avoidance of additional surgery (whether for division or thinning of the flap); and (3) lack of the joint limitations that result from the immobility that is typically necessary with pedicled flaps. Free tissue transfer is increasingly being accomplished at sites proximal to the hand to achieve more satisfactory results.

Nerves

Prevention of neuroma is the most difficult problem in upper extremity amputation. Distal ligation, proximal ligation, coagulation, chemical ablation of the end, simple division, traction and division, nerve repair to other divided nerves, and immediate burial of the transected nerve end have all been attempted with varying degrees of success. A divided nerve always attempts to regenerate and, in so doing, produces a neuroma of variable clinical significance. Thus, the goal is not to prevent the formation of a neuroma altogether, but rather to reduce the pain or dysesthesias from the neuroma that will predictably develop. In general, locating the divided, free nerve end as far from external stimuli as possible and placing it in a healthy, unscarred bed of tissue are the best preventive measures. Early postoperative therapy (desensitization or sensory re-education) is also an extremely important determinant of the patient’s ability to tolerate the dysesthesias that result from an amputation. Other techniques that can be performed in an elective scenario include centrocentral nerve union, in which severed nerve ends are connected to form a loop, and targeted reinnervation by way of nerve transfer techniques, which improve residual muscle and sensory function at the stump. ^,

Bone and Cartilage

Bony prominences must be optimally contoured, as irregularities lead to aesthetic abnormalities and difficulty in obtaining optimally fitting prostheses. Inadequate debridement of traumatized tissue and displaced bony fragments, improper initial contouring of bone, or failure to identify bone-producing periosteum, which must also be contoured, are the sources of such difficulties. Visual identification of the periosteum is easiest during initial management of the injury, and achievement of a natural bone contour is greatly assisted by palpating the end of the bone through the skin before closure. This is even more important in amputations through joints, where natural anatomic flares of the bone produce aesthetically unnatural contours and interfere with prosthetic fitting.

Tendons

The hand represents a very delicate balance between extensor and flexor forces. It is extremely difficult to duplicate the balance of these forces through myodesic methods (i.e., suturing of tendons or muscles to bones) or myoplastic techniques (i.e., suturing of tendons or muscles to tendons or muscles of the opposite functional group; for example, suturing an extensor tendon directly to a flexor tendon over a bony amputation site). In general, such techniques are not used distally in the fingers and hand because they often add to the functional deficit. However, they do have value proximally, where the balance is not as critical, and re-education and adaptation are easier.