Etiology

The majority of upper extremities requiring amputation are the result of trauma (80% to 90%).^1,2 It is not surprising, then, that upper extremity amputees are generally younger (20 to 40 years old on average) and predominantly male. Other etiologies do contribute, however. Vascular disease and tumors are the next most common indications and represent 7% and 0.6% of upper extremity amputations, respectively.^1,2 Even less frequent causes include infections, congenital anomalies, and iatrogenic reasons, such as complications related to catheterization, vasopressor administration, and vascular access. Thus, the general indications for amputation of portions of an arm or hand include tissue destruction, vascular compromise, and tumor development. This overall distribution is in contradistinction to that of lower extremity amputation, where vascular disease is the inciting etiology in nearly 80% of cases.^1,2

Ischemia as the cause of upper extremity amputation usually results from trauma. Atherosclerosis is distinctly less common in the arteries of the arm and is a rare form of peripheral arterial disease.³ Even in more chronic scenarios, the most frequent reason for upper extremity revascularization is traumatic injury.^4,5 Emboli from more proximal atherosclerotic or cardiac origins are much more common than chronic occlusive disease.⁶ Occupational arterial trauma is relevant to the arm, and several are well described (see Chapter 123). 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 has clearly been illustrated. Apart from atherosclerosis, a variety of arterial disorders leading to extremity arterial insufficiency may affect the arm, including vasospastic disorders (e.g., Raynaud’s disease), small-vessel diseases (e.g., Buerger’s disease), and radiation-induced arteritis.

Initial Management

As stated earlier, the majority of amputations are secondary to trauma and are usually managed in staged fashion to preserve as much of the arm as possible. This principle dates back to the care of battlefield injuries during World War II.²⁴ 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. With this in mind, definitive decisions on the level and length of amputation should not be made in the acute setting. In addition, as compared to the lower extremity, the majority of patients are less willing to lose a poorly functioning hand. Sequential stepwise débridement and later definitive closure are the keys to successful technical and functional results. One of the advancements over recent years is wound care and wound bed preparation before closure. The use of negative pressure therapy to promote granulation and assist in flap and graft coverage has become a mainstay in treatment. This technology is used even in the modern battlefield scenario, with multiple débridements and placement of these devices early after injury.²⁵ Although the basic techniques of surgery and débridement have not changed, emotional and functional rehabilitation has improved dramatically. Advancements in prosthesis design and functionality have allowed 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 both traumatic and nontraumatic indications, the level of upper extremity amputation required fundamentally 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 (tcPO₂) measurement, and occasionally even arteriography before amputation can ensure that no ischemic component of the injury will prevent healing. Each evaluation technique has benefits and shortcomings. As described in Chapters 119 and 120, use of noninvasive tests can be invaluable in facilitating success. This is no less true in amputation, and though rare when compared with lower extremity evaluation, low pressure, poor arterial waveforms, and low tcPO₂ measurements along the extremity must be recognized and management altered appropriately.

Guidance suggesting the appropriate blood flow for healing at specific levels has largely been described for lower extremity amputation (see Chapter 117). Within the context of tissue perfusion, however, these same principles can be applied to the upper extremity. Generally, healing will occur at the hand level when digital pressure is 40 mm Hg or higher and wrist Doppler pressure is greater than 60 mm Hg. For hand-level procedures, healing is unlikely to occur when digital pressure is less than 20 mm Hg. At the forearm and arm levels, healing will almost always take place when wrist or brachial pressure is at least 60 mm Hg or when tcPO₂ is 40 mm Hg or greater. Healing is less predictable when tcPO₂ 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, yet they remain nonspecific when blunted. Once a level for amputation is chosen, simple ligation of blood vessels during the procedure is usually sufficient as long as 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,^26–31 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 elective planned procedures when the cause is tumor resection or isolated traumatic injury and the procedures may need to be performed in staged fashion. Length-preservation techniques have a limited role when the underlying pathology involves vascular insufficiency because of concern for viability and perfusion of the grafted tissue. 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.^21,22,32 In fact, in select scenarios, such as clean traumatic severing without much tissue loss or associated trauma, these methods must be given initial consideration. However, in most acute trauma settings this decision cannot be made, and minimizing loss of length should be the goal. One concept that should be considered is that longer length may result in poorer healing whereas shorter length results in decreased function. Thus, acute amputation should be performed at a level at which healing is likely and function is maximized. Also, if at all possible the elbow joint should be retained to facilitate later prosthetic function.

Soft Tissue Coverage

Historically, maintenance of length depended on local soft tissue coverage; if soft tissue coverage was not adequate, one merely shortened the extremity until closure could be achieved. As mentioned earlier, skin grafts, free flaps, and composite tissue transfer have 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 (see Fingertip Amputation) abound, but their applicability is limited because of 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. As in all of medicine, the existence of many methods of treatment usually indicates that none of them is exceptionally good. Such is the case with prevention of neuroma. 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. The desire to eliminate painful focal sensation must be balanced against the secondary loss of sensibility induced by many of these techniques. A divided nerve always attempts to regenerate and, in so doing, produces a neuroma of variable clinical significance. Thus, in reality the goal is not to prevent the formation of a neuroma altogether but to prevent the patient from experiencing 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, nonscarred bed of tissue are the best preventive measures. In addition, early postoperative therapy (desensitization or sensory re-education) is an extremely important determinant of the patient’s ability to tolerate the dysesthesias that result from an amputation. Targeted reinnervation by way of nerve transfer techniques has also been described as a means of improving residual muscle function and sensory aspects of the stump and thus prosthetic utility.³³ Such procedures can be performed in either a planned elective or a staged scenario.

Bone and Cartilage

Whatever length is ultimately chosen for the amputation, the bony prominences must be optimally contoured. Lack of attention to bony prominences or irregularities in bony contour lead to aesthetic abnormalities and difficulty in obtaining optimally fitting prostheses. Inadequate débridement of traumatized tissue and displaced bony fragments, improper initial contouring of bone, or failure to identify bone-producing periosteum, which must also be contoured, is the source 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, then, 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.

Fingertip Amputation

Distal finger amputations are extremely common. The most frequent mechanism causing such injuries is a crushing blow, such as from a closing door. Although many people arrive at the emergency department with the tip of the finger available for reattachment, the injury is usually too distal for microsurgical reattachment. Many surgeons have attempted com­posite reattachment (i.e., reattachment without specific revascularization) with generally poor results. At present, such composite grafts are not indicated except in young children (younger than 2 years), in whom there is an increased chance of graft survival.³⁴ Most composite grafts fail because (1) the amount of tissue is generally more than can survive the ischemia until new circulation develops and (2) the zone of injury is greater than the area of amputation (i.e., the tip is usually damaged and thus is not capable of surviving as a composite graft).

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