The Mangled Upper Extremity

History

As always, the key components of the medical history focus on the “when,” “where,” and “how.” The time of injury is critically important, especially when dealing with devascularizing injuries. Bone, integument, and muscle have, in that order, decreasing tolerances to ischemia, with muscle being able to survive only 4 to 6 hours of it, even with the normal tissue cooling that occurs after ischemia. In addition, the longer the duration from the time of injury, the greater the risk for infection, with delays greater than 6 to 12 hours precluding primary closure or coverage. If ischemia is present, the temperature of the tissue during the ischemic period is critical inasmuch as extremity tissues devoid of muscle can be successfully revascularized after 12 to 24 hours if kept cool. In fact, successful digit replantation has been reported at 94 hours.

The “where” of an injury is also important. Farming injuries, for example, tend to be highly contaminated and require more than the usual amount of aggressive debridement, which often precludes primary closure. The presence of caustic industrial chemicals or other contaminated substances can also affect treatment choices. The social and economic aspects of the injury environment must likewise be weighed when planning treatment. A patient living in an area remote from an appropriate medical facility may not be able to follow through with the complex rehabilitation program required for a highly technical reconstruction and may be better served with a more straightforward reconstructive option.

Finally, the “how,” or mechanism of injury, can help reveal the force of it and the extent of tissue necrosis or zone-of-injury to anticipate and address during treatment. Sharp injuries tend to involve a limited zone of tissue and are therefore easier to manage, unless the injury is tangential in nature. High-velocity, high-pressure crushing or avulsion injuries have a much broader injury zone and require a modified approach to treatment, which needs to consist of more extensive debridement, thorough evaluation of adjacent tissues, removal of foreign bodies, and assessment for and treatment of compartment syndrome.

The patient’s overall health and comorbid conditions must be carefully evaluated in planning any type of complex or lengthy reconstructive procedure. The patient’s age and the presence of cardiovascular disease, pulmonary disease, bleeding disorders, or diabetes can greatly increase the risk for perioperative complications or even mortality; any of these should cause the surgeon to consider simplifying the reconstruction method or at least modifying perioperative treatment plans. Smoking or the use of other vasoactive drugs, such as cocaine, may be a relative contraindication to any type of complex microvascular reconstruction, although the data about smoking and microvascular surgery complications is somewhat mixed.

Perhaps the most important aspect of obtaining a history is determining the patient’s functional needs and goals. The age, occupation, socioeconomic environment, and social support systems should all be considered when formulating a treatment plan. Both the risks that the patient is willing to accept and the costs (financial, emotional, and time) must be considered. Willingness to endure a protracted reconstructive course and a patient’s ability to follow through with the necessary hand therapy are important issues. A self-employed farmer, without workers’ compensation insurance, will probably be interested in reconstructive options that offer an expeditious return to work and provide durable function suited for heavy work without multiple complex reconstructive procedures.

An office worker or technology professional may have very different goals and might be more willing and economically able to undergo multiple reconstructive procedures to restore optimal digit function to allow fine manipulation, keyboarding, and other such tasks. Again, the hand surgeon must make decisions based on personal knowledge and experience to try to predict the patient’s ultimate function with the available reconstructive options so that the most appropriate option can be selected for that particular patient. Both the patient and the patient’s family must be involved in this discussion, although this is often difficult to do when the patient has just suffered a mangling injury, therefore surgeons frequently must use their best judgment at the time by assessing all the known variables.

Examination

Because examination of a patient with a severely mangled extremity injury that is wrapped in blood-soaked towels or bandages is often difficult in the emergency department, definitive evaluation often must wait until the operating room. Nevertheless, assessment of injuries to major structures, in particular vascular status, is essential to determine the urgency of definitive treatment and to begin the determination of salvageability. Usually, a general assessment of vascular status, sensibility, and muscle–tendon unit function, as well as radiographic evaluation, can and should be done in the emergency department. Preliminary evaluation will also allow adequate preparation of the operating room: microsurgical equipment and supplies, implants and fixation devices, traction and radiographic devices, and other necessities.

Assessment of vascular status is best performed by direct inspection of the patient’s affected tissues and comparison to adjacent or similar well-vascularized tissues. Although nail bed capillary refill is traditionally considered a good indicator of peripheral perfusion, it is in fact an unreliable indicator of perfusion. A completely devascularized digit can have what appears to be intact capillary refill beneath the nail bed when in actuality stagnant blood is merely being pushed to the sides with compression and then moving back to the center with release of pressure on the nail bed.

A far more reliable area to assess digit perfusion is the dorsal paronychial tissue on the sides of the nail, which should be pink, be spongy, and have good turgor, compressing with pressure and refilling with release ( Fig. 43.3 ). A pink color that returns within 1 to 2 seconds after the application and release of pressure indicates healthy tissue, whereas a pale color without capillary refill or turgor can represent arterial insufficiency. A dusky color with exceptionally brisk refill can be indicative of venous congestion. Probably the most reliable clinical indicator of tissue vascularity is the color of the blood that oozes from the tissue after sticking it with a needle or scalpel. Bright pink oozing reflects healthy tissue, whereas dark purplish oozing reflects compromised perfusion if it is sluggish or venous insufficiency if it is profuse. Obviously, this should not be performed on the sensate tissue of an awake patient but is often useful in an anesthetized one.

For assessing the status of the major vessels of the upper extremity and even the digital vessels, a handheld Doppler probe is very useful. The standard Allen test, performed by compressing either the radial or the ulnar artery and listening for a signal over the palmar arch or the most distant digital artery, can help determine whether either the radial or the ulnar artery has antegrade flow and whether the palmar arch is intact. Angiography has a minimal role in mangling injuries of the forearm, hand, or fingers. In any mangling or crushing injury, a high index of suspicion for compartment syndrome must be maintained.

The diagnosis and treatment of compartment syndrome are covered elsewhere, but it is worth reinforcing the importance of recognizing the intense pain of it and, in particular, pain with passive stretch of muscle–tendon units. When suspected, the diagnosis is best confirmed by direct measurement of pressure in the muscle compartment, usually with a handheld device specifically designed for this purpose. The presence of compartment syndrome and attendant tissue ischemia warrants emergency decompression in the operating room.

Although obvious deformity, crepitus, or tenderness on examination can suggest underlying skeletal injury, evaluation of the skeletal system is always performed radiographically. In most instances, standard radiographs are sufficient if care is taken, whenever possible, to ensure that emergency splints or traction devices do not obscure the underlying bones or joints. Sometimes, additional views are needed, including oblique views to assess articular congruity or stress views to evaluate ligament injury (e.g., a clenched fist view to evaluate intercarpal ligamentous integrity). In questionable cases, comparison views with the contralateral extremity, if uninjured, may be necessary.

With most mangling injuries, advanced imaging techniques, such as computed tomography (CT) or magnetic resonance imaging (MRI), are rarely indicated, although at times if the patient is stable, CT scanning of suspected carpal injuries or intraarticular displacement can be useful. If amputated parts are involved and replantation is contemplated, radiographs of the amputated part(s) should be obtained. Moreover, the joint proximal and the joint distal to the area of injury must be evaluated ( Fig. 43.4 ). Ligamentous injuries can be identified by tenderness to palpation or to stress. Stability with the application of stress should also be reevaluated under anesthesia to remove any confounding effect of involuntary muscular splinting.

Evaluation of injury to muscle–tendon units is best performed by having the patient actively flex and extend the digits and wrist. In the presence of pain, and especially with underlying skeletal injury, this examination can be difficult to interpret. For the individual digits, noting aberrations in the normal resting cascade can indicate injury to the underlying flexor muscle–tendon unit. This simple observation can be performed even in an obtunded or sedated patient, as can evaluation of tendon function by passively flexing and extending the wrist and observing the normal cascade of digit flexion with wrist extension and digit extension with wrist flexion ( Fig. 43.5 ). In the end, however, with most mangling injuries, definitive evaluation of tendon injury must wait for careful examination in the operating room.

Nerve injury is evaluated by examining both motor and sensory function. The motor function of the median, radial, and ulnar nerves is assessed by testing both extrinsic and intrinsic muscle function. Three simple maneuvers test motor integrity: (1) resistance to palmar abduction of the thumb reflects median nerve–innervated abductor pollicis brevis function, (2) resistance to flexion of the metacarpophalangeal (MCP) joint of the small finger reflects ulnar nerve–innervated flexor digiti quinti function, and (3) resistance to extension of the MCP joint of the index finger reflects radial nerve–innervated extensor digitorum communis and extensor indicis proprius function.

Accurate sensory examination is much more difficult, especially in patients with severe injury. By using a light touch and, if questionable, pinprick testing, a reasonable assessment can nevertheless be obtained. If the injury is in the palm or digits, attention is directed to digital nerve function, whereas if the injury is more proximal, attention is directed to independent areas of sensory function, such as the volar aspect of the index or middle finger for median nerve function, the volar aspect of the small finger for ulnar nerve function, and the dorsum of the first web space for radial nerve function.

With penetrating injuries, if you “think the nerve is probably OK,” it usually is not. Equivocal results on examination generally indicate an underlying injury that warrants exploration, whereas normal sensory results usually indicate an intact nerve. With blunt or blast injuries, however, nerve contusion and neurapraxia with the nerve in continuity are common. The threshold of suspicion for exploration of nerves in patients with penetrating injuries should therefore be much lower than with blunt or blast injuries.

Laboratory studies should be obtained at the time of initial evaluation, including a complete blood count with platelets, electrolytes, and any other tests appropriate to the clinical situation (e.g., blood gas analysis, toxicology screen, amylase, and others). In addition, if there has been significant bleeding or considerable bleeding is anticipated during surgery, blood for typing and cross-matching should be obtained at this time.

Amputation/Skeletal Contribution

According to the guidelines of the American Medical Association (AMA) for evaluation of permanent impairment, the thumb accounts for 40% of hand function, the index and middle fingers for 20% each, and the ring and small fingers for 10% each. These contributions should be kept in mind when deciding between reconstruction/replantation versus amputation. In the case of mangling injuries, however, these relative contributions do not always apply. For example, with loss of the three central digits, the small finger effectively assumes 50% of hand function.

As discussed previously, surgeons must use their knowledge, experience, and best judgment in an effort to predict a patient’s ultimate function with amputation versus reconstruction and with the various reconstructive options. The factors of patient age, health, drug or nicotine use, occupation, and willingness and ability to undergo complex or multistage reconstructive procedures and rehabilitation must be taken into account. The topics of amputation, replantation, and thumb reconstruction are covered elsewhere in this text, and the reader is referred to these sections for more detailed coverage of the topics.

The thumb is, of course, the most important digit to preserve or reconstruct. The issues related to thumb amputation are discussed in Chapter 48 and vary depending on the level of injury. Interphalangeal (IP) joint motion and the distal phalanx are of relatively lower importance to preserve than multiplanar carpometacarpal (CMC) motion and, to a lesser extent, MCP motion. The ability to bring the thumb out of the plane of the hand and into a position of opposition is a key function that must be restored. If the thumb cannot be preserved, consideration should be given to primary pollicization ( Case Study 43.2 ). FLOAT NOT FOUND

The index finger is also important to preserve because of its independent profundus flexion and ability to abduct for precision pinch functions. Without good function and sensibility of the proximal interphalangeal (PIP) joint, however, the index finger is often bypassed in favor of the middle finger because it can be more of a hindrance than help. Index ray amputation can often improve function by opening the first web space. ^, Amputation at or proximal to the PIP level leaves only the intrinsic muscles for digit flexion, which is then limited to about 45 degrees. The long and ring fingers are important primarily for grip and grasp functions, although either can take over pinch functions for the radial digits if they are lost. Solitary loss of the ring finger probably results in the least associated functional deficit of all the digits. The small finger, even though it has the least flexion strength, is actually quite important in hand function in that it defines hand width for grip functions, use of tools, and other applications. An important component of this function is the significant CMC motion of the small finger that comes into play with terminal grip. This action has been called “ulnar opposition” by some authors.

With amputation at the proximal aspect of the middle phalanx (P2), PIP, or especially the MCP level, ray amputation also needs to be considered. Although ray amputation is usually esthetically preferable to a partial finger amputation, function can suffer. For the index finger, power grip, key pinch, and supination strength are diminished approximately 20% and pronation strength approximately 50%.

Loss of an isolated digit other than the thumb rarely results in significant compromise of hand function, and as Brown has noted, patient motivation is more important in regaining function than the actual digits lost. Loss of multiple digits, however, is common with mangling injuries and frequently results in significant functional deficits. Maintaining or reconstructing at least the thumb and one opposing digit is a minimum requirement for any type of pinch or grasp. Retaining or reconstructing an additional adjacent digit can nevertheless add significant function by providing lateral stability to the radial digit for power pinch and can allow three-jaw chuck pinch.

Joints

The choice of whether to salvage or fuse a joint is another decision that is often difficult. It is best made by weighing the potential loss of function from a given fusion or set of fusions against the risk for limited motion, pain, instability, or late arthrosis with reconstruction. Whenever anatomic articular congruity and ligamentous stability can be restored, reconstruction is usually worthwhile. When it cannot be achieved, the potential loss of function needs to be assessed. In general, distal interphalangeal (DIP) fusion of the digits or IP fusion of the thumb is tolerated well with limited loss of function. PIP joint motion is much more important to preserve. Littler and colleagues described the PIP joint as the “functional locus of finger function.”

Not only are fingers with fused PIP joints of little use for grip or grasp, but they also frequently get in the way and are easily injured because they do not follow the normal arc of the other fingers. An additional problem, though less so with the index finger, is the quadriga effect, which can occur when profundus excursion is impaired with arthrodesis. Although delayed arthroplasty can be considered, combined injuries involving the joint, nerve, and soft tissue, in the presence of an unreconstructible PIP joint, warrant serious consideration for amputation, especially of the ulnar two digits.

The MCP joint is perhaps the most important joint in terms of function for the index through small fingers in that it contributes 77% of the total arc of finger flexion. Most activities, however, do not require the full arc of MCP motion, and in fact as little as 35 degrees of motion can be acceptable if that arc is within the key functional range and the joint is stable. To that end, stable but markedly limited MCP motion, even arthrodesis, is far superior to an unstable, painful MCP joint ( Fig. 43.7 ).

The decision to perform partial or total wrist fusion is seldom made in the acute setting unless there is extensive, unreconstructible loss of articular surface. Usually, this decision is deferred until late function and pain can be better assessed, at which time elective arthroplasty or arthrodesis can be performed. Studies have shown that as little as 5 to 10 degrees of flexion and 30 to 35 degrees of extension are needed for most activities of daily living. ^, When wrist-level amputation is required, preservation of some wrist motion can be incorporated into mechanical prostheses, and preservation of an intact distal radioulnar joint can significantly improve pronation and supination under loading conditions. The functional benefit of preserving the distal radioulnar joint in a wrist-level amputation, although attractive in theory, has never been proven in practice.