Hand and Proximal Replantation
In their report on the first successful arm replant, Malt and McKhann remark that “the arm is progressively more valuable from shoulder to fingers; the leg, on the contrary, is progressively of less significance.”1
Function of the upper extremity is highly dependent on the dexterity and sensory feedback of the hand. Once amputated, its function is only marginally replicated with modern prosthetic technology, and a successful replantation offers markedly improved quality of life.2,3
The elbow and shoulder serve as a platform to position the hand in space, and even in proximal amputations or in cases where the hand is not salvageable, the restoration of a functional elbow through repair or reconstruction is valuable to remaining upper limb function, application of pros-theses, and quality of life.
The overlying theme must remain, however, that no single extremity is worth a patient′s life. Specific injury factors, patient factors, and timing of intervention are critical determinants of replantation success and functional outcome. Limb replantation remains an elective procedure, with prolonged recovery, a likelihood of secondary surgeries, and inherent risks.
Replantation is most successful in a healthy child or young adult with a sharp incomplete amputation distal to the midforearm, seen within 6 hours, with stable physiological status and high rehabilitative potential ( Fig. 53.1 ).
The actual age range for replantation is not defined. Functional demands, health status, and rehabilitation potential are more relevant factors.4
Injury type is an important consideration. There is a higher success rate following a guillotine-like amputation as compared with avulsion or crush-type amputations.
Incomplete amputations have a higher success rate following replantation than complete amputations.
Tissue-specific timelines for the beginning of irreversible tissue loss at normothermia are: 4 hours for muscle, 8 hours for nerve, 13 hours for fat, and 24 hours for skin ( Table 53.1 ).
The time to reestablishment of blood flow is one of the most important determinants of successful arm replantation, with the general timeline for replantation being 12 hours of cold ischemia and 6 hours of warm ischemia ( Table 53.2 ).
Reestablishment of the arterial inflow is the highest priority. Arterial and venous shunts are considered in cases where the definitive repair is delayed.
Unstable physiology such that further bleeding, prolonged surgery, physiological shifts, or other factors are a threat to life
Preexisting significant cardiopulmonary disease
Insufficient vessel integrity for repair or interposition grafts, or loss of distal capillary integrity
Inadequate bone for stable fixation
Severe broad crush injury of muscle and other tissues
Inability to participate in a rehabilitation program due to mental impairment or psychiatric illness
Evidence of irreversible tissue loss
Broad crush injury of muscle and other tissues, dependent on severity
Time to reperfusion exceeding the timelines for replantation
Preexisting mild to moderate cardiopulmonary or metabolic disease (vascular disease, diabetes, renal failure, or a prolonged history of smoking)
Impaired mental status with poor rehabilitation potential or risk of reinjury
Social history of drug dependence or severe alcohol abuse
Prolonged duration of rehabilitation (6–24 months) and possible secondary procedures not being acceptable to patient due to occupation, family concerns, or social situation
Examination and Imaging
The amputated extremity should be viewed as a distraction from the initial evaluation and resuscitation of the patient.
The vital signs and general physical status are examined and addressed first, including airway management, ventilation, and circulatory support.
A focused local examination is done in a timely manner to evaluate the condition of the vessels, nerves, and muscles secondary to the injury.
Radiographs are performed to identify the extent of the bony injury and determine the options for stable fixation, where time allows ( Fig. 53.2 ).
A complete blood count and coagulation series is done immediately and after resuscitation to assess for the degree of blood loss and coagulopathy.
Upper limb replantation involves the identification and repair of numerous structures.
The mechanism of injury aids surgical planning.
Sharp amputations tend to have well-localized trauma to the bone and muscle and to have vessels and nerves that are more readily identified and repaired ( Table 53.3 ).
Recommended maximum time from injury
Traction-avulsion mechanism amputations have broader zones of injury to vessels and nerves and may be more difficult to identify.
Vessels tend to tear off from the distal part, but close to the fracture.
Nerves tend to tear off from the proximal segment.
Tendons tend to tear at the musculotendinous junction.
Broad crush injuries have diffuse muscle damage and may have vessel occlusion despite apparent continuity. There may be associated segmental bone loss or fracture comminution, which precludes attempts at stable fixation.
The amputation site is wrapped in a gauze dressing and the bleeding is addressed with compression ( Fig. 53.3 ).
Tourniquets are not used before surgery to avoid additional ischemic tissue injury.
The amputated part is wrapped in a saline-moistened gauze in a plastic bag or container and cooled on ice.
Temporary vascular shunts are considered in cases where the definitive repair is delayed, such as for maintaining limb viability for long transport times.
This is particularly useful in incomplete amputations.
Complete amputations require a venous shunt also, or the patient may exsanguinate during transportation.
The shunts should be inserted and secured by a surgeon who is comfortable with the technique in the controlled setting of an operating room.
This adds time to the patient transport and carries the risk of exsanguination even after the shunts are secured, and hence should be used with caution.
Mechanism of injury
• Well-localized trauma
• Narrow zone of injury
• Minimal avulsion or crush
• Broader zone of injury
• Vessels tend to tear from distal part, close to fracture
• Nerves tend to tear from the proximal segment
• Tendons tend to tear at musculotendinous junction
• Diffuse muscle injury
• Vessel occlusion despite continuity
• Diminished capillary flow
• Possibility of inadequate bone for stable fixation
The assistance of another surgeon, particularly one with experience with revascularization, expedites treatment and makes the procedure easier.
Temporary vascular shunts can quickly restore perfusion to the amputated part to allow appropriate debridement.
Shortening of the limb is well tolerated in the forearm and arm, with up to 4 cm tolerated in the forearm and 5 cm in the humerus.
Anticipate reperfusion injury to muscle and consider fasciotomy where appropriate. Temporarily fix the thumb in abduction to prevent adduction contracture.