Hand and Wrist Reconstruction: Microsurgery and Replantation

Peter C. Rhee, DO, MSc

Rudolph H. Houben, MD

Allen T. Bishop, MD

Dr. Rhee or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Trimed and serves as a board member, owner, officer, or committee member of the American Association for Hand Surgery, the American Society for Surgery of the Hand, and the Clinical Orthopaedic Society. Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Houben and Dr. Bishop.

ABSTRACT

The mangled upper extremity consists of severe injuries to the bone, soft tissues, vessels, and/or nerves with associated contamination. Management of the mutilated hand and wrist starts with a thorough assessment of injured structures and should focus on radical initial wound débridement and excision of nonviable tissue. A goal-directed approach should be maintained to systematically reconstruct the upper extremity while preventing infectious complications, minimizing residual deformity, and restoring function. When amputations are present, adherence to the principles of replantation and revascularization can result in successful limb salvage.

Keywords: Amputation; damage control; débridement; limb salvage; mangled upper extremity; replantation; revascularization

Introduction

The mangled upper extremity can pose tremendous challenges in the acute and reconstructive stages. A mangled upper extremity is defined by trauma that results in severe injuries to three of four tissue types, such as bone, soft tissues, vessels, and nerves.¹ The trauma is typically a result of a high-energy injury with a crushing, tearing, and/or cutting mechanism that is often associated with marked contamination and segmental loss of the previously mentioned tissue types.² Successful reconstruction of the mangled upper extremity is largely based upon the outcomes of the initial surgical treatment that in turn is dependent on the adequacy of débridement. Once a stable bony framework and a clean, viable wound bed have been established, staged reconstruction can be performed toward the goal of achieving a functional upper extremity.

Reconstruction of the Traumatized Hand and Wrist: Principles of Treatment

Goals of Treatment

The primary goal in managing the patient with a mangled upper extremity is to preserve life. Often in the setting of the mangled upper extremity, patients may have sustained other life-threatening injuries, thus “life before limb” always remains the chief priority. In line with preservation of life, all sources of hemorrhage must be emergently controlled with pressure, tourniquets, or direct vessel ligation to prevent fatal exsanguination. In severe cases, a completion amputation should be considered in the hemodynamically unstable patient with a hemorrhagic, mangled upper extremity.³ Otherwise, the guidelines set forth by the Advanced Trauma Life Support program should be followed.

An early assessment of the viability of the injured upper extremity will provide a clear indication between attempting limb salvage or proceeding with early complete amputation. Careful consideration should be performed to determine if the morbidity of multiple failed attempts at reconstruction or the limited function that can be expected with limb salvage outweigh the benefits of proceeding directly to a primary amputation.³ However, unless the mutilated upper extremity is clearly beyond the indication for limb salvage, the initial management should be directed toward limb salvage.

Acute management of the mangled upper extremity must be goal-oriented which includes preventing infectious complications, minimizing residual disability, and restoring function. An important concept in limb salvage
requiring multiple staged procedures is that the surgeon who will be performing the limb reconstruction should be involved in surgical planning from the initial débridement. The reconstructive surgeon must visualize the end result and the pathway in which that can be achieved.⁴ Thus, staged procedures, such as incisions, skeletal fixation, vascular repair, and soft tissue coverage, can be strategically planned in a sequential fashion toward the end goal without inadvertently eliminating a surgical option secondary to poor and disjointed planning.

Biomechanics of Hand Function

Understanding the functional role of each digit in the hand is necessary when initially managing the mutilated hand. The index and long fingers serve as stable posts upon which an opposable thumb can perform various forms of pinch. Ulnarly, the ring and small finger act as mobile units, afforded though the motion at the carpometacarpal joints, to perform several forms of grasp. Lastly, the hand rests upon the wrist that positions the hand in space and can optimize digit function and strength.

To perform basic tasks, the mutilated hand must be reconstructed with some structural principles. At a minimum, the hand requires a stable wrist with two opposing digits that are stable enough to withstand the force of pinch.⁵ In addition, a cleft must be present between the two digits to accommodate prehensile movement and the digits must be pain-free and senate. Most importantly, a stable wrist is mandatory to preserve the forces generated by the extrinsic flexor and extensor tendons that are exerted onto the remaining digits. Although loss of the thumb can be restored with free toe-to-thumb transfer, the highest priority should be toward salvaging the thumb given the fact that its loss results in a 40% loss of function and 25% loss of total body function.⁶

Patient Assessment

Patient Characteristics

The patient’s preinjury functional status, occupation, handedness, general medical status, psychology, and socioeconomic status are important factors that influence the results of reconstructing the mangled upper extremity.⁷ Additionally, comorbidities such as diabetes or cardiopulmonary disease can affect the outcomes of limb salvage as well and should be considered in the overall assessment of the patient.⁶^,⁸ All of these factors, in concert, will determine the physiologic drive of the patient to heal their injuries and to participate in the rehabilitation after their definitive reconstructive procedures.

Injury Characteristics

The mechanism of injury is another important factor when determining the appropriate management of the mutilated hand and wrist. The zone of injury from a sharp penetrating mechanism will be considerably less than that of a blast injury. Similarly, a crush injury will typically not have the degree of contamination as an agricultural or industrial injury. These various mechanisms have implications on the management of associated skeletal, neurovascular, and soft-tissue injuries. Additionally, time from injury to presentation is also of importance since irreversible tissue necrosis can occur with prolonged ischemia. The recommended ischemia time prior to replantation or revascularization for the digits is 12 hours of warm and 24 hours of cold ischemia.⁶ In more proximal levels of injury, 6 hours of warm and 12 hours of cold ischemia are the recommended limits for attempted limb salvage.⁹

Injury Severity Scores

Although predictive scores can be calculated to guide the decision for limb salvage versus primary amputation in the mangled lower limb, it may not be applicable to the upper extremity.¹⁰ The Mangled Extremity Severity Score (MESS) takes into account the age of the patient, magnitude of shock based on the systolic blood pressure, limb ischemia, and the extent of bone and soft-tissue injuries to predict the success of limb salvage.¹¹ An injured limb with a MESS of seven points or higher is recommended to undergo amputation. However, the MESS was devised for the lower extremity that inherently has greater muscle mass and less collateral circulation than the upper extremity.

A hand specific injury severity score may be predictive of final outcome after limb salvage. The Hand Injury Severity Score (HISS) was developed to measure the extent of hand injuries and to permit comparisons of treatment results between institutions.¹² It takes into account the severity of injury to the skin, bone, tendon, and nerves of each finger with a score ranging from 0 (no injury) to 826 (maximum severity).¹³ Matsuzaki et al noted that the HISS could be utilized to accurately predict the functional outcome and return to work status in patients who had sustained mutilating hand injuries.¹³

Initial Management

Damage control procedures in the acute stage include wound débridement, irrigation, bone stabilization, revascularization, fasciotomy, and temporizing soft-tissue coverage or placement of a negative-pressure wound therapy dressing. Upon initial evaluation, the
patient should be administered intravenous antibiotics and tetanus toxoid. If the patient has not received a tetanus booster within the past 5 years, tetanus immunoglobulin is also administered.¹⁴

Wound Débridement

Although radical excision is the mainstay of initial wound débridement, marginal tissue should be preserved and excessive skin excision should be avoided in the initial débridement.³ Color, consistency, contractility, and the capacity to bleed are the dogmatic tenets of assessing muscle viability; however, the surgeon’s distinction of muscle viability in the mangled upper extremity is often incorrect. Sassoon et al¹⁵ noted that in 35 muscle specimens that the surgeon declared as nonviable or necrotic, 21 (60%) specimens were identified as normal or mildly inflamed under histologic evaluation and were erroneously excised. Therefore, débridement should be aggressive; however, marginal tissue can be observed between serial débridement to allow for declaration of viability.

The principles of wound débridement are outlined in Table 1. Bone fragments with viable soft-tissue attachments and no significant contamination should be left in place to be utilized for later reconstruction.³ In addition, intact longitudinal structures such as blood vessels, nerve, and tendons should be preserved to enhance final function in the hand.³ In more proximal levels of injury where completion amputation may be necessary, the uninjured distal segment or the “spare part” can be utilized as a free tissue transfer to provide soft-tissue coverage to preserve residual limb length.¹⁶ Similarly, vascularized skin flaps should not be excised as they can be utilized as fillet flaps to cover adjacent areas of soft-tissue loss (Figure 1).

If possible, wound débridement should be performed under tourniquet control to permit adequate visualization during wound exploration and to limit blood loss.¹⁷ The bloodless field afforded through the use of a tourniquet allows for a thorough and expeditious exploration of the wound to systematically evaluate and detect any injured structures.² Once all critical structures have been examined, release of the tourniquet and the resultant hyperemia will provide an assessment of tissue viability and declare those areas of nonviable tissue that should be radically excised.

Table 1 Principles of Initial Wound Management

Radical initial débridement
Restore tissue viability
Relieve the pressure of hematoma
Systematically inspect all structures
Preserve as much viable skin as possible
Preserve all surgical options

Figure 1 Photographs demonstrating the use of a vascularized skin as a fillet flap. Patient sustained traumatic loss of the second ray with preservation of the vascularized volar soft tissue (A). This skin flap was utilized to cover the area of soft-tissue loss on the dorsum of the hand (B).

High-pressure irrigation should not be performed in heavily contaminated wounds to prevent driving contaminants deeper into the tissues and causing pressure-related soft-tissue damage.¹⁴ The addition of antibiotics or soap into the irrigation does not provide any supplementary benefit and may even lead to higher revision surgery rates.¹⁸^,¹⁹ It is recommended to irrigate the wound with copious amounts of sterile normal saline under a low-pressure system.

Skeletal Injuries

In the initial stage, fractures within the hand and wrist should be stabilized to achieve and maintain proper length, rotation, and alignment. Due to the magnitude of soft-tissue contamination and other associated injuries, anatomic reduction and internal fixation should not be performed.²⁰ In the hand and carpus, Kirschner-wires (K-wires) are typically utilized while in the wrist and forearm (Figure 2), external fixation is most effective in providing fracture stability. Wrist spanning plate fixation can be utilized in the acute and subacute setting for select cases and is dictated by the degree of contamination and soft issue injury.²¹ In the presence of multilevel injuries in the upper extremity, stabilizing structures from a proximal to distal direction is recommended to restore a stable foundation upon which the reconstruction of more distal structures can be performed.

Figure 2 Initial skeletal fixation in a mutilated hand with Kirschner-wires. Photograph showing that the patient sustained multiple soft-tissue (A) and skeletal (B) injuries in a rollover motor vehicle accident. Injury (B) and postoperative (C) PA radiographs are shown.

Injuries to the hand can lead to soft-tissue and intrinsic joint contractures which can be extremely limiting. Injuries to the radial side of the hand can often lead to first web space contractures from crush or avulsion mechanisms and even from minor lacerations. Therefore, these contractures should be prevented with temporary K-wire transfixation or external fixation of the first ray in maximal palmar and radial abduction (Figure 3) for the first 4 to 6 weeks. Similarly, any trauma to the hand, carpus, or wrist can result in metacarpophalangeal (MCP) joint extension contractures secondary to a variety of reasons, mainly due to the sequelae of edema within the periarticular structures.²² This can be prevented by positioning the MCP joints in a flexed position with either an orthosis or temporary MCP joint K-wire transfixation with early range of motion.

Skeletal defects can be initially managed with antibiotic-impregnated polymethyl-methacrylate (PMMA) cement spacers to provide local antibiotic delivery, obliterate the dead space, and stimulate the formation of an induce membrane.²³^,²⁴^,²⁵ Bishop et al²⁶ noted that vancomycin eluted from PMMA cement at an increasing volume of up to 8 days and continued to be observed in the effluent until 60 days. Aho et al²⁷ performed a histologic evaluation of an induced membrane that was consistent with a maturing, vascularized fibrous tissue with the highest membrane samples of osteogenic factors such as VEGF, IL-6, and Col-1, at 4 weeks of age. Based on these findings, a staged secondary procedure for cement spacer removal and bone grafting should be performed at approximately 4 to 6 weeks after initial cement spacer implantation.²⁵^,²⁷

Vascular Injuries

Vascular injuries must be expediently addressed to reestablish blood flow when distal perfusion is absent. Arterial injury involving the brachial artery may still provide adequate perfusion distally through an intact profunda brachii artery and its collateral vessels that span the elbow.²⁸ Similarly, in the presence of an intact superficial and/or deep arch, perfusion to the hand can be present despite transection of either the radial or ulnar artery. As such, either artery can be ligated in the acute setting if the hand remains perfused. However, if critical ischemia is present, revascularization must be performed.

Vascular shunts can be inserted to temporarily establish blood flow prior to definitive revascularization when other life-preserving procedures are being performed, during patient transport to a facility that can provide higher level of care, or prior to performing skeletal stabilization techniques.²⁹ Shunts are intended to be temporary, up to 6 hours, until definitive vascular repair or reconstruction can be performed urgently. The use of routine systemic anticoagulation with vascular shunts is debatable; however, it is recommended in stable patients who do not have any other contraindications.²^,³^,²⁹ Nonetheless,
prolonged use of intraluminal shunts have been reported patency up to 52 hours without systemic anticoagulation.³⁰

Figure 3 Radiographs demonstrating the prevention of first web space contracture. Patient sustained a blast injury to the first web space (A). At the time of initial management, the trapeziometacarpal joint was temporarily transfixed with a Kirschner wire to keep the joint reduced while maintaining the first ray in maximal palmar and radial abduction (B).

Revascularization in the mangled upper extremity often requires vein graft reconstruction due to the extensive zone injury and segmental vessel loss. Paramount to successful vessel reconstruction is a healthy and clean wound bed. This can be facilitated by performing a thorough débridement and obtaining adequate vein graft length that can be routed out of the zone of injury. Fox et al³¹ noted that in eight mangled extremities that required amputation after vascular reconstruction, five were associated with contaminated wounds and infected grafts. It is of utmost importance to provide soft-tissue coverage over vein grafts and ligated arterial stumps which may otherwise desiccate and/or breakdown the anastomosis leading to complications such a thrombosis or hemorrhage.³²

Nerve Injuries

Acute primary repair of traumatic nerve injuries in the mangled extremity is challenging due to the inability to macroscopically detect the zone of injury which may lead to a neuroma-in-continuity or failure of nerve regeneration if the coapted nerve ends undergo progressive fibrosis. Therefore, it is advocated to place a large, colored suture temporarily into the nerve stump that can also be sutured into the adjacent tissues to prevent retraction and aid in identifying the nerve during a staged secondary procedure (Figure 4).³ In addition, segmental nerve loss is common in high-energy trauma to the upper extremity and tension-free primary repair is often not possible necessitating nerve graft or conduit reconstruction.³³ Thus, it is recommended to stage nerve reconstruction until the zone of neural injury has declared itself and the wound bed is clean, well-vascularized, with adequate soft-tissue coverage.³⁴

Soft-Tissue Injuries

Primary closure should not be performed in the mangled upper extremity and wounds should be left open to allow for egress of contaminated fluid while minimizing soft-tissue tension on the wound periphery which otherwise could lead to progressive tissue necrosis and potentiate the risk of infection.³^,¹⁴ Emergency-free soft-tissue coverage has been advocated in the past to
minimize the development of severe infection; however, with the advent of negative-pressure wound therapy (NPWT) and dermal substitutes, emergent-free or pedicle soft-tissue transfer is not necessary.³⁵ In fact, in areas of contaminated soft-tissue loss, NPWT can promote granulation and angiogenesis, remove edema, and reduce wound surface area that can even obviate the need for free tissue transfer.³⁶ However, caution must be maintained when applying a NPWT dressing over exposed tendon, nerve, or vascular structures as secondary injuries can occur.

Figure 4 Photographs demonstrating the identification sutures placed into transected nerve stumps. This patient sustained a gunshot wound into the brachium that resulted in transection of the median nerve and the brachial artery that required vein graft reconstruction. The nerve ends were tagged with sutures (blue suture held by forceps) to prevent retraction and to facilitate later identification (A). At the time of staged nerve reconstruction, 4 weeks from injury, the tagging sutures (blue sutures held by forceps) were easily identified amidst the scar tissue to assist with nerve stump exposure (B).

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