Vascularized composite tissue part transfer for central hand defect reconstruction. Case report

Abstract

Injuries to the hand with loss of joints, tendons, nerves, and soft tissue may require complex, innovative reconstructive techniques to achieve a favorable functional and aesthetic outcome. We present a case of a manual laborer who sustained a multifaceted injury from a metal press machine with loss of composite structures including the long and ring finger metacarpophalangeal joints, flexor and extensor tendons, digital nerves, and dorsal/volar soft tissues. Reconstruction included using the spare parts technique for transferring his ring finger proximal interphalangeal joint as a pedicle to reconstitute the missing metacarpophalangeal joint of his long finger. The soft tissue from the ring finger was rearranged to provide aesthetic coverage of the hand with like-to-like reconstruction of the glabrous and non-glabrous skin.

Introduction

The metacarpophalangeal (MCP) joint contributes substantially to hand dexterity (1–3). In addition to providing 77% of the arc of finger flexion, the MCP joint permits lateral movement and circumduction to facilitate thumb opposition for pinch grip (3). Management of a severely traumatized MCP joint is an operative challenge as there is no established reconstructive algorithm. Treatment options include amputation, arthrodesis, interposition arthroplasty, and autologous joint transfer (1, 2). However, many of these surgical techniques leave much to be desired from a functional and aesthetic standpoint.

We present a case of a laborer who sustained a traumatic loss of his left long and ring finger MCP joints. Operative repair expanded upon Chase’s concept of spare parts to reconstruct the long finger MCP joint with a vascularized pedicled joint transfer of the intact proximal interphalangeal (PIP) joint from his ring finger (4). This technique restored the joint and flexor/extensor tendons simultaneously while matching glabrous and non-glabrous skin for soft tissue coverage.

Case Report

A healthy 32-year-old right handed man sustained a 6 cm circular defect in his left palm from a metal press injury. This resulted in loss of the MCP joints and associated flexor/extensor tendons of the ring and long fingers (Figure 1). Examination revealed diminished sensation to the ring finger and ulnar aspect of the long finger, but both digits were vascularly intact, as confirmed by Doppler ultrasound of the digital arteries.

Figure 1.

Pre-operative Data A: Pre-operative x-ray of the left hand demonstrating traumatic loss of the ring and long finger MCP joints; B, C: Intra-operative photograph representing the extent of soft tissue and joint loss.

Emergent wound exploration revealed uninjured digits distal to the amputated MCP joints, cleanly severed flexor and extensor tendons, and preservation of the vascular supply to the long and ring fingers on the radial and ulnar aspect of the digits, respectively. After the initial debridement, we discussed reconstructive options with the patient. Operative repair involved a pedicled joint transfer of the ring finger proximal interphalangeal (PIP) joint to reconstruct the long finger MCP joint. The ring finger was vascularized, but insensate, which provided a good source of tissue for composite reconstruction of the long finger.

A midaxial incision was made along the radial border of the ring finger to preserve both glabrous and non-glabrous skin. Skin flaps were elevated at the level of the PIP joint while avoiding the ulnar-sided neurovascular supply to the joint (Figure 2). We then transferred the ring finger PIP joint with sufficient bone length to replace the missing long finger MCP joint. The bone length needed was determined intraoperatively by measuring the bony defect between the long finger metacarpal and proximal phalanx. Because of trauma to the donor finger proximal phalanx, the new long finger metacarpal was short when compared to adjacent digits. To compensate, the new proximal phalanx was made longer. The pedicled joint was fixed proximally and distally with T-shaped plates. Fluoroscopy confirmed longitudinal alignment (Figure 2).

Figure 2.

Vascularized Pedicled Joint Transfer A: Intra-operative photograph demonstrating the ring finger PIP pedicled transfer to the long finger MCP joint; B: Intra-operative photograph verifying under fluoroscopy appropriate fixation of the transferred PIP joint from the ring finger to the MCP joint of the long finger

We then harvested a graft from the extensor tendon mechanism of the ring finger to reconstitute the defect in the transected extensor digitorum communis of the long finger. To repair the flexor apparatus, the remnant flexor digitorum superficialis (FDS) of the long finger was dissected free and tacked down to the periosteum of the pedicled PIP joint transfer to reconstruct the A1 pulley. An additional tendon graft, obtained from the flexor digitorum profundus (FDP) of the ring finger, was tunneled under the reconstructed A1 pulley and used to bridge the gap between the proximal FDP and distal remnant FDP of the long finger to provide independent flexion. All tendon grafts were repaired with the Pulvertaft weave technique proximally and distally.

The ulnar digital nerve of the long finger was severely contused and avulsed into the palm. Nerve reconstruction was not performed because of the need for a 10 cm nerve graft with additional donor site morbidity and unpredictable sensory recovery. A traction neurectomy was preformed to permit the proximal retraction of the nerve end. Soft tissue closure was completed using skin flaps from the transferred PIP joint. This matched glabrous and non-glabrous skin on the volar and dorsal aspects, respectively (Figure 3).

Figure 3.

Intra-operative skin closure of the filet flap with matching of glabrous and non-glabrous skin

The patient was started on the Duran tendon rehabilitation protocol with passive range of motion exercises at one week and place and hold exercises at 3 weeks. After 2 months, he had active flexion of his long MCP joint to 45 degrees and passive motion to 80 degrees (Table 1). However, motion at both interphalangeal joints was limited. X-rays obtained 6 weeks postoperatively revealed excellent bony alignment with callus formation.

Table 1.

Motion measurements for reconstructed long finger

Joint	Range of motion	Four months after pedicle joint transfer				Two months after tenolysis
		Active	Arc of Motion	Passive	Arc of Motion	Active	Arc of Motion	Passive	Arc of Motion
Long finger MCP	Extension Flexion	+16° 45°	61	+20° 80°	100	+16° 65°	81	+20° 80°	100
Long finger PIP	Extension Flexion	+20° 35°	55	+20° 60°	80	+15° 40°	55	+15° 75°	90
Long finger DIP	Extension Flexion	+20° 30°	50	+20° 60°	80	+25° 30°	55	+25° 55°	80

DIP: Distal interphalangeal joint, MCP: Metacarpophalangeal joint, PIP: Proximal interphalangeal joint.

Seven months after initial injury, the patient underwent left long finger FDP tenolysis from the reconstructed A1 pulley to the A2 pulley along with excision of an ulnar digital neuroma, which was causing him discomfort. His active arc of motion after tenolysis was 81 degrees at the MCP joint and 55 degrees each at the PIP and DIP joints. He was able to oppose his thumb to his long finger (Figure 4). Grip strength on the injured side was 18 kgs compared to 54 kgs on the opposite side.

Figure 4.

Six-weeks post-operative photos from the tenolysis surgery with arc of motion

Discussion

Reconstruction of the MCP joint after trauma poses a complex surgical problem. Amputation should be favored over preservation of a stiff and painful finger. If reconstruction is pursued, the surgeon must consider the patient’s functional and aesthetic expectations. Vascularized joint transfers of nonreplantable spare digits are advantageous because they minimize donor site morbidity and can provide a satisfactory functional outcome. By using a pedicle technique, our approach avoided microsurgical revascularization and matched non-glabrous and glabrous skin.

Vascularized MCP joint transfers, obtained from metatarsophalangeal (MTP) joints or spare nonreplantable digits, provide the joint in its entirety including capsule, bone, ligaments, and skin and offer the promise of a meaningful functional recovery (1, 5–6, 9). Given the proximity of a vascularly intact non-replantable digit, we performed a pedicled joint transfer. Although nonvascularized joint transfers are possible, they carry an elevated risk of degenerative deterioration and avascular necrosis, leading to decreased arc of motion (1, 5). By preserving the ulnar digital artery of the donor joint, we obviated the need for microsurgical anastomosis. The intact joint also provided an ideal scaffold for tendon reconstruction and allowed matching of like-to-like soft tissue coverage. Our patient preferred this reconstruction to avoid the morbidity of harvesting 2 MTP joints.

There were biomechanical implications of our joint reconstruction. The PIP joint is a hinge that contains tight collateral ligaments which limit lateral motion in all phases of flexion/extension (3). In contrast, the MCP joint is a condylar joint that permits lateral motion in extension and medial-lateral rotation of the proximal phalanx on the metacarpal to maximize thumb opposition (3). By using a hinge joint as our pedicle joint transfer, we expected limitations in lateral mobility and less finger pulp contact during thumb opposition. We did not reconstruct the intermetacarpal ligament; however, the lateral joint stability was intact due to the formation of scar tissue.

Functional recovery in our patient’s reconstructed long finger MCP joint was comparable to the literature, with extension/flexion 0/16°/65°. Reported active motion after vascularized PIP joint transfer is approximately 40 degrees (6). Hierner et al. described 2 heterodigital PIP to MCP joint transfers with extension/flexion of 0/20°/80° and 0/15°/70° (6). Decreased arc of motion observed in our patient (Table 1) may have resulted from either tendon adhesions, damage to the pulley system, or pain prohibiting aggressive rehabilitation. Furthermore, our long finger FDP repair resulted in a distal juncture in zone II of the flexor sheath, a location that is susceptible to adhesions that can inhibit PIP and DIP joint flexion. To avoid this issue we could have performed a multi-staged flexor tendon reconstruction with a graft spanning from palm to distal phalanx, but several operations in a highly traumatized hand would risk disrupting the blood supply to the vascularized joint.

Arthroplasty and arthrodesis were other reconstructive considerations. Arthrodesis with an iliac crest bone graft would have provided skeletal stabilization; however, arthrodesis of a single MCP joint can disturb overall hand function (2, 7). Alternatively, we could have used the scaffold operation described by Foucher et al., which can serve as a salvage procedure for patients with extensive metacarpal loss. This involves fusing the traumatized base of the proximal phalanx to an adjacent digit, allowing synchronous motion of the injured digit through movement of a healthy digit. Although an attractive concept, the scaffold operation would not have addressed the substantial soft tissue loss (8).

Arthroplasty, an excellent option for joint reconstruction, would offer improved arc of motion, decreased pain, and earlier return to work (9). Unfortunately, literature evaluating MCP joint salvage with implant-based arthroplasties in acute trauma is lacking (2). Furthermore, in the setting of complete joint loss, implant arthroplasty would have required a staged approach, starting with the placement of bone grafts. Swanson advocated that in trauma, arthroplasty should be reserved for patients with good soft tissue coverage, intact neurovascular supply, ample bone stock, and an unscathed tendinous system (10). Moreover, both arthrodesis and arthroplasty would have required flaps for soft tissue coverage.

Patient-specific factors and the extent of structural damage dictate the type of MCP reconstruction possible. Our pedicled joint transfers using a nonreplantable spare digit minimized donor site morbidity and provide a satisfactory functional and aesthetic outcome by matching like-to-like soft tissue.