Use of superficial palmar arch for bridging the gap in digital revascularisation.

Traumatic hand injuries resulting in segmental loss of common digital artery are not uncommon. To bridge the gap and repair of transected common digital artery, the superficial palmar arch could be divided proximally on radial side and turned distally to the common digital artery for revascularisation. Revascularisation of the transversely crushed common digital artery can be performed based solely on superficial palmar arch for revascularisation of the segmental loss of common digital artery. However, because of known variability in the palmar arch, intraoperative verification is needed to ensure safe transfer of arch.

INTRODUCTION

The decision to proceed with revascularisation in the upper extremity depends on several factors. These include the mechanism of injury and the patient's age, occupation, and overall medical condition. Transverse injuries of the hand involving a loss of segment of common digital artery can present as a challenge to the reconstructive surgeon. Primary repair of the common digital artery is difficult and may be achieved by shortening of metacarpal bone if associated with fractures. The repair of the common digital artery is likely to require vein grafting, as significant segmental loss of common digital artery often results due to injuries in this area. To bridge the gap and repair the transected common digital artery, palmar arch could be utilized by turning the arch distally to reach the common digital artery without vein graft.

CASE REPORTS

Case 1

A 23-year-old mill worker sustained a mutilating injury to his dominant right hand [Figures 1 and 2]. Radiograph of the right hand antero-posterior view showed fracture at the level of neck and shaft of the second, third, fourth and fifth metatarsal bones [Figure 3]. Intraoperatively, transection of the common digital artery was at the level of neck and shaft of the second, third, fourth and fifth metatarsal bones. Capillary refill of all the four fingers was inadequate. Skeletal fixation was achieved with Kirschner wires driven from the dorsum through metacarpal head. The hand was then turned over for exploration of the volar compartments. The flexor tendons and extensor tendons were intact. Dissection of the common digital nerve revealed contusion of nerve fibres, however, the fibres were intact. The common digital artery was found to be transected at the metacarpal neck level with segmental loss [Figure 4]. Primary repair was difficult, as there was segmental loss. To bridge the gap, the superficial palmar arch was dissected till its radial end, ligated, divided proximally and turned distally to reach the common digital artery of the index and middle finger. Then the proximal part of common digital branch to the index and middle finger, middle and ring finger could be utilized to revascularise the middle and ring finger, little finger simultaneously facilitating end-to-end repair without vein graft [Figure 5]. On release of the tourniquet, good blood flow into the fingers was noted [Figures 6 and 7]. Intraoperatively, the patient was started on low-molecular-weight dextran (dextran 40) that continued for 4 days. After an uneventful hospital course, the patient was discharged on the tenth postoperative day.

Figure 1

Crush injury right hand - volar view of case 1 in the case report

Figure 2

Crush injury right hand - dorsal view of case 1 in the case report

Figure 3

Radiograph of the right hand anteroposterior view showing fracture of proximal phalanx thumb and 2nd, 3rd and 4th metacarpal bone fracture of case 1 in the case report

Figure 4

Segmental loss of common digital arteries to fingers in case 1 in the case report

Figure 5

Superficial palmar arch for direct anastomosis in case 1 in the case report

Figure 6

Post operative picture - volar view of case 1 in the case report

Figure 7

Post operative picture - dorsal view of case 1 in the case report

Case 2

A 20-year-old mill worker sustained a mutilating injury to her dominant right hand [Figures 8 and 9]. Radiograph of the right hand antero-posterior view showed fracture at the level of neck and shaft of the second, third, fourth and fifth metatarsal bones [Figure 10]. Intraoperatively, transection of the common digital artery was at the level of neck and shaft of the second, third, fourth and fifth metatarsal bones. Circumferential crush was present over the ring finger proximal interphalangeal joint level [Figure 11]. Capillary refill of all the four fingers was inadequate. Skeletal fixation was achieved with Kirschner wires driven from the dorsum through metacarpal head. The extensor tendons and flexor tendons were intact. Dissection of the common digital nerve revealed contusion of nerve fibres. The common digital artery was found to be transected at the metacarpal neck level with segmental loss. Segmental loss was bridged by distally turning the radial end of the superficial palmar arch to reach the common digital artery of the index and middle finger. Then the proximal part of common digital branch to the index and middle finger, middle and ring finger was utilized to revascularize the middle finger, ring finger and little finger simultaneously, facilitating end-to-end repair without vein graft [Figure 12]. On release of the tourniquet, good perfusion was noted. Intra operatively, the patient was started on low-molecular-weight dextran (dextran 40) that continued for 4 days. Patient developed venous congestion and necrotic changes in the ring finger beyond PIP joint which necessitated ray amputation of ring finger. Index, middle and little fingers were viable [Figure 13].

Figure 8

Crush injury right hand - volar view of case 2 in the case report

Figure 9

Crush injury right hand - dorsal view of case 2 in the case report

Figure 10

Radiograph of the right hand anteroposterior view showing fracture proximal phalanx thumb, middle finger, index finger and fracture dislocation metacarpophalangeal joint index finger of case 2 in the case report

Figure 11

Segmental loss of common digital arteries to fingers of case 2 in the case report

Figure 12

Superficial palmar arch for direct anastomosis of case 2 in the case report

Figure 13

Late post operative picture of case 2 in the case report

DISCUSSION

The superficial and deep palmar arches provide the dominant blood supply to the hand, forming an intricate network of collateral flow.[1] As early as 1753, a Swiss anatomist, Albrecht von Haller, studied the anastomoses of the superficial and deep palmar arches with the ulnar and radial arteries.[2] In the nineteenth century, Tiedemann, Quain, Jachtschinski and later Lanz and Wachsmuth dissected a large number of cadavers and described variations of the palmar arches and their anatomical courses.[3] The progression of hand surgery and the advent of arteriography have made knowledge of the vasculature of the hand essential. Based on several cadaveric and radiographic studies, the vascular anatomy of the palmar arches is known for its great variability.[4] Conventionally, the superficial palmar branch of the ulnar artery and the superficial palmar branch of the radial artery supply the superficial palmar arch. Predominantly, the ulnar artery appears to contribute as the main feeding vessel.[1] In a classic study of 265 specimens, Coleman and Anson[5] classified the variations in patterns of the common digital arteries into seven categories. In 77.3 percent of the dissected hands, the most common pattern is of four common digital arteries leaving a complete superficial palmar arch. In 8.8 percent, only three common digital arteries are present along a complete arch. In the remaining variations, an incomplete arch is described, with all of the existing common digital branches originating independently from the superficial palmar branch of the ulnar artery. Reconstitution of arterial flow for revascularisation of hand at the common digital artery level depends on the anatomical configuration of the superficial palmar arch. Ideally, a single end-to-end primary arterial repair of the arch on its ulnar or radial aspect can obviate the need for two anastomotic sites, as is the case with vein grafting. If variations in the superficial palmar arch are present, the surgeon should test the expendability of the superficial branch of radial artery to avoid ischemia to adjacent digits.

Tonkin et al.[6] described the survivability of multiple digits in a transmetacarpal amputation based on the patency of one common digital artery repair. The digits on the amputated part were dependent on flow from the transverse commissural vessels that connected the digital vessels proximal to the proximal and distal interphalangeal joints. Retrograde flow to the adjacent common digital vessels revascularized the other digits. Nakamura et al.,[7] reported a case of metacarpal amputation of all fingers at the common digital artery level. After failed anastomosis of the second common digital artery, an end-to-end anastomosis of the third common digital artery resulted in flow to all four fingers. Angiographic evidence confirmed the presence of transverse branches originating at the digital artery level. Through the preserved bifurcations of the second and fourth common digital arteries, flow was diverted to the border digits. The presence of communicating branches that connect the radial and ulnar digital arteries has long been recognized. It appears that the presence of transverse branches had clinical importance in these special circumstances. These factors may add to the survival of the revascularized hand; however, we do not recommend relying on the presence of transverse vessels as a rule in the clinical setting. Superficial palmar arch could be safely transferred distally to the common digital artery for revascularisation of the fingers [Figure 14 and 15]; however, the possibility of utilising reverse radial forearm flap for resurfacing the palmar or dorsal defect associated with these types of injury may be compromised. The distance between the cut ends of the common digital artery was approximately 18 mm. Approximately 20 mm of the length of radial end of superficial palmar arch could be dissected from the common digital artery branch to index and middle finger which could be utilized for revascularization [Figure 16]. This principle could very well be utilized in case of transverse metacarpal amputation at the level of common digital artery were venous grafts may be avoided for establishing the circulation.

Figure 14

Schematic diagram representing the segmental loss of common digital arteries following transverse injury at metacarpal neck level

Figure 15

Schematic diagram representing reconstruction of the segmental loss of common digital arteries with superficial palmar arch

Figure 16

Schematic diagram to show the approximate length of radial end of palmar arch transferred for revascularisation

CONCLUSIONS

Revascularization of the transversely crushed hand is a challenging and rewarding experience for the reconstructive surgeon. Knowledge of the superficial palmar arch, its landmarks, and its anatomical variability is critical for successful revascularization. Nevertheless, inconsistency in arch configuration is quite common. Therefore, bridging the gap to repair the transected common digital artery, the superficial palmar arch could be safely transferred distally to the common digital artery for revascularisation.