Reconstruction of Severely Crushed Fingertip Amputations with Basic Fibroblast Growth Factor Slow Release System

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The treatment of fingertip amputations in subzone 2 (amputations between the eponychial fold and midpoint of the nail) according to Ishikawa’s classification is difficult and controversial when the amputated part is severely crushed. Simple replacement of the amputated part as a composite graft is prone to fail, whereas crush injury precludes microvascular replantation and establishing venous outflow is frequently unfeasible at this level. To achieve superior aesthetic and functional outcome, alternative reconstructive technique was proposed using the combination of local flaps to provide length and bulk to the finger pulp, and perionychial graft (nail matrix, hyponychium, and perionychium) from the amputated part to restore the nail.1 Though the flap increases the area of contact with a vascular bed and increases the survival rate of the graft, “tissue involving nail matrix grafted on the neurovascular pedicle flap” has not always taken with a high rate of success, and the loss of the nail matrix or distal phalanx can occasionally lead to a hooked nail deformity.2 Basic fibroblast growth factor 2 (b-FGF) is a potent mitogen for mesenchymal cells, and a local application of recombinant human b-FGF has been reported to accelerate take of the composite grafts3 as well as to facilitate bone union.4 Moreover, their effects were enhanced when a biodegradable gelatin microsphere was used as the carrier in a slow release system. We report here our technique of elevating an oblique triangular flap and applying osteo-onychial graft harvested from the amputated part to the dorsum of the flap, between which a b-FGF slow release system was introduced to the severely crushed fingertip amputations in subzone 2. Figure 1 demonstrates surgical procedures that consists of 4 steps; elevation of oblique triangular flap (step 1), preparation of osteo-onychial graft (step 2), topical application of b-FGF impregnated in gelatin microsphere (step 3), and combination of the graft on flap with distal phalanx fixation (step 4; see video, Supplemental Digital Content 1, which demonstrates the surgical procedure of fingertip amputation; this video is available in the Related Videos section of the Full-Text article on PRSGlobalOpen.com. http://links.lww.com/PRSGO/A467). Three patients have been treated with this method. In all cases, osteo-onychial grafts and local flaps survived satisfactorily without obvious hook nail deformity. Bone union was observed in all cases radiographically (Fig. 2). Our technique differs from others reported in that we graft hyponychium, nail matrix, and perionychium along with the underlying distal phalanx. Inclusion of distal phalanx into the graft is essential to prevent hook nail deformity. Taking the biologic nature of b-FGF into consideration, we believe that b-FGF can improve tissue viability of the complicated nail composites of the fingertip including distal phalanx even when they are severely crushed. When microvascular replantation is not possible and composite graft replacement is likely to fail with severely crushed injury, our technique can be an effective option. The extensive application of b-FGF slow release system may change clinical practice for various fingertip reconstructions, as it provides an amputated part with substantially good vascularity without microsurgical anastomosis.
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