BLAST INJURY OF THE FIRST COMMISSURE: CLASSIFICATIONS AND THERAPEUTIC STRATEGY

Abstract

Purpose: Blast injury of the hand generally occurs during manipulations of unstable explosives. The explosion greatly damages the first commissure. The aim of this study was to define a classification system useful for establishing therapeutic strategy.

Material and methods: From 1988 to 2002, we treated eight patients (nine hands, five dominant) with blast injury of the hand. Mean age was 24 years. Five hands were injured during manipulation of firecrackers and four during manipulation of munitions. The thumb was amputated on five hands, including three cases of index or medius amputation. Thumb revascularisation was successful in only one case. Two proximal thumb amputations were treated by twisted toe transfer. For one of these patients, the transfer was prepared by translocation of M2 on M1 using an inguinal flap. Two patients required a composite osteocutaneous reconstruction of M1 using the index as the bone source. In one final patient, lesions were limited to soft tissues.

Discussion: Blast injured hands present several types of lesions: extensive soft tissue damage, diffuse vessel damage making revascularisation difficult or impossible, combined thenar and joint lesions leading to secondary closure of the first commissure. We distinguished three stages. Stage 1 involves only muscle and skin damage. After opening the first commissure with M1-M2 pinning, cover is achieved with a posterior interosseous flap or a skin graft. Stage 2 involves osteoarticular damage. Bone loss of M1 and P1 is often associated with dislocation. Bone reconstruction is often achieved using the distally amputated or greatly damaged thumb. Stage 3 involves amputation or devascularisation of the thumb. Reconstruction of the thumb is particularly difficult in these cases. If the amputation is distal beyond MP, M1 lengthening or classical toe transfer can be used. If the amputation is proximal, prior M1 reconstruction is required with a skin envelope using M2 fashioned with an interosseous or inguinal flap, followed by twisted toe transfer of the second toe. Stage 3 translocations are difficult because of the often damaged index and scar formation.