Blast Injury to the Hand: Assessing the Injury Pattern and Functional Outcome of the Thumb

BACKGROUND: In the United States, approximately 30% of about 10,000 annual blast injuries involve the hand, causing a broad spectrum of injury severity. The first web space is typically most severely affected. As the carpometacarpal (CMC) joint is critical to the unique function of the thumb, we evaluated typical patterns of injury to this joint, subsequent salvageability and functional outcomes of the thumb. METHODS: We conducted a retrospective chart review on patients with blast injuries to the hand from January 1995 through July 2019 and excluded penetrating trauma. We assessed hand function as reported in occupational therapy records. Injury severity was classified independently by structures. RESULTS: Twenty-one patients were included, two with bilateral injuries, for a total of 23 hands. Eighteen patients had injuries to one or both thumbs, for a total of 20 thumbs evaluated. Average follow-up was 1.58 years. Most injuries qualified as severe in at least one category: soft tissue, neurovascular, or bone/joint. All 10 CMC joint dislocations required surgical fixation and pinning. Eight patients had applicable occupational therapy notes available. Severely injured thumbs had statistically significant decreased range of motion (ROM) at the interphalangeal joint, metacarpophalangeal joint and with radial abduction compared to mildly injury thumbs (P value 0.02, 0.03, 0.04, respectively). CONCLUSIONS: Blast injury to the hand often results in severe deficits, frequently affecting thumb functionality and irreversibly altering occupational capabilities. Half the patients studied had severe damage to the thumb CMC joint. Objectively, severely injured thumbs had significantly worse ROM than mildly injured thumbs.