Surgical Management of Swan Neck Deformity Following Mallet Finger Injury: A Review of 25 Patients Over 20 Years

Introduction: Swan neck deformity develops as a sequela of chronic mallet finger. Surgical management can include soft tissue reconstruction or distal interphalangeal joint (DIPJ) fusion. Studies examining the incidence and management of posttraumatic swan neck deformity following mallet fracture are limited. Methods: A retrospective, single-institution review of patients undergoing surgical management of swan neck deformity following a traumatic mallet finger from 2000 to 2021 was performed. Patients with preexisting rheumatoid arthritis were excluded. Injury, preoperative clinical, and surgical characteristics were recorded along with postoperative outcomes and complications. Results: Twenty-five patients were identified who had surgical intervention for swan neck deformity. Sixty-four percent of mallet fingers were chronic. Median time to development of mallet finger was 2 months. Twelve (48%) mallet fingers were Doyle class I, 6 (24%) were class III, and 7 (28%) were class IVB. Forty percent of injuries failed nonoperative splinting trials. Sixteen (64%) underwent primary DIPJ arthrodesis, 8 (32%) underwent DIPJ pinning, and 1 underwent open reduction and internal fixation of mallet fracture. The complication rate was 50% overall, and 33% of surgeries experienced major complications. The overall reoperation rate was 33%. Proximal interphalangeal joint hyperextension improved by 11° on average. Median follow-up was 61.2 months. Conclusions: The development of symptomatic swan neck deformity following traumatic mallet finger injury is rare. All patients warrant an attempt at nonsurgical management. Attempts at surgical correction had a high rate of complications, and DIPJ fusion appeared to provide the most reliable solution.