Outcome Differences between Conservatively Treated Acute Bony and Tendinous Mallet Fingers

Introduction: Tendinous and bony mallets are very different injuries that present with extensor lag at the distal interphalangeal joint. This study aimed to evaluate the differences in outcomes between acute bony and tendinous mallet fingers treated conservatively with splints. Materials and Methods: We retrospectively collected data on patients with acute tendinous or bony mallets who received conservative treatment in our occupational therapy clinic. The patients were examined at an outpatient clinic, where data on pain, extension lag, and loss of flexion were recorded. Outcomes were classified according to the criteria described by Crawford. Results: Data were collected from 133 patients (43 with bony and 90 with tendinous mallets). We found that bony mallet patients were predominantly younger (mean, 36 vs. 46 years), and more likely to be female (60% vs. 34%), than tendinous mallet patients. We also found that tendinous mallet injuries predominantly affected the middle and ring fingers, while bony mallet injuries predominantly affected the ring and little fingers. The initial extensor lag was worse in tendinous than in bony mallets (median, 28° vs. 15°). In addition, patients with bony mallets had significantly better outcomes with regard to the extension lag (median 0° vs. 5° p = 0.003) and the Crawford Criteria Assessment (p = 0.004), compared with those with tendinous mallets. Discussion: Mallet injuries, both tendinous and bony, are common. They are often studied together and typically treated in the same manner using extension splints. However, evidence clearly shows that these are different injuries which present in the same manner. This study reinforces these findings and suggests that the outcome of conservative treatment is better for bony than for tendinous mallet fingers.