Figure 1. Lateral radiograph of mallet finger affecting the middle finger.
Figure 2. Photograph taken 1 month after removing splint.
A 34-year-old man presents 3 months after being treated for mallet finger to his right third finger. Lateral radiograph of the finger at the time of injury is shown in Figure 1. He was treated with an extension splint for 6 weeks followed by nighttime splinting for an additional 2 weeks. When he took the splint off last month, the deformity returned. He is now unable to extend the distal phalanx and has an approximately 45° flexion deformity to the distal interphalangeal joint (DIP) joint (Figure 2).
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Mallet finger is a disruption of the terminal extensor tendon where it attaches to the dorsal distal phalanx. The extensor tendon can avulse a piece of bone off (bony mallet) or be purely a soft tissue avulsion.1 The injury occurs as a result of a sudden forced flexion to the DIP joint.2 Treatment of acute mallet finger includes extension splinting of the DIP joint for 6 to 8 weeks. Residual extensor lag of 20° or less after treatment is considered a satisfactory outcome.2,3
Mallet finger presenting 4 weeks after injury (from either benign neglect or failed treatment) is considered to be a chronic injury. Extension splinting is recommended for treating chronic injuries and has a similar success rate to treatment of acute injuries. Surgical repair is reserved after failure of nonoperative treatment. A complication of mallet deformity may include the formation of a swan-neck deformity caused by compensatory hyperextension at the PIP joint.3
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Alla SR, Deal ND, Dempsey IJ. Current concepts: mallet finger. Hand. 2014;9(2):138-144. doi:10.1007/s11552-014-9609-y
2. Bendre AA, Hartigan BJ, Kalainov DM. Mallet finger. J Am Acad Orthop Surg. 2005;13(5):336-344. doi:10.5435/00124635-200509000-00007
3. Okafor B, Mbubaegbu C, Munshi I, Williams DJ. Mallet deformity of the finger: five-year follow-up of conservative treatment. J Bone Joint Surg Br. 1997;79(4):544-547. doi:10.1302/0301-620x.79b4.7432