Figure 1. Anteroposterior radiograph of the left hand
Figure 2. Lateral radiograph of the fourth digit
A 32-year-old woman presents with pain and deformity to the fourth digit of the left hand. She reports jamming her finger while playing basketball 2 days earlier. On physical examination, she has a flexion deformity to the distal interphalangeal joint (DIP) and is unable to extend the joint. Anteroposterior and lateral radiographs of the left hand are taken (Figures 1 and 2).
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A mallet finger is a common injury that must be recognized and treated promptly or a permanent extensor lag deformity of the finger can result.1,2 A mallet finger is a bony avulsion or soft tissue rupture of the extensor tendon from the base of the dorsal distal phalanx.1
Treatment of a mallet finger involves putting the DIP in an extension splint as soon as possible after the injury. The splint should be up to the proximal interphalangeal joint (PIP) but not past to allow for PIP joint motion. Several types of splints can be used such as the common stack split and dorsal or volar aluminum foam splints. The extension splint should be worn at all times (24 hours per day) for 6 to 8 weeks. The DIP joint must be kept in extension if the splint is taken off for hygiene.1.2
Surgical fixation may be necessary if the bony avulsion fracture involves greater than 50% of the joint surface and there is a greater than 2 mm gap. Volar subluxation of the distal phalanx also is an indication for surgery, which usually involves percutaneous pin fixation. Some extensor lag may occur even after 100% compliance with splinting but this rarely impairs finger function.1,2
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 Orthopaedics for Physician Assistants.
1. Bendre AA, Hartigan BJ, Kalainov DM. Mallet finger. J Am Acad Orthop Surg. 2005;13(5):336-344. doi:10.5435/00124635-200509000-00007
2. Alla SR, Deal ND, Dempsey IJ. Current concepts: mallet finger. Hand (N Y). 2014;9(2):138-144. doi:10.1007/s11552-014-9609-y