Review Question - QID 218821

This patient presents with a boney mallet injury without distal interphalangeal joint (DIPJ) subluxation, which should be treated with a trial of DIPJ extension splinting for a minimum of 6 weeks.

Mallet finger injuries occur secondary to disruption of the terminal extensor insertion along the dorsal aspect of the distal phalanx. They can result from a hyperflexion moment (i.e avulsing the terminal extensor tendon insertion) or from an axial load on an extended finger (i.e. boney injury from the abutment of the distal phalanx on the head of the middle phalanx). In the setting of stable “boney mallet” injuries, full-time splint immobilization is recommended for a duration of 6 weeks. Isolated tendinous disruptions require at least 8 weeks of full-time splint immobilization to account for the longer duration required for tendon healing compared to that of bone. Even in a delayed presentation (>1 month from injury), a period of full-time splinting can lead to acceptable outcomes and negate the need for surgical intervention. Ultimately, patient compliance is the key to successful nonoperative management with full-time DIPJ extension splinting immobilization. Additional immobilization of the proximal interphalangeal (PIPJ) and metacarpophalangeal (MCPJ) joints does not result in improved outcomes, and therefore a stax splint is often utilized for ease of use (Illustration A).

Sivakumar and colleagues reviewed the epidemiology, pathophysiology, and treatment options for acute mallet fingers. They discuss that closed tendinous injuries and closed osseous injuries can be treated with extension splinting as long as there is acceptable joint alignment without DIPJ subluxation. If the injury is open or the DIPJ is unstable with joint subluxation despite splinting immobilization, open or closed reduction internal fixation should be sought. The authors conclude that the majority of these injuries can be treated with nonoperative management.

Bendre and colleagues provided an in-depth review of the anatomy behind mallet finger injuries and the various treatment options. They emphasized that the vast majority of mallet finger injuries can be treated with nonoperative management, with surgery reserved for failed nonoperative treatment or grossly unstable fractures with DIPJ subluxation. They conclude that patients should be informed of the potential for residual extensor lag and the development of swan neck deformity despite the type of management pursued.

Figure A shows the lateral radiographic imaging of this patient’s finger with a boney mallet injury. The avulsed bone fragment is relatively small (~25% of the articular surface) and the joint is well reduced even without being placed in full extension. Illustration A shows a commercially available stax splint.

Answers 2-5: A number of fixation strategies have been reported for unstable (subluxated) boney mallet injuries including screws, plates, wires, or sutures. All of these methods have been shown to be appropriate fixation strategies, depending on the fracture pattern and the size of the osseous fragment. Fusion is often a last resort option in chronic injuries. Deformity correction may also be addressed at the time of fusion. However, in the setting of a boney mallet finger with a small avulsion fragment and well-reduced DIPJ, a trial of extension splinting should first be attempted.