Review Question - QID 211831

In a transverse proximal phalanx fracture, an apex volar deformity often develops with proximal fragment flexion and distal fragment extension.

Proximal phalanx fractures are difficult to treat secondary to displacement at the fracture site and the stiffness following operative treatment. Non-operative management is possible without rotation or angular displacement of the digit. However, less than 60% of active motion is maintained in younger patients following the non-operative management of proximal phalanx fractures. Soft tissue injury may further compromise soft digit mobility. The apex volar angulation at the fracture site, which can be difficult to manage in a closed manner, causes an extension lag at the PIPJ.

Vahey et al. performed a cadaveric analysis on extensor lag following proximal phalanx fractures. After the typical apex volar fracture posture. The average slope was 12degrees of lag for every millimeter of bone-tendon discrepancy. In a simulated apex palmar displacement angulation of 16 degrees, the PIPJ lagged by 10 degrees. The authors underscore the importance of establishing the bone-tendon relationship following proximal phalanx fractures.

The Meals family comprehensively review proximal phalanx fractures. Minimally displaced extra-articular fractures in compliant patients can be buddy taped for four weeks. Unstable fractures, intra-articular fractures (especially longitudinal unicondylar fractures of the proximal phalanx head) should be treated with fixation. Fixation allows for earlier range of motion which is critical to prevent stiffness. Open reduction internal fixation allows for immediate ROM a the risk of violating the extensor mechanism. The soft tissue sequelae of proximal phalanx fractures may be more significant than the boney injury.

Kozin et al. reviewed the operative management of proximal phalanx fractures. These can be treated closed with percutaneous pinning or open reduction internal fixation. Volar, Dorsal, or lateral approaches may be used for ORIF. Interfragmentary screws alone can be used in oblique fractures. Soft tissue trauma should be limited as much as possible to optimize range of motion postoperatively.

Illustration A is a radiograph showing an apex volar deformity of a transverse proximal phalanx fracture.

Incorrect Answers:
Answer 1: It is possible to develop a rotational deformity, but the classic deforming forces typically cause an apex volar position.
Answer 2: The interossei pull the proximal fragment into flexion, while the central slip pulls the distal fragment extends from the pull of the central slip.
Answer 3: This would represent an apex dorsal deformity, which is the opposite of the typical displacement.
Answer 4: The interossei pull the proximal fragment into flexion, while the central slip pulls the distal fragment extends from the pull of the central slip.