Review Question - QID 217901

Proximal phalanx fractures with significant dorsal angulation (apex palmar) must be reduced in order to prevent functional extension lag associated with the chronic deformity.

Proximal phalanx fractures often displace with apex palmar deformity secondary to the central slip extending the distal fracture fragment and the intrinsic musculature flexing the proximal fracture fragment. This deformity results in the loss of the moment arm of the extensor tendon secondary to overall functional shortening of the proximal phalanx. Similar to metacarpals, there is a linear relationship between proximal phalangeal shortening and resultant extension lag observed at the level of the proximal interphalangeal joint.

Faruqui et al. performed a retrospective review of fixation strategies for extra-articular fractures of the proximal phalanx. They found that extra-articular cross pinning and trans-articular techniques result in similar outcomes with both being acceptable treatment options. They concluded that closed pinning minimizes soft tissue damage and allows early range of motion of the digit, however, there is no superiority in comparing these two fixation strategies.

Henry et al. reviewed treatment options for metacarpal and proximal phalanx fractures. They discuss that chronic apex palmar proximal phalanx deformities result in loss of extensor tendon moment arm and digit shortening, resulting in a predictable corresponding extensor lag at the proximal interphalangeal joint. They conclude that nondisplaced and inherently stable isolated fractures of the hand do not require operative intervention, however, early active motion should be emphasized if formal stabilization is required.

Vahey et al. utilized cadaveric models the quantify the linear relationship between the proximal phalanx malunion angulation and the resultant extension lag. They report apex palmar angulations of 16 degrees, 27 degrees, and 46 degrees resulting in extension lags of 10 degrees, 24 degrees, and 66 degrees, respectively.

Figure A shows AP and lateral imaging of this patient’s index finger proximal phalanx fracture with apex palmar deformation.

Incorrect Answers:
Answer 1: While there may be some degree of loss of function, amputation of the digit would be an aggressive treatment modality reserved for truly egregious deformities that impair the patient’s overall quality of life. Corrective osteotomy would be considered a more appropriate, first-line treatment in chronic deformities of the proximal phalanx.
Answer 2: The resulting deformity would primarily affect the extension range of motion. While it can be argued there may be some degree of loss of flexion secondary to finger stiffness, the patient would likely still be able to make a closed fist.
Answer 4: As discussed, apex palmar deformities of the proximal phalanx have a predictable loss in extension range of motion at the level of the proximal interphalangeal joint.
Answer 5: While scissoring of digits is possible in proximal phalanx fractures, he does not appear to have a rotational deformity on radiographic imaging and did not demonstrate any malrotation of the digit on exam. Therefore, extension lag would be the more likely expected outcome.