Dorsal surgical approaches to the proximal interphalangeal joint: a comparative anatomic study

Adequate exposure of the articular surface of the head of the proximal phalanx is essential for reduction of intra-articular fractures of the proximal interphalangeal (PIP) joint. We compared the articular exposure obtained by a dorsal extensor-tendon splitting (Swanson), an extensor tendon-reflecting (Chamay), and an extensor mechanism-sparing approach.

The PIP joints of 24 digits from 6 fresh-frozen cadaveric specimens were randomly assigned to 1 of 3 dorsal surgical exposures: an extensor tendon-splitting, extensor tendon-reflecting, or extensor mechanism-sparing approach. The exposed surface was painted with methylene blue and the PIP joints were disarticulated to reveal the distal articular surface of the proximal phalanx. Using 3-dimensional digital mapping, we calculated the percentage of the exposed dyed surface area to the total surface area and compared the 3 approaches.

The mean percent exposed joint surface area for the extensor tendon-splitting, extensor tendon-reflecting, and extensor mechanism-sparing approaches were 41%, 52%, and 16%, respectively. Each approach provided a significantly different percentage of articular PIP joint surface area from the other 2.

The amount of articular surface visualized using 3 dorsal approaches to the PIP joint must be weighed against the amount of extensor mechanism violated. Exposure of the articular surface by the extensor mechanism-sparing approach to the PIP joint allowed nearly a third of the exposure gained by the extensor tendon-reflecting exposure. Although the extensor tendon-reflecting technique revealed the greatest amount of surface, nearly 50% of the proximal phalanx articular surface remained inaccessible as long as the collateral ligaments were intact.

Understanding the limitations inherent in dorsal exposure of the PIP joint may help guide the surgical approach for the individual patient.