Optimizing Volar Tilt Restoration and Plate Position in Distal Radius Fractures

Distal radius fractures are common and often treated surgically with a volar plate. A complication of volar plating includes tendonitis or rupture of the flexor pollicis longus (FPL) tendon. We hypothesize that failure to restore the volar tilt of the distal radius results in increased pressure on the FPL tendon.

Ten fresh-frozen cadaveric wrists were assessed for this study. During testing, weights were suspended from the FPL tendon to stimulate muscle contraction. Reproducible fractures were created and fixed via volar plating. The contact force between FPL and the bone or plate edge was measured with a force transducer in 5 surgical conditions. These were assessed to evaluate whether failure to restore the volar tilt increases the pressure with a plate proximal or distal to the watershed line.

Significant increases in contact forces were observed between the control and both conditions in which volar tilt was not restored, with mean increases of 1.9 N and 3.0 N. A significant increase in the contact force was found when placing the plate distal to the watershed line with a mean increase of 2.03 N comparing the failure to restore volar tilt and after restoring the volar tilt. Significant increases in contact force were also observed between the dorsal plate condition, which failed to restore the volar tilt, and both plate conditions with placement distal to the watershed line, with mean differences of 0.94 N and 1.09 N, respectively.

Failure to restore the volar tilt in surgically treated distal radius fractures causes increased pressure on the FPL tendon. Plate placement distal to the watershed line also causes increased FPL tendon pressure over the plate edge.

This study demonstrates the importance of restoring the volar tilt of the distal radius in surgically treated distal radius fractures and confirms that plate placement distal to the watershed line will increase pressure on the FPL tendon.