How placement affects force and contact pressure between a volar plate of the distal radius and the flexor pollicus longus tendon: a biomechanical investigation.

Open reduction and internal fixation of a distal radius fracture can leave a volar plate in close proximity or touching the tendons of the wrist. This cadaveric study examines the how volar plate position changes contact pressure and force against the flexor pollicis longus (FPL) tendon in multiple wrist extension positions. This study suggests that moving the plate from an ideal position (distal edge at the watershed line) to a malposition (5 mm distal to the watershed line) significantly increased the force by 72.7% and contact pressure by 33.5% on the FPL. Multiple clinical case reports have described rupture of the flexor tendons associated with distally positioned plates or protruding screw heads, creating prominent or sharp edges. This study illustrates that in order to minimize contact pressure on the flexor tendons, plating distal to the watershed line should be avoided when possible.