Transverse ultrasound assessment of the flexor pollicis longus tendon movement on the distal radius during wrist and finger motion in distal radius fracture with volar plating.

INTRODUCTION: We investigated the movement of the flexor pollicis longus (FPL) tendon on the distal radius during wrist and finger motions using transverse ultrasound in patients with distal radius fractures who underwent volar locking plating.

METHODS: Both wrists of 39 distal radius fracture patients with volar locking plate fixation were evaluated by transverse ultrasound to examine the location of the FPL tendon on the distal radius at varied wrist positions in full finger extension and flexion.

RESULTS: At all wrist positions during finger motion, the FPL tendon shifted significantly more dorsally on the affected side than on the unaffected side. Additionally, at the wrist dorsal flexion position with finger flexion, the FPL tendon moved significantly the most dorsally, and the distance between the FPL tendon and the plate or the radius was the smallest among all wrist positions during finger motion.

CONCLUSIONS: This study showed that the wrist dorsal flexion position with finger flexion could be the appropriate position to examine FPL tendon irritation after plating. Moreover, it would be effective for preventing FPL rupture to cover the FPL transverse gliding area approximately 10 mm radial to the vertex of the palmar bony prominence of the distal radius with the pronator quadratus and the intermediate fibrous zone.