Evaluation of the pulley function of the hamulus of the hamate for the flexor tendons.

PURPOSE: The aim of this study was to measure the curvature radii of the finger flexor tendons on CT acquired using tendon conditions to examine whether the hamulus of the hamate functions as a pulley of the flexor tendon.

METHODS: The subjects were 20 healthy volunteers (40 hands) (14 males and 6 females, mean age: 27.5 years old). Their hands were imaged in extension and flexion of the fingers on CT. The curvature radii of the little and middle finger flexor tendons at the hamulus of the hamate were calculated.

RESULTS: The curvature radii of the little and middle finger flexor tendons were 24.8 ± 7.3 and 327.1 ± 343.9 mm in finger extension, respectively, and 21.3 ± 5.3 and 265.1 ± 202.9 mm in finger flexion, respectively. The curvature radius of the little finger flexor tendon was significantly smaller than that of the middle finger flexor tendon in both finger extension and flexion (P < 0.01).

CONCLUSIONS: Our study suggested that the hamulus of the hamate functions as a pulley for the little finger flexor tendon.