Biomechanical evaluation of flexor tendon function after hamate hook excision.

PURPOSE: Hamate hook fractures are uncommon injuries for which treatment is controversial. Excision of the hamate hook is considered to be the preferred method of treatment but the effects of hamate excision are not clearly delineated. The purpose of this study was to determine what effect, if any, excision of the hamate has on flexor tendon function.

METHOD: The biomechanical effects of hamate hook excision on flexor tendon function were studied in fresh cadaveric forearm specimens with wrists fixed in 3 positions (neutral, 30 degrees extension, 30 degrees extension with 30 degrees ulnar deviation). Flexor tendon force, flexor tendon excursion, and flexor tendon shift were evaluated.

RESULTS

Flexor tendon force decreased after hamate hook excision (11% in neutral, 14% in 30 degrees extension, and 15% in 30 degrees extension with 30 degrees ulnar deviation). The flexor profundus tendons had a 7- to 11-mm increase in proximal tendon excursion after hamate hook excision depending on the position of the wrist, and the flexor profundus tendons of the small finger shifted 4 to 5 mm in ulnar direction.

CONCLUSIONS

The hamate hook provides some biomechanical advantage for flexor tendon function and cadaveric changes in tendon force after its excision suggest that power grip may be decreased after hamate hook excision.