The pulley function of hamate hook for the flexor tendon and the change in the curvature radius before and after hamate hook excision

Abstract

The ulnar flexor tendon rupture is the one of the complications of the hamate hook nonunion. The reason is considered that the hamate hook has a pulley function for the flexor tendon. Then we researched whether the hamate hook has a pulley function for the flexor tendon by measuring the radius of curvature (ROC) of flexor tendons using Computerized Tomography (CT) of tendon condition. Moreover we investigated the change of the ROC of the little finger flexor tendon before and after the hamate hook excision using cadaveric bodies. The subjects were 20 healthy volunteers (40 hands) for the study of CT and 6 fresh frozen cadaveric forearms for study for the change of the ROC before and after the hamate hook excision. We measured the ROC of the middle and little finger flexor tendon with fingers flexion and extension using CT. And we measured the ROC of the little finger flexor tendon with fingers extension and flexion before and after the hook excision and calculated the change of the ROC. The ROC of the little and middle finger flexor tendon were 24.8 ± 7.3 and 327.1 ± 343.9 mm at the extension position, and 21.3 ± 5.3 and 265.1 ± 202.9 mm at the flexion position. In both positions, the ROC of the little finger flexor tendon was significantly smaller than that of the middle finger flexor tendon (P