Biomechanical changes of cadaveric finger flexion: the effect of wrist position and of the transverse carpal ligament and palmar and forearm fasciae.

This study was designed to investigate whether the position of the wrist or sectioning of the transverse carpal ligament (TCL), as well as the palmar fascia and forearm fascia, modifies the biomechanical behavior of the finger flexion, as defined by changes of excursion, load (force), and work of the flexor tendons. The parameters were measured in fresh-frozen cadaver hands with the wrist in 30 degree extension, neutral, and 30 degree flexion, before and after division of the TCL. Having the wrist in extension improved excursion efficiency, whereas flexing the wrist produced the opposite effect, with a 16% decrease in excursion efficiency after division of the TCL. Change in excursion efficiency between the intact and cut TCL was 8% in the flexed position, 5% in the neutral position, and 0.3% in the extended position. Change in load efficiency between intact and cut TCL was 11% in the flexed position, 6% in the neutral position, and 0% in the extended position. Change in the work efficiency between intact and cut TCL groups was noted most with the wrist in the flexed position (13%), compared to a small change (3%) in neutral wrist position and no change in wrist extension. A significant decrease in the excursion efficiency of the flexor tendons was demonstrated when the wrist was in the flexed position. Any increase in the excursion of the flexor tendons could clinically result in decreased grip strength when the wrist is flexed. Furthermore, the effects of TCL division were not significant when wrist position was in extension.