Tensions in the palmar ligaments of the wrist. I. The normal wrist

We developed a method for measurement of the in situ tensions in the ligaments of the palmar side of the wrist in cadaver specimens. The technique is based on deflecting the ligaments transversely (i.e., perpendicular to their longitudinal axis) using an instrumented probe. Based on measurement of the load required to deflect the ligament, magnitude of the transverse deflection, and axial length of the ligament, the axial tension in the ligament can be determined without otherwise disturbing it. The tensions in 8 palmar ligaments in 10 functional positions of the wrist in each of 5 fresh cadaver specimens were assessed. The position of the wrist was monitored, but the specimen was not loaded. We concluded that (1) the palmar ligaments are in tension, even with the wrist in neutral position and unloaded; (2) the following ligaments act as passive stabilizers: in neutral the triquetrocapitate and distal part of the radioscaphocapitate, in radial deviation the radiolunate, in ulnar deviation the ulnolunate, in pronation the proximal part of the radioscaphocapitate, in supination the ulnolunate, and in extension the ulnolunate, radiolunate, and radioscaphocapitate; (3) in any position some ligaments are in a state of greater tension than others. The radiolunate, ulnolunate, radioscaphocapitate had the greatest tension; and the lunotriquetral, trapeziocapitate, and scaphocapitate had the least.