TENSIONS IN THE PALMAR LIGAMENTS OF THE WRIST .1. THE NORMAL WRIST

We developed a method for measurement of the in situ tensions in the l igaments of the palmar side of the wrist in cadaver specimens. The tec hnique is based on deflecting the ligaments transversely (i.e., perpen dicular to their longitudinal axis) using an instrumented probe. Based on measurement of the load required to deflect the ligament, magnitud e of the transverse deflection, and axial length of the ligament the a xial tension in the ligament can be determined without otherwise distu rbing it. The tensions in 8 palmar ligaments in 10 functional position s 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 ligament s act as passive stabilizers: in neutral the triquetrocapitate and dis tal part of the radioscaphocapitate, in radial deviation the radioluna te, in ulnar deviation the ulnolunate, in pronation the proximal part of the radioscaphocapitate, in supination the ulnolunate, and in exten sion 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 ten sion; and the lunotriquetral, trapeziocapitate, and scaphocapitate had the least.