Lunotriquetral ligament properties: A comparison of three anatomic subregions

The physical attributes of 3 subregions of the lunotriquetral ligament were tested in a computer-controlled multiaxis testing machine using 12 specimens. This allowed measurement of forces, moments, and displacements when ligaments were subjected to distraction, dorsopalmar translation, proximal-distal translation with a 20 N limit, and rotation with a 0.5 Nm limit. After an intact test run, selected subregions were cut randomly. Together with an additional 12 bone-ligament-bone complexes, specimens were tested to failure with servo-hydraulic load at 5 mm/s. The palmar subregion was thickest (2.3±0.3 mm), the dorsal and proximal progressively less. Intact rotational displacement was 35°±5.1°, dorsopalmar displacement was 1.6±0.4 mm and 1.2±0.5 mm, respectively, proximal-distal displacement was 1.8±0.5 mm and 1.3±0.5 mm, respectively, and distractional displacement was 0.3±0.1 mm. The dorsal subregion provided 62.3%±27.1% of the rotational resistance. The palmar subregion resisted 67.3%±14.1% of palmar translation, while with dorsal translation both regions resisted equally. Rotational displacement increased 15.3°±5.6° after dorsal subregion sectioning. The palmar component failure force was 301±36 N; the dorsal 121±42 N; and the proximal, 64±14 N.