Biomechanical properties of the scapholunate ligament and the importance of its portions in the capitate intrusion injury

BackgroundRepair of the dorsal component of the scapholunate ligament alone is the usual surgical treatment for scapholunate injuries. Recent literature has suggested that additionally repairing the palmar component of the scapholunate ligament leads to improved and lasting clinical outcomes. The aim of this study was to determine the biomechanical properties of both portions of scapholunate ligaments derived from the same wrist and compare them with the whole scapholunate ligament. The goal was to further elucidate the importance of the palmar portion of the scapholunate ligament from a biomechanical perspective.MethodsScapholunate ligaments and their components were harvested from the same fresh frozen cadaveric wrists. Force at failure and stiffness were measured.FindingsThe mean maximum loads to failure for the entire scapholunate ligament, dοrsal and palmar portions were found to be 147 (SD 54)N, 83 (SD 18)N and 86 (SD 16)N respectively. No statistical difference was found between the mean maximum load and stiffness for palmar and dorsal components (P = 0.05). Mean maximum load and stiffness, of the intermediate portion, were 36 (SD 15)N and 25 (SD 23)N/mm.InterpretationOur biomechanical findings on the dorsal and palmar portions of the scapholunate ligament suggest that each portion contributes approximately 50% to the whole ligament tensile force. These results appear to agree with other reports about the stabilizing role of the palmar portion of the scapholunate ligament and suggest that the palmar portion of the ligament should be considered for surgical repair.