The role of extrinsic ligaments in maintaining carpal stability - A prospective statistical analysis of 85 arthroscopic cases.

Several biomechanical studies have shown that the scapholunate (SL) and lunotriquetral (LT) ligaments are not the only stabilizers of the proximal carpal row. However, no study has yet analyzed the range of ligament lesions leading to instability in vivo. Arthroscopy has been used to assess the condition of the wrist's extrinsic ligaments by palpating and tensioning the various ligament and capsule structures. In this prospective study, this arthroscopic method was used in 85 cases of wrist sprain without static instability to evaluate the correlation between lesions of the intrinsic and extrinsic carpal ligaments and carpal instability. In SL instability, a scapholunate interosseous ligament (SLIL) lesion was statistically correlated with lesions of the long radiolunate ligament (P<0.05). There also was a statistically significant correlation between lesions of the SLIL and the radioscaphocapitate, scaphotrapezial and dorsal intercarpal ligaments. There was a correlation between the stage of SL instability and the number of lax extrinsic ligaments (P<0.05) but not with the severity of the extrinsic ligament lesions. In LT instability, a LT interosseous ligament lesion was statistically correlated with lesions of the dorsal intercarpal ligament (P<0.05). There also was a correlation between the stage of LT instability and the number (P<0.005) and severity (P<0.001) of the extrinsic ligament lesions. Arthroscopy can reveal hidden radiographic instability and can also be used to define the number and severity of injured ligaments. In carpal instability, a lesion of one intrinsic carpal ligament was associated with a lesion of one or more extrinsic ligaments.