Wide scapholunate joint space in lunotriquetral coalition: a normal variant?

The radiologic appearances of 70 lunotriquetral coalitions in 52 patients were evaluated to determine whether a wide scapholunate joint space in subjects with this congenital abnormality reflects a scapholunate ligament disruption or is a normal variant. When the middle of the scapholunate joint space was larger than the capitolunate or third carpometacarpal joint space widths, it was considered to be abnormally wide. In 32 of 70 wrists (46%), a wide scapholunate joint space was detected. Results of instability radiographic series (n = 28) and arthrography (n = 11) were normal with respect to the scapholunate ligament in all cases, but the scapholunate joint space was markedly widened in six cases (55%) in which arthrography was performed. Arthroscopy, performed in one case, showed an intact scapholunate ligament. Because of the high prevalence of a wide scapholunate joint space and because of negative arthrographic and arthroscopic examinations, the authors conclude that widening of the scapholunate joint space is a normal variant that is common in patients with lunotriquetral coalition.