The Floating Lunate: Arthroscopic Treatment of Simultaneous Complete Tears of the Scapholunate and Lunotriquetral Ligaments

Carpal instabilities continue to be a controversial topic in hand surgery. Accurate diagnosis of the ligament injuries is usually difficult without an arthroscopic evalu-ation. Few studies have focused on the diagnosis and proper management of simultaneous scapholunate (SL) and lunotriquetral (LT) ligament tears. This is an uncommon injury that leads to marked disability and chronic wrist pain. This is essentially a “floating lunate” and indicates a severe ligamentous lesion. Thirteen patients (six female and seven male) with complete SL and LT tears and with gross arthroscopic dynamic carpal instability were included in the present study. None of the patients showed radiographic evidence of lunate dislocation. One patient presented acutely and was operated on 3 days after the injury. The average time from the initial injury to the arthroscopy for the other 12 patients was 13.5 months (range 1.5–84 months). All patients underwent arthroscopic debridement of the SL and LT ligaments coupled with percutaneous pinning (two 0.045-in. Kirschner wires) in both joints. At the final follow-up, the average range of motion was 50°of flexion, 54° of extension, 77° of pronation, 80° of supination, 25° of ulnar deviation, and 15° of radial deviation. The average final grip strength was 67% from the non-affected side. All patients had negative shifting tests at final follow-up. Furthermore, there was no evidence of any static or dynamic instability in all the patients except for one patient who developed a volar intercalated segment instability 8 months after the surgery. At the final follow-up, ten patients had no pain, one had mild pain, and two experienced moderate pain.

Keywords: Carpal instabilities – Arthroscopy – Ligamentous tears – Lunate instability