Biomechanical Comparison of Monofascicular and Bifascicular Reconstruction of the Dorsal Ligaments of the Trapeziometacarpal Joint

Background: There are no studies about the biomechanical behavior of ligamentous reconstructions in the trapeziometacarpal (TM) joint. The aim of our study was to analyze the stabilizing effect of 2 different dorsoradial ligament reconstructions of the TM joint: (1) monofascicular ligament reconstruction; and (2) bifascicular ligament reconstruction. Methods: Ten fresh-frozen human cadaveric upper extremities were used. The dorsoradial dislocation of the thumb metacarpal (MC1) after applying a dislocating force was measured in 4 different situations using a 3-dimensional motion tracking system: (1) with the dorsoradial and ulnar ligaments intact; (2) after their section; (3) after dorsal ligament reconstruction with the bifascicular technique; and (4) after reconstruction with the monofascicular technique. The data were further analyzed and considered statistically significant at P < .05. Results: The MC1 moved dorsoradially 0.36 cm (standard deviation [ SD ] 0.19 cm) with the intact ligaments. After sectioning the ligaments, the displacement was 0.64 cm ( SD 0.24 cm). With the bifascicular technique, the MC1 moved 0.31 cm ( SD 0.16 cm), and with the monofascicular technique, it moved 0.57 cm ( SD 0.19 cm). Conclusions: The monofascicular reconstruction technique seems to be insufficient to stabilize the TM joint. Dorsal ligament reconstruction with the bifascicular technique restores the original stability of the TM joint. Moreover, it is not necessary to reconstruct the ulnar ligament to restore the dorsoradial stability of the TM joint after bifascicular reconstruction.