Biomechanical comparison of the hand-based transplant used in bone-tissue-bone scapho-lunate ligament reconstruction

Although work has been published comparing the five most commonly used transplant techniques to the properties of the scapho-lunate interosseous ligament (SLIL), no study has been carried out which compares the biomechanical properties of the different bone-tissue-bone autografts to each other, using a standard methodology of testing. The hypothesis of this study was that mechanically significant differences in the material properties of commonly used bone-tissue-bone exist when compared to each other. We tested the dorsal part of the SLIL and the five most quoted transplants in the literature: capitate to trapezoid; trapezoid to second metacarpal; third metacarpal-carpal; dorsal capitate-hamate; 4-5 extensor retinaculum. For each transplant, we measured failure load, failure displacement, width, and thickness. Anova was used to compare the different results obtained and the level of significance attributed to P<0.05. Load to failure were: SLIL 94.3±42.86N; capitate to trapezoid 37.7±23.13N; trapezoid to second metacarpal 45.43±14.28N; third metacarpal-carpal 60.11±19.94N; dorsal capitate-hamate 63±25.51N; 4-5 retinaculum 15.67±10.7N. Only the dorsal capitate-hamate ligament showed to have no significant (P>0.05) difference in term of load to failure, all the others was significantly weaker (P<0.05). Previous biomechanical studies have identified the dorsal region of the SLIL as the most structurally and functionally important area of the SLIL. As a result, attention has been more specifically brought to the replacement of the dorsal portion of the SLIL. An attempt to achieve a reconstruction that reproduces more closely the SLIL has generated research on the use of bone-tissue-bone composite graft, several donor sites have been used in order to find the most similar. Our results suggest that, using a normalized method to compare the previously described grafts harvested at the wrist level, that the dorsal capitate-hamate ligament has the closest properties to the native dorsal scapho-lunate ligament.