Tarsal autografts for reconstruction of the scapholunate interosseous ligament: a biomechanical study

A biomechanical cadaver study was performed to identify a potential bone-ligament-bone autograft from the foot for reconstruction of the scapholunate interosseous ligament (SLIL). In this study the biomechanical properties of 9 dorsal tarsal ligaments and the anterior tibiofibular ligament were investigated and compared with those of the dorsal part of the SLIL. Fifteen fresh-frozen human cadaver feet and 14 fresh-frozen human cadaver wrists were used. In a Monsanto Tensometer testing apparatus (Monsanto Limited Instruments, Dorean Swindon, England) the complexes were uniaxially elongated at a constant velocity of 6.35 mm/min until rupture occurred. The stiffness and strength values for each tarsal ligament were calculated and compared with those of the dorsal part of the SL ligament. Analysis indicated that the third dorsal tarsometatarsal ligament (143 +/- 42 N) and the dorsal calcaneocuboid ligament (149 +/- 41 N) were comparable to the dorsal part of the SL ligament (141 +/- 20 N) while all other ligaments were stronger. The stiffness values of the third dorsal tarsometatarsal ligament (67 +/- 17 N/mm) and the dorsal calcaneocuboid ligament (55 +/- 14 N/mm) were comparable to the dorsal part of the SL ligament (61 +/- 6 N/mm). All the other ligaments had values that were higher than the dorsal part of the SL ligament. The strongest ligament appeared to be the medial dorsal cuneonavicular ligament (479 +/- 65 N), which had a stiffness value of 127 +/- 19 N/mm. Although the third dorsal tarsometatarsal ligament and the dorsal calcaneocuboid ligament are biomechanically most similar to the dorsal part of the SLIL, at present it is unclear how strength and stiffness values of ligaments are sustained following transplantation. From this selection of tarsal ligaments, the medial dorsal cuneonavicular ligament is the strongest ligament and it is therefore concluded that this ligament is the most suitable ligament to be used as an autograft for reconstruction of the SLIL.