Ligamentous injury of the tarsometatarsal joint complex is uncommon but disabling. Injuries to individual ligaments can be visualised with MRI. The relative mechanical contribution of the three ligaments of the second TMTJ is unknown.
The second and third metatarsals and the first cuneiform were dissected from twenty pairs of cadaveric feet. In group I, seven pairs were submaximally loaded to determine stiffness with the dorsal, plantar, and Lisfranc ligaments intact. One of each pair underwent sectioning of the dorsal ligament and was then loaded to failure. In the contralateral specimen both plantar and Lisfranc ligaments were divided before retesting. In group II all 13 pairs underwent dorsal ligament excision and stiffness determination. One of each pair was randomly assigned to undergo sectioning of the plantar ligament, the other sectioning of the Lisfranc ligament, before retesting.
The Lisfranc ligament is stronger and stiffer than the plantar ligament. The dorsal ligament is weaker than the Lisfranc/plantar complex. This suggests that ligamentous injuries of the second tarsometatarsal joint may be considered stable if the Lisfranc ligament is intact – even if the other two ligaments are disrupted. If the Lis-franc ligament is injured then the complex is less stiff and may be unstable.
