We evaluated two reconstruction techniques for a simulated posterolateral corner injury on ten pairs of cadaver knees. Specimens were mounted at 30° and 90° of knee flexion to record external rotation and varus movement. Instability was created by transversely sectioning the lateral collateral ligament at its midpoint and the popliteus tendon was released at the lateral femoral condyle. The left knee was randomly assigned for reconstruction using either a combined or fibula-based treatment with the right knee receiving the other. After sectioning, laxity increased in all the specimens. Each technique restored external rotatory and varus stability at both flexion angles to levels similar to the intact condition. For the fibula-based reconstruction method, varus laxity at 30° of knee flexion did not differ from the intact state, but was significantly less than after the combined method. Both the fibula-based and combined posterolateral reconstruction techniques are equally effective in restoring stability following the simulated injury.
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.
