RESUMO
OBJECTIVES: To compare displacement between the cuneiforms and metatarsals for a typical Lisfranc screw and a transmetatarsal base screw under biomechanical loading. METHODS: Eight pairs of cadaveric feet (16 total) were evaluated. The Lisfranc ligamentous structures were transected in all specimens. All feet were repaired with screws traversing the first and second tarsometatarsal joints. A Lisfranc screw was placed from the first cuneiform to the second metatarsal in 8 specimens. A transmetatarsal base screw from the first metatarsal to the second metatarsal was placed in the remaining 8 corresponding feet. The repairs were randomized by side. Markers were placed on the dorsum of the midfoot for optical tracking. The feet were mounted into a load frame and loaded on the plantar forefoot to 100, 400, 800, and 1100 N. Displacement was measured and recorded using 3D camera tracking. RESULTS: Displacement between the first cuneiform and second metatarsal base was found to be significantly less (P = 0.02) with the transmetatarsal screw than the Lisfranc screw. There were no significant differences between displacements at any other articulations. CONCLUSIONS: This study demonstrates biomechanical superiority using a modified transmetatarsal base screw compared with the highly used Lisfranc screw for fixation of ligamentous Lisfranc injuries.
Assuntos
Parafusos Ósseos , Ossos do Metatarso , Fenômenos Biomecânicos , Cadáver , Humanos , Ligamentos Articulares , Ossos do Metatarso/cirurgiaRESUMO
OBJECTIVE: To biomechanically assess the angular stability provided by 3 techniques for reconstruction of the lateral ulnar collateral ligament. METHODS: Eight cadaveric elbows were tested with the lateral collateral ligament complex intact, disrupted from the origin at the lateral epicondyle, and reconstructed with 3 different techniques using ulnar bone tunnels: a suture "lasso" or palmaris longus tendon "lasso" both docked with a metal button at the origin, and a doubled-over palmaris longus tendon docked with metal buttons at both the origin and ulnar insertion. Elbows were tested with a physiologic elbow simulator, and varus angular position was quantified with an optical tracking system. Statistical analysis was performed using a repeated measures analysis of variance test to determine whether significance existed, and a Tukey post hoc analysis to compare statistical difference between native, disrupted, and repair states. RESULTS: There was a statistically significant difference between all repairs and the disrupted state (P < 0.05). The varus angulation after the repairs showed that the suture reconstruction was closest to the native case. The tendon reconstructions were similar to each other but less similar to the native elbow. Quantitatively, the suture reconstruction was within an average of 0.86 degrees of the native elbow throughout range of motion. CONCLUSIONS: A suture reconstruction was most similar to a native elbow, but both tendon reconstructions significantly improved angular stability under varus gravitational loads.