Determining the strongest orientation for "Lisfranc's screw" in transverse plane tarsometatarsal injuries: a cadaveric study.

UNLABELLED: The treatment of tarsometatarsal joint fracture-dislocations generally consists of realignment followed by stabilization with rigid internal fixation. The purpose of this study was to determine the strongest orientation for the "Lisfranc's screw" for repair of disruption of the articulation between the first and second metatarsals and the medial and intermediate cuneiforms. To this end, Lisfranc's ligament was sectioned in 6 pairs of fresh-frozen, human cadaver feet, after which a 3.5-mm partially threaded, cannulated screw was placed across the Lisfranc joint in 1 of 2 opposing directions. In one group, the screw was oriented in the more traditional medial cuneiform to second metatarsal base direction. In the other group, the screw was oriented from the second metatarsal base to the medial cuneiform. After fixation, each construct was pulled to transverse plane failure at the tarsometatarsal joint with a servohydraulic mechanical testing system. The overall force to failure was 157.04 +/- 54.79 N (range, 96.8-249.2 N). For the traditional medial cuneiform to second metatarsal base screw orientation group, the mean force to failure was 148.97 +/- 54.93 N, whereas for the second metatarsal base to medial cuneiform group the mean force to failure was 165.12 +/- 58.57 N, and this difference was not statistically significant (P = .2475). Although not statistically significantly different in regard to force to failure strength, the authors describe an alternative approach to the orientation of "Lisfranc's screw" for stabilization of the relationship of the medial cuneiform to the second metatarsal.

LEVEL OF CLINICAL EVIDENCE: 5.