Use of Bio-integrative Screws for Fixation of Lisfranc Instability; Pros and Cons from Surgeons' Point of View in a Cadaver Study.

Objectives: Majority of Lisfranc fracture-dislocations require anatomic reduction and rigid internal fixation to prevent debilitating sequelae. Current methods include solid screws and flexible fixations which have been in use for many years. Biointegrative screw is a newer option that has not yet been thoroughly investigated for its effectiveness for Lisfranc injuries.

Methods: The ligaments of the Lisfranc complex were resected in eight lower-leg cadaveric specimens. This was done by eight foot and ankle surgeons individually. Distraction forces were applied from opposite sides at the joint to replicate weight bearing conditions. Three methods of fixation - flexible fixation, metal, and biointegrative screws- were evaluated. The diastasis and area at the level of the ligament were measured at four conditions (replicated injury and each type of fixation) in neutral and distraction conditions using fluoroscopy images. The Wilcoxon test and Kruskal Wallis test were used for comparison. P value <0.05 was considered statistically significant.

Results: The diastasis value for the transected ligament scenario (2.47 ± 0.51 mm) was greater than those after all three fixation methods without distraction (2.02 ± 0.5 for flexible fixation, 1.72 ± 0.63 mm for metal screw fixation and 1.67 ± 0.77 mm for biointegrative screw fixation). The transected ligament diastasis was also greater than that for metal screw (1.61 ± 1.31mm) and biointegrative screws (1.69 ± 0.64 mm) with distraction (p<0.001). The area at the level of the ligament showed higher values for transected ligament (32.7 ± 13.08 mm2) than the three fixatives (30.75 ± 7.42 mm2 for flexible fixation, 30.75 ± 17.13 mm2 for metal screw fixation and 29.53 ± 9.15 mm2 for biointegrative screw fixation; p<0.05).

Conclusion: Metal screws, flexible fixation and biointegrative screws showed comparable effectiveness intra-op, in the correction of diastasis created as a consequence of Lisfranc injury.