Cannulated screws versus nitinol staple for tarsometatarsal fusion: A cadaveric biomechanical comparison model.

ABSTRACT

BACKGROUND: The objective of this study was to evaluate the biomechanical stability of a medially placed nitinol staple compared to two crossed-screws in the first TMT-1 joint fusion in a cadaveric cyclic loading model. METHODS: Seven matched pairs (N = 7) of lower limb cadaveric specimens were utilized. TMT-1 joints from each donor were fixed with a medially placed nitinol staple or dorsally placed two 3.5 mm partially threaded cannulated crossed-screws. Specimens were tested in a 4-point bending setting with increasing cyclic forces. RESULTS: The mean plantar gapping was not significantly different between the two groups at any loading stage below 200 N. Specimens fixed with a nitinol staple failed at a mean load of 305 ± 57 N. Conversely, those fixed with crossed-screws failed at 373 ± 86 N. (P = .09). CONCLUSION: There was no statistical difference between a medially placed nitinol staple and dorsally placed crossed-screws in failure loads and plantar gapping under cyclic loads at the TMT-1 joint, however, the staple fixation was much more variable. LEVEL OF EVIDENCE Level V, basic science study, biomechanics.