Stability of a cannulated screw versus a kirschner wire for the proximal crescentic osteotomy of the first metatarsal: a biomechanical study

Abstract The purpose of this study was to compare the stability of a Kirschner wire (K-wire) versus a single cannulated screw for fixation of the proximal crescentic first metatarsal osteotomy. Seven matched pairs of fresh-frozen human cadaver first metatarsal specimens were dissected out en bloc at the first metatarsal-medial cuneiform complex; right and left specimens were randomized as to fixation. In screw specimens, a cannulated screw was mounted from the proximal medial side of the metatarsal, traversing osteotomy and engaging the lateral diaphyseal cortical bone. In the corresponding specimen, a K-wire was placed from the distal medial metatarsal cortex oriented as close to the longitudinal metatarsal axis as possible. Using a materials testing machine, a continuous load was applied to the plantar aspect of the metatarsal head at a rate of 5 mm/min until a displacement of 10 mm was reached. The following parameters were measured: initial stiffness of the entire specimen, stiffness of the osteotomy, the force required to create a 1-mm displacement, the force required to create a 0.15-mm gap across the osteotomy, and the ultimate force to create the 10-mm displacement. Both specimen and osteotomy stiffness were found to be significantly higher for screw fixation versus the K-wire ( P