Effect of the Reverse Cotton Osteotomy on First Metatarsal Position: A Cadaveric Study.

Abstract

Flatfoot deformities are characterized by collapse of the medial arch due to tendinous and ligamentous dysfunction. The degree of deformity can be evaluated radiographically by measuring the talo-first metatarsal angle (Meary angle). These deformities have traditionally been corrected using a medial cuneiform dorsal opening wedge (Cotton) osteotomy; however, this procedure requires bone grafting to fill the osteotomy site and results in lengthening of the medial column. To address these concerns, the plantar closing wedge of the medial cuneiform bone, known as the reverse Cotton osteotomy (RCO), was developed. In this study, we aim to determine the effect of the RCO on the position of the first metatarsal, thus providing guidance and recommendations for surgeons employing the reverse Cotton osteotomy in the correction of adult-acquired flatfoot. In this cadaveric study, we characterized the mean angular correction achieved by 1-, 2-, 3-, and 4-mm RCO by radiographically measuring Meary angle under simulated weight-bearing conditions. Secondary outcomes included radiographic measurements of the navicular-cuneiform incongruency angle (NCIA) and calcaneal pitch angle. Statistically significant increases in Meary angle were observed following 1-mm (<i>P</i> = .020), 2-mm (<i>P</i> = .049), and 3-mm (<i>P</i> = .049) osteotomies but not following the 4-mm osteotomy (<i>P</i> = .081). The mean angular correction achieved by the 1-, 2-, and 3-mm wedge sizes was 0.97°/mm. With the numbers available, no significant increase in NCIA could be detected following any of the RCO wedge sizes, and calcaneal pitch increased significantly only after 2-mm RCO (<i>P</i> = .036). The RCO was associated with significant (<i>P</i> ≤ .049) plantarflexion of the first ray in a cadaveric model; however, the authors recommend limiting the wedge size to a maximum of 3 mm, as larger wedges were not associated with further angular correction of the medial arch. The findings of this study can guide surgeons performing RCO to correct flatfoot deformities, thereby potentially contributing to improved postoperative outcomes.