Geometric analysis of the Weil osteotomy

BACKGROUND: The Weil osteotomy has been reported to be a clinically effective treatment of metatarsalgia and intractable plantar keratosis. The plantar inclination of the metatarsal influences the effect of the osteotomy but has never been studied in detail. METHODS: This study examined five fresh or fresh-frozen cadaver specimens. The data obtained from the specimens was used to model the geometry of the Weil osteotomy. The effect of thick saw blades on the Weil osteotomy was determined. RESULTS: The inclination of the second metatarsal averaged 24.6 (range 19 to 31) degrees. The displacement of the capital fragment in the plantar direction was dependent on the angle of the osteotomy and the inclination of the metatarsal. A 5-mm proximal displacement along a 25-degree osteotomy displaced the capital fragment in a plantar direction if the inclination of the metatarsal was 19 degrees and displaced it dorsally if the inclination was 25 degrees or more. CONCLUSIONS: The results of this study showed that a thick saw blade could offset a portion of the plantar displacement of the capital segment that can occur with the Weil osteotomy. A 1-mm thick saw blade is recommended for most osteotomies, and a 2-mm thick saw blade is recommended for shortening of more than 5 mm or with plantar inclination of the lesser metatarsal of less than 19 degrees. A thicker saw blade should be considered for the treatment of plantar keratosis.