The opening base wedge osteotomy and subsequent lengthening of the first metatarsal: an in vitro study.

UNLABELLED: Traditionally, the opening base wedge osteotomy has been indicated in a moderate to severe hallux abducto valgus deformity with a short first metatarsal. This in vitro study aimed to address the question of how much lengthening is inherent to the geometric design of an opening wedge in the first metatarsal. The preosteotomy length of a first metatarsal segment was compared with postosteotomy length after performing transverse and oblique basilar osteotomies while maintaining the opening wedge with a prefabricated spacer. In the current bench study, it was found that the opening base wedge osteotomy does indeed lengthen the first metatarsal, albeit a small percentage of the total length (1%-2.8%), and there was no significant difference between the lengths achieved through a transverse or oblique osteotomy based on a confidence interval of 95%. LEVEL OF CLINICAL EVIDENCE: 5.