Proposition d'une nouvelle ostéotomie métatarsienne médiane: L'ostéotomie cervicale de raccourcissement axial (OCRA). Approche expérimentale comparative avec l'ostéotomie de Weil

The cervical shortening axial osteotomy, is a distal metatarsal osteotomy, preserving the joint, with a cylindrical piece of bone removed in the line of the metatarsal axis, and with the preservation of a stabilising bone block, on the head fragment. After a first mathematical and geometric analysis, this second experimental study on sawbones, was to compare Weil osteotomy, Weil osteotomy with resection of a bone slice on the proximal fragment, made after the proximal translation of the distal fragment, and the cervical shortening axial osteotomy. These were performed on 20 sawbones, divided into four groups: Weil osteotomies were performed in the first three groups: using a horizontal cut in group 1, a 10° oblique cut in group 2, and a 20° oblique cut in group 3; cervical shortening axial osteotomies were performed in group 4. In a second part, the Weil osteotomies were completed by bone slice resections on the proximal fragment. In each group, the head fragment was translated one centimeter proximally. The radiographic assessement used bony lanmarks to analyse morphological changes, and the projection of these landmarks on the horizontal line. The length, heigth, and declination angles variations were mesured. With an horizontal Weil osteotomy, we found no plantar displacement of the head, but an increased metatarsal declination angle, averaging 2.6°. In an oblique Weil osteotomy, head plantar displacement is associated with a greater metatarsal declination angle. For the 10° angle oblique oteotomy, the head's plantar displacement average 2.2 mm and the metatarsal declination angle 4.2° and for 20° angle oblique osteotomy, the head plantar displacement average 2.8 mm and the metatarsal declination angle 6.4°. The bone slice resection, made just after the proximal translation of the metatarsal head, in the Weil osteotomy, resulted in the correction of head plantar displacement and metatarsal angle modifications. For the 10° angle oblique Weil ostetomy, the head displacement is 1,8 mm dorsal, and the declination angle is reduce to 0.4°; and for an 20° oblique Weil osteotomy, the results are 2.2 mm for the head dorsal displacement, and 0.4° for the declination angle. In the shortening cervical axial osteotomy, the metatarsal head follow a dorsal displacement but also a plantar displacement secondary to the plantar bone block preserved on the distal fragment, resulting in a 1.2 mm dorsal position. The metatarsal declination angle is 1.6° greater.