Distal osteotomy of the first metatarsal bone for the correction of hallux valgus: comparison of the sagittal stability of two percutaneous techniques-a cadaveric study.

ABSTRACT

BACKGROUND: Distal first metatarsal osteotomy is used to correct mild or moderate hallux valgus (HV). We designed a cadaveric study to compare the resistance to axial load between two percutaneous distal first metatarsal osteotomies Bösch osteotomy and percutaneous chevron. The first aim of this study was to develop a systematic technique for measuring the sagittal displacement on lateral foot X-rays. Our second objective was to measure the resistance to axial load for both of these osteotomies. METHODS: Ten pairs of freshly frozen cadaveric feet were randomly assigned to one of the two techniques investigated. Pre- and post-operative lateral X-rays were obtained. After surgery, the feet were placed under progressive axial loads up to 60 kg. Metaphyseo-diaphyseal angle (MDA) and the distance between bone fragments were measured, and the differences between the two techniques were statistically assessed. RESULTS: The MDA decreased in both surgical techniques. The mean plantar tilt was -6.90 degrees (SD = 10.251) for chevron osteotomy and -5.34 degrees (SD = 16.621) for Bösch osteotomy. There was no significant difference between the techniques (p = 0.41). Regarding the distance between the bone fragments, the Bösch osteotomy produced more plantar displacement than the chevron osteotomy, which was statistically significant for the 10 and 20 kg loads (p = 0.031 and 0.04, respectively). At loads ≥ 30 kg, the bone fragment distance did not differ significantly between the techniques (p = 0.114). CONCLUSIONS: Although the chevron technique confers higher stability regarding fragment displacement during axial loading, both techniques increase the plantar angulation of the metatarsal head. LEVEL OF EVIDENCE Cadaveric study.