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.

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.