Correction of hallux abductus valgus by Mitchell's metatarsal osteotomy: comparing standard fixation methods with absorbable polydioxanone pins

Abstract

Thirty-nine Mitchell's first metatarsal osteotomies were performed in 28 individuals with hallux abductus valgus at two centres. Seventeen osteotomies were stabilized with standard fixation (Vicryl ® bone suture or K wire) and 22 were fixated with absorbable polydioxanone Orthosorb ® Absorbable Pins (Johnson & Johnson Orthopaedics, Bracknell, UK). Patients were assessed preoperatively and at 3, 6 and 12 months postoperatively. Clinical evaluation was undertaken by an independent assessor unaware of the fixation method with radiographic assessment performed by the consultant. On review, one patient (one foot) that received absorbable fixation was lost to follow-up and another was last seen 4 months postoperatively. Average follow-up was 10.7 months (2–24 months). There was no statistical difference between the two groups in terms of age or weight. Statistical analysis by Mann-Whitney U test revealed no significant difference between the treatment and control groups for first metatarsophalangeal joint (MTPJ) range of motion, hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal length ratio both preoperatively and postoperatively. Analysis of the patients combined by signed rank test revealed no significant change in the first MTPJ range of motion but there was a significant reduction in the hallux valgus angle, intermetatarsal angle, hallux rotation and first to second metatarsal ratio following surgery. The average postoperative hallux valgus angle (17.1°) suggests that the Mitchell's metatarsal osteotomy is less effective for large preoperative deformities. There was no evidence of foreign body reaction, persistent or increased pin tract lucency or sinus formation in any patients receiving absorbable fixation. One foot required removal of the K wire fixation. In conclusion, absorbable polydioxanone pins present no additional complications to those associated with standard fixation methods and avoids the possible need for a second procedure to remove metalwork.