Comparative results of uncalcined hydroxyapatite/poly-L-lactic acid composite screw fixation and titanium screw fixation in the Mitchell osteotomy for moderate hallux valgus deformity.

Abstract

No study has reported on the use of bioabsorbable screws in modified Mitchell osteotomies. This study aimed to clarify the clinical and radiographic findings of modified Mitchell osteotomy using a bioabsorbable screw compared with the use of a titanium screw. Fifty-one feet from 43 patients with hallux valgus angles (HVAs) > 20° and <40° were included in the study. The osteotomy was fixed using an unsintered hydroxyapatite/poly-l-lactic acid (u-HA/PLLA) screw in 29 feet from 23 patients (group A) and by a titanium headless screw in 22 feet from 20 patients (group B). Patient sex, age, and body mass index (BMI) at surgery, and preoperative and postoperative Japanese Society for Surgery of the Foot (JSSF) hallux scale scores of the two groups were compared. The HVA, intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA) were measured on weight-bearing radiographs preoperatively and 1 year postoperatively. Postoperative dorsal displacement of the 1st metatarsal head (DD1MH) was also assessed. No significant preoperative differences in these parameters were observed between the groups. The median JSSF scores improved from 75 to 95 in group A and from 64 to 95 in group B. Preoperatively and 1 year postoperatively, the HVAs were 27.5 and 11.0 in group A, 25.5 and 11.3 in group B; the IMAs were 14.3 and 9.4 in group A, 13.6 and 8.8 in group B; the DMAAs were 6.7 and -2.2 in group A, 7.9 and 4.5 in group B. The DD1MHs were 0.5 in group A and 0.0 in group B. No significant differences in the postoperative JSSF scale, HVA, IMA or DD1MH were noted between the groups. The results of Mitchell osteotomy with u-HA/PLLA screws did not significantly differ from those with titanium screws in clinical outcomes, HVA, IMA and DD1MH at 1 year postoperatively. Case control study; Level of evidence, 3.