Significant Early Loss of Correction in Modified Lapidus Compared to Original Lapidus for Hallux Valgus

Abstract

Category: Bunion; Other Introduction/Purpose: The Lapidus procedure (first tarsometatarsal joint (TMT1) fusion) is an established treatment for correcting hallux valgus with 1st ray hypermobility. The original Lapidus (OL) technique involves fusing the TMT1 joint and first metatarsal base to the second, while the modified Lapidus (ML) technique involves fusing only the TMT1 joint. The purpose of this study was to investigate whether the ML procedure results in an early loss of correction. Methods: This retrospective study analyzed the outcomes of 45 feet in 40 patients with hallux valgus who underwent either the ML (21 feet) or OL (24 feet) procedure between 2014 and 2022 at a single center. All fixations were performed with 3.5 cortical screws, except for 9 cases that were fixed with a plantar locking plate. Differences in the immediate postoperative (6 weeks) and postoperative (6 months) intermetatarsal angle (IMA) and hallux valgus angle (HVA) were analyzed using Mann-Whitney tests, and complications were reported. Results: The mean preoperative IMA and HVA for the OL were 15.8° ± 3.5° and 36.4° ± 9.5°, respectively, and 14.5° ± 2.3° and 33.0° ± 7.0° for the ML. The immediate postoperative IMA and HVA were similar for both procedures (7.2° ± 2.0° and 7.7° ± 4.3° for OL, 7.3° ± 2.1° and 8.5° ± 5.5° for ML). Although from 6 weeks to 6 months postoperatively, the loss of correction of the HVA did not differ between both procedures (4.2° for OL, 5,6° for ML), the IMA loss of correction was significantly higher in the ML (1.1° ± 1.4° vs 0.5° ± 1.1°) (p < 0.05). One case of delayed union was reported in the OL group, but it did not require revision. Conclusion: The study results suggest that the ML procedure does not provide the same stability as the OL procedure in the early postoperative period, as there was a significantly greater early loss of correction of the IMA at 6 months postoperatively in the ML group compared to the OL group. Although there were no differences in the loss of correction of the HVA angle (HVA), an observed loss of 5 degrees remains a concern. Further studies are necessary to better understand the indications of the modified and original procedures.