First cuneo-metatarsal arthrodesis (Modified Lapidus) with plantar plate for the treatment of hallux valgus: clinical and radiological outcomes at one year follow-up.

Introduction: The modified Lapidus arthrodesis, involving the first cuneo-metatarsal joint, is a well-established surgical method and widely utilized for treating moderate to severe hallux valgus deformities with hypermobility in the first tarsometatarsal joint. The purpose of this study was to assess the rate of union following the Lapidus procedure using a plantar plate and an immediate full weight-bearing protocol. Secondary objectives included examining radiological corrections and potential associated complications.

Methods: A retrospective study included 66 patients (80 feet) who underwent a modified Lapidus procedure for the treatment of hallux valgus associated with hypermobility of the first ray, performed by a single senior surgeon at our institution between May 2013 and November 2019. All patients had a minimum follow-up of 12 months. Patients were clinically assessed at 3 weeks, 3 months, and 1 year. Radiological measurements were taken on weight-bearing dorsoplantar views preoperatively, at 3 months, and at 12 months postoperatively.

Results: Bone union was achieved in 79 cases (98.75%). There was one case of non-union, two wound complications (one infection and one dehiscence), two cases of symptomatic hardware requiring hardware removal, and one stress fracture associated with recurrence of hallux valgus that required revision. The mean hallux valgus angle (HVA) improved from 30.5 ° ±10.4 ° to 10.1 ° ±6.6 ° (p < .001), the mean intermetatarsal angle (IMA) improved from 13.4 ° ±3.6 ° to 5.6 ° ±2.9 (p < .001), The average sesamoid position improved from stage 5.9 ± 1.6 to stage 2.6 ± 1.2 (p < .001). The mean shortening of the first metatarsal was 3.6 mm ± 1.8. There was no significant difference between measurements at 3 and 12 months postoperatively.

Conclusion: Modified Lapidus with a planter plate and compression screw is a reliable method of fixation with a high union rate, permit an immediate protected weight bearing and a low complications rate.

Level of evidence: IV; Retrospective study.