Early radiographic loss of intermetatarsal angle correction after single first TMT arthrodesis (Modified Lapidus) versus three-corner TMT arthrodesis.
INTRODUCTION: The Lapidus procedure treats hallux valgus with first-ray hypermobility. It can be performed as a single first tarsometatarsal (TMT) arthrodesis or a three-corner TMT construct with additional intermetatarsal fusion. Early loss of correction remains a concern. This study compared early radiographic stability between techniques. METHODS: Fifty patients (15 three-corner TMT arthrodesis, 35 single first TMT arthrodesis) treated between 2014 and 2023 were retrospectively reviewed. Hallux valgus angle (HVA), intermetatarsal angle (IMA), Méary's angle, and tibial sesamoid position were measured on weight-bearing radiographs at 6 weeks and 6 months postoperatively. RESULTS: Both techniques achieved significant correction. The three-corner TMT arthrodesis group showed greater initial IMA correction at 6 weeks (p = 0.020) and maintained a lower IMA at 6 months (p = 0.001). Early IMA loss was greater after single first TMT arthrodesis (1.5°±1.7° vs 0.6°±0.8°, p = 0.013). CONCLUSION: Three-corner TMT arthrodesis was associated with greater early intermetatarsal stability than single first TMT arthrodesis.