Hallux Valgus with Increased DMAA Correction by Modified Lapidus Procedure

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus is one of the most common deformities treated by orthopedic foot and ankle surgeons. Hallux valgus can frequently present with an increased distal metatarsal articular angle (DMAA), which may require correction in addition to treating the hallux valgus deformity. Many surgical procedures can correct hallux valgus with an increased DMAA with varying levels of success. Thus, we investigate the efficacy of the modified Lapidus procedure, a triplanar correction, in correcting the DMAA in hallux valgus surgery. Methods: A retrospective chart review was performed on patients who underwent the hallux valgus reconstruction with a modified Lapidus procedure between April 26th, 2018 and November 19th, 2020. Exclusion criteria included any patient undergoing hallux valgus correction not receiving a modified Lapidus procedure and patients with inadequate follow up. Hallux valgus angle (HVA), intermetatarsal angle (IMA) and DMAA were measured on pre-operative, immediate post-operative and at final follow up weight bearing radiographs. Results: The study included a total of 99 cases of modified Lapidus procedure for hallux valgus on 85 subjects with an average follow up of 5.4 months. On radiologic assessment, the average DMAA decreased from 17.72 +- 6.18 degrees pre-operatively to 9.19 +- 5.19 degrees immediately post-operatively (p < 0.0001) and 9.79 +- 4.62 degrees at the final follow up (p < 0.0001). The average HVA decreased from 31.34 +- 10.39 degrees pre-operatively to 13.34 +- 6.16 degrees immediately post-operatively (p < 0.0001) and 15.05 +- 7.43 degrees at final follow up (p < 0.0001). Lastly, the IMA decreased from 14.99 +- 3.82 pre-operatively (p < 0.0001) to 4.66 +- 2.59 immediately post-operative and 6.62 +- 3.46 degrees at final follow up (p < 0.0001). The rate of recurrence was 3.03%. Conclusion: The modified Lapidus procedure is an effective procedure in correcting the HVA, IMA, and DMAA in hallux valgus surgery without the need for additional distal or proximal metatarsal osteotomies. Surgeons should consider this technique in patients with moderate to severe hallux valgus deformity who may require correction of their DMAA.