Hallux MTP Arthrodesis for Treatment of Severe Hallux Valgus Using a Dorsal Locking Plate

Abstract

Category: Bunion Introduction/Purpose: First metatarsophalangeal (MTP) joint arthrodesis is widely accepted as a treatment option for severe hallux valgus deformities. Although successful results of first MTP joint arthrodesis for hallux valgus have been reported in previous studies, the reported rates of fusion have been lower than for the general hallux rigidus population. The purpose of this study was to demonstrate the failure rate of first MTP joint arthrodesis for severe hallux valgus deformities and to evaluate radiographic correction of hallux valgus parameters after the surgery. Methods: From January 2014 to June 2017, 34 patients underwent first MTP joint arthrodesis surgery for severe hallux valgus deformity and were included in this retrospective study. Severe hallux valgus was defined as having a hallux valgus angle (HVA) of greater than 40 degrees and an intermetatarsal angle (IMA) greater than 15 degrees. For radiographic evaluation, the patients were evaluated by measuring the IMA and HVA in preoperative and postoperative weight-bearing AP foot x-rays. We defined failure after first MTP joint arthrodesis as non-union, incomplete union, or implant breakage or migration leading to a symptomatic recurrence of hallux valgus deformity. Results: The mean preoperative IMA and HVA were 16.7 ± 4.2 degrees (range 8.4 to 26.5) and 45.2 ± 8.6 degrees (range 28.7 to 71.1) respectively, and the postoperative IMA and HVA were 11.3 ± 3.8 degrees (range 4.1 to 20.4) and 20.9 ± 11.8 degrees (range 0.4 to 51.1) respectively. The postoperative IMA and HVA were significantly improved after surgery (< 0.001). Among the 34 patients in this study, a 14.7% failure rate was reported (n=5). For fusion procedures performed without lag screw fixation, there was a 12.6-fold increase in failure risk when we used the small dorsal locking plate compared with the medium dorsal locking plate (Odds ratio = 12.571). Conclusion: First MTP joint arthrodesis is an effective and reliable option for severe hallux valgus correction. However, for this challenging cohort, the 14.7% failure rate in this study is consistent with other studies in the literature. For severe hallux valgus deformities, selection of implant may play a more significant role. The use of longer plates to gain additional purchase in the diaphyseal bone, lag screw augmentation, and utilizing flat cuts instead of cup and cone reaming to realign the joint may help mitigate the increased stresses placed on the fixation constructs for MTP arthrodesis.