Revision First Metatarsophalangeal Joint Fusion for Non-Union, Implant Failures, and Failed Hallux Valgus Correction: Does the Indication Matter?

CATEGORY: Midfoot/Forefoot; Bunion INTRODUCTION/PURPOSE: The most common indications for revision of 1st Metatarsophalangeal (MTP) joint surgery are symptomatic failures of prior fusion, failed hallux valgus correction, and failed MTP arthroplasty implants. The outcome of revision 1st MTP fusion has rarely been studied. The purpose of this study was to compare the clinical, radiographic, and patient-reported outcomes of revision MTP fusion for different indications. METHODS: A retrospective chart review was performed for patients who underwent revision 1st MTP fusion between January 2015 and December 2019 in a single-center, by 4 fellowship-trained foot and ankle surgeons. The complication, revision, and non- union rates as well as VAS and PROMIS scores and pre-operative and post-operative radiographs were analyzed and compared between the different indication groups. Univariate and multivariate analysis and logistic regression models were used to obtain odds ratio of the explanatory variables for outcome measures. RESULTS: A total of 79 cases of revision MTP fusion were included. Thirty-eight cases of hallux valgus corrections salvage, 22 failed MTP arthroplasty implants, 6 failed polyvinyl alcohol hydrogel implants, 13 prior MTP fusion non-unions. The mean follow-up time was 350 days (Median 226, SD 306). Seven cases (8.9%) required structural iliac-crest bone graft during the revision. Seven cases (8.9%) required allograft augmentation. The overall complication rate was 40.7%. Fifteen patients (18.5%) were classified as Clavien-Dindo grade 3, which represents a complication that may require a revision surgery (i.e. non-union, deep infection, loss of correction). Eventually, 7 cases (8.9%) underwent further revision surgery. The logistic regression model demonstrated that indication for revision was not significantly related to union rate (p=0.280). Visual-Analogue-Scale significantly improved at 6 weeks, 3 months, and at last follow-up in all indications for revision (p=0.001). PROMIS-10 Physical and PROMIS-10 Mental did not change significantly during follow-up (p=0.860, p=0.589). CONCLUSION: Treatment of 1st MTP joint surgery failures is a clinical challenge in orthopaedic surgery. In our study, revision of 1st MTP joint surgery with MTP fusion had higher non-union rates and higher overall complication rates compared to primary 1st MTP fusion. Nevertheless, revision rates remained comparable to primary 1st MTP fusion. Complication rates and patient- reported outcomes were similar between the different indications for revision groups. Visual-analogue-scale improved significantly during follow-up in all groups. Diabetes mellitus had a significant impact on non-union rates and overall complication rates.