Influence of First Metatarsophalangeal Joint Degenerative Changes on Functional Outcomes Following Hallux Valgus Correction

CATEGORY: Bunion; Midfoot/Forefoot INTRODUCTION/PURPOSE: Previous studies have documented the prevalence of 1st metatarsophalangeal (MTP) joint arthritis in the setting of hallux valgus, with the articulation between the metatarsal head and the sesamoids being particularly vulnerable. However, little is known as to whether such degenerative changes of the metatarsal head-sesamoid articulation have any influence on postoperative functional and pain scores following hallux valgus correction. The purpose of this study is to determine the influence of degenerative changes of the 1st metatarsal head on outcomes at 2 years postoperatively. METHODS: Patients underwent correction of a hallux valgus deformity from 2016-2017 by a single fellowship trained foot and ankle surgeon. Degenerative changes were classified by dividing the articular surface of the metatarsal head into 6 zones: zones 1 through 4 represented the surface articulating with the base of the proximal phalanx, while zones 5 and 6 represented the plantar aspect. Cartilage loss in each zone was graded from 0-2, with 0 representing the absence of arthritis, 1 indicating fissures without exposed bone, and 2 representing degenerative changes with exposed bone. Scoring was performed via direct visualization during the procedure. At 2 years postoperatively, patients were contacted to complete the Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and Sports subscales and Visual Analog Scale (VAS) for pain. Spearman’s correlations and one-way analysis of variance (ANOVA) were performed to determine if degree of arthritis had any influence on outcomes. RESULTS: One hundred and forty-one patients (87.9% female) with both intraoperative arthritic grading and 2-year functional outcomes were included. At a mean of 25.4 (range, 23.0-34.8) months postoperatively, patients reported a mean (+- standard deviation) FAAM-ADL of 88.9 +- 17.3, FAAM-Sport of 77.3 +- 26.0, and VAS pain of 20.8 +- 27.1. Arthritis in zone 2 (r=0.20, p= 0.027) was found to be positively correlated with FAAM-Sport scores. ANOVA revealed those with a total arthritis grade of 0 or 2 or more in zones 1-4 had a significantly greater reduction in VAS pain scores (means of -35.1 and -37.7, respectively) than those with a grade of 1 (mean: -14.3) (p=0.008). CONCLUSION: Patients demonstrated a significant influence of arthritis on 2-year functional outcomes following HV correction, with higher levels of degenerative changes in zone 2 generally associated with better functional outcomes. Patients with more severe arthritic changes in zones 1-4 and those whose arthritic changes were localized solely to zones 5 and 6 demonstrated greater pain relief than those with mild degenerative changes. While these findings were unexpected, it demonstrates that those with more pronounced arthritis may benefit more from surgical correction of HV. Furthermore, surgeon intraoperative evaluation of arthritis may allow for improved counseling of patients regarding expected postoperative functional improvement.