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

CATEGORY: Bunion; Other 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 who underwent correction of a hallux valgus deformity from 2016 to 2017 with 1 of 4 foot and ankle fellowship-trained orthopaedic surgeons were included in this study. Degenerative changes were classified using a novel grading system dividing the articular surface of the metatarsal head into 6 zones, with zones 1 through 4 representing the surface which articulates with the base of the proximal phalanx and zones 5 and 6 representing the plantar aspect of the metatarsal head. Cartilage loss in each zone was graded from 0-2, with a score of 0 representing the absence of arthritis, a score of 1 indicating fissures without exposed bone, and a score of 2 representing degenerative changes with exposed bone, for a maximum score of 12. Scoring was performed by the operating surgeon at the time of the index procedure by direct visualization. Photographic documentation of the metatarsal head was obtained in every case for secondary confirmation. At 2 years postoperatively, patients with intraoperative grading 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 ANOVA were performed to determine if the degree of arthritis had any influence on outcomes. RESULTS: Seventy-six patients (92.1% female) with both intraoperative arthritic grading and 2-year functional outcomes were included. At a mean of 24.6 (range, 23-28) months postoperatively, patients reported a mean (+- standard deviation) FAAM-ADL of 93.0 +- 11.9/100, FAAM-Sport of 84.8 +- 21.4/100, and VAS pain of 16.8 +- 22.2/100. Arthritis in zone 1 (r=0.345, p= 0.005) and zone 4 (r=0.249, p=0.044) was found to be positively correlated with FAAM-Sport scores. ANOVA analysis 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 -36.5 and -48.1, respectively) than those with a grade of 1 (mean: +5.0) (p=0.005). CONCLUSION: We have demonstrated a significant influence of arthritis on 2-year functional outcomes following HV correction, with higher levels of degenerative changes in zones 1 and 4 generally associated with better functional outcomes. While this finding was unexpected, it demonstrates that those with 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.