Metatarsophalangeal Arthrodesis: Risk Factors for Nonunion in a 10-Year Retrospective Cohort

First metatarsophalangeal (MTP) joint fusion is a common surgical procedure to treat hallux rigidus and malalignment at the MTP joint. Nonunion after first MTP arthrodesis can cause continued pain and limitation in function. The present study aims to provide a single-site analysis of nonunion risk factors after first MTP fusion. We hypothesized that diabetes, smoking, and a body mass index (BMI) ≥30 are associated with increased risk of nonunion.

This is a retrospective cohort study. All patients who underwent first MTP fusion performed by 3 orthopaedic foot and ankle surgeons between September 20, 2013, and September 20, 2023, were included. Patient demographics, comorbidities, intraoperative medications, and postoperative complications were collected. Relationships to nonunion were evaluated using the multivariable logistic regression (a < 0.05) and both odds ratio (OR) and adjusted odds ratio (aOR) were calculated.

A total of 417 patients (450 feet) were included. Average BMI was 27.94 ± 6.79. There were 25 nonunions, which did not statistically differ in sex or age. Per-patient models identified idiopathic peripheral neuropathy and bilateral surgeries as independent predictors, with BMI ≥30 showing a trend toward significance. Diagnosis of peripheral neuropathy was subdivided into diabetic and idiopathic peripheral neuropathy, with increased nonunion rates in the idiopathic group. Osteoporosis, bisphosphonate use, and smoking history showed no statistical difference in nonunion rates. BMI and diabetes showed statistical differences with univariate logistic regression but were deemed insignificant on multivariate analysis.

In this single-institution cohort, idiopathic peripheral neuropathy and bilateral MTP fusions were associated with higher odds of nonunion; findings for BMI ≥30 and diabetes should be interpreted prudently, given the limited events and wide CIs.

Level III, retrospective cohort study.