Rates of Nonunion for Different Joints after Foot And Ankle Surgery: A Review of 2301 Fusions

CATEGORY: Ankle, Ankle Arthritis, Hindfoot, Midfoot/Forefoot INTRODUCTION/PURPOSE: Nonunion after fusion results in ongoing pain and a request for repeat surgery in many patients. Nonunion is therefore a failure of the primary surgery. Patients undergoing fusion surgery need to understand the risk for nonunion and the risk for repeat surgery. This is a review of fusions performed at a single institution by 4 foot and ankle surgeons to outline the nonunion rate after foot and ankle fusion for different joints. METHODS: Data on fusions performed between January 1, 2010 to July 31, 2006 were retrospectively extracted from database. The records were reviewed to determine the union status of each fusion. Demographic and clinic risk factors of nonunion were recorded. The nonunion rate for each joint (ankle, subtalar, talonavicular, calcaneocuboid, navicular cuneiform, tarsometatarsal and metatssophalengeal joints) was estimated. Due to multiple surgeries performed on individual patient and fusions in the same surgery, random effects logistic regression models were conducted to assess the impact of risk factor on nonunion. The study include 2301 fusions preformed on 1320 patients. The minimum follow up was two years. The majority of patients were female (70%), with mean age of 57 years old and mean body mass index (BMI) of 28. There were 9% of patients with diabetes, 11% being smokers, 18% having lung disease, 8% with renal disease, and 29% with high blood pressure. RESULTS: The risk of nonunion by joint is outlined in figure 1. The ankle showed the highest nonunion rate at 8%, and the calcaneocuboid joint had the lowest rate at 2%. Comparing to ankle, the nonunion rate was significantly lower at Talocalcaneal (Subtalar) joint (Odd ratio [OR]=0.05, p-value= 0.02) and Tarsometatarsal (OR=0.03, p-value=0.01). Across all joints the nonunion rate was higher in males, smokers, having a higher BMI and diabetes Age had a minimal effect. CONCLUSION: Union rate varied among fusion sites. Patient’s demographic and clinic characteristics might be potential risk factors for nonunion. This paper assists surgeons in determining the risk factors for nonunion after foot and ankle fusions. The ankle joint is at highest risk for nonunion, and the tarsometatarsal joint and the subtalar joints the lowest risk.