An Analysis of Fibular Osteotomy Healing in Transfibular Total Ankle Arthroplasty

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Transfibular total ankle arthroplasty requires a fibular osteotomy, reflection of the fibula during arthroplasty, and then fibular reduction and fixation after arthroplasty component implantation. While this approach offers advantages such as the ability to adjust fibular length and alignment in cases with coronal, sagittal and rotational deformity, some surgeons have concerns about the potential complication of fibular nonunion. The reported incidence of delayed fibular union or nonunion is highly variable, ranging from 0-18%. The purpose of this study is to examine this potential complication further by reporting our observed incidence of fibular nonunion from a single surgeon ankle arthroplasty database. Methods: We queried a total ankle replacement database from a single surgeon, examining 686 consecutive cases performed between 2012 – 2022. 406 cases had at least two year clinical follow up and had consented to study inclusion. Fibular osteotomy fixation was performed with a lateral locking plate and screw construct. Standard 3 view weightbearing ankle radiographs were analyzed at 3,6,12, and 24 months postoperatively by a fellowship trained foot and ankle orthopedic surgeon. Fibular osteotomy healing (healed vs. not completely healed) was documented at each time point based upon the appearance of mature bridging bone across the osteotomy. Rates of fibular healing at 3 and 6 months were secondarily analyzed based upon age ( < 55 yo vs. >=55 yo), history of diabetes, and smoking history (active or former smokers vs. nonsmokers). Secondary comparisons were made using chi-square tests (p < 0.05). Results: 406 patients (208 male, 198 female) with a mean age 60 years (range 23 – 85) were included in this analysis. At 3 months, 16.3% of patients had incomplete healing at their fibular osteotomy. The rate of incomplete osteotomy healing decreased sequentially over time (5.9 % at 6 months, 1.5% at 12 months), but was stable between at 12 and 24 months (1.5%). Rates of incomplete osteotomy healing at 3 and 6 months were not statistically different based upon patient age, history of diabetes, or smoking status (p>0.05). Four fibular nonunions were observed in total. Two nonunions occurred in former smokers, and one in a patient with diabetes mellitus. One nonunion was symptomatic, underwent revision fixation with bone grafting, and healed. Conclusion: In this large clinical series of consecutive transfibular total ankle arthroplasty cases, most patients had radiographic healing of the fibular osteotomy by 3 months. A small group of patients did not have complete healing for 6 to 12 months postoperatively. There was no association between osteotomy healing and patient age, smoking status, or history of diabetes at 3 and 6 months postoperatively. This secondary analysis was limited by the low overall number of fibular nonunions observed (4/406). Our results should be reassuring to surgeons with concerns about this infrequent complication (< 2%) when considering lateral approach total ankle arthroplasty.