Iatrogenic Medial Malleolar Fracture and Stress Fracture Considerations in Total Ankle Joint Replacement: A Multicenter Retrospective Study.

Abstract

Total ankle replacement (TAR) is a challenging but rewarding treatment option for primary or post-traumatic tibiotalar osteoarthritis. Acute and latent postoperative stress fractures of the medial malleolus, however, pose a common potential complication that may arise during joint resection, especially during implantation of the tibial component. This is a multicenter retrospective study highlighting considerations for iatrogenic medial malleolar fractures during and after TAR surgery by assessing relationships between fractures and medial malleolus width (MMW). 159 patients undergoing primary TARs without prophylactic tibial fixation from 2016-2022 were selected from multiple institutions. MMW (mm) was measured as the distance between the tibial tray component placement and the medial malleolus' outer cortex using standard AP ankle radiographs intraoperatively and postoperatively. Demographics included BMI, gender, age, and implant type. Average MMW of the 148 patients without fracture was 11.12 mm. Average MMW was 9.43 mm in the 11 patients who suffered intraoperative medial malleolus fracture (n = 7) or developed postoperative stress fracture (n = 4). Tibial fixation was performed only in the fracture group. The difference in MMW between the two groups was statistically significant (p < 0.05). There were no statistically significant differences among all the demographics. Mean follow-up, age, and BMI were 20.9 months, 64.4 years, and 30.4, respectively, and there were no statistically significant differences among demographics. This data demonstrates how shorter MMW, specifically a threshold of 9.43 mm or shorter, may be associated with higher probability of intraoperative or postoperative stress fracture of the medial malleolus.