Cast versus removable orthosis for the management of stable type B ankle fractures: a systematic review and meta-analysis

Purpose There is currently no consensus on nonoperative management in adult patients after a stable type B ankle fracture. The aim of this review is to compare a removable orthosis versus a cast regarding safety and functional outcome in the NOM of stable type B ankle fractures. Methods A systematic review and meta-analysis were performed using randomized clinical trials and observational studies. The methodological quality of the included studies was assessed with the methodological index for non-randomized studies instrument. Nonoperative management was compared using the number of complications and functional outcome measured using the Olerud and Molander Score (OMAS) or the American Academy of Orthopaedic Surgeons Ankle Score. Results Five studies were included. Two were randomized clinical trials, and three were observational studies, including a total of 516 patients. A meta-analysis showed statistically significant higher odds of developing complications in the cast group [odds ratio (OR), 4.67 (95% confidence interval (CI) 1.52-14.35)]. Functional outcome in OMAS did not vary significantly at 6 weeks, mean difference (MD) - 6.64 (95% CI - 13.72 to + 0.45), and at 12 weeks, MD - 6.91 (95% CI - 18.73 to + 4.91). The mean difference of functional outcome in OMAS at 26 weeks or longer was significantly better in the removable orthosis group; MD - 2.63 (95% CI - 5.01 to - 0.25). Conclusion Results of this systematic review and meta-analysis show that a removable orthosis is a safe alternative type of NOM, as complication numbers are significantly lower in the orthosis group. In addition, no statistically significant differences were found in terms of functional outcome between a removable orthosis and a cast at 6 and 12 weeks. The 6-week and the 26-week OMAS results show that in patients with stable type B ankle fractures, a removable orthosis is non-inferior to a cast in terms of functional outcome.