Immediate Weight-Bearing Compared with Non-Weight-Bearing After Operative Ankle Fracture Fixation Results of the INWN Pragmatic, Randomized, Multicenter Trial

Background: There has been weak consensus and a paucity of robust literature with regard to the best postoperative weight-bearing and immobilization regime for operatively treated ankle fractures. This trial compared immediate protected weight-bearing (IWB) with non-weight-bearing (NWB) with cast immobilization following ankle fracture fixation (open reduction and internal fixation [ORIF]), with a particular focus on functional outcomes, complication rates, and cost utility. Methods: This INWN (Is postoperative Non-Weight-bearing Necessary?) study was a prospective, pragmatic, randomized controlled trial (RCT), with participants allocated in a 1:1 ratio to 1 of 2 parallel groups. IWB from postoperative day 1 in a walking boot was compared with NWB and immobilization in a cast for 6 weeks, following ORIF of all standard types of unstable ankle fractures. Skeletally immature patients and patients with tibial plafond fractures were excluded. The type of surgical fixation was at the surgeon’s discretion. Patients were randomized postoperatively by an operating room nurse using computerized block randomization (20 patients per block). Surgeons were blinded until after the operation. The study was multicenter and included 2 major orthopaedic centers in Ireland. Analysis was performed on an intention-to-treat basis. The primary outcome was the functional outcome assessed by the Olerud-Molander Ankle Score (OMAS) at 6 weeks. A cost-utility analysis via decision tree modeling was performed to derive an incremental cost-effectiveness ratio (ICER). Results: We recruited 160 patients between January 1, 2019, and June 30, 2020, with 80 patients per arm, who were 15 to 94 years of age (mean age, 45.5 years), and 54% of patients were female. The IWB group demonstrated a higher mean OMAS at 6 weeks (43 ± 24 for the IWB group and 35 ± 20 for the NWB group, with a mean difference of 10.4; p = 0.005). The complication rates were similar in both groups, including surgical site infection, wound dehiscence, implant removal, and further operations. Over a 1-year horizon, IWB was associated with a lower expected cost (€1,027.68) than NWB (€1,825.70) as well as a higher health benefit (0.741 quality-adjusted life-year [QALY]) than NWB (0.704 QALY). IWB dominated NWB, yielding cost savings of €798.02 and a QALY gain of 0.04. Conclusions: IWB in a walking boot following ankle fracture fixation demonstrated superior functional outcomes, greater cost savings, earlier return to work, and similar complication rates compared with NWB in a cast for 6 weeks. These findings support the implementation of IWB as the routine mobilization protocol following ankle fracture fixation.