Effect of Earlier Weightbearing on Ankle Range of Motion and Complications After Primary Total Ankle Arthroplasty

Abstract

Background:

Total ankle arthroplasty (TAA) is a viable option for the treatment of end-stage ankle arthritis. Initiating weightbearing after a TAA has traditionally been conservative, with anywhere from 6 to 12 weeks of non-weightbearing recommended by surgeons. There is a scarcity of literature examining the impact of earlier weightbearing after TAA on postoperative outcomes. This study aimed to compare weightbearing at 3 weeks vs 6 weeks on functional recovery after primary TAA. We hypothesized that patients allowed to weightbear earlier would exhibit greater improvements in ankle range of motion (ROM) without an increase in postoperative complications.

Methods:

This retrospective study analyzed patients who underwent a primary TAA by a single surgeon using the INBONE II prosthesis. These patients were separated into 2 groups: those who initiated weightbearing at 3 weeks (n = 50) or 6 weeks (n = 27). Demographic data and postoperative complications were collected for both groups. Ankle ROM was measured from pre- and postoperative ankle dorsiflexion and plantarflexion radiographs at routine postoperative visits. Comparisons between groups were performed with Student t test for independent variables, paired t test for in-group comparisons, and χ² test for categorical variables. Kaplan-Meier survival plots were created for overall, minor, and major complication rates. Mixed model linear regression analysis was used to control for differences in patient demographics and preoperative ROM.

Results:

Sex, smoking status, diabetes, obesity, and arthritis etiology did not statistically differ between groups. The 3-week weightbearing group was significantly older than the 6-week group (67.8 years vs 61.1 years, respectively, P = .013). The 3-week group had improvements in their postoperative ankle ROM at 6 weeks, 1 year, and 2 years compared with their preoperative ankle ROM after recovering to baseline by 6 weeks. The 3-week group had statistically greater increases in postoperative ankle ROM at 6 weeks, 6 months, 1 year, and 2 years compared with their 6-week counterparts, even after controlling for patient demographics and preoperative ROM. Total number of, as well as time to, overall, minor, or major complications did not differ significantly between groups.

Groups were similar across demographics and comorbidities, although the 3-week cohort was older (67.8 vs 61.1 years; P = .013). In the 3-week group, total ankle ROM returned to baseline by 6 weeks and exceeded preoperative values at 6 months, 1 year, and 2 years; the 6-week cohort did not demonstrate significant improvement over baseline from 3 months onward. Across time points, the 3-week group achieved greater total ankle ROM at 6 weeks, 6 months, 1 year, and 2 years than the 6-week group, including after adjustment for age, BMI, and preoperative ROM. Overall, minor, and major complication rates, and time to first complication, did not differ between groups; survivorship was 98.0% (3-week) vs 100% (6-week), and reoperation rates were 6.0% vs 7.4%, respectively.

Conclusion:

Initiating earlier weightbearing after a primary TAA brings about greater improvements in postoperative ankle ROM compared with preoperative ROM, sustained even up to 2 years postoperative. Earlier weightbearing group demonstrated increased ankle ROM compared with the delayed weightbearing group at early follow-up without an increase in complications. These findings suggest earlier initiation of weightbearing after a primary TAA is safe and beneficial in terms of motion.

Level of Evidence:

Level III, retrospective cohort study.