Bilateral balance improves in low and high fall risk groups after unilateral total ankle arthroplasty

Ankle osteoarthritis (OA) affects ∼1 % of the global population and impairs postural stability, increasing fall risk. Total ankle arthroplasty (TAA) is one of the most common surgical treatments, but balance impairments may persist post-op. The study examined differences in load symmetry across time for patients with ankle OA and post-TAA at low (LFR) or high fall risk (HFR) and then compared these groups with healthy controls.

All participants completed a balance assessment consisting of four static stances: shoulder width (BS), feet together (BFT), semi-tandem, and tandem. Fall risk was determined pre-operatively. Ground reaction forces were collected using force plates (AMTI, Watertown, MA) and load symmetry was calculated using the normalized symmetry index (NSI). A mixed effects model analyzed interactions between group (LFR, HFR) and time (pre-op, post1yr, post2yr) for the BS and BFT stances. A chi-square analysis examined changes in fall risk group assignment over time. Differences between healthy controls and the LFR and HRF groups at post2yr were examined with a mixed effects model.

HFR participants showed a significant decrease in average NSI from pre-op to post1yr (p < 0.001) and post2yr (p = 0.001) for BS. BFT NSI decreased significantly from pre-op to post2yr. The chi-square test indicated a significant shift toward LFR classification at post2yr (p = 0.021). At post2yr, there were no significant NSI differences between LFR, HFR, and controls.

TAA improves load symmetry during quiet standing, with high fall risk participants showing the most pronounced changes, indicating the potential to reduce fall risk in post-TAA older adults.