Elif Aygun POLAT, Yunus Emre OZBILEN, Yusuf POLAT
Turkish Journal of Kinesiology - 2026;12(4):420-428
This study aimed to compare functional mobility and dynamic balance under single-task and dual-task conditions in patients after primary total knee arthroplasty (TKA) and revision TKA, and to examine dual-task cost as an indicator of motor performance deterioration under cognitive load. In this cross-sectional comparative study, 80 patients aged 55 years or older who had undergone primary TKA (n=40) or revision TKA (n=40) at least 12 months previously were evaluated. Functional mobility and dynamic balance were assessed using the Timed Up and Go (TUG) test and the Four Square Step Test (FSST) under single-task and dual-task conditions. Under dual-task conditions, participants simultaneously counted backward aloud by twos from a randomly selected number below 100. The revision TKA group showed worse unadjusted performance in single-task TUG (13.37+/-3.93 vs 11.64+/-2.13 s, p=0.017) and dual-task FSST (17.57+/-5.55 vs 14.86+/-3.94 s, p=0.014). After adjustment for age and sex, dual-tasking significantly worsened performance in both TUG and FSST (both p<0.001). For TUG, the revision TKA group had poorer overall performance than the primary TKA group (p=0.029), but the condition-by-group interaction was not significant (p=0.799). For FSST, both the between-group difference (p=0.033) and the condition-by-group interaction were significant (p=0.001), indicating a greater adverse effect of cognitive load in the revision TKA group. FSST dual-task cost was significantly higher in the revision TKA group than in the primary TKA group (16.39+/-13.82% vs 6.59+/-13.72%, p=0.002), whereas TUG dual-task cost did not differ significantly between groups (p=0.604). These findings suggest that dual-task multidirectional stepping may be more sensitive than general mobility testing for detecting residual functional deficits after revision TKA. Dual-task FSST may therefore be a useful clinical assessment tool for identifying persistent balance-related limitations after revision TKA.
