Effects of tDCS combined with TENS in relieving pain and improving gait patterns during stepping over obstacles among older adults with knee osteoarthritis.

Abstract

Purpose: Older adults with knee osteoarthritis (KOA) exhibit an elevated risk of falls during obstacle negotiation, primarily due to pain-induced gait deviations. While transcutaneous electrical nerve stimulation (TENS) offers modest pain relief and limited gait modulation, combining it with transcranial direct current stimulation (tDCS) may enhance the effects. This study evaluated the comparative efficacy of tDCS + TENS vs. TENS alone in mitigating pain and optimizing gait patterns during obstacle crossing in older adults with KOA.

Methods: Twenty-three participants with KOA (mean age: 67.6 ± 5.0 years; BMI: 25.9 ± 2.4 kg/m²) were randomized to either tDCS + TENS (n = 12; 7F/5M) or TENS-only (n = 11; 7F/4M) groups. Both interventions involved 20-minute sessions, administered thrice weekly for six weeks. Outcome measures included pain intensity (visual analog scale, VAS) and gait variables (foot clearance height, crossing velocity) assessed pre- (week 0) and post-intervention (week 7). Data were analyzed using mixed-design two-way ANOVAs with Bonferroni corrections.

Results: Statistically significant group-by-time interactions were observed for pain (p = 0.002, η ² _p = 0.378), foot clearance (p = 0.038, η ² _p = 0.190), and crossing velocity (p < 0.001, η ² _p = 0.588). post hoc analyses revealed that the tDCS + TENS group (week0 = 4.72 ± 1.01, week7 = 1.98 ± 0.88, p < 0.001) experienced significantly greater reductions in pain scores compared to the TENS-only group (week0 = 5.02 ± 1.19, week7 = 3.56 ± 1.18, p < 0.001); tDCS + TENS group experienced significantly greater improvements in foot clearance (week0 = 0.19 ± 0.04, week7 = 0.20 ± 0.03, p < 0.001) and crossing velocity (week0 = 0.53 ± 0.11, week7 = 0.62 ± 0.08, p < 0.001), compared to the TENS-only group (week0 = 0.17 ± 0.02, week7 = 0.17 ± 0.02, p < 0.001; week0 = 0.52 ± 0.09, week7 = 0.54 ± 0.09).

Conclusion: The combination of tDCS and TENS significantly outperformed TENS-only in reducing pain and enhancing gait adaptability during obstacle negotiation in older adults with KOA. These findings support the integration of tDCS as an adjunctive neuromodulatory strategy to amplify the therapeutic benefits of TENS in this population.