TDCS+TENS Outperforms TENS-along In Pain Relief And Proprioception Improvement Among Older Adults With Knee Osteoarthritis

PURPOSE: Pain and proprioception deficits are primary symptoms among older adults with Knee osteoarthritis (KOA). The transcutaneous electrical nerve stimulation (TENS) is frequently used to alleviate pain and enhance proprioception, yet its efficacy is limited. The transcranial direct current stimulation (tDCS) combined with TENS may yield superior effects in pain relief and proprioception improvement. This study aimed to assess whether the combined intervention (tDCS+TENS) could achieve better effects than TENS alone. METHODS: Twenty-three older adults with KOA were recruited and randomly assigned to either the tDCS+TENS group (n = 11, age 66.9 ± 3.7 years, height 160.9 ± 5.7 cm, weight 68.8 ± 7.8 kg) or the TENS group (n = 12, age 64.8 ± 5.8 years, height 164.6 ± 8.5 cm, weight 74.7 ± 14.4 kg). Participants in the tDCS+TENS group received the combined intervention, while those in the TENS group received TENS with sham tDCS for six weeks, with three sessions per week, each lasting 20 minutes. Pain was assessed using the WOMAC questionnaire, and proprioception thresholds were measured during knee flexion and extension before (week 0) and after (week 7) the intervention. Two-way ANOVA with repeated measures were used to analyze the data. RESULTS: Significant group-by-intervention interactions were detected in pain score (p = 0.001, η2p = 0.400), and proprioception thresholds during knee flexion (p = 0.038, η2p = 0.189) and extension (p = 0.003, η2p = 0.354). Both tDCS+TENS (week0 = 18.64 ± 9.05, week7 = 10.09 ± 7.09, p < 0.001, d = 1.052) and TENS groups (week0 = 20.33 ± 8.08, week7 = 17.08 ± 8.11, p = 0.003, d = 0.401) were effective to reduce pain, with greater effectiveness in the tDCS+TENS group (p = 0.040, d = 0.918). The proprioception thresholds during knee flexion (week0 = 5.32 ± 3.35, week7 = 2.90 ± 2.37, p < 0.001, d = 0.834) and extension (week0 = 5.73 ± 2.71, week7 = 3.56 ± 2.10, p < 0.001, d = 0.895) decreased in the tDCS+TENS group better than in the TENS group (Flexion: week0 = 6.46 ± 4.15, week7 = 5.48 ± 3.55, p = 0.043, d = 0.254; Extension: week0 = 4.30 ± 3.90, week7 = 3.63 ± 3.21, p = 0.038, d = 0.188) from week0 to week7. CONCLUSIONS: The combined intervention of tDCS + TENS can be considered a clinical treatment for KOA to relieve pain and improve proprioception, making it a promising clinical treatment.