Abstract
OBJECTIVE: To clarify the analgesic efficacy of transcutaneous electrical nerve stimulation (TENS) in knee osteoarthritis (KOA) and examine whether stimulation parameters moderate treatment effects. METHODS: We meta-analysed randomized controlled trials evaluating TENS for pain in KOA. Thirty-six trials (n = 2518) were included. Pain outcomes were pooled overall and stratified by comparator (control/placebo vs other active treatments). Mixed-effects models examined moderation by frequency, intensity, session duration, and number of sessions. RESULTS: Across all trials, TENS produced a small but statistically significant reduction in pain. Effects were larger versus control/placebo, suggesting a specific benefit relative to minimal or no intervention. Effects were smaller versus other active treatments, likely reflecting effective co-interventions. Session duration moderated analgesia, with greater pain relief when stimulation lasted ≥40 min. No significant moderation was observed for frequency, intensity, or number of sessions. CONCLUSION: TENS may provide clinically relevant pain relief in KOA when delivered with treatment fidelity to pre-specified, literature-informed dosing criteria. However, higher-quality sham-controlled trials with complete parameter reporting and pain assessed during or immediately after stimulation are needed to better quantify the specific analgesic effect beyond contextual influences.