Transcutaneous electrical nerve stimulation for postoperative pain control after total knee arthroplasty: A meta-analysis of randomized controlled trials

BACKGROUND: This meta-analysis aimed to evaluate the efficiency and safety of transcutaneous electrical nerve stimulation (TENS) for pain control after total knee arthroplasty. METHODS: A systematic search was performed in Medline (1966 to June 2017), PubMed (1966 to June 2017), Embase (1980 to June 2017), ScienceDirect (1985 to June 2017), and the Cochrane Library. Only randomized controlled trial (RCT) was included. The fixed/random effect model was used according to the heterogeneity tested by I statistic. Meta-analysis was performed using Stata 11.0 software. RESULTS: Five RCTs including 472 patients met the inclusion criteria. The present meta-analysis indicated that there were significant differences between groups in terms of visual analogue scale score at 12 hours (average: 3.58 vs 4.34, SMD = -0.260, 95% CI: -0.442 to -0.078, P = .005), 24 hours (average: 3.18 vs 3.52, SMD = -0.244, 95% CI: -0.426 to -0.063, P = .008), and 48 hours (average: 2.70 vs 2.96, SMD = -0.214, 95% CI: -0.395 to -0.033, P = .021) after total knee arthroplasty. Significant differences were found regarding opioid consumption at 12 hours (average: 14.44 vs 18.54, SMD = -0.503, 95% CI: -0.687 to -0.319, P = .000), 24 hours (average: 16.10 vs 18.40, SMD = -0.262, 95% CI: -0.443 to -0.080, P = .005), and 48 hours (average: 12.92 vs 15.12, SMD = -0.183, 95% CI: -0.364 to -0.002, P = .048). «Foul: declaring statistical significance without acknowledging low effect sizes.» CONCLUSION: TENS could significantly reduce pain and opioid consumption after total knee arthroplasty. «“could” — now there’s a funny word to use here!» In addition, there were fewer adverse effects in the TENS groups. Higher quality RCTs are required for further research.