effect of transcutaneous electrical nerve stimulation on shoulder pain: a systematic review and meta-analysis of randomized clinical trials

Context: transcutaneous electrical nerve stimulation (tens) is a standard conservative treatment for shoulder pain. objectives: this systematic review aims to explore the effectiveness of tens in relieving shoulder pain. methods: a comprehensive search was performed on pubmed, embase, scopus, web of knowledge, and cochrane databases from inception until may 2023. the primary outcomes were pain and range of motion. the risk of bias (rob) was evaluated using the cochrane rob tool by two authors. the grade approach was used to evaluate the level of certainty in the evidence. results: the meta-analysis comprised 16 studies, including 1,024 participants with shoulder pain. the tens was as effective as the control group in pain reduction immediately (i²: 91%; p = 0.7) and at long-term follow-up (i²: 50%; p = 0.11). the certainty of the evidence was very low. the tens is equally effective as the control group in improving shoulder range of motion at different times. conclusions: the tens has the same effectiveness as the control group in reducing pain and improving range of motion. high-quality randomized controlled trials (rcts) with larger sample sizes and longer follow-ups should be conducted to investigate the effectiveness of tens on pain and range of motion in individuals with shoulder pain of different etiologies.