The effectiveness of transcutaneous electrical nerve stimulation on adhesive capsulitis : a systematic review

Abstract

Background: Adhesive capsulitis, commonly known as frozen shoulder, is a common condition associated with pain, stiffness and reduced mobility. The pathology affects between 2 to 8% of the general population, primarily females aged 40 years and older. Patients diagnosed with diabetes mellitus, hypothyroidism and cardiovascular disease carry a higher risk of the development of adhesive capsulitis. Transcutaneous electrical stimulation (TENS) is a conservative treatment option, the evidence supporting its effectiveness remains inconsistent and varied in methodological quality. Therefore, this systematic review aimed to critically appraise the available literature and summarise the evidence to determine the level of support of the use of TENS in the management of adhesive capsulitis. Methods: The researcher searched eight electronic databases (Google Scholar, CINAHL, Cochrane databases, Cochrane review databases, PubMed, and SCOPUS). The search terms used were namely, “adhesive capsulitis”, “shoulder adhesive capsulitis”, “frozen shoulder”, “shoulder pain”, “transcutaneous electrical nerve stimulation”, “TENS” and “electrical stimulation”. The inclusion criteria included randomised controlled trials (RCTs), non-randomised controlled trials (nRCTs), and observational studies focused on adhesive capsulitis following the use of TENS as a part of the intervention. The citations and abstracts were filtered based on the relevance to keywords and the full text articles identified based on the inclusion criteria. The final list of articles was reviewed by seven reviewers using PEDro, Newcastle Ottawa and the Liddle Scales (the scales used to evaluate the articles were based on the study design), to establish the methodological rigor of the studies. Once the data collection concluded (viz., full text articles), each article was screened and reviewed by the reviewers. Therefore, the article was evaluated based on the outlined criteria, specified scales, and the limitations of the study reported. The primary outcomes were the effectiveness of TENS in the management of adhesive capsulitis either as a single treatment and/or in combination with other modalities. The data was summarised and presented in tables, illustrating the data found. Results: The initial database search yielded 4 282 studies (after 148 duplicated articles were removed), of which 23 articles fulfilled the eligibility criteria for inclusion in this systematic review. The studies provided mixed results specifically, with only one study utilized TENS as a single treatment modality, while the majority (n=22) examined TENS as part of a multimodal treatment approach. In addition, one study did not specify whether the evidence was related to TENS as the intervention was broadly described as electrical stimulation. The included studies reported improvements in pain, shoulder range of motion and functional outcomes following the interventions that incorporated TENS. However, these improvements were noted when TENS was used in combination with other treatment interventions, rather than a standalone treatment. There is limited evidence supporting the use of TENS as a single modality in the management of adhesive capsulitis, whereas the evidence supporting the use of TENS in combination therapy was deemed favourable, but the evidence was limited in respect to the contribution of TENS in the multimodal protocols. Conclusion: The evidence in support of combination therapy with the addition on TENS in the management of adhesive capsulitis was favourable as participants reported improvements in terms of pain, range of motion and in some cases functionality. Considering the current evidence, it is recommended that future studies investigate the use of TENS in combination therapy and its long-term efficacy.