What is the efficacy of Transcutaneous electrical nerve stimulation (TENS) in patients with osteoarthritis of the knee?
Background: Osteoarthritis (OA) is a disease that affects synovial joints causing degeneration and destruction of hyaline cartilage. To date, no curative treatment for OA exists. The primary goals for OA therapy are to relieve pain and maintain or improve functional status. Transcutaneous electrical nerve stimulation (TENS) is a non-invasive modality that is commonly used to control both acute and chronic pain arising from several conditions.
Aims: To assess the effectiveness of TENS in the treatment of knee OA. The primary outcomes of interest were effect on pain relief and functional status. The secondary objective was to determine the most effective mode of TENS application for pain control.
Methods: CINAHL, MEDLINE and SPORTDiscus were searched from 1st of December up until 1st February 2017 using a strategy to describe TENS and knee OA pain. Inclusion criteria were primary research papers, participants with knee OA, intervention to include TENS, and pain and function as primary outcome measures. Eligible papers were critically appraised using CASP checklists, given a quality grading and summarised in tables. The papers’ results and common themes were identified and discussed.
Results: Six RCTs papers were included in the review with methodological quality ratings ranging from fair to excellent. Five studies compares the effect of TENS against sham and one with before/after design.
Discussion: Even though there was variety in the methodological quality of the studies there was sufficiently common evidence across all of the papers to confirm that TENS resulted in reduction of pain and improved function and quality of life in patients presenting with knee OA. Nevertheless, its effect was overall similar to sham intervention. However, the studies commonly had too small a sample for their results to be generalised and there was a lack of evidence regarding the long-term effects.
Conclusions: Although active TENS is shown not to be as effective as sham TENS treatment, this review provides evidence for the use of TENS in management of knee OA due to the reduction of its symptoms in comparison to baseline. There was no significant difference in effectiveness of different type of TENS against each other. The current systematic review is inconclusive, hampered by the inclusion of only small trials. More well designed studies with a standardized protocol and adequate numbers of participants are needed to conclude the effectiveness of TENS in the treatment of OA of the knee.
Key Words: Knee Osteoarthritis, Transcutaneous Electrical Nerve Stimulation, Knee OA management.