OBJECTIVE: To investigate the effect of transcutaneous electrical nerve stimulation (TENS) on knee pain and comprehensive physical function in preradiographic knee osteoarthritis.
DESIGN: A single, participant-blinded, randomized controlled trial (RCT) with pre-post design.
SETTING: University research laboratory.
PARTICIPANTS: Patients with knee pain belonging to Kellgren-Lawrence grade 0 or 1 (N=50; aged 50-69y) were randomly assigned to the TENS (n=25) and sham-TENS groups (n=25).
INTERVENTIONS: All participants wore the TENS device under the patella of the symptomatic knee. After measurement, the TENS devices in the TENS group were turned on, and those in the sham-TENS group were not connected.
MAIN OUTCOME MEASURES: The primary outcome measures included the stair climb test, timed Up and Go (TUG) test, 6-minute walk test (6MWT), and knee pain evaluated using the visual analog scale (VAS) for stair climb test, TUG test, and 6MWT. Secondary outcomes included knee extensor strengths and the 2-step test and stand-up test from the locomotive syndrome risk test.
RESULTS: Multiple regression analysis revealed that TENS intervention significantly improved the walk distance and VAS score of the 6MWT, after adjusting for premeasurement data (distance; P=.015, VAS; P=.030).
CONCLUSIONS: Use of TENS improved the VAS score for pain and the distance walked in the 6MWT for individuals with Kellgren-Lawrence grade 0 or 1 of the knee. Thus, TENS may be effective for long-distance walking in patients with preradiographic knee osteoarthritis.
|Rehab Clinician (OT/PT)|
The benefit was marginal and largely comparable to sham procedure. However TENS involves very little, if any, risk.
This study has major flaws. The verum TENS can be recognized by the tingling, so the sham TENS will be recognized and the study not be double blind. Of the 7 outcomes, 4 were NS anyway and these so-called significant differences are not clinically relevant, probably due to the very low VAS pain values (applying the MDC values given by the authors). The conclusions of this paper are misleading.
TENS is not a complete treatment for OA. Hence the study's outcome may be of limited application in the clinic. Comparing TENS with sham TENS is also unethical.
Although currently there is no strong recommendation that TENS is beneficial for subjects with OA of the knee, this study does provide some evidence it could be beneficial. Considering the fact that TENS only offers symptomatic benefits, the true value of this option has to be considered and kept in mind recommending TENS to patients.
The study has a very limited scope and it is difficult to see how that can be applied to clinical practice. The authors acknowledged the limitations of the study and hopefully this one will be a stepping stone for others. Having said that, it is always good to understand what modalities might help our patients be more functional.