The Use of Transcutaneous Electrical Nerve Stimulation After Total Knee Arthroplasty: A Prospective Randomized Controlled Trial.

INTRODUCTION: Multimodal pain management is used after total knee arthroplasty (TKA) to reduce opioid intake. Transcutaneous electrical nerve stimulation (TENS) has generated much interest as a non-pharmacologic, patient-controlled therapy. The aims of this study were to evaluate the efficacy of TENS in reducing opioid intake and improving recovery after TKA.

MATERIALS AND METHODS: This was a prospective, parallel-group, double-blinded, randomized trial of patients receiving femoral nerve catheter block with allocation to either active or placebo TENS device groups. All participants were 18-85 years and underwent unilateral, primary TKA at two academic hospitals. Device usage was monitored during inpatient and outpatient phases. Participants were requested to return at second, fourth, and sixth postoperative weeks for follow-up. The primary endpoint was opioid usage, as indicated by medication intake in equianalgesic equivalents to morphine. Secondary measures included: visual analogue scale (VAS) pain scores; functional assessments as measured from knee joint range of motion (ROM) and Timed Up and Go (TUG) test; and clinical outcomes as defined by modified Knee injury and Osteoarthritis Outcome Scores (KOOS) and the 12-item Short Form Survey Instrument (SF-12).

RESULTS: Among 116 participants, overall withdrawal was 37.9% (44 patients) at similar rates in both study arms. After excluding for non-femoral nerve catheter (FNC) blocks (i.e., protocol deviations), there were 35 patients in the active group and 31 patients in the placebo group whose complete records were analyzed. There were no significant differences between groups in any of the clinical endpoints.