title: Effects of transcutaneous electrical nerve stimulation on pain, pain sensitivity, and function in people with knee osteoarthritis: a randomized controlled trial.
abstract: BACKGROUND
  Transcutaneous electrical nerve stimulation (TENS) is commonly used for the management of pain; however, its effects on several pain and function measures are unclear.
  
  
  OBJECTIVE
  The purpose of this study was to determine the effects of high-frequency TENS (HF-TENS) and low-frequency TENS (LF-TENS) on several outcome measures (pain at rest, movement-evoked pain, and pain sensitivity) in people with knee osteoarthritis.
  
  
  METHODS
  The study was a double-blind, randomized clinical trial.
  
  
  METHODS
  The setting was a tertiary care center.
  
  
  METHODS
  Seventy-five participants with knee osteoarthritis (29 men and 46 women; 31-94 years of age) were assessed.
  
  
  METHODS
  Participants were randomly assigned to receive HF-TENS (100 Hz) (n=25), LF-TENS (4 Hz) (n=25), or placebo TENS (n=25) (pulse duration=100 microseconds; intensity=10% below motor threshold).
  
  
  METHODS
  The following measures were assessed before and after a single TENS treatment: cutaneous mechanical pain threshold, pressure pain threshold (PPT), heat pain threshold, heat temporal summation, Timed "Up & Go" Test (TUG), and pain intensity at rest and during the TUG. A linear mixed-model analysis of variance was used to compare differences before and after TENS and among groups (HF-TENS, LF-TENS, and placebo TENS).
  
  
  RESULTS
  Compared with placebo TENS, HF-TENS and LF-TENS increased PPT at the knee; HF-TENS also increased PPT over the tibialis anterior muscle. There was no effect on the cutaneous mechanical pain threshold, heat pain threshold, or heat temporal summation. Pain at rest and during the TUG was significantly reduced by HF-TENS, LF-TENS, and placebo TENS.
  
  
  CONCLUSIONS
  This study tested only a single TENS treatment.
  
  
  CONCLUSIONS
  Both HF-TENS and LF-TENS increased PPT in people with knee osteoarthritis; placebo TENS had no significant effect on PPT. Cutaneous pain measures were unaffected by TENS. Subjective pain ratings at rest and during movement were similarly reduced by active TENS and placebo TENS, suggesting a strong placebo component of the effect of TENS.
authors.affiliation: Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Carol Grace T
authors.initials: CG
authors.lastname: Vance
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Rakel
authors.forename: Nicole P
authors.initials: NP
authors.lastname: Blodgett
authors.forename: Josimari Melo
authors.initials: JM
authors.lastname: DeSantana
authors.forename: Annunziato
authors.initials: A
authors.lastname: Amendola
authors.forename: Miriam Bridget
authors.initials: MB
authors.lastname: Zimmerman
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Walsh
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000628:therapy*; D010147:Pain Measurement; D017288:Pain Threshold; D018709:Statistics, Nonparametric; D004561:Transcutaneous Electric Nerve Stimulation; D016896:Treatment Outcome