title: Optimal stimulation duration of tens in the management of osteoarthritic knee pain.
abstract: OBJECTIVE
  This study examined the optimal stimulation duration of transcutaneous electrical nerve stimulation (TENS) for relieving osteoarthritic knee pain and the duration (as measured by half-life) of post-stimulation analgesia.
  
  
  METHODS
  Thirty-eight patients received either: (i) 20 minutes (TENS20); (ii) 40 minutes (TENS40); (iii) 60 minutes (TENS60) of TENS; or (iv) 60 minutes of placebo TENS (TENS(PL)) 5 days a week for 2 weeks.
  
  
  METHODS
  A visual analogue scale recorded the magnitude and pain relief period for up to 10 hours after stimulation.
  
  
  RESULTS
  By Day10, a significantly greater cumulative reduction in the visual analogue scale scores was found in the TENS40 (83.40%) and TENS60 (68.37%) groups than in the TENS20 (54.59%) and TENS(PL) (6.14%) groups (p < 0.000), such a group difference was maintained in the 2-week follow-up session (p < 0.000). In terms of the duration of post-stimulation analgesia period, the duration for the TENS40 (256 minutes) and TENS60 (258 minutes) groups was more prolonged than in the other 2 groups (TENS20 = 168 minutes, TENS(PL) = 35 minutes) by Day10 (p < 0.000). However, the TENS40 group produced the longest pain relief period by the follow-up session.
  
  
  CONCLUSIONS
  40 minutes is the optimal treatment duration of TENS, in terms of both the magnitude (VAS scores) of pain reduction and the duration of post-stimulation analgesia for knee osetoarthritis.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. rsgladys@polyu.edu.hk
authors.forename: Gladys L Y
authors.initials: GL
authors.lastname: Cheing
authors.forename: Amy Y Y
authors.initials: AY
authors.lastname: Tsui
authors.forename: Sing Kai
authors.initials: SK
authors.lastname: Lo
authors.forename: Christina W Y
authors.initials: CW
authors.lastname: Hui-Chan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000698:Analgesia / Q000379:methods; D000704:Analysis of Variance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000534:rehabilitation*; D010147:Pain Measurement; D017288:Pain Threshold; D017060:Patient Satisfaction; D011336:Probability; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D012720:Severity of Illness Index; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D016896:Treatment Outcome