title: Effect of tens on pain in relation to central sensitization in patients with osteoarthritis of the knee: study protocol of a randomized controlled trial.
abstract: BACKGROUND
  Central sensitization has recently been documented in patients with knee osteoarthritis (OAk). So far, the presence of central sensitization has not been considered as a confounding factor in studies assessing the pain inhibitory effect of tens on osteoarthritis of the knee. The purpose of this study is to explore the pain inhibitory effect of burst tens in OAk patients and to explore the prognostic value of central sensitization on the pain inhibitory effect of tens in OAk patients.
  
  
  METHODS
  Patients with knee pain due to OAk will be recruited through advertisements in local media. Temporal summation, before and after a heterotopic noxious conditioning stimulation, will be measured. In addition, pain on a numeric rating score, WOMAC subscores for pain and function and global perceived effect will be assessed. Patients will be randomly allocated to one of two treatment groups (tens, sham tens). Follow-up measurements will be scheduled after a period of 6 and 12 weeks.
  
  
  CONCLUSIONS
  Tens influences pain through the electrical stimulation of low-threshold A-beta cutaneous fibers. The responsiveness of central pain-signaling neurons of centrally sensitized OAk patients may be augmented to the input of these electrical stimuli. This would encompass an adverse therapy effect of tens. To increase treatment effectiveness it might be interesting to identify a subgroup of symptomatic OAk patients, i.e., non-sensitized patients, who are likely to benefit from burst tens.
  
  
  BACKGROUND
  ClinicalTrials.gov: NCT01390285.
authors.affiliation: Vrije Universiteit Brussel, Department of Physiotherapy, Faculty of Physical Education & Physiotherapy, Laarbeeklaan 103, B-1090 Brussels, Belgium. David.Beckwee@vub.ac.be
authors.forename: David
authors.initials: D
authors.lastname: Beckwée
authors.forename: Willem
authors.initials: W
authors.lastname: De Hertogh
authors.forename: Pierre
authors.initials: P
authors.lastname: Lievens
authors.forename: Ivan
authors.initials: I
authors.lastname: Bautmans
authors.forename: Peter
authors.initials: P
authors.lastname: Vaes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control* / Q000523:psychology; D001530:Belgium; D059333:Central Nervous System Sensitization; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D010147:Pain Measurement; D017288:Pain Threshold; D012107:Research Design; D012720:Severity of Illness Index; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation; D016896:Treatment Outcome