title: The association between pre-operative pain sensitisation and chronic pain after knee replacement: an exploratory study.
abstract: OBJECTIVE
  Chronic pain after total knee replacement (TKR) is a prevalent condition, affecting about 20% of patients. The aim of this study was to explore the relationship between pre-operative pain thresholds and chronic pain after TKR.
  
  
  METHODS
  Patients listed for a TKR because of osteoarthritis participated in a Quantitative Sensory Testing (QST) session prior to surgery. Pressure pain thresholds (PPTs) and hot pain thresholds were assessed at the osteoarthritic knee and the forearm. Patients were followed-up at 1-year after TKR, and the severity of pain in the replaced knee was assessed using the WOMAC Pain score. Pre-operative median QST thresholds were compared to thresholds from a normative database collected from 50 people with no knee pain. The relationship between pre-operative pain thresholds and pain severity post TKR were tested using correlations.
  
  
  RESULTS
  Fifty-one patients participated in a pre-operative QST session and completed a 1-year WOMAC Pain score. Pre-operatively, patients demonstrated evidence of localised (knee) and widespread (forearm) pain sensitisation in response to pressure stimuli compared to healthy participants. Pre-operative PPTs at the forearm were found to be significantly correlated with 1-year WOMAC Pain scores (r = 0.37, P = 0.008).
  
  
  CONCLUSIONS
  This study provides preliminary evidence that pre-operative widespread pain sensitisation, measured using pressure algometry, may be associated with chronic pain after TKR. Further research is needed to explore the predictive value of an assessment of pre-operative widespread pain sensitisation in identifying who is likely to develop chronic pain after TKR.
authors: Musculoskeletal Research Unit, University of Bristol, Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK. V.Wylde@bristol.ac.uk
authors: V
authors: V
authors: Wylde
authors: S
authors: S
authors: Palmer
authors: I D
authors: ID
authors: Learmonth
authors: P
authors: P
authors: Dieppe
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D059350:Chronic Pain / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011312:Pressure / Q000009:adverse effects
keywords: Knee; Osteoarthritis; Pain; Quantitative Sensory Testing; Replacement