title: History of knee surgery is associated with higher prevalence of neuropathic pain-like symptoms in patients with severe osteoarthritis of the knee.
abstract: OBJECTIVE
  Neuropathic pain (NP) mechanisms contribute to the pain experience in osteoarthritis (OA). We aimed to characterise the factors that contribute to NP-like symptoms in knee OA patients.
  
  
  METHODS
  A total of 139 patients with knee OA were recruited from secondary care, and completed a nurse- administered PainDetect questionnaire (PD-Q ), a visual analogue scale (VAS) for pain intensity, and the Western Ontario MacMaster questionnaire (WOMAC). Cases with any previous history of total joint replacement were excluded.
  
  
  RESULTS
  Almost 75% of patients had non-zero PD-Q scores, and 34% had PD-Q scores corresponding to possible NP. No association was seen between PD-Q scores and duration of symptoms, gender, and radiographic severity. Possible NP was strongly associated (p < 1 × 10(-3)) with worse quality of life scores, worse sleep scores, higher pain intensity, worse WOMAC pain, stiffness and function scores. A history of previous knee surgery (arthroscopy, ligament repair or meniscectomy) was strongly associated with possible NP (odds ratio [OR] = 6.86; 95% CI = 1.78-26.43; p < 0.005). This association remained statistically significant after adjustment for pain intensity (OR = 6.37; 95% CI = 1.55-26.11; p < 0.010) whereas an association between history of knee surgery and the other measures of pain was found to be mediated by PD-Q scores.
  
  
  CONCLUSIONS
  NP-like symptoms are highly prevalent in patients with clinically severe painful OA and are a significant contributor to decreased quality of life and higher pain intensity. The cross-sectional association with previous history of knee surgery suggests that some of the NP-like symptoms may result from nerve damage.
authors.affiliation: Academic Rheumatology, Clinical Sciences Building, Nottingham City Hospital Hucknall Road, Nottingham NG5 1PB, UK. Electronic address: ana.valdes@nottingham.ac.uk.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Valdes
authors.affiliation: Academic Rheumatology, Clinical Sciences Building, Nottingham City Hospital Hucknall Road, Nottingham NG5 1PB, UK; Arthritis Research UK Pain Centre, University of Nottingham, City Hospital, Nottingham NG5 1PB, UK.
authors.forename: Anu K
authors.initials: AK
authors.lastname: Suokas
authors.affiliation: Academic Rheumatology, Clinical Sciences Building, Nottingham City Hospital Hucknall Road, Nottingham NG5 1PB, UK.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Doherty
authors.affiliation: Academic Rheumatology, Clinical Sciences Building, Nottingham City Hospital Hucknall Road, Nottingham NG5 1PB, UK.
authors.forename: Wendy
authors.initials: W
authors.lastname: Jenkins
authors.affiliation: Academic Rheumatology, Clinical Sciences Building, Nottingham City Hospital Hucknall Road, Nottingham NG5 1PB, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Doherty
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000209:etiology* / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000503:physiopathology / Q000601:surgery; D010147:Pain Measurement; D011788:Quality of Life; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: Knee arthroscopy; Neuropathic pain; Osteoarthritis; PainDETECT questionnaire; Quality of life