History of knee surgery is associated with higher prevalence of neuropathic pain-like symptoms in patients with severe osteoarthritis of the knee

ObjectiveNeuropathic 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.Patients and methodsA 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.ResultsAlmost 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.ConclusionsNP-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.