Central sensitization (CS) has been identified as a factor that induces chronic pain in patients with osteoarthritis (OA). Although there are some reports of CS in knee OA, studies on CS in hip OA are lacking. We aimed to evaluate chronic pain related to CS in patients with hip OA using the CS Inventory (CSI). Additionally, we aimed to clarify the characteristics of patients with pain related to CS.
A total of 100 patients scheduled to undergo total hip arthroplasty (THA) for hip OA were retrospectively reviewed. We investigated the CSI score as an assessment of the extent to which the patients had pain related to CS. Additionally, we assessed the relationships between the CSI score and clinical factors, including age, duration of pain, degree of pain at rest and on activity, by using the visual analogue scale (VAS) and the Harris Hip Score.
The mean CSI score was 19.54 ± 11.25 points. Twenty-one percent of the patients with a score of ≥ 30 were diagnosed as having chronic pain related to CS. The CSI score correlated significantly only with the VAS pain score at rest (r = 0.348, P < 0.001). Fifteen patients were diagnosed with CS syndromes (CSSs) in the assessment of CSI Part B. The mean CSI score was significantly higher in patients diagnosed with CSSs (30.00 ± 12.50) than in patients without a CSS (17.70 ± 10.00; P < 0.001).
Twenty-one percent of the patients scheduled to undergo THA for hip OA were diagnosed with chronic pain related to CS, which might influence the clinical results after THA. As the VAS pain score at rest was significantly correlated with the CSI score, pain at rest might be a predictive factor of chronic pain related to CS in patients with hip OA.