Pre-operative widespread pain in total knee arthroplasty (TKA) was associated with greater pain at 12 months and failure to reach the minimally clinically important difference (MCID), a recent study found. Therefore, widespread pain—as captured by a pain diagram, along with a pain catastrophizing score—may help identify persons with suboptimal TKA outcome. Researchers conducted a prospective analysis that included 241 patients with knee osteoarthritis (OA) undergoing unilateral TKA who completed questionnaires preoperatively and up to 12 months post-operatively. Questionnaires included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scale and a body pain diagram. The mean subject age was 66 years (SD 9), and 61% were females. Researchers found:

• Adjusting for age, sex, co-morbid conditions, baseline pain, pain catastrophizing, and mental health, more widespread body pain was associated with a higher likelihood of reporting 12-month WOMAC pain score >15 and a greater likelihood of failing to achieve the MCID.
• Pain catastrophizing was an independent predictor of persistent pain and failure to improve by the MCID.