Abstract
BACKGROUND: Pain is the primary indication for both primary and revision total knee arthroplasty (TKA); however, most arthroplasty outcome measures do not take pain into account.OBJECTIVE: To document the prospective pain experience following TKA, with subjective pain-specific questionnaires to determine if comorbidities, preoperative pain or preoperative pain catastrophizing scores are predictive of long-term pain outcomes.METHODS: Fifty-five patients with a primary diagnosis of osteoarthritis of the knee, who were scheduled to undergo TKA, were asked to fill out the McGill Pain Questionnaire (MPQ) and the Pain Catastrophizing Scale (PCS) preoperatively and at three, 12 and 24 months follow-up. Comorbidities were extracted from the Queen Elizabeth II Health Sciences Centre health information system.RESULTS: The overall response rate (return of completed questionnaires) was 84%. There was a significant decrease in the MPQ scores (P<0.05) postoperatively. PCS scores did not change over time. Receiver operating characteristic curves revealed the number of comorbidities per patient predicted the presence of pain postoperatively, as documented by the numerical rating subscale of the MPQ at 24 months (P<0.05). Receiver operating characteristic curves for pre-operative PCS and rumination subscale scores predicted the presence of pain, as measured by the Pain Rating Index subscale of the MPQ at 24 months (P<0.05). Preoperative PCS scores and comorbidities were significantly higher in the persistent pain group (P<0.05).CONCLUSIONS: The number of comorbidities predicted the presence of pain at 24 months follow-up and, for the first time, preoperative PCS scores were shown to predict chronic postoperative pain. This may enable the identification of knee arthroplasty patients at risk for persistent postoperative pain, thus allowing for efficient administration of preoperative interventions to improve arthroplasty outcomes.