Preoperative risk factors associated with chronic pain profiles following total knee arthroplasty.

BACKGROUND: One in five patients experience chronic pain 12 months following total knee arthroplasty (TKA). This longitudinal study used a person-centred approach to identify subgroups of patients with distinct chronic pain profiles following TKA and identified preoperative characteristics associated with these profiles. METHODS: On the day before surgery, 202 patients completed questionnaires that assessed pain, interference with functioning, fatigue, anxiety, depression and illness perceptions. Average and worst pain were assessed prior to surgery, on postoperative day 4, at 6 week and at 3 and 12 months following surgery. Using growth mixture modelling, two subgroups with distinct average and worst pain profiles were identified. RESULTS: Patients in the "lower average" and "lower worst" pain classes had moderate preoperative pain scores that decreased over the remaining 9 months following TKA. Patients in the "higher average" and "higher worst" pain classes had relatively higher preoperative pain scores that increased during the first three months and then decreased slightly over the remaining 9 months. Patients in the higher pain classes had higher interference with function scores; used opioids prior to surgery more often, were more likely to receive a continuous nerve block and ketamine; had higher preoperative fatigue severity and interference scores; and had worse perceptions of illness than patients in the lower pain classes. CONCLUSIONS: These risk factors may be used to identify subgroups of patients at higher risk for more severe pain after TKA. Future studies should test whether modifying these risk factors can improve patients' outcomes after TKA. SIGNIFICANCE STATEMENT: The present study provides a novel and original analysis of pain profiles following total knee arthroplasty that may contribute to our understanding of the transition from acute to chronic pain. Our results may be used to identify patients at higher risk for poorer outcomes based on preoperative risk factors.

More Severe Radiographic Osteoarthritis Is Associated With Increased Improvement in Patients' Health State Following a Total Knee Arthroplasty.

BACKGROUND: To assess whether preoperative radiological severity of osteoarthritis (OA) is related to the level of improvement in patients' health state measured 1 year after total knee arthroplasty (TKA). METHODS: Radiographic severity of OA was graded using the Kellgren-Lawrence (KL) classification. Two independent observers were blinded to patients' outcome scores. Health-related quality of life was measured using EQ-5D-3L preoperatively and at 12-month follow-up. The 5 dimensions of the EQ-5D were converted into a health state index score. The association between KL grade and improvement in health state score was analyzed using multiple linear regression. RESULTS: Among 156 consecutive patients (68% females, mean age 69 years) who underwent primary TKA, 3 knees (2%) were classified as KL grade 2, 115 as KL grade 3 (74%), and 38 as KL grade 4 (24%). Follow-up rate was 77%. There was substantial intra-rater and inter-rater agreement (Cohen's kappa = 0.80 and 0.79). Most patients (64%) had clinically significant improvement in their health state score 1 year after TKA. However, after adjusting for relevant covariates, patients with severe OA (KL grade 4) were found to have significantly more improvement in their health state score than patients with mild or moderate OA (KL grade 2 or 3, respectively). Separate analysis of the 5 EQ-5D dimensions showed that the KL group differences were most evident in the "usual activities" and "pain/discomfort" dimensions. CONCLUSION: Patients with severe OA have significantly more improvement in their usual activities and pain/discomfort 1 year after TKA than patients with less severe OA.

Pain characteristics and self-rated health after elective orthopaedic surgery - a cross-sectional survey.

AIMS AND OBJECTIVES: To describe the postoperative pain and to examine the relationship between pain intensity, pain interference and self-rated health after elective orthopaedic surgery. BACKGROUND: Pain is a problem for many surgical inpatients and can lead to postoperative complications. Limited knowledge exists about the relationship between postoperative pain, function and self-rated health. DESIGN: Cross-sectional survey. METHODS: Pain characteristics, self-rated health, sociodemographic status and comorbidity were measured in 123 elective orthopaedic inpatients recruited consecutively from a hospital in eastern Norway in 2012. On the day they were discharged from the surgical unit, patients completed items about pain intensity and pain interference from the Brief Pain Inventory and about self-rated health from the Medical Outcome Short Form-36 Health Survey. Clinical data were retrieved from the medical records. Patients were divided into three diagnostic groups: shoulder surgery, hip or knee replacement and other surgery. RESULTS: Mean age was 60 years (SD 17·2) and 50% were females. Average pain intensity was 4·2 (SD 2·2) on a 0-10 numeric rating scale and 60% reported moderate/severe pain during the entire hospital stay. Shoulder surgery patients reported significantly higher pain intensity compared to other surgical groups. Pain interfered mostly with daily activity and sleep. Higher pain intensity was significantly associated with poorer self-rated health. The linear regression analysis showed that average pain intensity was related to poorer self-rated health, controlling for sociodemographic variables and pain interference with function. CONCLUSION: High pain intensity is related to poorer self-rated health. Postoperative pain is undermanaged, affects functional areas and could delay rehabilitation. RELEVANCE TO CLINICAL PRACTICE: Postoperative pain management should be given high priority after elective orthopaedic surgery, in order to improve self-rated health and function. Pain treatment for shoulder surgery patients may require more attention than it currently receives.