Risk Assessment for Chronic Pain and Patient Satisfaction After Total Knee Arthroplasty

The estimated prevalence of patients who report minor or no improvement of their symptoms and pain after total knee arthroplasty (TKA) remains high, ranging from 5% to 40%. The authors sought to determine whether chronic pain and functional health are related to specific variations in demographic data, surgical techniques, or radiographic pre- and postoperative findings. They also sought to identify independent risk factors for persistent moderate-to-severe chronic pain after TKA. A total of 272 patients who underwent primary TKA from October 2006 to August 2008 with a minimum follow-up of 1 year were identified from electronic medical records. A questionnaire to identify persistent postoperative pain (36-item Short Form Health Survey [SF-36]) was mailed to these patients. Linear regression and logistic regression were used to identify predictors for SF-36 and chronic pain, respectively. Thirty-nine percent of patients reported persistent pain after TKA, with a median average pain score of 3 out of 10 and worst pain score of 5 out of 10. Independent risk factors for persistent pain are the length of the operative procedure (odds ratio [OR]=1.013), medical history of diabetes mellitus (OR=0.430), presence of preoperative flexion contracture (OR=1.089), and patellofemoral joint overstuffing (OR=0.915). Persistent postoperative pain is a common finding after TKA. Nonmodifiable risk factors could be used for risk stratification, whereas modifiable risk factors could be used as a clinical guidance for modification of some aspects of existing surgical techniques.