Prolonged postoperative pain is a frequent problem after uncomplicated total knee replacement (TKR). The purpose of this study was to evaluate the effect of anxiety and pain catastrophizing on postoperative pain after TKR.
A total of 150 patients were enrolled in this prospective study. Preoperatively, anxiety was assessed using the State-Trait Anxiety Inventory (STAI) and pain catastrophizing was assessed using the Pain Catastrophizing Scale (PCS). The primary outcome measure was postoperative pain on a numerical rating scale (NRS). The secondary outcome parameters were the different Knee Osteoarthritis Outcome Score (KOOS) subscales and patient satisfaction. Intergroup differences were tested with an independent t test. The odds ratio was calculated to determine the probability of an unsatisfactory outcome.
Preoperatively and at 6 and 12 months postoperatively, patients with anxiety and particularly patients with pain catastrophizing usually had a higher NRS score, lower knee function before and after surgery, and higher dissatisfaction. These intergroup differences were significant preoperatively and at 6 months postoperatively.
Psychopathologic factors, particularly pain catastrophizing, have an impact on postoperative pain after TKR. Preoperative screening and concurrent treatment of the diagnosed psychological disorder may improve patient-perceived outcomes.