Influence of somatization and depressive symptoms on the course of pain within the first year after uncomplicated total knee replacement: a prospective study

Purpose Approximately 10-25 % of patients are reportedly dissatisfied with the results of bicondylar knee prosthesis implantation. The purpose of this study was to evaluate the effect of depressive symptoms and particularly somatization dysfunction on outcomes after total knee replacement (TKR). Methods One hundred fifty patients were enrolled in this prospective study. Pre-operatively, depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9) and somatization was assessed using the PHQ-15. The primary outcome measure was self-assessed knee function evaluated with the Knee Osteoarthritis Outcome Score (KOOS). Pain was measured on a numerical rating scale (NRS). The secondary outcome measures were the KOOS subscales and patient satisfaction. Intergroup differences were tested using an independent t-test. The odds ratio was used to determine the probability of an unsatisfactory outcome. Results At 12 months post-operatively, patients with depressive symptoms and particularly patients with somatization dysfunction usually had a significantly higher NRS score at rest and during activities, a lower knee function before and after surgery, and higher dissatisfaction. Conclusions Psychopathologic factors, particularly somatization dysfunction, have an impact on TKR outcomes. Preoperative screening and concurrent treatment of the diagnosed psychological disorder may improve patient-perceived outcomes.