Effect of psychopathology on patient-perceived outcomes of total knee arthroplasty within an indigent population

Background: Factors other than surgical technique and implants impact patient outcomes following a total knee arthroplasty. The purpose of this study was to analyze the effects of psychopathology on the rate of improvement following total knee arthroplasty in an indigent population. Methods: One hundred and fifty-four consecutive indigent patients undergoing a primary total knee arthroplasty for arthritis were enrolled and available for follow-up. Patients were classified as having psychopathology on the basis of the presence of somatization, depression, and/or a panic or anxiety disorder as assessed with the Patient Health Questionnaire. Outcome measures were completed preoperatively and one year postoperatively. Univariate analyses, controlled for sex and age, were used to compare the rates of improvement in patients who exhibited psychopathology with the rates in those without psychopathology. Results: Fifty-four patients (35%) were diagnosed with at least one Axis-I psychological disorder. The psychopathology group showed significantly lower Short Form-36 mental component summary scores both at baseline and one year postoperatively (p < 0.001 for both). The psychopathology group also reported significantly higher levels of perceived disability at baseline on the Pain Disability Questionnaire (p < 0.001) and worse scores on the Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.004); however, the improvement on both of these scales did not differ significantly between the two groups (p > 0.05). The Knee Society Score differed significantly between the two groups at both baseline and the one-year follow-up evaluation (p = 0.003 and p = 0.001, respectively), but there was no significant difference in the total rate of improvement between the two comparison groups (p > 0.05). Conclusions: Not only is there a high prevalence of psychopathology in the indigent population, but psychopathology may result in lower patient-perceived outcome scores at one year after a total knee arthroplasty. Even though outcome scores may be worse for patients with psychopathology, our study showed that these patients still benefit, with the same degree of improvement in function. Level of Evidence: Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.