Abstract
BACKGROUND: The pain and limitations associated with osteoarthritis of the hip and knee have a notable variation that does not correspond directly with pathophysiology. The purpose of this study is to assess the influence of location of the arthritis on pain intensity and magnitude of limitations accounting for personal and psychological factors. METHODS: One hundred and fifty four patients with osteoarthritis of the hip (41 patients) or the knee (113 patients) were enrolled in this prospective cross sectional cohort study. Patients answered questionnaires which included demographics, site of arthritis (hip or knee), laterality (unilateral or bilateral), pain intensity, Patient-Reported Outcomes Measurement Information System Physical Function Computer Adaptive Test (PROMIS PF CAT), and psychologic questionnaires including the Tampa Scale of Kinesiophobia (TSK-4), Pain Catastrophizing Scale (PCS-4), Generalized Anxiety Disorder (GAD-2) and Patient-Reported Outcomes Measurement Information System Depression Computer Adaptive Test (PROMIS Dep CAT). Kellgren-Lawrence classification was classified by the treating surgeon. Associations of these factors with pain and function were assessed using bivariate and multivariable regression models. RESULTS: In a multivariable model accounting for potential confounding, magnitude of limitations was independently associated with years of education, work status, time spent exercising, catastrophic thinking (PCS-4), and symptoms of depression. They accounted for 50% of variability in physical function, with the major contributor being catastrophic thinking. The model for pain intensity included time spent exercising and fear of painful movement (TSK-4). Anatomic site and radiographic severity of arthritis were not associated with either physical function or pain in our patient sample. CONCLUSIONS: This study confirms that limitations and pain from osteoarthritis of the hip and knee are more closely related to personal and psychological factors, less effective cognitive coping strategies such as catastrophic thinking and kinesiophobia in particular, than to pathological and anatomical factors such as location and severity of arthritis. Care that incorporates incremental correction of common misconceptions that accompany the nociception from osteoarthritis have the potential to improve function and comfort in people with osteoarthritis. LEVEL OF EVIDENCE: Prognostic Level II.