(Research Hub Theater) Clinical Correlates of Physical Function in Patients Undergoing Total Knee or Hip Arthroplasty

Background and/or Objectives: Knee and hip osteoarthritis are associated with pain and loss of function which may progress to cause patients to elect joint replacement surgery. Few studies have specifically evaluated factors associated with disability and impaired physical function in these patients. Therefore, this study aimed to specifically evaluate factors related to functional status in this population.

Design: Cross-sectional cohort study.

Setting: Orthopedic Surgery Department of CHUSJ, Porto, Portugal. Department of PM&R, Northwestern University.

Participants: Convenience sample of 120 patients (95 KOA and 25 HOA patients) scheduled for total joint replacement.

Interventions: Not applicable.

Main Outcome Measures: Functional status in activities of daily living, measured with the Knee/Hip Injury and Osteoarthritis Outcome Score, Activities of Daily Living (KOOS/HOOS-ADL) sub-scale.

Results: Mean age (± SD) of the KOA population 65.6 (0.7) years, mean BMI 30.3 (4.92); 80% (n=75) female. Mean age of the HOA population 59.4 (8.24) years, mean BMI 28.2 (3.68); 68% (n=17) male. Univariate analyses showed pain intensity, neuropathic pain score, anxiety, depression, pain catastrophizing, and functional physical capacity had a significant association with functional disability scores in patients with KOA (p < 0.05, FDR-corrected). In contrast, neither age, BMI, radiographic severity, nor pain duration were significantly associated. For the HOA population, pain interference, pain catastrophizing, depression, and functional physical capacity showed a significant relation with impairment in daily living activities (p < 0.05, FDR-corrected). For KOA, multivariable analysis showed that greater pain and worse functional physical capacity were independent predictors of approximately 50% of ADL disability (R2 = 0.46, p< 0.03).

Conclusions: Our results demonstrate that functional outcomes in the activities of daily living of patients with hip and knee osteoarthritis are related to pain quality/intensity, psychological qualities, and physical performance. On the contrary, age, BMI, or radiographic severity of OA were not associated with ADL disability. We believe interventions targeting disability in OA patients should include pain management and psychological/mood interventions.