Standardized Patient Reported Outcomes Do Not Capture Functional Deficits of Patients Following Contemporary Total Knee Replacement: Descriptive Study.

Background: The physical function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC-PF) is widely used and endorsed by professional organizations for patients with knee osteoarthritis. Its use post total knee replacement (TKR) has been challenged as it may not represent the high level of functional performance that is expected by patients who undergo contemporary TKR with more advanced techniques and care pathways.

Objective: To assess whether the items of the WOMAC-PF reflect the activity limitations identified by patients following TKR.

Design: Data for this descriptive study were obtained from baseline assessments of a randomized clinical trial comparing exercise interventions following TKR.

Methods: Participants completed the WOMAC-PF and identified activity limitations in the Canadian Occupational Performance Measure (COPM) in the same day. The responses to both questionnaires were compared.

Results: This investigation included 50 participants (36 women, mean age 63.8±6.7). The WOMAC-PF failed to capture 50% of the activity limitations identified by participants in the COPM. These activities included kneeling, squatting, carrying/lifting items, strength/endurance exercise, floor transfer, lower extremity exercise, walking up/down hills, yard work, climbing a ladder, driving, managing the environment, carrying objects up/down stairs, gait initiation, balance, and going up/down curbs. Only one activity on the WOMAC-PF (going shopping) was not identified by participant responses on the COPM.

Limitations: Participants were included if they had TKR between 3 and 6 months prior, which may limit generalizability to those immediately after TKR, and the study sample was relatively small.

Conclusions: In individuals following TKR, the WOMAC-PF failed to represent a subset of higher level, more physically demanding activities that were identified as important by patients following TKR.