Physical functions assessed by lower limb performance-based and self-reported outcome measures for knee musculoskeletal conditions: A scoping review

Background: Physical function assessment is key for the management of knee musculoskeletal conditions. There are a wide variety of self-reported outcome measures (SROMs) and performance-based outcome measures (PBOMs) to assess physical function of individuals with knee conditions. However, the content of these measures has not been explored. Objective: To explore the range and frequency of physical functions assessed by lower limb PBOMs and SROMs for people with knee osteoarthritis (OA), anterior cruciate ligament (ACL) injuries, and patellofemoral pain (PFP). Methods: A scoping review was conducted. We included development or measurement properties studies of knee functional outcome measures for populations with knee OA, ACL injuries, and PFP. We extracted the physical functions assessed in each measure. Each identified physical function was linked to a code from the International Classification of Functioning, Disability and Health (ICF) framework. Results: 4146 articles were screened. A total of 143 articles were included. The median number of physical functions assessed was nine for SROMs and one for PBOMs. The three most assessed physical functions were climbing stairs, walking short distances, and standing up from sitting. Climbing stairs was the most assessed physical function in measures for knee OA and PFP populations, whereas jumping was in measures for the ACLinjured population. Conclusion: SROMs assess a broader range of physical functions, whereas PBOMs focus on discrete activities. ACL and PFP measures evaluated more challenging physical functions than knee OA measures. Current physical function outcome measures are not well suited to assess performance in knee OA populations with mild or diverse levels of impairment.