Physical activities assessed by outcome measures for knee musculoskeletal conditions: a scoping review.

This scoping review aimed to identify all existing physical activities assessed in functional outcome measures for people with knee osteoarthritis (OA), anterior cruciate ligament (ACL) injuries, and patellofemoral pain (PFP).

Four electronic databases were searched from inception to February 2023 for studies that described the development or assessment of measurement properties of measures of knee function for people with knee OA, ACL injuries, and PFP. We extracted the physical activities assessed in each measure and developed a ranking of the most commonly assessed physical activities. Each identified physical activity was linked to a code from the International Classification of Functioning, Disability and Health (ICF) framework.

We screened 4,146 articles and included 146 for data extraction. We found 53 performance tests, 37 questionnaires, and 3 mixed measures. A total of 73 different physical activities were extracted. The three most assessed physical activities were climbing, walking short distances, and arising from sitting. Climbing was the most assessed physical activity in measures for knee OA and PFP populations, whereas jumping was most assessed in measures for people with ACL injury. Questionnaires assessed a median of 9 physical activities and rarely assessed unilateral activities.  Performance tests tended to assess only one activity. The extracted physical activities were linked to 50 different ICF codes. We found high variability in the descriptions of physical activities within the questionnaires.

ACL and PFP outcome measures evaluated more challenging physical activities than knee OA outcome measures. Questionnaires assess a broader range of activities but focus on bilateral ones. In contrast, performance tests focus on discrete physical activities and assess a mixture of bilateral and unilateral activities. 

Many outcome measures are available for clinical use to assess physical function in people with knee musculoskeletal conditions. When choosing an outcome measure, physiotherapists should consider the current and potential future physical function of the person being assessed. Clinicians need to be cautious when using performance tests as measures of overall physical function, given most include very few activities. When using questionnaires to assess impairments related to an injured lower limb, clinicians should consider how they instruct patients, as most included activities require bilateral performance. Finally, researchers should consider being more specific when constructing items for newly developed questionnaires to help respondents  answer accurately and consistently.