The Hip Disability and Osteoarthritis Outcome Score - Physical Function Short Form (HOOS-PS) is a short form of the HOOS that was developed using Rasch analysis. It includes five items of physical function related to one’s hip problem. For each item, patients are asked to rate their level of difficulty over the past week on a 5-point Likert scale, where higher scores indicate more difficulty. The HOOS-PS provides both a raw summed score of ability that ranges from 0-20, with 0 representing no difficulty, and a normalized summary score of disability that ranges from 0-100, with 100 representing no difficulty.

The Knee Injury and Osteoarthritis Outcome Score Activities of Daily Living (KOOS-ADL) subscale consists of 17 questions regarding physical function in daily life. For each item, the respondent is asked to indicate the degree of difficulty they have had in the past week because of their knee problem on a 5-point Likert scale ranging from none to extreme, coded as scores of 0 to 4. The subscale is scored and normalized to a summary score of 100, with 100 indicating no problems and 0 indicating extreme problems.

The Knee Injury and Osteoarthritis Outcome Score - Physical Function Short-form (KOOS-PS) is a 7-item measure of physical function derived from the 22 items of the activities of daily living and function, sports and recreational activity subscales of the KOOS. The KOOS-PS is intended to elicit people’s opinions about the difficulties they experience with activity due to problems with their knee. An item response theory approach was used to convert ordinal data (such as the responses in the KOOS-PS items of none, mild, moderate, severe, extreme) to an interval level summary score.