doctor performing an ultrasound of the knee

The Knee Injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS JR) was created as a result of clinicians wanting a quicker patient reported outcome measure than what was available at the time. At the time of its publication, the creators of the KOOS JR cited that Medicare was rapidly moving towards the use of patient reported outcomes, however the only approved PRO measures for knee replacements was the KOOS. While the KOOS is a great, validated tool, it is also quite lengthy and time consuming – making administration difficult and creating disruption to workflow.

The KOOS JR was developed using the full KOOS by retaining only those questions that were most relevant for patients undergoing a total knee replacement procedure. The KOOS JR contains just seven questions, in contrast to the full KOOS which contains 42 questions. The questions in the KOOS JR focus on three categories: joint pain, stiffness and function in daily living. The brevity of the KOOS JR allows for faster completion and greater patient engagement.


The main advantage of the KOOS JR is its significantly shortened length. With a completion time of under three minutes, it is an attractive alternative to the longer KOOS reporting measure.

The HSS validation cohort and the FORCE-TJR registry have validated the KOOS JR. Its internal consistency was found to be high and research suggested that there was near-perfect correlation with both the pain and activities of daily living/function domains of the full KOOS survey and the WOMAC reporting measure (Spearman’s correlations 0.80-0.94). Additionally, as a validated measure, the KOOS JR score can be derived from the longer KOOS survey.

Another advantage of the KOOS JR is the ease of its scoring methodology. In the KOOS JR measure, patients rate each activity by indicating the amount of pain or disability they experience while carrying them out. Raw scores are added up (range 0-28) and converted to an interval score (0-100) using the appropriate table. The interval score represents a patients’ total joint disability where 0 corresponds to total joint disability and a score of 100 is perfect joint health.


It is important to keep in mind that the KOOS JR was created as an instrument that is specifically focused on end-stage osteoarthritis and its treatment. Additionally, given its length of 7 questions, research studies may benefit from the full KOOS or another long-form PROM. Overall, given its short length, ease of completion, and the acceptance as a validated PRO-PM tool by CMS, the KOOS JR is a great patient reported outcome measure.

License and Cost

Free. The KOOS JR measure does not require a license. Surveys may not be altered without written permission from the developer. To learn more about the KOOS JR, please visit their website: www.hss.edu/hoos-jr-koos-jr-outcomes-surveys.asp.

Sources |  The joint commission: Candidate Performance Measure Profile  |  Patient Reported Outcomes Summit for Total Joint Arthroplasty Report. August 2015  | Joint Communication from the American Association of Orthopaedic Surgeons, the American joint replacement registry, The Hip Society, The Knee Society, and the American Association of Hip and Knee Surgeons  |  The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis  |  The Knee Injury and Osteoarthritis Outcome Score (KOOS): A Review of Its Psychometric Properties in People Undergoing Total Knee Arthroplasty  | Comparative, validity and responsiveness of the HOOS-PS and KOOS-PS to the WOMAC physical function subscale in total joint replacement for Osteoarthritis


See The Knee PRO Tools Guide

Do you know the difference between the Womac, the KOOS, and the Oxford? If not, have no fear! We’ve broken down the strengths and considerations of all the most popular measures in our Knee PRO Measures Guide.

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