Knee Injury And Osteoarthritis Outcome Score (KOOS)
Assesses level of physical and functional impairment after knee and leg injury.
Find out more about the 5 territories analysed in the score and read instructions on how to interpret the result in the text below the calculator.
The knee injury and osteoarthritis outcome score evaluates 5 domains referring to symptoms, pain assessment, function and daily living, extreme function and overall quality of life.
This is aimed at providing an insight into the level of physical and functional impairment linked to knee and leg injury.
This is a score recommended in the assessment of patients suffering from: post traumatic osteoarthritis (OA), ACL (anterior cruciate ligament) or meniscus injury.
Each of the 42 items in the KOOS (divided in the 5 functional territories) are assessed on a variety of Likert based scales awarded a number of points from 0 to 4 (from no to severe impact).
The final score is correlated on a 0 to 100 scale (as percentage of total possible score achievable), where 0 means perceived extreme knee problems and 100 means no knee problems.
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In order to assess the perceived physical and functional impairment caused by knee injury, a self-administered questionnaire consisting in 5 domains of function is applied.
■ The Symptoms domain refers to signs during the week before the assessment. Some items refer to joint stiffness which is a sensation of restriction or slowness in the ease with which the knee joint can be moved.
■ The Pain domain refer to the amount of knee pain experienced during the past week, while performing certain activities.
■ The Function, daily living domain contains questions referring to the ability to move around or look after one self.
■ The Extreme function domain refers to active or highly active physical function during sport and recreational activities.
■ Quality of Life domain refers to the perceived disruption caused by knee symptoms and impairment.
The KOOS is often employed in clinical studies, to assess the result of treatment or surgery or to monitor patient short or long term recovery. It has been successfully used in a range of knee injuries such as:
■ ACL (anterior cruciate ligament) injury;
■ Post traumatic osteoarthritis (OA);
■ Meniscus injury;
■ Chondral injury.
KOOS score interpretation
Each of the 6 functional domains consist of a different number of questions. Each question is assessed on a Likert scale (from 0 to 4):
■ Symptoms - 7 (S1 to S7);
■ Pain assessment - 9 (P1 to P9);
■ Function, daily living - 17 (A1 to A17);
■ Extreme function - 5 (SP1 to SP5);
■ Quality of life - 4 (Q1 to Q4).
Scores are calculated for each domain and then transformed into a percentage (score out of possible total score). This results in 5 answers from 0 to 100.
There are no specific interpretations and the general rule is that the lower the score, the greater the functional impairment caused by knee problems. Scores closer to 100 indicate very little to no knee problems.
An overall KOOS score is not calculated because its reliability has not been validated to this point.
About the study
KOOS is a self-administered questionnaire created by Roos et al. based on a study that started from the WOMAC Osteoarthritis Index. It has so far been used in patients of 13 to 79 years to assess short- and long-term patient-relevant outcomes after knee injury.
The study recorded a high test–retest reliability ranging from 0.6 to 0.97 across each of the six scales. The Minimal Detectable Change varies between 5 in Symptoms and 21.2 in Quality of Life. The overall Minimal Important Change was found to be around 8 to 10 points.
KOOS was found reliable in the evaluation of response to surgery and physical therapy of patients who underwent anterior cruciate ligament reconstruction.
Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD. (1998) Knee Injury and Osteoarthritis Outcome Score (KOOS)--development of a self-administered outcome measure. J Orthop Sports Phys Ther. 1998; 28(2):88-96.
1. Roos EM, Lohmander LS. The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis. Health Qual Life Outcomes. 2003; 1: 64.
2. Kessler S, Lang S, Puhl W, Stove J. [The knee injury and osteoarthritis outcome score - a multifunctional questionnaire to measure outcome in knee arthroplasty] Z Orthop Ihre Grenzgeb. 2003;141:277–282.
No. Of Items: 42
Year Of Study: 1998
Published On: May 22, 2017 · 08:32 AM
Last Checked: May 22, 2017
Next Review: May 22, 2023