About the KOOS - Knee injury and Osteoarthritis Outcome Score
The Knee injury and Osteoarthritis Outcome Score (KOOS) is a comprehensive, patient-reported outcome measure that evaluates your opinion about your knee and associated problems. It assesses five important areas: pain, other symptoms (like swelling and stiffness), function in daily living, function in sport and recreation, and knee-related quality of life. The KOOS has been validated in numerous languages and is widely used by clinicians and researchers to track knee health over time.
Medical Specialties
Anatomic Areas
Clinical Indications
Developer Information
The KOOS was developed by Dr. Ewa Roos, Dr. HP Roos, Dr. L Stefan Lohmander, Dr. Christina Ekdahl, and Dr. Bruce Beynnon between 1995-1998. Originally created at Lund University in Sweden and University of Vermont in the USA, the KOOS was designed as an extension of the WOMAC Osteoarthritis Index to evaluate short-term and long-term consequences of knee injury, particularly relevant for younger and more active patients.
Copyright & Licensing
The KOOS is protected by international copyright. Permission for use must be obtained from the KOOS Development Group or through Mapi Research Trust. The questionnaire is freely available for clinical and research use with proper citation, but requires permission for commercial applications or electronic implementations. Contact: www.koos.nu or ePROVIDE™ platform.
Administration Instructions
Answer all questions about your knee based on your experiences over the past week. Select the response that best describes your situation. If you did not perform an activity, give your best estimate of your ability.
Scoring Methodology
The KOOS uses a 5-point Likert scale (0-4) for each question: 0 = No problems, 1 = Mild, 2 = Moderate, 3 = Severe, 4 = Extreme problems. Each subscale score is calculated independently using the formula: Score = 100 - ((sum of items / number of items) × 100 / 4). This results in a 0-100 scale where 100 represents no problems and 0 represents extreme problems. Higher scores indicate better knee function. No total KOOS score is calculated; subscales remain independent for clinical interpretation.
Meaningful Change Threshold
A change of 8-10 points in any subscale score is considered clinically significant. Minimal clinically important difference (MCID) varies by subscale: Pain MCID ≈ 8-10 points, Symptoms MCID ≈ 7-10 points, ADL MCID ≈ 8-10 points, Sport/Rec MCID ≈ 9-11 points, QoL MCID ≈ 8-12 points.
Score Interpretation
Understanding what your score means
poor
0 - 39Extreme problems - poor knee function with major impact on daily life
fair
40 - 59Severe problems - fair knee function with significant limitations
good
60 - 79Moderate problems - good knee function with some limitations
excellent
80 - 100Mild problems - excellent knee function with minimal impact on activities
Subscales
This questionnaire measures multiple dimensions
Activities of Daily Living (0-100)
Measures difficulty with daily activities including stairs, sitting/rising, walking, domestic duties, personal care, and mobility
Quality of Life (0-100)
Evaluates awareness of knee problem, lifestyle modifications, confidence in knee, and overall difficulty
Pain (0-100)
Assesses knee pain frequency and severity during various activities including walking, stairs, sitting, lying, and standing
Symptoms (0-100)
Evaluates swelling, stiffness (morning and later), mechanical symptoms (catching, clicking, grinding), and range of motion limitations
Sport and Recreation Function (0-100)
Assesses difficulties in sporting activities including squatting, running, jumping, twisting/pivoting, and kneeling
Clinical Limitations & Considerations
The KOOS is self-reported and subject to patient perception and mood. It may not capture all aspects of knee function in highly active or athletic populations. The Sport/Recreation subscale may have ceiling effects in very active patients. Cultural and linguistic adaptations require validation. The questionnaire focuses on subjective symptoms and may not correlate directly with objective clinical measures or imaging findings.
Related Outcome Measures
Other clinical questionnaires for similar specialties and conditions
KOOS-12 - Knee injury and Osteoarthritis Outcome Score (Short Form)
A concise 12-item questionnaire assessing knee function across three domains: pain (4 items), function in daily living (4 items), and quality of life (4 items). Derived from the full KOOS questionnaire for reduced respondent burden.
Oxford Knee Score
A concise questionnaire evaluating knee-related pain and functional ability in patients undergoing total knee replacement.
WOMAC Osteoarthritis Index
A questionnaire to assess knee and hip osteoarthritis symptoms, including pain, stiffness, and physical function over the last 48 hours.
Forgotten Joint Score
A questionnaire assessing joint awareness after joint replacement surgery. Measures how well patients can "forget" their artificial joint during daily activities.
Kujala Anterior Knee Pain Scale
A 13-item self-report questionnaire that assesses subjective symptoms and functional limitations related to anterior knee pain syndrome, scored from 0 to 100.
VISA-P
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This questionnaire is provided free of charge. Patient Watch charges only for platform services (data storage, automated reminders, analytics) - not for use of clinical instruments. This non-commercial model supports academic and clinical use. View full licensing disclosure