About the KOOS-12 - Knee injury and Osteoarthritis Outcome Score (Short Form)
The KOOS-12 is a concise, 12-item version of the Knee injury and Osteoarthritis Outcome Score (KOOS) designed to assess knee-related pain, function, and quality of life with reduced respondent burden. It includes questions about pain frequency and during activities, difficulty with daily tasks, and how your knee problem affects your daily life. The KOOS-12 provides three subscale scores plus a Summary Knee Impact Score, making it particularly useful in clinical settings where time efficiency is important.
Medical Specialties
Anatomic Areas
Clinical Indications
Developer Information
The KOOS-12 was developed from the original 42-item KOOS questionnaire through item reduction studies. The original KOOS was developed by Dr. Ewa Roos, Dr. HP Roos, Dr. L Stefan Lohmander, Dr. Christina Ekdahl, and Dr. Bruce Beynnon between 1995-1998 at Lund University in Sweden and University of Vermont in the USA. The 12-item short form was validated to maintain the psychometric properties of the full instrument while reducing respondent burden.
Copyright & Licensing
The KOOS-12 is protected by international copyright as part of the KOOS family of instruments. 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-12 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 using the formula: Score = 100 - ((sum of items × 100) / max possible score). This results in a 0-100 scale where 100 represents no problems and 0 represents extreme problems. A Summary Knee Impact Score is calculated as the average of the three subscale scores. Higher scores indicate better knee function.
Meaningful Change Threshold
A change of 8-10 points in any subscale score or the Summary Knee Impact Score is considered clinically significant. The KOOS-12 has demonstrated comparable responsiveness to the full KOOS questionnaire.
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
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 walking, stairs, and at rest
Summary Knee Impact Score (0-100)
Average of Pain, Function, and QoL subscale scores providing an overall measure of knee health
Function, Daily Living (0-100)
Measures difficulty with daily activities including rising, standing, getting in/out of car, and twisting/pivoting
Clinical Limitations & Considerations
The KOOS-12 is self-reported and subject to patient perception and mood. As a shortened version, it may have reduced sensitivity to detect small changes compared to the full KOOS. It does not include the Symptoms or Sport/Recreation subscales from the full KOOS. The Summary Score requires all three subscale scores to be calculated. Cultural and linguistic adaptations require separate validation.
Supporting Literature
Key validation and development studies for the KOOS-12 - Knee injury and Osteoarthritis Outcome Score (Short Form)
- 1
Item selection for 12-item short forms of the Knee injury and Osteoarthritis Outcome Score (KOOS-12) and Hip disability and Osteoarthritis Outcome Score (HOOS-12)
Gandek B, Roos EM, Franklin PD, Ware JE Jr
Osteoarthritis and Cartilage, 2019
- 2
Validation of the Spanish version of the KOOS-12
Garcia-Moreno C, et al.
Knee Surgery, Sports Traumatology, Arthroscopy, 2020
- 3
Responsiveness and validation of the KOOS-12 in knee replacement
Clement ND, Bardgett M, Weir D, Holland J, Gerrand C, Deehan DJ
The Bone & Joint Journal, 2019
- 4
Cross-cultural adaptation and validation of Persian version of the KOOS-12
Ebrahimi N, et al.
Journal of Orthopaedic Surgery and Research, 2025
- 5
Development of the Knee injury and Osteoarthritis Outcome Score (KOOS)
Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD
Journal of Orthopaedic & Sports Physical Therapy, 1998
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