Knee Injury and Osteoarthritis Outcome Score (KOOS)

Measurable knee-related quality of life

The Knee Injury and Osteoarthritis Outcome Score (KOOS) is a 42-item tool for evaluation of knee-specific health that was developed in 1998. With its 5 dimensions (pain, symptoms, activities of daily living, sport/recreation function and knee-related quality of life) and the high number of items, the questionnaire allows a detailed assessment of knee-related outcomes in patients.

The KOOS has application in orthopedic patients undergoing various medical interventions, for example patients with osteoarthritis and cartilage lesions of the knee, as well as patients who have undergone total knee replacement and anterior cruciate ligament reconstruction.

Indication

The KOOS is a disease-specific tool for knee injuries and knee osteoarthritis 1. It has been used in patients with knee cartilage lesions 2 3 and knee osteoarthritis 4. It has also been administered to patients after total knee arthroplasty 5 6 and anterior cruciate ligament reconstruction 7 8.

Items - Dimension - Completion time

The 42 items must be answered by selecting 1 of 5 response options. 9 Dimensions: The items fall under 5 dimensions: pain (9 items), symptoms (7 items), activities of daily living (17 items), sport/recreation function (5 items) and knee-related quality of life (4 items). The patient is asked to answer based on how he or she has felt for the last week. 10 Roos and Lohmander reported a completion time of 10 minutes. 11

Scoring method

A score is calculated for each dimension. Each response is scored from 0 to 4 points, 4 being the response associated with the worst health status. The scores are calculated as follows:

KOOS pain = 100 − mean score (P1−P9)×100/4

KOOS symptoms = 100 − mean score (S1−S7)×100/4

KOOS ADL = 100 − mean score (A1−A17)×100/4

KOOS sport/recreation = 100 − mean score (SP1−SP5)×100/4

KOOS quality of life = 100 − mean score (Q1−Q4)×100/4

A dimension score can still be calculated if up to 50% of items in a dimension have not been answered: These items are given the average score for the dimension items. If more than 50% of items in a dimension have not been answered, the dimension score will be invalid and should not be calculated. 9 12

Score interpretation

The higher the score, the better the patient’s knee-related health. A score of 0 is linked with extreme knee problems, and score of 100 represents no knee-related problems. Normative population-based data are available 13.
The KOOS has been validated in several languages 14 15 16 5, and a validated English document is available.
All the relevant documents are available at KOOS.nu. 12
No license is necessary. The measure is free of charge.
The KOOS allows a very detailed overview of the patient’s knee-related health. Normative data for statistical analysis are available. 5
The questionnaire is lengthy, which could lead to longer completion times, especially in an older patient.

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References

  1. Collins, N. J., et al. “Knee Injury and Osteoarthritis Outcome Score (KOOS): systematic review and meta-analysis of measurement properties.” Osteoarthritis and Cartilage 24.8 (2016): 1317-1329.
  2. Engelhart, Luella, et al. “Validation of the Knee Injury and Osteoarthritis Outcome Score subscales for patients with articular cartilage lesions of the knee.” The American journal of sports medicine 40.10 (2012): 2264-2272.
  3. Vaquero, Javier, et al. “Reliability, validity and responsiveness of the Spanish version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with chondral lesion of the knee.” Knee Surgery, Sports Traumatology, Arthroscopy 22.1 (2014): 104-108.
  4. Ornetti, P., et al. “Cross-cultural adaptation and validation of the French version of the Knee injury and Osteoarthritis Outcome Score (KOOS) in knee osteoarthritis patients.” Osteoarthritis and cartilage 16.4 (2008): 423-428.
  5. Peer, Maria A., and Judith Lane. “The Knee Injury and Osteoarthritis Outcome Score (KOOS): a review of its psychometric properties in people undergoing total knee arthroplasty.” Journal of Orthopaedic & Sports Physical Therapy 43.1 (2013): 20-28.
  6. Gandek, Barbara, and John E. Ware Jr. “Validity and responsiveness of the knee injury and osteoarthritis outcome score: a comparative study among total knee replacement patients.” Arthritis care & research 69.6 (2017): 817-825.
  7. Muller, Bart, et al. “Defining thresholds for the patient acceptable symptom state for the IKDC subjective knee form and KOOS for patients who underwent ACL reconstruction.” The American journal of sports medicine 44.11 (2016): 2820-2826.
  8. Salavati, M., et al. “Knee injury and Osteoarthritis Outcome Score (KOOS); reliability and validity in competitive athletes after anterior cruciate ligament reconstruction.” Osteoarthritis and Cartilage 19.4 (2011): 406-410.
  9. Collins, Natalie J., et al. “Measures of knee function: international knee documentation committee (IKDC) subjective knee evaluation form, knee injury and osteoarthritis outcome score (KOOS), knee injury and osteoarthritis outcome score physical function short form (KOOS‐PS), knee outcome survey activities of daily living scale (KOS‐ADL), Lysholm Knee Scoring Scale, Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Activity Rating Scale (ARS), and Tegner Activity Score (TAS).” Arthritis care & research 63.S11 (2011): S208-S228.
  10. Roos, Ewa M., et al. “Knee Injury and Osteoarthritis Outcome Score (KOOS)—development of a self-administered outcome measure.” Journal of Orthopaedic & Sports Physical Therapy 28.2 (1998): 88-96.
  11. Roos, Ewa M., and L. Stefan Lohmander. “The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis.” Health and quality of life outcomes 1.1 (2003): 1-8.
  12. http://www.koos.nu
  13. Paradowski, Przemyslaw T., et al. “Knee complaints vary with age and gender in the adult population. Population-based reference data for the Knee injury and Osteoarthritis Outcome Score (KOOS).” BMC musculoskeletal disorders 7.1 (2006): 1-8.
  14. Roos, Ewa M., and Sören Toksvig-Larsen. “Knee injury and Osteoarthritis Outcome Score (KOOS)–validation and comparison to the WOMAC in total knee replacement.” Health and quality of life outcomes 1.1 (2003): 1-10.
  15. Roos, Ewa M., et al. “Knee injury and Osteoarthritis Outcome Score (KOOS)‐validation of a Swedish version.” Scandinavian journal of medicine & science in sports 8.6 (1998): 439-448.
  16. Kessler, S., et al. “The Knee Injury and Osteoarthritis Outcome Score–a multifunctional questionnaire to measure outcome in knee arthroplasty.” Zeitschrift fur Orthopadie und ihre Grenzgebiete 141.3 (2003): 277-282.