When you weigh yourself on a scale and you receive a number, how do you make sense of the value? How do you know if you are overweight, underweight or normal? Who do you compare yourself to?

In order to determine what is normal and to make sense of your own score, you would likely compare your weight with other people who share similar characteristics to you such as sex, age, and height. It wouldn’t make sense to compare yourself to someone with different characteristics since what may be normal for them is likely different for you. This same concept applies to normative values.

Normative data identifies what is usual or typical and describes observed characteristics of a specific population at a particular point in time.[1] The use of normative values allow you to make sense of your test scores by comparing your score to scores of individuals with similar characteristics as you.[2]

As explained in part 1 of the KOOS blog series, the knee injury and osteoarthritis score (KOOS) is a questionnaire designed specifically for people with various knee conditions.[3] Completing the KOOS provides insight into the course of your knee injury and allows you and your healthcare provider to track the effects of treatment over time.[3] While comparing your own preoperative and postoperative KOOS scores provides insight into your recovery process, you can also compare your scores to normative KOOS values to determine your level of impairment or your level of progress relative to people who have undergone a similar injury, surgery or treatment.

Check out the normal KOOS scores blog for populations who have sustained an ACL injury,[4][5][6] total knee replacement (TKR) surgery, [7][8][9] as well as those who have knee osteoarthritis,[10] and populations with no known knee ailments [11] in part 2 of the KOOS blog series.

If you have had a knee injury or surgery try our app Curovate for your daily recovery. Curovate provides video-guided daily exercises, progress tracking, the ability to measure your knee and hip range of motion and the ability to complete the KOOS outcome measure all within the app.

If you need further customized assistance during your surgery or injury recovery check out our Virtual Physical Therapy page to book your 1-on-1 video session with a physical therapist.

Learn more about the KOOS and what normative values are. Also learn about how to interpret your KOOS score in this YouTube video presented by Joey Wong, Kinesiologist.
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1. O’Connor PJ. Normative data: their definition, interpretation, and importance for primary care physicians. Fam Med. 1990;22(4):307-311.

2. Schmidt S, Pardo Y. Normative Data. Encyclopedia of Quality of Life and Well-Being Research. 2014. 4375-4379. doi:10.1007/978-94-007-0753-5_1964

3. Roos EM, Lohmander LS. The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis. Health and Quality of Life Outcomes. 2003;1(64). doi:10.1186/1477-7525-1-64

4. Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD. Knee injury and osteoarthritis outcome score (koos)—development of a self-administered outcome measure. Journal of Orthopaedic and Sports Physical Therapy. 1998;28(2):88-96. doi:10.2519/jospt.1998.28.2.88

5. Samuelsson K, Magnussen RA, Alentorn-Geli E, et al. Equivalent knee injury and osteoarthritis outcome scores 12 and 24 months after Anterior Cruciate Ligament Reconstruction: Results from the Swedish National Knee Ligament Register. The American Journal of Sports Medicine. 2017;45(9):2085-2091. doi:10.1177/0363546517702871

6.Ingelsrud LH, Terwee CB, Terluin B, et al. Meaningful change scores in the knee injury and osteoarthritis outcome score in patients undergoing anterior cruciate ligament reconstruction. The American Journal of Sports Medicine. 2018;46(5):1120-1128. doi:10.1177/0363546518759543

7. Nilsdotter AK, Toksvig-Larsen S, Roos EM. A 5 year prospective study of patient relevant outcomes after total knee replacement. Osteoarthritis Cartilage 2009;17:601-6.

8. Roos EM, Toksvig-Larsen S. Knee injury and Osteoarthritis Outcome Score (KOOS) – validation and comparison to the WOMAC in total knee replacement. Health and Quality of Life Outcomes. 2003;1, 17. doi:10.1186/1477-7525-1-17

9. Nilsdotter AK, Toksvig-Larsen S, Roos EM. Knee Arthroplasty: Are patients’ expectations fulfilled? Acta Orthopaedica. 2009;80(1):55-61. doi:10.1080/17453670902805007

10. Mills KAG, Naylor JM, Eyles JP, Roos EM, Hunter DJ. Examining the minimal important difference of patient-reported outcome measures for individuals with knee osteoarthritis: A model using the knee injury and osteoarthritis outcome score. The Journal of Rheumatology. 2016;43(2):395-404. doi:10.3899/jrheum.150398

11. Cameron KL, Thompson BS, Peck KY, Owens BD, Marshall SW, Svoboda SJ. Normative values for the koos and Womac in a young athletic population. The American Journal of Sports Medicine. 2013;41(3):582-589. doi:10.1177/0363546512472330