This knee injury and osteoarthritis outcome score (KOOS) calculator evaluates physical and functional impairment caused by knee and leg injuries. There is more information about the score domains and instructions on how to interpret it below the form.


S1Do you have swelling in your knee?
S2Do you feel grinding, hear clicking or any other type of noise when your knee moves?
S3Does your knee catch or hang up when moving?
S4Can you straighten your knee fully?
S5Can you bend your knee fully?
S6How severe is your knee joint stiffness after first wakening in the morning?
S7How severe is your knee stiffness after sitting, lying or resting later in the day?

Pain while ...

P1How often do you experience knee pain?
P2Twisting/pivoting on your knee.
P3Straightening knee fully.
P4Bending knee fully.
P5Walking on flat surface.
P6Going up or down stairs.
P7At night while in bed.
P8Sitting or lying.
P9Standing upright.

Function, daily living (ADL)

A1Descending stairs.
A2Ascending stairs.
A3Rising from sitting.
A5Bending to floor/pick up an object.
A6Walking on flat surface.
A7Getting in/out of car.
A8Going shopping.
A9Putting on socks/stockings.
A10Rising from bed.
A11Taking off socks/stockings.
A12Lying in bed (turning over, maintaining knee position).
A13Getting in/out of bath.
A15Getting on/off toilet.
A16Heavy domestic duties (moving heavy boxes, scrubbing floors, etc).
A17Light domestic duties (cooking, dusting, etc).

Extreme function difficulty (sport/rec)

SP4Twisting/pivoting on your injured knee.

Quality of life (QOL)

Q1How often are you aware of your knee problem?
Q2Have you modified your life style to avoid potentially damaging activities to your knee?
Q3How much are you troubled with lack of confidence in your knee?
Q4In general, how much difficulty do you have with your knee?

How does the knee injury and osteoarthritis outcome score (KOOS) calculator work?

This is a health tool that assesses the perceived dysfunctionality caused by knee problems which was developed based on the 1990 instrument and the further validation studies.

There are 5 territories analyzed in the knee injury and osteoarthritis outcome score (KOOS) calculator and a knee related QOL, as described below:

■ Symptoms – These questions should be answered thinking of your knee symptoms during the last week.

Stiffness – The following questions concern the amount of joint stiffness you have experienced during the last week in your knee. Stiffness is a sensation of restriction or slowness in the ease with which you move your knee joint.

Pain assessment – What amount of knee pain have you experienced the last week during certain activities.

Function, daily living – The following questions concern your physical function. By this we mean your ability to move around and to look after yourself. For each of the following activities please indicate the degree of difficulty you have experienced in the last week due to your knee.

Extreme function – Sports and recreational activities.The following questions concern your physical function when being active on a higher level. The questions should be answered thinking of what degree of difficulty you have experienced during the last week due to your knee.

Quality of life – overall evaluation.

KOOS is commonly used due to its psychometric properties in several research trials, and allows medical professionals to collect information for databases and registries.

Clinical usage of this easy to administer scale is not limited to one time usage as it can be employed for monitoring purposes as well to assess the result to treatment on the short term but also rehabilitation on the long term.

It allows the clinician to better understand the difficulties the patients is meeting due to knee injury and the following types of conditions caused by it:

post traumatic osteoarthritis (OA);

ACL (anterior cruciate ligament) injury;

meniscus injury;

chondral injury.

KOOS score interpretation

Each of the 6 categories comprise of a different number of questions:

Symptoms - 5 (S1 to S5);

Stiffness - 2 (S6 & 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).

These are all based on Likert schemes with answer choices on a scale from 0 to 4, from no impact to severe impact. These are calculated for each of the 6 areas.

Scores are then transformed to a 0 - 100 scale, with zero representing perceived extreme knee problems and 100 indicating no knee problems. This is used in order to relate to result reporting in other orthopaedic scales and measures.

Scores between 0 and 100 represent the percentage of total possible score achieved. To this point, there hasn’t been validated an overall score and therefore it is not calculated.

KOOS is a self administering questionnaire that has been so far used on patients from 13 to 79 of age and presents with a high test–retest reliability with different values for each of the six scales, values varying between 0.6 and 0.97.

The Minimal Detectable Changes in patients with knee injury also vary between 5 for symptoms and 21.1 for quality of life while the Minimal Important Change is assessed to be around 8 to 10 points.


1) Roos EM, Lohmander LS. (2003) The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis. Health Qual Life Outcomes; 1: 64.

2) Roos EM, Roos HP, Ekdahl C, Lohmander LS. (1998) Knee injury and Osteoarthritis Outcome Score (KOOS)--validation of a Swedish version. Scand J Med Sci Sports; 8(6):439-48.

3) 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; 28(2):88-96.

21 Jan, 2016