Knee Injury and Osteoarthritis Outcome Score (KOOS)
An instrument to evaluate symptoms, pain, daily functioning, sports/recreation, and quality of life in patients with knee injuries or post-traumatic osteoarthritis.
Scale Development & Technical Details
Scale Overview
The Knee Injury and Osteoarthritis Outcome Score (KOOS) was developed by Roos E, Roos H, Lohmander LS (1998). It is designed to measure Knee-related symptoms, pain, physical function, and quality of life. The scale is intended for use with Adults with knee injury or osteoarthritis.
Scale Structure
This instrument consists of 42 items organized into 5 factors/subscales: Symptoms, Pain, Activities of Daily Living, Sport and Recreation, Knee-related Quality of Life.
| Factor / Subscale | Items | N |
|---|---|---|
| Symptoms | 1,2,3,4,5,6,7 | 7 |
| Pain | 8,9,10,11,12,13,14,15,16 | 9 |
| Activities of Daily Living | 17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33 | 17 |
| Sport and Recreation | 34,35,36,37,38 | 5 |
| Knee-related Quality of Life | 39,40,41,42 | 4 |
Response Format
Respondents rate each item using a custom response format.
Response anchors: 0 = None / Never / Always (for joint mobility), 1 = Mild / Rarely / Often (for joint mobility), 2 = Moderate / Sometimes, 3 = Severe / Often / Rarely (for joint mobility), 4 = Extreme / Always / Never (for joint mobility).
Scoring
Items are scored by subscale, with each subscale sum representing a distinct dimension.
Total scores range from 0 to 100. Interpretation guidelines:
- Severe symptoms and limitations: 0 – 49
- Moderate symptoms and limitations: 50 – 79
- Mild to no symptoms and limitations: 80 – 100
Psychometric Properties
Internal Consistency: The scale has demonstrated good to excellent internal consistency with reported Cronbach’s alpha values of High internal consistency (Cronbach's alpha typically > 0.70 across all subscales).
Administration
The scale is self-administered and typically takes approximately 10 minutes to complete. It can be administered individually or in group settings. No special training is required for administration.