What is the KOOS?KOOS is developed as an instrument to assess the patients opinion about their knee and associated problems. KOOS is intended
to be used for knee injury that can result in post traumatic osteoarthritis
(OA); i.e. ACL (anterior cruciate ligament) injury, meniscus injury, chondral
injury, etc. KOOS is meant to
be used over short and long time intervals; to assess changes from week
to week induced by treatment (medication, operation, physical therapy)
or over years due to the primary injury or post traumatic OA. KOOS can be used
to assess groups and to monitor individuals. KOOS content validity
was ensured through literature search, a pilot study and an expert panel
(US and Sweden); patients, orthopedic surgeons and physical therapists. KOOS consists of
5 subscales; Pain, other Symptoms, Function in daily living
(ADL), Function in sport and recreation (Sport/Rec) and knee
related Quality of life QOL. The last week is taken into consideration
when answering the questions. Standardized answer options are given (5
Likert boxes) and each question gets a score from 0 to 4. A normalized
score (100 indicating no symptoms and 0 indicating extreme symptoms) is
calculated for each subscale. The result can be plotted as an outcome
profile. KOOS is patient-administered,
the format is user friendly, and takes about 10 minutes to fill out. KOOS is self-explanatory
and can be administered in the waiting room or used as a mailed survey. KOOS has been used
in patients 14-78 years old. KOOS reference values
from a group of 50 subjects (mean 53 years, 37-79) with no previous and
no current clinical signs of injury to the ACL or menisci and no radiographic
signs of OA has been established (4). KOOS has high test-retest
reproducibility (ICC >0.75). KOOS includes WOMAC
Osteoarthritis Index LK 3.0 (2,1)
in its complete and original format (with permission), and WOMAC scores
can be calculated. WOMAC is valid for elderly subjects with knee OA. KOOS construct validity has been determined in comparison with SF-36 (7,6) and expected correlations were found (5,3). Moderates to high correlations were found when comparing to the Lysholm knee scoring scale (3). KOOS subscales "Sport
and Recreation function" and "Quality of Life" were more
sensitive and discriminative than the WOMAC subscales "Pain",
"Stiffness", and "Function" when studied in subjects
meniscectomized 21 years ago and with definite radiographic signs of OA
(mean 57 years, 38-76) compared to age- and gendermatched controls (4). KOOS responsiveness
has been determined in two separate studies. Significant improvement was
found after reconstruction of the ACL (5),
after physical therapy (5),
and three months after arthroscopic partial meniscectomy (3).
High effect sizes (mean score change/preoperative SD) were found, indicating
fewer subjects needed to yield statistically significant differences.
The subscales "Sport and Recreation function" and "Quality
of life" were the most responsive with Effect Sizes ranging from
1.16 to 1.65. KOOS validation work
is ongoing. KOOS is currently being used in several clinical studies involving
patients with meniscus injury, ACL-injury, cartilage injury, and post-traumatic
osteoarthritis. Three methodological papers regarding the KOOS were published
during 1998 (5,3,4). KOOS is currently available in three versions, an American-English version, a Swedish version, and a Danish version. The validation work of a German version is ongoing, and an unvalidated Italian version is available. |