The KSS 2011 reflects symptoms, physical activities, and radiographic grades in a Japanese population.
BACKGROUND
Cultural and ethnic differences are present both in subjective and objective measures of patient health, but scoring systems do not always reflect these differences, and so validation of outcomes tools in different cultural settings is important. Recently, a revised version of The Knee Society Score® (KSS 2011) was developed, but to our knowledge, the degree that this tool evaluates clinical symptoms, physical activities, and radiographic grades in the general Japanese population is not known.


OBJECTIVE
We therefore asked: (1) how KSS 2011 reflects knee conditions and function in the general Japanese population, in particular evaluating changes with increasing patient age; (2) can objective measures of physical function be correlated with KSS 2011; and (3) does radiographic osteoarthritis (OA) grade correlate with KSS 2011?


METHODS
Two hundred twenty-six people in the general Japanese population, aged 35 to 92 years, with and without knee arthritis, voluntarily participated in this cross-sectional study. Residents who had no serious disease or symptoms based on a self-assessment were recruited. This study consisted of a questionnaire including self-administered KSS 2011, physical examination, and weightbearing radiographs of the knee. Leg muscle strength, Timed Up and Go test, and body mass index (BMI) were examined in all the participants. Radiographs were graded according to the Kellgren and Lawrence scale (KL grade).


RESULTS
Multivariable linear regression analysis showed that KSS 2011 correlated with age (coefficient: -0.30±0.12, p=0.011), BMI (coefficient: -1.47±0.42, p<0.001), leg muscle strength (coefficient: 0.41±0.13, p=0.002), and Timed Up and Go Test (coefficient: -1.96±0.92, p=0.034), but not sex, as independent variables by a stepwise method. KSS 2011 was also correlated with radiographic OA evaluated by KL grade (coefficient: -12.2±2.9, p<0.001).


CONCLUSIONS
KSS 2011 reflects symptoms, physical activities, and radiographic OA grades of the knee in an age-dependent manner in the general Japanese population.


METHODS
Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo, Kyoto, 606-8507, Japan.
Naoya
N
Taniguchi
Shuichi
S
Matsuda
Takahisa
T
Kawaguchi
Yasuharu
Y
Tabara
Tome
T
Ikezoe
Tadao
T
Tsuboyama
Noriaki
N
Ichihashi
Takeo
T
Nakayama
Fumihiko
F
Matsuda
Hiromu
H
Ito
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007719:Knee Joint / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D053580:Muscle Strength; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000208:ethnology / Q000503:physiopathology; D010808:Physical Examination; D011237:Predictive Value of Tests; D011859:Radiography; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires