L. Ryd et al., KNEE SCORING SYSTEMS IN GONARTHROSIS - EVALUATION OF INTEROBSERVER VARIABILITY AND THE ENVELOPE OF BIAS, Acta orthopaedica Scandinavica, 68(1), 1997, pp. 41-45
10 experienced orthopedic surgeons assessed 15 patients using 3 common
ly used composite scoring systems and by some simple variables to eval
uate knee replacements. Statistical evaluation showed that the scores
were valid and reflected the disease process with a reasonable reprodu
cibility. In the individual case, however, considerable changes of the
total scores and the simple variables are needed to represent a true
difference at the 95% confidence limit. The coefficient of repeatabili
ty varied from 45 to 72 for the scores. Our study, which is suggested
to represent any clinical investigation, showed that clinical measurem
ents are not robust and meticulous efforts in terms of study design mu
st be made to protect an investigation against the action of bias. Kne
e scores are exceedingly unreliable.