Table 2

 Factors affecting risk of knee replacement

Univariate analysisMultivariate analysis*95% CIp Value
*Multivariate analysis with age, sex, BMI, % tibial cartilage loss, WOMAC score, and bone size in regression equation.
†Change per five year increase in age.
‡Change per 100 mm2 increase in tibial bone area.
§Change per 1% increase in tibial cartilage loss.
¶Change per 100 unit increase in WOMAC score.
**Based on Kellgren–Lawrence grade: change per unit increase in grade.
BMI, body mass index; CI, confidence interval; F, female; M, male; OA, osteoarthritis; WOMAC, Western Ontario and McMaster Universities osteoarthritis index
Age†0.0050.90.7 to 1.30.55
Sex (F v M) to 65.40.02
BMI0.050.90.8 to 1.10.38
Tibial bone area‡0.0011.21.0 to 1.40.02
Per cent tibial cartilage loss§ to 1.30.008
WOMAC¶0.0021.51.1 to 2.00.01
Radiological grade of OA**0.771.80.6 to 6.10.32