TABLE I.
Model Input Parameters
| Parameter | Estimate | Source of Data* |
| Mean BMI (and stand. dev.) at age of 25 yr† (kg/m2) | NHANES 2005-200820,21 | |
| Male | 27.0 ± 6.1 | |
| Female | 27.6 ±7.8 | |
| Annual incidence of total knee replacement, given end-stage knee osteoarthritis (95% CI) (%) | Wise et al.23 and OAI16 | |
| <45 yr old | ||
| Male | 1.6 (0.8, 2.4) | |
| Female | 2.0 (1.1, 2.9) | |
| 45-64 yr old | ||
| Male | 6.4 (3.0, 9.7) | |
| Female | 8.1 (4.5, 11.8) | |
| 65-84 yr old | ||
| Male | 11.9 (6.7, 17.0) | |
| Female | 10.9 (6.5, 15.3) | |
| ≥85 yr old | ||
| Male | 3.0 (1.7, 4.3) | |
| Female | 2.7 (1.6, 3.8) | |
| Annual failure of total knee replacement leading to revision (%) | Paxton et al.6 | |
| <65 yr old | ||
| First year | 1.9 | |
| Subsequent years | 1.5 | |
| ≥65 yr old‡ | ||
| First year | 1.0 | |
| Subsequent years | 0.4 |
*
NHANES = National Health and Nutrition Examination Survey, and OAI = Osteoarthritis Initiative.
†
BMI = body mass index.
‡
For individuals who were eighty-five years of age or older, only 10% of primary total knee replacement failures were revised on the basis of data that show few revision total knee replacements are performed in patients over this age.