Table 2.
Concordant and disconcordant pairs and tetrachoric correlations by zygosity in twin pairs where both twins in the pair were alive at entry
| Zygosity | Concordant TKA due to OA pairs (n) | Discordant TKA due to OA pairs (n) | Concordant pairs without OA pairs (n) | Tetrachoric correlation (rho) (p valuea) |
|---|---|---|---|---|
| MZ males | 1 | 29 | 4509 | 0.45 (0.05) |
| DZ males | 4 | 72 | 8176 | 0.51 (<0.0001) |
| MZ females | 10 | 52 | 4701 | 0.73 (<0.0001) |
| DZ females | 6 | 122 | 7575 | 0.42 (<0.0001) |
| OS-DZ | 3 | 158 | 17,490 | 0.36 (0.004) |
aTest of within-pair independence for TKA due to OA
DZ dizygotic, MZ monozygotic, OA osteoarthritis, OS-DZ opposite-sex dizygotic, rho tetrachoric correlation coefficient, TKA total knee arthroplasty