Table 4.
Specification of variables used for the estimation of detectable differences, including implant types, total sample size, unbalanced sample distribution between moderate and severe OA, standard deviation (SD) values with corresponding references, and the resulting minimal detectable differences
| Implant type | Total, n | Moderate OA, n | Severe OA, n | SD a for MTPM (mm) | Detectable difference (mm) |
|---|---|---|---|---|---|
| Cementless TKA | 260 | 86 | 174 | 0.7 b | 0.26 |
| Cementless UKA | 391 | 140 | 251 | 0.6 c | 0.18 |
| Cemented TKA | 226 | 76 | 150 | 0.4 b | 0.16 |
| Cemented UKA | 113 | 78 | 35 | 0.3 c | 0.27 |
MTPM: maximum total point motion, OA: osteoarthritis, SD: standard deviation, TKA: total knee arthroplasty, UKA: unicompartmental knee arthroplasty.
SD values used for the estimation of the detectable difference were from RSA studies that reported SD values for mean MTPM (measured in mm) of tibial implant components at 12-month follow-up.
For TKA, the study of Nakama et al. [26] was used.
For UKA, we used data from an unpublished RSA study from our institution.