Table 2.
Median difference between planned versus postoperative plus migration values from direct postoperative to 1-year follow-up
| Factor | Deviation from planned cup position | First year migration | Repeatability limit a | |||||
| median | IQR | range | median | IQR | range | Postop. | 1 year | |
| Inclination (°) | 3.6 | 1.0 to 5.4 | –11 to 11 | 0.04 | –0.06 to 0.09 | –0.22 to 0.98 | 0.48 | 0.51 |
| Anteversion (°) | –2.8 | –7.5 to 1.2 | –12 to 5.7 | –0.13 | –0.23 to –0.06 | –0.41 to 0.05 | 2.1 | 1.0 |
| Rotation (°) | –1.2 | –3.3 to 0.0 | –7.4 to 14 | 0.05 | –0.07 to 0.36 | –0.46 to 1.4 | 0.97 | 0.99 |
| Translation of COR (mm) | ||||||||
| AP plane (anterior +) | –0.5 | –2.9 to 0.7 | –7.0 to 3.4 | –0.08 | –0.18 to –0.04 | –0.48 to 0.43 | 0.28 | 0.25 |
| ML plane (medial +) | –0.6 | –1.8 to –0.1 | –3.6 to 2.2 | 0.14 | –0.08 to 0.22 | –0.35 to 0.51 | 0.63 | 0.34 |
| SI plane (superior +) | 1.1 | –1.6 to 2.8 | –9.7 to 8.9 | 0.06 | –0.02 to 0.35 | –0.15 to 0.61 | 0.44 | 0.26 |
Values are presented as signed, thus indicating the direction of the migration except for rotation where signed values are positive for clockwise rotation after signed values for left hips are shifted.
a Repeatability limit: the value less than or equal to which the absolute difference between two tests results obtained under repeatability conditions may be expected to have a probability of 95%.
IQR: interquartile range.