Table 3.
Stem migration during 25 years of follow-up: per-protocol analysis (i.e., only stems with verified coating), using the 1-year postoperative RSA radiograph as a baseline (i.e., unknown initial migration). Values are count, median (range)
| FU year | Hydroxyapatite | Fluorapatite | Uncoated | p-value | |||
|---|---|---|---|---|---|---|---|
| Longitudinal translation, mm a | |||||||
| 2 | 7 | 0.04 (–0.19 to 0.32) | 5 | 0.20 (–0.02 to 0.27) | 8 | –0.03 (–0.16 to 0.12) | 0.1 b |
| 5 | 2 | –0.06 (–0.07 to –0.04) | 5 | 0.09 (–0.16 to 0.44) | 6 | 0.00 (–0.12 to 0.12) | 0.6 c |
| 10 | 2 | 0.04 (0.02 to 0.06) | 4 | 0.07 (–0.08 to 0.12) | 7 | –0.07 (–0.41 to 0.37) | |
| 15 | 3 | 0.07 (–0.16 to 0.44) | 3 | 0.04 (–0.15 to 0.13) | 5 | –0.18 (–0.52 to 0.12) | 0.5 c |
| 20 | 0 | – | 1 | – | 1 | – | |
| 25 | 0 | – | 1 | – | 1 | – | |
| Internal rotation, degrees | |||||||
| 2 | 3 | –0.21 (–1.35 to 0.24) | 2 | –1.02 (–1.23 to –0.81) | 3 | –0.50 (–0.76 to 0.25) | 0.5 b |
| 5 | 1 | – | 2 | –0.53 (–0.74 to –0.32) | 2 | –0.10 (–0.48 to 0.28) | – |
| 10 | 1 | – | 2 | –0.14 (–0.22 to –0.05) | 2 | –0.33 (–0.52 to –0.13) | |
| 15 | 0 | – | 2 | 1.08 (–0.46 to 2.62) | 2 | –0.02 (–0.45 to 0.42) | – |
| 20 | 0 | – | 0 | – | 0 | – | |
| 25 | 0 | – | 0 | – | 0 | – | |
aNegative values correspond to subsidence (i.e., distal migration).
bMain effect, per protocol
cPrespecified time point, per protocol