Table 2.
Mean segment motion (95% CI) of the Bi-Metric (BM) and the Echo Bi-Metric (EBM) stems at follow-up until 24 months. Outliers are included in the analysis
| 3 months | 6 months | 12 months | 24 months | |
|---|---|---|---|---|
| BM/EBM, n | 29/31 | 29/31 | 28/31 | 27/30 |
| Stem translation, mm | ||||
| Y–translation: proximal (+), distal (–) | ||||
| BM | –2.2 (–2.3 to –1.7) | –2.0 (–2.5 to –1.6) | –2.1 (–2.6 to –1.6) | –2.3 (–3.0 to –1.7) |
| EBM | –2.5 (–3.2 to –1.9) | –2.4 (–3.0 to –1.7) | –2.4 (–3.0 to –1.7) | –2.7 (–3.5 to –2.0) |
| X–translation | ||||
| BM | –1.1 (–0.5 to –0.1) | –0.4 (–0.7 to –0.1) | 0.1 (–0.3 to 0.0) | –0.4 (–0.6 to –0.1) |
| EBM | –0.5 (–0.7 to –0.3) | –0.6 (–0.9 to –0.4) | –0.3 (–0.4 to –0.1) | –0.5 (–0.8 to –0.3) |
| Z–translation | ||||
| BM | –0.8 (–1.0 to –0.5) | –0.5 (–0.7 to –0.3) | –0.9 (–1.2 to –0.6) | –0.7 (–1.1 to –0.4) |
| EBM | –0.8 (–1.0 to –0.6) | –0.4 (–0.6 to –0.2) | –0.9 (–1.2 to –0.7) | –0.9 (–1.1 to –0.6) |
| Stem rotation, degrees | ||||
| Y–rotation: anteversion (–), retroversion (+) | ||||
| BM | 2.2 (1.5 to 5.0) | 2.4 (1.7 to 3.2) | 2.5 (1.7 to 3.2) | 2.5 (1.6 to 3.3) |
| EBM | 2.5 (1.8 to 3.5) | 2.6 (1.9 to 3.5) | 2.7 (1.9 to 3.7) | 2.7 (1.9 to 3.8) |
| X–rotation | ||||
| BM | –0.6 (–0.9 to –0.3) | –0.2 (–0.5 to 0.1) | –0.6 (–1.0 to –0.2) | 1.2 (0.7 to 1.6) |
| EBM | –0.4 (–0.8 to –0.03) | 0.0 (–0.2 to 0.3) | –0.8 (–1.2 to –0.5) | 1.1 (0.7 to 1.6) |
| Z–rotation: varus (–), valgus (+) | ||||
| BM | 1.7 (1.0 to 2.5) | 1.7 (0.9 to 2.5) | 1.8 (1.0 to 2.7) | 2.0 (1.1 to 2.8) |
| EBM | 1.7 (0.9 to 2.4) | 1.8 (1.0 to 2.5) | 1.8 (1.1 to 2.6) | 2.0 (1.2 to 2.8) |