Table 4.
Relative risks of aseptic stem revision during entire observation period (Lubinus SP, Spectron EF Primary) or within 3 years (Exeter) and 95% CI for implant-related parameters for each stem type. Data from Cox regression adjusted for age, sex, diagnosis, bilaterality, side, and implant-specific parameters (see text). Implant-related parameters with statistically significant influence are shown
| Relative Risk | 95% CI | p-value | ||
|---|---|---|---|---|
| [Exp (B)] | Lower | Upper | ||
| Exeter polished (n = 21,008) | ||||
| Femoral head diameter | ||||
| 22 mm | 2.37 | 1.32 | 4.23 | 0.004 |
| 26 mm | 0.02 | 0.00 | 30.03 | 0.3 |
| 28 mm, reference | 1.00 | |||
| 30 mm | 0.79 | 0.19 | 3.28 | 0.7 |
| Lubinus SPII (n = 43,036) | ||||
| Size | ||||
| x-small | 1.72 | 1.22 | 2.44 | 0.002 |
| small | 0.99 | 0.74 | 1.32 | 0.9 |
| medium, reference | 1.00 | |||
| large | 0.94 | 0.70 | 1.26 | 0.7 |
| x and xx-large | 1.01 | 0.69 | 1.47 | 1.0 |
| Head | ||||
| ceramic | 0.52 | 0.36 | 0.76 | 0.001 |
| cobalt-chromium, reference | 1.00 | |||
| Offset + neck | ||||
| 1 | 0.73 | 0.55 | 0.97 | 0.03 |
| 2 reference | 1.00 | |||
| 3 | 1.11 | 0.86 | 1.43 | 0.4 |
| 4 | 1.72 | 1.09 | 2.71 | 0.02 |
| Spectron EF Primary (n = 7,140) | ||||
| Size | ||||
| 1 | 2.23 | 1.25 | 3.97 | 0.006 |
| 2 reference | 1.00 | |||
| 3 | 0.75 | 0.40 | 1.41 | 0.4 |
| 4+5 | 0.55 | 0.17 | 1.84 | 0.3 |
| Off-set + neck | ||||
| 1 | 1.27 | 0.68 | 2.37 | 0.4 |
| 2 reference | 1.00 | |||
| 3 | 1.54 | 0.80 | 2.98 | 0.2 |
| 4 | 2.03 | 0.81 | 5.11 | 0.1 |
| 5 | 6.89 | 2.54 | 18.63 | < 0.001 |