Table 1.
Accuracy of model-based and marker-based RSA (phantom model)
| RSA method | Translation (mm) | Translation (mm) | Translation (mm) | Rotation (degrees) |
|---|---|---|---|---|
| x axis | y axis | z axis | y axis | |
| Model-based RSA | ||||
| Mean difference | −0.01 | −0.01 | 0.02 | −0.23 |
| 95% CI | (−0.02 to −0.01) | (−0.03–0.00) | (−0.04–0.07) | (−0.41 to −0.06) |
| Accuracy | 0.02 | 0.03 | 0.13 | 0.39 |
| Marker-based RSA | ||||
| Mean difference | 0.00 | −0.02 | −0.02 | −0.15 |
| 95% CI | (−0.01–0.01) | (−0.04–0.01) | (−0.03 to −0.01) | (−0.23 to −0.07) |
| Accuracy | 0.02 | 0.06 | 0.03 | 0.18 |
| Marker-based RSA (UmRSA®) | ||||
| Mean difference | −0.01 | −0.01 | −0.02 | −0.04 |
| 95% CI | (−0.02–0.00) | (−0.01–0.00) | (−0.04–0.00) | (−0.17–0.10) |
| Accuracy | 0.02 | 0.01 | 0.04 | 0.30 |
Mean difference = paired difference between micrometer-measured actual displacements and RSA-measured values; accuracy = t × SD/√2.