Reliability of Intra-articular Rotational Axes at Standard Tibial Resection Level and Effect of Resecting Distally

We determine the most reliable tibial intra-articular axis for rotational alignment of the tibial component at the standard resection level and at a distal resection level. The angles between the surgical transepicondylar axis and posterior condylar line, perpendicular to Akagi line, tibial anterior condylar line (ACL), and tibial maximum mediolateral line were measured at the standard resection level and 5 mm distal to the standard resection level. All axes exhibited relatively large standard deviations and ranges at the standard and distal resection level. t-test showed that there was a statistically significant difference (p < 0.05) for all the axes between the two resection levels, while only ACL showed a statistically significant difference (p = 0.047) with the equality of variance F-test. Akagi line exhibited good interobserver and intraobserver reliabilities but must be used with caution. Intra-articular axes are not reliable for tibial component alignment.