Errors in the identification of the transepicondylar and anteroposterior axes of the distal femur in total knee replacement using minimally-invasive and conventional approaches: a cadaver study.

We have investigated the errors in the identification of the transepicondylar axis and the anteroposterior axis between a minimally-invasive and a conventional approach in four fresh-frozen cadaver knees. The errors in aligning the femoral prosthesis were compared with the reference transepicondylar axis as established by CT. The error in the identification of the transepicondylar axis was significantly higher in the minimal approach (4.5 degrees of internal rotation, sd 4) than in the conventional approach (3 degrees of internal rotation, sd 4; p < 0.001). The errors in identifying the anteroposterior axis in the two approaches were 0 degrees (sd 5) and 1.8 degrees (sd 5) of internal rotation, respectively (p < 0.001).