Abstract
Introduction: Defects in rotational alignment of the femoral component in total knee replacements (TKR) may cause poor alignment of the extensor apparatus. There are numerous references concerning the correct alignment of the femoral component of a prosthesis: transepicondylar axis, anteroposterior axis, and posterior condylar axis.
Materials and methods: Computer-assisted measurement of the relative differences between the transepicondylar axis, anteroposterior axis and posterior condylar axis in 38 TKR patients, excluding those with varus or valgus deformity greater than 15 degrees.
Results: The difference between the anteroposterior axis and the transepicondylar axis was 3.13 degrees of external rotation in the former.
Between the posterior condylar axis and the transepicondylar axis it was 1.18 degrees of internal rotation in the former.
Between the anteroposterior axis and the posterior condylar axis it was 5.51 degrees of external rotation of the former.
Conclusions: Probably the transepicondylar axis is the best landmark to enable reproducing the biomechanics of the knee in a patient bearing a prosthesis, although it is often difficult to reproduce it precisely. Several studies have noted errors among observers that are too great to make us feel certain that we are doing the best thing.
Although it is accepted that the perpendicular to the anteroposterior axis is reliable and corresponds to 4° of external rotation in relation to the posterior condylar axis, we have observed significant differences from one patient to another.
It would seem preferable to use a combination of the different axes, which we can do with a surgical browser.
The abstracts were prepared by Dr. E. Carlos Rodríguez-Merchán, Editor-in-Chief, Spanish Journal of Orthopaedics and Traumatology (Revista de Ortopedia y Traumatología). Correspondence should be addressed to him at: Sociedad Española de Cirugía Ortopédica y Traumatología (SECOT), Calle Fernández de los Ríos 108, 28015-Madrid, Spain
