Introduction. The tibial tunnel aperture in the anterior cruciate ligament
reconstruction is usually analyzed as an ellipse, generated as an
intersection between a tibial plateau and a tibial bone tunnel. The aim of
this study is to show that the tibial tunnel aperture, which utilizes 3D
tibial surface bone model, differs significantly from common computations
which present the tibial tunnel anterior cruciate ligament aperture surface
as an ellipse. Material and Methods. An interactive program system was
developed for the tibial tunnel aperture analysis which included the real
tibia 3D surface bone model generated from a series of computed tomography
images of ten male patients, their mean age being 25 years. In aperture
calculation, the transverse drill angle of 10o was used, whereas sagittal
drill angles of 40o, 50o and 60o were used with the drill-bit diameter set to
10 mm. The real 3D and 2D tibial tunnel aperture surface projection was
calculated and compared with an ellipse. Results. According to the
calculations, generated 3D aperture surfaces were different for every patient
even though the same drill parameters were used. For the sagittal drill
angles of 40?, 50? and 60?, the mean difference between the projected 3D and
2D area on the tibial plateau was 19.6 ? 5.4%, 21.1 ? 8.0% and 21.3 ? 9.6%,
respectively. The difference between the projected 3D area on the tibial
plateau and ellipse surface was 54.8 ? 16.3%, 39.6 ? 10.4% and 25.0 ? 8.0%
for sagittal drill angles of 40?, 50? and 60?, respectively. Conclusion. The
tibial tunnel aperture surface area differs significantly from the ellipse
surface area, which is commonly used in the anterior cruciate ligament
reconstruction analysis. Inclusion of the 3D shape of the tibial attachment
site in the preoperative anterior cruciate ligament reconstruction planning
process can lead to a more precise individual anatomic anterior cruciate
ligament reconstruction on the tibial bone. Both tibial aperture area
generated in 3D and its projection on a tibial plateau are larger than the
ellipse surface; therefore, individual characteristics of each patient have
to be taken into consideration.