Comparison between rendering 3D-CT and transparent 3D-CT in ACL tunnel positioning

Abstract

Objective: To compare the transparent 3D computed tomography (CT) image protocol against conventional 3D-CT image-rendering protocol to assess femoral tunnel position in anatomic anterior cruciate ligament (ACL) reconstructions. Methods: Eight knee CT scans from cadavers were analyzed by image rendering 3D-CT protocol, using Rhinoceros® software. The central point of the ACL tunnel was set using the sagittal plane. Same CT scans were analyzed using transparent 3D-CT measurement protocol with OsiriX® software. Central point of the ACL tunnel was set using sagittal, coronal and axial planes. The grid system described by Bernard and Hertel was used to compare tunnel positions between protocols, using height and length parameters. Results: There was a significant difference between measurements using image rendering 3D-CT and transparent 3D-CT protocol for height (23.8 ± 7.9mm and 33.0 ± 5.0mm, respectively; p = 0.017) and no differences for length (18.6 ± 4.2mm and 18.3 ± 4.5mm, respectively; p = 0.560). Conclusion: Height in transparent CT protocol was different and length was the same as compared to 3D-CT rendering protocol in Bernard and Hertel method for tunnel measurements.