Femoral tunnel drilling angles for the posterolateral corner in multiligamentary knee reconstructions: computed tomography evaluation in a cadaveric model

Abstract

Purpose: The goal of this study was to determine the best angle at which to drill the femoral tunnels of the popliteus tendon (PT) and fibular collateral ligament (FCL) in combined reconstructive procedures so as to avoid either short tunnels or tunnel collisions with the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) femoral tunnels.

Methods: Eight cadaveric knees were studied. ACL/PCL femoral tunnels were arthroscopically drilled. PT and FCL tunnels were drilled at 0° and 30° axial and coronal angulations. They were scanned by computed tomography to document relations of the PT and FCL tunnels to the intercondylar notch and ACL/PCL tunnels. A minimum tunnel length of 25 mm was required.

Results: Drilling the PT tunnel at 0° axial angulation was associated with an increased risk of tunnel collision with the ACL (P < .001). Interference with the PCL tunnel can be avoided only if the K-wire guiding the PT tunnel is drilled with 30° coronal angulations (P < .001). The minimum tunnel length of the PT could be obtained only with both axial and coronal angulations of 30° (P = .003). Sufficient tunnel lengths of the FCL were obtained at all angulations evaluated (P = .036). However, only the tunnels drilled at 30° axial and 0° coronal angulations did not collapse with the ACL tunnels (P < .001). No intersections between FCL and PT tunnels were observed.

Conclusions: When posterolateral reconstructions are performed in combination with concomitant anterior and posterior cruciate procedures, PT tunnels should be drilled at 30° axial and 30° coronal angulations. FCL tunnels should be drilled at 30° axial and 0° coronal angulations. These angulations should minimize such potential complications as short tunnels or collisions with the ACL/PCL tunnels.

Clinical relevance: Specific drilling angles are necessary to avoid short tunnels or collisions between the drilled tunnels when FCL and PT femoral tunnels are performed in multiligament knee reconstructions.