Femoral Tunnel Drilling Angles for Posteromedial Corner Reconstructions of the Knee

Abstract

Purpose: To determine the best angle to drill the femoral tunnels of the superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) with concomitant posterior cruciate ligament (PCL) reconstruction to avoid either short tunnels or tunnel collisions.

Methods: Eight cadaveric knees were studied. Double-bundle PCL femoral tunnels were arthroscopically drilled. Drilling of the sMCL and POL tunnels was performed in 4 different combinations of 0° and 30° axial (anteriorly directed) and coronal (proximally directed) angulations. Specimens were scanned with computed tomography to document the relations of the sMCL and POL tunnels to the intercondylar notch and PCL tunnels. A minimum tunnel length of 25 mm was required.

Results: When the sMCL femoral tunnel was drilled at 0° axial and 30° coronal (proximally directed) angulations or 30° axial (anteriorly directed) and 0° coronal angulations, the risk of tunnel collision with the PCL tunnels increased in comparison with the remaining evaluated angulations (P < .001). No POL tunnels collided with either PCL tunnel bundle with the exception of tunnels drilled at 0° axial and 30° coronal (proximally directed) angulations, which did so in 3 of 8 cases (P < .001). The minimum required tunnel length was obtained in all the sMCL and POL tunnels (P < .001 and P = .02, respectively). However, some of those angled at 0° on the axial plane violated the intercondylar notch.

Conclusions: When one is performing posteromedial reconstructions with concomitant PCL procedures, the sMCL and POL femoral tunnels should be drilled anteriorly and proximally at both 30° axial and 30° coronal angulations. The POL femoral tunnel may also be angled 0° in the coronal plane. Tunnels at 0° axial angulations showed a shorter distance to the intercondylar notch and a higher risk of collision with the PCL tunnels.

Clinical relevance: Specific drilling angles are necessary to avoid short tunnels or collisions between the drilled tunnels when sMCL and POL femoral tunnels are placed with concomitant PCL reconstruction.