Avoiding tunnel collisions between fibular collateral ligament and ACL posterolateral bundle reconstruction

The purpose of this study was to evaluate the risk of tunnel collisions of the fibular collateral ligament (FCL) and posterolateral bundle anterior cruciate ligament (PLB-ACL) tunnels during a combined FCL and double-dundle (DB) ACL reconstruction. Thirty-six 4th-generation synthetic femurs (Sawbones, Pacific Research Laboratories, Vashon, WA) were utilized, and two different femur sizes were used. A FCL tunnel and a PLB-ACL tunnel were reamed on each femur. The tunnels of synthetic specimens that did not have a collision were filled with an epoxy resin augmented with BaSO(4) and radiographic evaluation, and Multidetector CT exams of the specimens were performed. The rate of tunnel collision when the FCL tunnel was reamed to a depth of 30 mm was 75 and 69.4% for the 25 mm depth. There was a significantly increased risk of tunnel collision when the FCL tunnel was reamed proximally with coronal angulations of 20A degrees and 40A degrees. No collisions were noted when the FCL tunnel was reamed parallel to the distal condylar line and with axial angulations of 20A degrees and 40A degrees. This study provides new insight into tunnel positioning during a combined FCL and DB-ACL reconstruction. The results show that a concomitant FCL injury do not represent a contraindication to perform a DB-ACL reconstruction as long as the FCL tunnel is reamed with no proximal angulation and is directed anteriorly with an axial angulation between 20A degrees and 40A degrees.