Three-dimensional analysis of femoral tunnel placement in canine cranial cruciate ligament reconstruction

Accurate femoral tunnel placement is essential for successful anatomical intra-articular reconstruction of the cranial cruciate ligament (CrCL), a standard treatment for anterior cruciate ligament disease in humans. Surgical outcomes are influenced by multiple factors related to tunnel placement, including ligament footprint restoration, tunnel length, and graft bending angle (GBA), among others. However, no consensus has been reached regarding the optimal placement of the femoral tunnel for CrCL reconstruction in dogs. This study aimed to investigate the effects of various femoral tunnel entry (FTE) points on these key parameters to determine favourable tunnel locations for canine CrCL reconstruction. The influences of various FTE points were evaluated based on six parameters: footprint coverage, footprint overhang, footprint similarity, tunnel length, tunnel-face angle, and GBA. Three-dimensional femoral models reconstructed from CT scans of 25 canine cadaveric hindlimbs were used to simulate tunnel placement. In addition, tibiofemoral kinematic data from 13 client-owned dogs during treadmill gait were analysed to quantify the GBA associated with each simulated tunnel. A more proximal extracapsular tunnel aperture relative to Blumensaat's line provided greater footprint coverage, improved similarity, and longer tunnel length. However, along the cranial-caudal axis, a trade-off emerged between these factors and GBA, suggesting that a mid-range position may offer the most balanced compromise. Placing the FTE point proximally is preferable, while a mid-range cranial-caudal position may best balance key factors affecting postoperative outcomes in dogs.