The Hidden Mismatch: Quantifying Tendon Position and Footprint Coverage in Bone–Patellar Tendon–Bone Anterior Cruciate Ligament Reconstruction
E.S. Mameri, D. Kaplan, Z. Khan, B. Cole, J. Chahla, N. VermaObjectives:
To quantify the spatial relationship between the native anterior cruciate ligament (ACL) footprints, tunnel center, and the intra-articular tendinous portion of bone–patellar tendon–bone (BTB) grafts following anatomic ACL reconstruction, and to determine whether anatomic tunnel centering results in an anatomic graft position.
Methods:
Ten fresh-frozen human cadaveric knees underwent BTB ACL reconstruction with tunnels visually aimed at the centers of the native ACL footprints. Three-dimensional mapping using a MicroScribe digitizer was performed to delineate the native footprints, drilled tunnel apertures, and tendinous portion of the fixed graft. Cross-sectional areas, centroid locations and their distances were calculated for femoral and tibial sides. Footprint coverage by the graft tendon was determined. Paired statistical comparisons were used to assess differences between tunnel-to-footprint and tendon-to-footprint centroid distances.
Results:
On the femoral side, the graft tendon covered 37.8% of the native footprint. displaced inferiorly relative to the tunnel centroid by 2.57±0.19mm. On the tibial side, graft tendon coverage was 32.1%. The tendon centroid was significantly farther from the footprint centroid than the tunnel centroid on both femoral (2.63±0.71mm vs 0.61±0.08mm;
Conclusion:
In BTB ACL reconstruction, anatomic tunnel centering does not ensure an anatomic intra-articular graft position, and the femoral tunnel should be shifted at a “cheat” distance of 2.5mm superiorly, and the tibial tunnel at a “cheat” distance of 2.5mm anteromedially.