Anterior Cruciate Ligament Bundles Elongation Patterns During Fast Running and Single-Leg Drop Landing: An In Vivo...

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Sports Medicine

Background:

• Understanding anterior cruciate ligament (ACL) bundle elongation is crucial for optimizing graft tensioning in double-bundle ACL reconstructions.
• Limited in vivo data exists on ACL anteromedial bundle (AMB) and posterolateral bundle (PLB) elongation during high-impact activities.

Purpose of the Study:

• To quantify the relative elongation of the AMB and PLB during fast running and single-leg drop landing.
• To determine the knee flexion angle at which peak elongation occurs for each bundle.

Main Methods:

• Nineteen healthy athletes underwent biplane radiography during fast running and single-leg drop landing.
• A validated model-based tracking process analyzed tibiofemoral motion using subject-specific 3D bone models.
• Relative elongation of AMB and PLB was calculated and compared to supine CT measurements.

Main Results:

• During fast running, AMB peak relative elongation was significantly greater than PLB (2.6% difference).
• During single-leg drop landing, PLB and AMB peak relative elongation were comparable (-0.9% difference).
• Peak elongation occurred at different knee flexion angles for each activity and bundle.

Conclusions:

• The AMB exhibits greater elongation than the PLB during fast running.
• The PLB and AMB show similar elongation patterns during single-leg drop landing.
• Findings suggest specific graft fixation angles may better replicate native bundle function during high-impact activities.