Lateral extra-articular reconstruction length changes during weightbearing knee flexion and pivot shift: A simulation...

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Sports Medicine

Background:

• Lateral extra-articular reconstruction (LER) is crucial for knee stability.
• Previous studies focused on LER length changes during knee flexion.
• LER behavior during pivot shift remains uninvestigated.

Purpose of the Study:

• To assess LER tension changes during weightbearing knee flexion.
• To evaluate LER tension during a simulated pivot-shift scenario.
• To determine optimal femoral and tibial tunnel placement for LER.

Main Methods:

• A computer model simulated weightbearing knee flexion and pivot shift.
• LER tension was calculated based on femoral and tibial tunnel locations.
• Six femoral attachment sites and two tibial tunnel locations (Gerdy's tubercle and ALL) were analyzed.

Main Results:

• LER tightened by up to 22% during early weightbearing flexion, then relaxed between 40°-60°.
• The anterolateral ligament (ALL) tibial tunnel position facilitated LER relaxation.
• During pivot shift, LER tightened more with Gerdy's tubercle (20%-34%) than ALL (11%-26%) placement.

Conclusions:

• Femoral tunnel placement posterior and proximal to the epicondyle promotes early LER tightening during weightbearing flexion.
• LER tightening during pivot shift supports the efficacy of this tunnel position in dynamic knee motion.
• ALL tibial tunnel placement aids LER relaxation, potentially improving outcomes.