Knee joint motion and ligament forces before and after ACL reconstruction

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Biomedical Engineering

Background:

• Anterior cruciate ligament (ACL) injuries are common, necessitating surgical reconstruction.
• Restoring normal knee biomechanics after ACL reconstruction is a primary surgical goal.
• Variability in graft types and surgical techniques may influence postoperative knee function.

Purpose of the Study:

• To evaluate the initial postoperative mechanical state of knee joints following different ACL reconstruction methods.
• To compare ligament forces and joint motion in reconstructed knees versus normal and ACL-deficient knees.
• To assess the impact of graft type and surgical control on knee joint mechanics.

Main Methods:

• Development of an experimental in vitro knee testing system for measuring ligament forces and 3D joint motion.
• Testing of fresh knee specimens under applied external loads.
• Comparison of three knee states: normal, ACL-deficient, and reconstructed (two techniques).

Main Results:

• ACL reconstructions resulted in highly variable and abnormal knee forces and motions compared to normal knees.
• Increased surgical control in one technique did not reduce this variability.
• Poor correlation observed between knee motion and ACL graft force.
• Little consistent difference in outcomes between the tested surgical procedures.

Conclusions:

• Current ACL reconstruction techniques, including patellar tendon and hamstring grafts, do not consistently restore normal knee joint mechanics.
• Postoperative knee function remains unpredictable and deviates from the healthy state.
• Further research is needed to improve ACL reconstruction outcomes and achieve normal knee biomechanics.