Characterising knee motion and laxity in a testing machine for application to total knee evaluation

Area of Science:

• Biomechanics
• Orthopedic Surgery

Background:

• Understanding knee joint mechanics is crucial for developing effective total knee replacement (TKR) designs.
• Existing methods for evaluating TKR may not fully capture complex in-vivo loading conditions.

Purpose of the Study:

• To establish a benchmark dataset of knee motion and laxity under combined physiological loading conditions.
• To provide data for evaluating the performance and alignment of total knee replacement (TKR) designs.

Main Methods:

• Utilized optical tracking to measure continuous knee flexion and determine the motion of the femoral axis relative to the tibia.
• Quantified neutral path of motion and anterior-posterior laxities of the medial and lateral condyles under combined forces.
• Analyzed tibial surface contact patches throughout the range of motion.

Main Results:

• The neutral path of knee motion was independent of compressive load, showing consistent medial contact and posterior lateral displacement.
• Anterior-posterior laxities of both condyles were similar under applied forces or torques.
• Lateral laxity was primarily anterior, while medial laxity was less pronounced and predominantly posterior to the neutral path.

Conclusions:

• The developed methodology provides a comprehensive benchmark for evaluating total knee replacement (TKR) designs.
• The data generated offers insights into knee joint kinematics and laxity crucial for implant development and surgical planning.