Interactions between kinematics and loading during walking for the normal and ACL deficient knee

Area of Science:

• Biomechanics
• Orthopedics
• Sports Medicine

Background:

• Anterior cruciate ligament (ACL) injuries are common, leading to knee instability and potential long-term joint degeneration.
• Understanding knee kinematics after ACL deficiency is crucial for developing effective rehabilitation and treatment strategies.

Purpose of the Study:

• To identify specific walking cycle phases where extrinsic knee forces cause abnormal kinematics in ACL-deficient knees.
• To correlate altered knee kinematics with joint loading and potential degenerative changes.

Main Methods:

• Compared intersegmental forces and moments with tibial motion (translation and rotation) relative to the femur during key walking phases.
• Analyzed kinematic changes in ACL-deficient knees during heel strike, weight acceptance, terminal extension, and swing phases.

Main Results:

• ACL deficiency primarily caused abnormal knee kinematics during the terminal swing phase, characterized by reduced tibial external rotation and anterior translation.
• A consistent internal rotation offset of the tibia was observed throughout the gait cycle in ACL-deficient knees.
• This rotational offset correlated with the flexion moment during weight acceptance, suggesting quadriceps muscle compensation.

Conclusions:

• Muscle activation patterns can adapt to compensate for altered knee kinematics following ACL loss.
• Altered tibiofemoral contact due to abnormal rotation may contribute to meniscus and articular cartilage degeneration after ACL injury.