Preclinical evaluation method for total knees designed to restore normal knee mechanics

Area of Science:

• Biomedical Engineering
• Orthopedic Biomechanics

Background:

• Total knee arthroplasty (TKA) aims to restore natural knee function.
• Evaluating new TKA designs requires accurate kinematic assessment.
• Existing methods may be complex or costly.

Purpose of the Study:

• To develop a simple, rapid, and low-cost method for evaluating TKA models.
• To assess the kinematic characteristics of three different TKA designs using this new method.

Main Methods:

• A desktop knee testing rig applied forces and moments across a full flexion range.
• Femoral positions on the tibia were measured to determine the neutral path and laxities.
• Eight human knee specimens provided benchmark data for TKA evaluations.

Main Results:

• A posterior-stabilized TKA exhibited abnormal anterior sliding and lacked normal external femoral rotation.
• A medial-pivot TKA demonstrated comparable medial stability but failed to replicate natural rotation and displacement.
• A cam-post design introduced rotation and displacement, but only after 75° of flexion.

Conclusions:

• The developed desktop testing method is effective for evaluating TKA designs.
• The method can serve as a design tool for creating TKAs with more anatomical characteristics.
• Current TKA designs may require further refinement to fully replicate natural knee kinematics.