Are current total knee arthroplasty implants designed to restore normal trochlear groove anatomy?

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Knee biomechanics

Background:

• External rotation of the femoral component in total knee arthroplasty (TKA) improves patellar tracking.
• However, patellar tracking is not fully restored to physiologic levels with current TKA designs.

Purpose of the Study:

• To investigate if differences in trochlear groove geometry between TKA and normal knees explain incomplete patellar tracking restoration.
• To evaluate the effect of femoral component external rotation on restoring normal trochlear anatomy.

Main Methods:

• A virtual total knee arthroplasty (TKA) procedure was simulated on 3D models of healthy femurs.
• Femoral components were virtually mounted with and without external rotation.
• Trochlear groove geometry was measured before and after the simulated TKA.

Main Results:

• External rotation of the femoral component moved the trochlear groove closer to normal anatomy compared to no external rotation.
• Despite external rotation, the trochlear anatomy was only partially restored to normal parameters.

Conclusions:

• The trochlear groove geometry of TKA differs from normal knees, contributing to incomplete patellar tracking restoration.
• Further investigation is required to determine the clinical implications for patellofemoral complications in TKA patients.