Evolution of trochlear compartment geometry in total knee arthroplasty

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Implant design

Background:

• Total knee arthroplasty (TKA) aims to restore knee function through prosthetic joint replacement.
• The trochlear groove is a critical component influencing patellar tracking and overall knee biomechanics.
• Previous TKA designs have been associated with suboptimal patellofemoral outcomes, potentially due to trochlear geometry.

Purpose of the Study:

• To compare the trochlear profiles of contemporary total knee arthroplasty (TKA) models with their predecessors.
• To evaluate whether recent TKA designs exhibit more anatomic trochlear geometries.
• To determine if recent TKA models have overcome issues of trochlear dysplasia.

Main Methods:

• Geometric analysis of six TKA models (PFC, Attune, NexGen, Persona, Noetos, KneeTec) using engineering software.
• Mediolateral trochlear profiles were measured at multiple flexion angles (0°, 15°, 30°, 45°).
• Sulcus angle was calculated to quantify trochlear geometry and compare designs.

Main Results:

• Recent TKA models demonstrate a convergence towards more anatomic sulcus angles compared to older designs.
• At 30° flexion, recent TKA models show deepened trochlear profiles.
• Despite improvements, sulcus angles in recent TKA models still exceed radiologic signs of trochlear dysplasia by 2-5°.

Conclusions:

• Contemporary TKA designs feature more anatomic trochlear geometries than earlier models.
• The hypothesis that recent TKA models are free from trochlear dysplasia is refuted.
• Awareness of these design limitations is crucial for surgeons to optimize implant choice and extensor mechanism alignment.