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A convex lateral tibial plateau for knee replacement
J V Baré1, H S Gill, D J Beard
1OOEC/Nuffield Department of Orthopaedic Surgery, University of Oxford, Nuffield Orthopaedic Centre, Oxford, UK.
The Knee
|January 13, 2006
Summary
Unicompartmental knee replacements for the lateral compartment may perform better with a 75 mm spherical dome tibial component. This optimal shape for lateral tibial plateau resurfacing could improve knee flexion and overall implant performance.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Medical device design
Background:
- Unicompartmental knee replacement (UKR) outcomes are less favorable in the lateral compartment compared to the medial.
- Current lateral tibial components often feature flat or concave surfaces, ill-suited for the convex native lateral tibial plateau.
Purpose of the Study:
- To determine the optimal radius for a convex tibial component for lateral unicompartmental knee replacement.
- To evaluate the impact of different tibial component shapes on knee kinematics and joint distraction during flexion.
Main Methods:
- Acquisition and contour analysis of 12 lateral tibial plateaus from knee replacements.
- Fitting optimal circles to determine plateau radius and superimposing various tibial component designs.
- Utilizing published data to calculate knee flexion gaps at different flexion angles.
Main Results:
- The average native lateral tibial plateau radius was 40 mm, but its polyradial nature complicated direct application.
- A flat tibial plateau significantly distracted the knee (8 mm) in full flexion (p<0.001).
- A 75 mm radius spherical tibial plateau minimally impacted knee kinematics (1.5 mm distraction), while 50 mm and 25 mm radii significantly altered kinematics (3 mm and 4 mm distraction, respectively, p<0.001).
Conclusions:
- A spherical dome shape with a radius of approximately 75 mm is likely optimal for lateral unicompartmental tibial plateau resurfacing.
- Integrating this optimized shape into lateral total knee replacement components may enhance flexion and improve clinical outcomes.