A mobile-bearing knee prosthesis can reduce strain at the proximal tibia

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Biomechanics

Background:

• Total knee prostheses (TKP) can alter proximal tibial strain distribution.
• Strain gradients influence bone remodeling, implant integration, and stability.
• Distinct strain patterns may arise from mobile-bearing (MB) versus fixed-bearing (FB) TKPs.

Purpose of the Study:

• To compare the effects of MB and FB total knee prostheses on proximal tibial strain distribution.
• To evaluate the biomechanical performance of a specific MB prosthesis under axial and torsional loading in cadaveric specimens.

Main Methods:

• Cadaveric tibial specimens were subjected to combined axial and torsional loading.
• Rosette strain gauges and an optical full-field strain acquisition system measured cortical strain.
• Tibial torsion was documented in response to simulated knee rotation.

Main Results:

• No significant difference in cortical strain under axial loading (1.5 kN) between MB and FB prostheses.
• MB prostheses induced 22% less compressive strain during internal tibial rotation compared to FB.
• MB prostheses induced 33% less compressive strain during external tibial rotation compared to FB.
• MB prostheses reduced proximal tibial torque by 68-73% during knee rotation.

Conclusions:

• The tested MB total knee prosthesis demonstrated potential for reducing elevated strain levels in the proximal tibia.
• Reduced strain and torque may contribute to improved long-term implant integration and stability.
• Further investigation into MB prosthesis biomechanics is warranted.