Computational study on synovial fluid flow behaviour in cartilage contact gap under osteoarthritic condition

Area of Science:

• Biomechanical Engineering
• Biomedical Physics
• Rheumatology

Background:

• Osteoarthritis (OA) is characterized by cartilage degradation and altered synovial fluid properties.
• Understanding fluid dynamics in the cartilage contact gap is crucial for OA pathogenesis.

Purpose of the Study:

• To numerically investigate the effects of cartilage surface roughness and synovial fluid characteristics on fluid flow in the contact gap.
• To quantify changes in gap permeability under osteoarthritic conditions.

Main Methods:

• Numerical construction of cartilage surface topographies (healthy and OA).
• Development of constitutive equations for synovial fluid viscosity.
• Utilizing a gap flow model to predict permeability based on roughness and fluid properties.

Main Results:

• OA cartilage surface roughness decreased gap permeability by 30%-60%.
• Reduced gap size amplified the decrease in permeability, potentially leading to early fluid ultrafiltration.
• Pathological synovial fluid significantly increased gap permeability (hundreds of times), inhibiting ultrafiltration.

Conclusions:

• Altered fluid flow in the contact gap is a significant factor in osteoarthritic joint dysfunction.
• Synovial fluid pathology has a more pronounced effect on gap permeability than cartilage surface roughness.
• These findings highlight the complex interplay between joint tissues and fluid dynamics in OA progression.