Fluid pressurization and tractional forces during TMJ disc loading: A biphasic finite element analysis

Area of Science:

• Biomechanics
• Biomaterials Science
• Computational Biology

Background:

• The temporomandibular joint (TMJ) disc plays a crucial role in load distribution and joint function.
• Tractional forces on the TMJ disc surface are implicated in disc degeneration.
• The precise mechanism of ploughing force formation on the TMJ disc remains incompletely understood.

Purpose of the Study:

• To investigate the ploughing mechanism responsible for tractional force generation on the temporomandibular joint (TMJ) disc surface.
• To elucidate the role of interstitial fluid pressurization and extracellular matrix (ECM) mechanics in TMJ disc loading.

Main Methods:

• Mechanical properties of porcine TMJ discs were characterized using confined compression tests.
• A biphasic finite element model (FEM) was developed incorporating the determined mechanical properties.
• The FEM simulated in vitro plough experiments to analyze load carriage and ploughing mechanisms within the TMJ disc ECM.

Main Results:

• Biphasic mechanical properties, including aggregate modulus and hydraulic permeability, were quantified for different TMJ disc regions.
• Finite element simulations confirmed interstitial fluid pressurization as a primary load-bearing mechanism in the TMJ disc.
• Increased contact load and duration resulted in elevated ECM strain and stress, alongside increased surface ploughing forces.

Conclusions:

• Sustained mechanical loading contributes to ECM load carriage and ploughing force generation during condylar translation.
• This research clarifies the ploughing mechanism in tractional force formation, offering a foundation for future TMJ mechanics and degeneration studies.
• Findings provide insights into cartilage fatigue and early TMJ degeneration processes.