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

To investigate the ploughing mechanism associated with tractional force formation on the temporomandibular joint (TMJ) disc surface.

Ten left TMJ discs were harvested from 6- to 8-month-old male Yorkshire pigs.

Confined compression tests characterized mechanical TMJ disc properties, which were incorporated into a biphasic finite element model (FEM). The FEM was established to investigate load carriage within the extracellular matrix (ECM) and the ploughing mechanism during tractional force formation by simulating previous in vitro plough experiments.

Biphasic mechanical properties were determined in five TMJ disc regions (average±standard deviation for aggregate modulus: 0.077±0.040 MPa; hydraulic permeability: 0.88±0.37×10^-3 mm⁴ /Ns). FE simulation results demonstrated that interstitial fluid pressurization is a dominant loading support mechanism in the TMJ disc. Increased contact load and duration led to increased solid ECM strain and stress within, and increased ploughing force on the surface of the disc.

Sustained mechanical loading may play a role in load carriage within the ECM and ploughing force formation during stress-field translation at the condyle-disc interface. This study further elucidated the mechanism of ploughing on tractional force formation and provided a baseline for future analysis of TMJ mechanics, cartilage fatigue and early TMJ degeneration.