Structure-function relationships of TMJ lateral capsule-ligament complex

Area of Science:

• Anatomy and Biomechanics
• Biochemistry
• Orthopedics

Background:

• The human temporomandibular joint (TMJ) lateral capsule ligament (LCL) complex structure is debated, requiring further investigation into its role in TMJ anatomy and mechanics.
• Understanding regional and sex-specific differences in the LCL complex is essential for evaluating potential etiological mechanisms of TMJ disorders.

Purpose of the Study:

• To explore the ultrastructural arrangement, biomechanical tensile properties, and biochemical composition of the human LCL complex.
• To identify region-specific differences, particularly the presence of a distinct temporomandibular ligament.
• To investigate sex-specific differences within the LCL complex.

Main Methods:

• Analysis of ultrastructural arrangement, biomechanical properties, and biochemical composition using cadaveric TMJ samples.
• Statistical modeling to assess sex- and region-specific effects on LCL complex tissue properties.

Main Results:

• Collagen fiber coherency, bundle size, and elastin fiber count did not significantly differ between sexes, though females trended higher in elastin.
• Collagen content was significantly higher in the anterior LCL region compared to the posterior region, and higher in males than females.
• Anterior LCL complex exhibited significantly greater failure stress than the posterior region.

Conclusions:

• Regional differences confirm the existence of a mechanically and compositionally distinct temporomandibular ligament within the LCL complex.
• Baseline sex-specific differences in LCL collagen content are critical for investigating sex disparities in TMJ disorders.
• These findings provide essential baseline tissue properties for TMJ musculoskeletal models and etiological research into temporomandibular disorders.