Age-related degenerative changes in the mouse mandibular joint

Area of Science:

• Gerontology
• Orthopedics
• Histopathology

Background:

• The temporomandibular joint (TMJ) is susceptible to degenerative changes with age.
• Osteoarthrosis (OA) is a common joint disease characterized by cartilage degradation.
• Understanding early OA development is crucial for potential interventions.

Purpose of the Study:

• To investigate the early pathological changes in the mandibular joints of ageing male ICR mice.
• To characterize the ultrastructural alterations in the condylar cartilage matrix.
• To elucidate the role of chondrocytes in age-related TMJ degeneration.

Main Methods:

• Light and electron microscopy were used to examine mandibular joints.
• Histopathological analysis focused on condylar cartilage.
• Ageing male ICR mice were utilized as the model system.

Main Results:

• A high incidence of degenerative joint disease, including osteoarthrosis, was observed early in adult life (by 7 months).
• Initial changes included chondromalacia in isolated foci, progressing to fibrillation, fibrous ankylosis, lipping, and subchondral osteosclerosis.
• Ultrastructural examination revealed significant heterogeneity in lesions, with deep fissures and matrix macromolecular alterations.

Conclusions:

• Ageing chondrocytes may produce a matrix less capable of withstanding mechanical stress.
• This matrix degradation is proposed as the primary driver of chondromalacia and subsequent osteoarthrosis in the mandibular joint.
• The findings highlight early cellular and matrix changes in age-related TMJ osteoarthritis.