Early changes in lapine menisci during osteoarthritis development: Part I: cellular and matrix alterations

Area of Science:

• Orthopedics
• Rheumatology
• Biomedical Engineering

Background:

• Osteoarthritis (OA) is a prevalent degenerative joint disease.
• Meniscal and ligament injuries, particularly in the knee, significantly increase OA risk.
• Understanding early pathological changes is crucial for developing preventative strategies.

Purpose of the Study:

• To investigate early-stage degenerative changes in the medial and lateral menisci of rabbit knees following anterior cruciate ligament (ACL) transection.
• To assess the impact of ACL injury on meniscal matrix organization and cellularity during the onset of OA.

Main Methods:

• Rabbit knees underwent anterior cruciate ligament (ACL) transection.
• Meniscal tissues were analyzed using histology and immunohistochemistry.
• Assessment focused on extracellular matrix organization, composition, and cell distribution.

Main Results:

• Extensive extracellular matrix deterioration was observed in menisci by 3 and 8 weeks post-ACL transection.
• Medial menisci showed altered cell distribution (depletion and clustering), unlike lateral menisci.
• Both menisci exhibited altered collagen distribution; Type I and III collagen increased, while Type II collagen significantly increased only in the medial meniscus.

Conclusions:

• ACL transection triggers early extracellular matrix deposition and altered matrix organization in the medial meniscus.
• Cell distribution changes are also an early indicator of OA development in the medial meniscus post-ACL injury.
• These findings highlight the medial meniscus's vulnerability in the early stages of post-traumatic OA.