Critical-sized cartilage defects in the equine carpus

Area of Science:

• Orthopedics
• Regenerative Medicine
• Comparative Anatomy

Background:

• The horse joint serves as a valuable translational model for human articular cartilage repair studies due to anatomical similarities.
• Establishing critical defect sizes is essential for standardizing evaluations of novel cartilage treatment strategies.

Purpose of the Study:

• To determine the critical size of cartilage defects in the equine carpus.
• To establish a benchmark for assessing new cartilage repair treatments in a translational model.

Main Methods:

• Full-thickness chondral defects (2, 4, 8 mm) and osteochondral defects (3.5 mm depth) were created in the carpal joints of 5 horses.
• Repair tissue was evaluated after 12 months using macroscopic, MRI, micro-CT, polarized light microscopy, histology, and immunohistochemistry.

Main Results:

• 2 mm chondral defects showed good filling but proteoglycan depletion. Larger chondral defects had poor filling.
• Osteochondral defects showed better neotissue quality and type II collagen presence than chondral defects.
• Subchondral bone pathologies were prevalent in osteochondral defects, deeming overall repair unsatisfactory.

Conclusions:

• A 2 mm defect size is recommended as critical for chondral lesions in equine carpal joint research.
• A 4 mm defect size is recommended as critical for osteochondral lesions in equine carpal joint research.
• These critical sizes will serve as benchmarks for evaluating future cartilage repair interventions.