Retained cartilage in the distal radial physis of foals.

The research paper looks at defects in the growth plates (the area of growing tissue near the ends of the long bones) of the distal radial physis (the lower parts of the bone that forms the joint with the wrist) in young horses. These imperfections may include retained cartilage, widening cells, and microfractures.

Overview of Findings

• The study involved the examination of growth plate defects in the lower parts of the forearm bone that connects to the wrist, specifically in foals ranging from three to 70 days old. In all, 13 foals were included in the study.
• The defects identified were found in both the lateral (side) and medial (middle) aspects of this part of the bone, known as the distal radial physis. It was noted that the lateral defects were more numerous and easier to detect.

Nature of Lesions

• The nature of the identified lesions varied. They largely consisted of a widening of the zone of hypertrophying cells – this is where cells increase in size, often related to the retained cartilage of the metaphyseal growth plate. This growth plate is the area of growing tissue near the ends of the long bones of animals.
• Other lesions included retained cartilage, which was seen in conjunction with a discontinuity of cartilage and primary spongiosa. Primary spongiosa is bone tissue found in the ends of the bone that increases in mineralization as it ages. The discontinuity could potentially compromise the integrity and strength of the bone.
• Also observed were microfractures in the primary spongiosa. Microfractures are tiny cracks in the bone that often occur due to overuse or repetitive stress. In this case, they seemed to appear in correlation with the retained cartilage.

Possible Cause of Cartilage Retention

• In some of the examined foals, it was hypothesized that the retention of the cartilage could be due to the microfracture of the primary spongiosa. However, researchers also considered the possibility that the microfracture could have been a subsequent event following the cartilage abnormality. The study did not definitively establish which of these two scenarios was the correct causal relationship.