High detail radiography and histology of the centrodistal tarsal joint of Icelandic horses age 6 months to 6 years.

The research investigates early signs of Osteoarthrosis (OA), a common bone condition, in the tarsal joint region of Icelandic horses aged between 6 months and 6 years. The study concluded that poor conformation or joint structure, rather than trauma or overloading, contributes to OA in young Icelandic horses.

Research Objective

• The objective of the research was to determine the nature, location, and onset of early radiographic and histological changes in the centrodistal (CD) tarsal joint of young Icelandic horses which could be indicative of Osteoarthrosis (OA).

Methodology

• To achieve this, the authors examined slab sections from the CD joint of young Icelandic horses from 6 months to 6 years old using high detail radiography and histology.
• In total, 111 samples were examined by high detail radiography and 82 samples by histology.
• Horses younger than 5 years were not ridden, eliminating the potential impact of riding on the joints.

Results

• From the research, chondronecrotic lesions, which are similar to changes seen at the onset of OA, were found in 33% of the joints. These lesions were located both medially and laterally.
• 60% of the specimens had radiographic sclerosis found mostly on the medial side of the subchondral bone. This sclerosis was infrequent on the lateral side and was considered secondary to chondronecrosis in the corresponding part of the joint.
• Small defects detected by radiography in the subchondral bone were considered to be the most significant signs of OA as they were strongly associated with chondronecrosis.

Conclusions

• This high prevalence of chondronecrosis in young horses indicated an early and slow progression of OA that is unrelated to riding.
• However, these early stages of OA are unlikely to result in any outward clinical symptoms.
• The researchers determined that subchondral bone sclerosis is not a leading factor in the development of OA in the CD joint.
• Their findings suggested that the uneven distribution of biomechanical forces within the joint led to sclerosis, not OA.
• Last but not least, the findings implied that the development of OA in the CD joint of young Icelandic horses is more likely due to poor conformation or joint architecture rather than trauma or overloading.
• This also suggests the need for further studies on the influence of hindlimb conformation and architecture of distal tarsal joints on the biomechanics of joints, ideally through locomotion analysis of young horses.