Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities.

The study investigates the relationship between hyaline and calcified cartilage abnormalities in osteochondral lesions in the joints of young Icelandic horses, and the implications this has on our understanding of the early stages of osteoarthritis.

Study Methodology

• The study focuses on a sample size of 22 Icelandic horses aged 30 months, specifically examining the left distal tarsal region joint.
• The researchers used various imaging modalities to examine the joints, including confocal scanning light microscopy, backscattered electron scanning electron microscopy (which incorporated iodine staining), and three-dimensional microcomputed tomography. These methods were applied on specimens obtained through guidance from clinical imaging.
• The identified osteochondral lesions were classified into groups according to their morphological features.
• The lesions’ positions in the hyaline articular cartilage (HAC), articular calcified cartilage (ACC), subchondral bone (SCB), and the joint margin tissues were identified and the frequency of their occurrence in the joints was recorded.

Findings and Significance

• Considerable associations and correlations were discovered between the types of lesions in the centrodistal joints, specifically HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest, and ACC advance.
• These types of lesions were moderately to highly frequent in centrodistal joints but had low frequency in tarsometatarsal and talocalcaneal-centroquartal joints.
• No significant relationship was found between joint margin lesion types and other lesion types in the centrodistal joints despite their high frequency in both the centrodistal and tarsometatarsal joints.
• The frequency of SCB lesion types in all joints studied was low.
• Hypermineralised infill phase lesion types were detected.
• Overall, the results highlight a close relationship between HAC and ACC lesions in equine centrodistal joints and stress the significance of ACC lesions in the early onset of osteoarthritis in equine low-motion compression-loaded joints.