What is an osteochondroma?

Arthroscopic removal of a solitary osteochondroma interfering with the podotrochlear apparatus in a foal

“…The location can be used to differentiate between true exostosis and SO. 4 A true exostosis is located at the physeal scar, while SO drift progressively toward the diaphysis following longitudinal bone growth. A defining feature of SO is its continuity with the underlying cortex and, in some cases, with the medullary cavity.…”

“…Although they develop in growing horses, SO in the distal radius are typically detected in equine adults 3 to 12 years old due to the expansive nature of the osseous herniation impinging on the adjacent soft tissue structures 5 . Other less frequently reported sites for SO are distal caudal tibia, cranial aspect of distal radius, rib, vertebra, scapula, dorsal aspect of the proximal phalanx, and flat bones 4 . Solitary osteochondromas causing clinical signs in foals are rare, and, to the best of our knowledge, only two cases have been described 6,7 .…”

“…This aberrant subperiosteal physeal cartilage establishes a separate focus of endochondral ossification, and this results in an outgrowth from the metaphysis, or extremity of the diaphysis, that ceases growing at the time of skeletal maturity. 4 Although they develop in growing horses, SO in the distal radius are typically detected in equine adults 3 to 12 years old due to the expansive nature of the osseous herniation impinging on the adjacent soft tissue structures. 5 Other less frequently reported sites for SO are distal caudal tibia, cranial aspect of distal radius, rib, vertebra, scapula, dorsal aspect of the proximal phalanx, and flat bones.…”

“…5 Other less frequently reported sites for SO are distal caudal tibia, cranial aspect of distal radius, rib, vertebra, scapula, dorsal aspect of the proximal phalanx, and flat bones. 4 Solitary osteochondromas causing clinical signs in foals are rare, and, to the best of our knowledge, only two cases have been described. 6 , 7 In one previous case report, a 2‐month‐old foal with an SO located on the second phalanx (P2) was described, but this foal was euthanized because of poor prognosis.…”

“…They are thought to originate from an accidental separation and migration toward the diaphysis of a portion of physeal cartilage during skeletal development. This aberrant subperiosteal physeal cartilage establishes a separate focus of endochondral ossification, and this results in an outgrowth from the metaphysis, or extremity of the diaphysis, that ceases growing at the time of skeletal maturity 4 . Although they develop in growing horses, SO in the distal radius are typically detected in equine adults 3 to 12 years old due to the expansive nature of the osseous herniation impinging on the adjacent soft tissue structures 5 .…”