Changes in mineralised tissue at the site of origin of condylar fracture are present before athletic training in Thoroughbred horses

Authors: Firth EC, Doube M, Boyde A
Publication: New Zealand Veterinary Journal, Volume 57, Issue 5, pp 278-283, Oct 2009
Publisher: Taylor and Francis

Animal type: Horse, Livestock
Subject Terms: Skeletal/bone/cartilage, Minerals/elememts, Fractures, Disease/defect, Growth/development, Nutrition/metabolism, Surgery
Article class: Rapid Communication

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Abstract: AIM: To show that changes are  present at the site of origin of metacarpal condylar fracture in young  Thoroughbred horses before they enter race training.  
METHOD: Bone slices, 2 mm thick,  in three mediolateral planes through the centre of rotation of the metacarpo-phalangeal  joint (MCPJ) of both distal third metacarpal bones (Mc3) of 12 Thoroughbred  horses aged 17 months, were imaged using point-projection digital X-ray  imaging (μXR).  
RESULTS: In some horses, linear or  ovoid radiolucency was found in articular calcified cartilage (ACC) and  subchondral bone of the palmaro-distal aspect of the sagittal groove, exactly  at the site of more advanced stages of condylar fatigue fracture. An  incidental finding was ovoid radiolucency in the apex of the dorso-distal aspect  of the sagittal ridge, with or without fragmentation or disturbance of the  subchondral mineralised tissue line, resembling equine osteochondrosis.  
CONCLUSIONS AND CLINICAL  RELEVANCE: The findings imply that the aetiology of condylar fatigue fracture  in young Thoroughbred horses includes abnormality in development of the bone  and joint that is present before athletic activity occurs.  
KEY WORDS: Condyle, fatigue  fracture, calcified cartilage, subchondral bone, equine, bone development,  osteochondrosis

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