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| − | ===Osteochondrosis=== | + | ===[[Osteochondrosis]]=== |
| − | [[Image:Pig elbow osteochondrosis.jpg|right|thumb|100px|<small><center>Osteochondrosis in pig elbow (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]] | |
| − | [[Image:Osteochondrosis dissecans.jpg|right|thumb|100px|<small><center>Osteochondrosis dissecans (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Defect in cartilage growth (i.e. '''dyschondroplasia''')
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| − | *In growing animals: large breeds of dogs (4-8 months), pigs (5-7 months) and horses (weeks - 2 years)
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| − | *Involves both the [[Bones - Anatomy & Physiology|growth plate]] and the immature [[Joints - Anatomy & Physiology#Articular cartilage|joint cartilage]]
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| − | *Multifactorial:
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| − | **Trauma
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| − | **Genetic
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| − | **Rapid growth
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| − | **Ischaemia
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| − | **Nutritional
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| − | *Essentially idiopathic
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| − | *Failure of [[Cartilage - Anatomy & Physiology|endochondral ossification]]
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| − | *Lesions bilateral in 70% of cases but lameness often unilateral, sometimes no clinical signs
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| − | *Some authors consider this condition more generalised, in which case e.g. [[Joints Developmental - Pathology#Elbow dysplasia|ununited anconeal process]] would be part of osteochondrosis syndrome
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| − | Different manifestations include:
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| − | *'''1. ''Osteochondrosis dissecans''''' (OCD):
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| − | **Retained cartilage cores
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| − | ***White, wedge-shaped areas of retained cartilage in the metaphysis
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| − | ***Clefts -> separation of cartilage from bone -> flaps or free '''joint mice'''
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| − | ***May interfere with joint function
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| − | **Lysis → bone cysts
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| − | **Focal disruption of [[Cartilage - Anatomy & Physiology|endochondral ossification]]
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| − | **-> Angular limb deformities and [[Joints Degenerative - Pathology#Degenerative joint disease (DJD)|degenerative joint disease]]
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| − | **May be present together with '''synovitis'''
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| − | **Predilection sites:
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| − | ***<u>In dogs:</u>
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| − | ****Proximal humerus
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| − | ****Lateral femoral condyle
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| − | ****Coronoid process of ulna
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| − | ***<u>In pigs:</u>
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| − | ****Humeral and medial femoral condyles
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| − | ****Anconeal process of elbow
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| − | ***<u>In horses:</u>
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| − | ***Medial femoral condyle
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| − | ***Distal tibia
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| − | **''Osteochondrosis dissecans'' in dogs:
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| − | ***Grossly:
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| − | ****Lesion in central part of the caudal aspect of developing ossification centre in humeral head
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| − | ***Histologcally:
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| − | ****Lesion filled with [[Granulation Tissue|granulation tissue]] (fibroplasia)
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| − | ****Surrounding thickened bone spicules
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| − | ****Cap of thickened [[Joints - Anatomy & Physiology#Articular cartilage|articular cartilage]] over the defect
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| − | ****-> May fragment - joint mice
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| − | ****Calcified cartilage fragments may be in the posterior pocket of joint capsule
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| − | *****May grow through synovial fluid nourishment
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| − | *'''2. Epiphysiolysis'''
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| − | **Not associated with retention of cartilage
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| − | **Separation of epiphysis from the metaphysis
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| − | **Likely to be due to trauma to degenerated [[Bones - Anatomy & Physiology|growth plate]]
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| − | **Possibly the basis of ununited anconeal process and ununited coronoid process in dogs
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| − | [[Category:Joints - Developmental Pathology]]
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