Difference between revisions of "Osteochondrosis"

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[[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>]]
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==Introduction==
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[[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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[[Image:Pig elbow osteochondrosis.jpg|right|thumb|200px|<small><center>Osteochondrosis in pig elbow (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
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[[Image:Osteochondrosis dissecans.jpg|right|thumb|200px|<small><center>Osteochondrosis dissecans (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
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Osteochondrosis describes a defect in [[Cartilage - Anatomy & Physiology|endochondral ossification]] of the epiphyseal cartilage. The term is currently used to describe the clinical manifestation of the disorder. The term '''dyschondrodysplasia''' is preferred when referring to early lesions because primary lesions are seen in the cartilage.
 
  
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It is one of the '''most prevalent and important developmental orthopaedic diseases''' of dogs and horses, and is seen in growing animals. '''Large breeds of dogs''' present at 4-8 months, '''horses''' from weeks to 2 years, and '''pigs''' from 5-7 months.
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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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It involves both the [[Bones - Anatomy & Physiology|growth plate]] and the immature [[Joints - Anatomy & Physiology#Articular cartilage|joint cartilage]]. Lesions are '''bilateral in 70% of cases''' but lameness is often unilateral.
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Different manifestations include:
  
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The condition mainly affects '''articular growth cartilage''', but the metaphysis may also be involved. If the physeal metaphyseal cartilage is affected, bone contours and longitudinal growth are disturbed. Involvement of articular cartilage at the periphery of joint surfaces leads to regressive changes at the joint margins, '''dissecting lesions''', and the '''formation of flaps'''. Central articular lesions, because of weight-bearing effects, involve focal retention of cartilage within the subchondral bone ('''Subchondral Bone Cysts'''). Axial skeletal involvement includes vertebral articular facets, and this may lead to '''stenosis of the vertebral canal''' and, ultimately, ataxia and proprioceptive deficits (ie, [[Cervical Vertebral Stenotic Myelopathy|wobbler syndrome]] in horses).
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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 [[Degenerative Joint Disease|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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The exact cause is unknown, but contributing factors include:
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*'''2. Epiphysiolysis'''
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'''excessive nutrition, rapid growth, trauma, mineral imbalance and a hereditary component'''.
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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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In dogs, '''[[Elbow Dysplasia|ununited anconeal process and fragmented coronoid process]]''' may be related conditions, linked to separation of the epiphysis from the metaphysis likely due to osteochondrosis which predisposes the growth plate to failure following trauma.
 
  
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==Osteochondrosis dissecans (OCD)==
 
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This is one manifestation of osteochondrosis, and involves '''retention of cartilage cores''' at the articular surface.
 
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White, wedge-shaped areas of [[Retained Cartilage Cores|retained cartilage]] are found in the metaphysis. Clefts lead to the separation of cartilage from bone and the formation of '''flaps or free joint mice''' which may interfere with joint function.
 
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This condition may lead to [[Angular Limb Deformity|angular limb deformities]] and [[Degenerative Joint Disease|degenerative joint disease]] and may be present together with '''synovitis'''.
 
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Predilection sites include:
 
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<u>In dogs:</u> proximal humerus, lateral femoral condyle and the coronoid process of ulna
 
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<u>In pigs:</u> humeral and medial femoral condyles and anconeal process of elbow
 
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<u>In horses:</u> femoropatellar joint, tibiotarsal joint, fetlock joint and the shoulder.
 
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==Clinical Signs==
 
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Clinical signs are difficult to characterise due to the variety of sites and lesions involved.
 
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In '''horses''', signs may begin with '''mild stiffness and lameness''' progressing to pain and loss of performance. The most common sign is '''non-painful distention of the affected joints'''.
 
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'''Foals''' tend to spend more time lying down and show stiffness, an upright limb conformation and a difficulty in keeping up with other animals in the paddock. Signs in older horses are usually linked to the '''onset of training''' and include stiffness, flexion responses and variable lameness. Marked lameness is not usually a feature.
 
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Shoulder OC cases usually show more severe lameness and possibly some muscle atrophy.
 
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'''Dogs''' show lameness, joint effusion and a reduced range of motion in the affected joints.
 
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==Diagnosis==
 
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Clinical diagnosis is usually made on the basis of clinical signs and signalment.
 
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'''Radiographic examination''' is usually useful in making a diagnosis, although early lesions involving cartilage without significant subchondral bone damage will not be visualised. Oblique views may be helpful.
 
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Radiographic signs include: '''flattening of joint surfaces, subchondral bone lucency or sclerosis, osteophytosis, joint effusion, and joint mice'''.
 
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'''Contrast radiography''' can be used to delineate cartilage flaps. '''Ultrasonography''' may delineate articular damage and joint mice.
 
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'''Arthroscopy''' is the most accurate way to confirm the diagnosis and most sites are accessible.
 
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Evaluation of '''synovial fluid''' will help rule out inflammatory causes of swollen joints.
 
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'''Histological findings''' include: lesion filled with granulation tissue (fibroplasia), surrounding thickened bone spicules, cap of thickened articular cartilage over the defect.
 
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==Treatment==
 
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Treatment depends on the site and severity of signs.
 
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'''In horses''', mild cases resolve spontaneously and a '''conservative approach''' may be adequate. Young animals should have their '''exercise restricted''' and their '''feed intake reduced''' to slow growth. Correcting the diet may not aid resolution but may help prevent further cases on a stud farm. '''Intra-articular medication''' with hyaluronic acid may be beneficial, and injection of long-acting corticosteroids may help reduce swelling and improve any associated synovitis.
 
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'''Surgical cases''' can be treated '''arthroscopically'''. Damaged cartilage and joint mice are removed and the bone overlying the lesion is curetted and the joint flushed extensively.
 
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'''Prognosis is good''' except in cases with severe joint disruption and secondary osteoarthritis.
 
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'''Shoulder osteochondrosis''' is more problematic and the prognosis is guarded.
 
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'''In dogs''', treatment involves '''surgical removal of flaps and joint mice''' and curettage of subchondral bone to stimulate fibrocartilage formation. The joint can also be management '''conservatively''' and the animal given [[NSAIDs]] at times of need. Joint fluid modifiers such as polysulfated glycosaminoglycans may also help prevent cartilage degeneration.
 
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'''Prognosis''' for recovery is excellent for the shoulders, good for the stifle joint, and fair for the elbow and tarsal joints. Concomitant signs of degenerative joint disease, other joint conditions, or instability deleteriously affect recovery.
 
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{{Learning
 
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|flashcards = [[Equine Orthopaedics and Rheumatology Q&A 14]]
 
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}}
 
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==References==
 
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Kahn, C. (2005) '''Merck veterinary manual''' ''Merck and co''
 
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Morgan, J. (2000) '''Hereditary bone and joint diseases in the dog''' ''Schültersche''
 
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{{review}}
 
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{{OpenPages}}
 
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[[Category:Musculoskeletal Diseases - Pig]]
 
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[[Category:Expert Review]]
 
 
[[Category:Joints - Developmental Pathology]]
 
[[Category:Joints - Developmental Pathology]]
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[[Category:Musculoskeletal Diseases - Dog]]
 
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[[Category:Musculoskeletal Diseases - Horse]]
 

Revision as of 16:03, 3 March 2011

Osteochondrosis in pig elbow (Image sourced from Bristol Biomed Image Archive with permission)
Osteochondrosis dissecans (Image sourced from Bristol Biomed Image Archive with permission)
  • Defect in cartilage growth (i.e. dyschondroplasia)
  • In growing animals: large breeds of dogs (4-8 months), pigs (5-7 months) and horses (weeks - 2 years)
  • Involves both the growth plate and the immature joint cartilage
  • Multifactorial:
    • Trauma
    • Genetic
    • Rapid growth
    • Ischaemia
    • Nutritional
  • Essentially idiopathic
  • Failure of endochondral ossification
  • Lesions bilateral in 70% of cases but lameness often unilateral, sometimes no clinical signs
  • Some authors consider this condition more generalised, in which case e.g. ununited anconeal process would be part of osteochondrosis syndrome

Different manifestations include:

  • 1. Osteochondrosis dissecans (OCD):
    • Retained cartilage cores
      • White, wedge-shaped areas of retained cartilage in the metaphysis
      • Clefts -> separation of cartilage from bone -> flaps or free joint mice
      • May interfere with joint function
    • Lysis → bone cysts
    • Focal disruption of endochondral ossification
    • -> Angular limb deformities and degenerative joint disease
    • May be present together with synovitis
    • Predilection sites:
      • In dogs:
        • Proximal humerus
        • Lateral femoral condyle
        • Coronoid process of ulna
      • In pigs:
        • Humeral and medial femoral condyles
        • Anconeal process of elbow
      • In horses:
      • Medial femoral condyle
      • Distal tibia
    • Osteochondrosis dissecans in dogs:
      • Grossly:
        • Lesion in central part of the caudal aspect of developing ossification centre in humeral head
      • Histologcally:
        • Lesion filled with granulation tissue (fibroplasia)
        • Surrounding thickened bone spicules
        • Cap of thickened articular cartilage over the defect
        • -> May fragment - joint mice
        • Calcified cartilage fragments may be in the posterior pocket of joint capsule
          • May grow through synovial fluid nourishment
  • 2. Epiphysiolysis
    • Not associated with retention of cartilage
    • Separation of epiphysis from the metaphysis
    • Likely to be due to trauma to degenerated growth plate
    • Possibly the basis of ununited anconeal process and ununited coronoid process in dogs
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