Changes

==Introduction==

==Introduction==

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.

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.

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.

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.

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, wobbler syndrome in horses).

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).

The exact cause is unknown, but contributing factors include:

The exact cause is unknown, but contributing factors include:

==Osteochondrosis dissecans (OCD)==

==Osteochondrosis dissecans (OCD)==

This is one manifestation of osteochondrosis, and involves '''retention of cartilage cores''' at the articular surface.

This is one manifestation of osteochondrosis, and involves '''retention of cartilage cores''' at the articular surface.

White, wedge-shaped areas of 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.

White, wedge-shaped areas of 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.

This condition may lead to angular limb deformities and [[Degenerative Joint Disease|degenerative joint disease]] and may be present together with '''synovitis'''.

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'''.

Predilection sites include:

Predilection sites include:

<u>In horses:</u> femoropatellar joint, tibiotarsal joint, fetlock joint and the shoulder.

<u>In horses:</u> femoropatellar joint, tibiotarsal joint, fetlock joint and the shoulder.

==Clinical signs==

==Clinical Signs==

Clinical signs are difficult to characterise due to the variety of sites and lesions involved.

Clinical signs are difficult to characterise due to the variety of sites and lesions involved.

'''Shoulder osteochondrosis''' is more problematic and the prognosis is guarded.

'''Shoulder osteochondrosis''' is more problematic and the prognosis is guarded.

'''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.

'''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.

'''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.  

'''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.  

Morgan, J. (2000) '''Hereditary bone and joint diseases in the dog''' ''Schültersche''

Morgan, J. (2000) '''Hereditary bone and joint diseases in the dog''' ''Schültersche''

[[Category:Joints - Developmental Pathology]]

[[Category:Joints - Developmental Pathology]]

[[Category:To Do - Manson]]

[[Category:Musculoskeletal Diseases - Dog]]

[[Category:Musculoskeletal Diseases - Horse]]