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| − | {{toplink
| + | #redirect[[:Category:Joints - Degenerative Pathology]] |
| − | |backcolour =CDE472
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| − | |linkpage =Musculoskeletal System - Pathology
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| − | |linktext =Musculoskeletal System
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| − | |maplink = Musculoskeletal System (Content Map) - Pathology
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| − | |pagetype =Pathology
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| − | |sublink1=Joints - Pathology
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| − | |subtext1=JOINTS
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| − | }}
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| − | <br>
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| − | ===Degenerative joint disease (DJD)===
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| − | [[Image:DJD horse.jpg|right|thumb|100px|<small><center>DJD in a horse (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *'''Osteoarthritis, osteoarthrosis'''
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| − | *Due to acceleration of normal ageing process - wear and tear
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| − | *Destructive disease leading to:
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| − | **Loss of weight-bearing [[Joints - normal#Articular cartilage|articular cartilage]]
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| − | **Erosion, fibrillation of cartilage
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| − | ***Clefts in the cartilage, perpendicular to the surface
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| − | **Complete exposure of underlying bone
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| − | ***Bone appears polishes, dense - [[Musculoskeletal terminology|eburnation]]
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| − | ***Radiographically - joint space reduction due to loss of cartilage
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| − | **[[Musculoskeletal terminology|Osteophyte]] formation at joint margins
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| − | **Remodelling of adjacent bone
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| − | **Brown/yellow discolouration
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| − | **Synovial hypertrophy
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| − | **Capsular fibrosis
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| − | *May affect one or multiple joints
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| − | *May or may not be symptomatic
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| − | *Pathogenesis:
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| − | **Not entirely clear but linked to loss of [[Joints - normal#Articular cartilage|proteoglycans]] and subsequent lubrication
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| − | **Increased water content due to improper binding -> softening of cartilage = chondromalacia
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| − | | |
| − | *Predisposing factors:
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| − | **Persistent trauma
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| − | **Joint instability / dysplasia
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| − | ***[[Joints Degenerative - Pathology#Luxations and subluxations|Luxations and subluxations]]
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| − | ***[[Joints Developmental - Pathology#Hip dysplasia|Hip dysplasia]]
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| − | ***[[Joints Developmental - Pathology#Elbow dysplasia|Elbow dysplasia]]
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| − | **Conformational abnormalities / congenital malformations
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| − | **[[Joints Developmental - Pathology#Osteochondrosis|Osteochondrosis dissecans]]
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| − | **Intra-articular fractures
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| − | **[[Joints Degenerative - Pathology#Calve Legg-Perthe's disease|Calve Legg-Perthe's disease]]
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| − | ===Luxations and subluxations===
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| − | ====Patellar====
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| − | *In stifle joints of dogs and horses
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| − | *Possibly inherited
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| − | *'''Small''' dog breeds:
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| − | **'''Medial''' luxation
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| − | **Due to underdevelopment of medial femoral condyle
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| − | *'''Large''' dog breeds and '''horses''':
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| − | **'''Lateral''' luxation
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| − | ====Atlantoaxial====
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| − | *In dogs, calves, horses and goats
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| − | *Miniature dog breeds:
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| − | **Failure of fusion of odontoid process to rest of axis
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| − | *Calves:
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| − | **Aplasia or hypoplasia of odontoid process
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| − | ====Temporomandibular====
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| − | *In dogs, particularly Basset Hounds, Irish Setters
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| − | *Normal movement of mandibular coronoid process is interfered with by zygomatic arch
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| − | *Happens on one side -> open jaw locking
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| − | ===Calve Legg-Perthe's disease===
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| − | *Almost exlusively in small dogs, particularly terriers and poodles
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| − | *Clinical signs appear at age of 4-11 months
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| − | *Grossly:
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| − | **[[Bones Degenerative - Pathology#Osteosis|Aseptic ischaemic necrosis]] in central parts of femoral head
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| − | ***Possibly due to occlusion of blood vessels
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| − | **Fragmentation of [[Bones - normal#Bone organisation|trabecular bone]]
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| − | **Collapse of femoral head
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| − | **Revascularisation of femoral head
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| − | **Formation of new bone and [[Musculoskeletal terminology|osteophyte]] formation around femoral head and acetabular rim prior to old bone reabsorption
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| − | **-> severe degenerative arthropathy
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| − | ===Degenerative arthropathy===
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| − | *In older dogs (8+ years)
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| − | *Occurs bilaterally
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| − | *In shoulders
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| − | *?Due to gradual atrophy of muscles with age -> joint laxity
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| − | ===Traumatic injuries===
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| − | *Sudden
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| − | *Varying severity
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| − | *Acute injuries:
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| − | **Sprains
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| − | ***Minor - resolved without any consequences
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| − | ***More severe may result in persistent capsular and ligament laxity -> degenerative arthrosis -> impaired function
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| − | **Subluxations
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| − | **Luxations
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| − | **Intra-articular fractures
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| − | ***[[Bones Fractures - Pathology#Fracture repair|Fracture healing]] may cause discontinuity of the articular surfaces
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| − | **Puncture wounds to foot may allow infection to travel to [[Joints - inflammatory|joints]], bursae and tendon sheaths
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| − | **Haemorrhage into joint
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| − | ***May occur in animals with clotting defects without special trauma
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| − | ****Usually polyaricular
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| − | ****Recurrent
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| − | ****May cause pitting of articular surfaces -> degenerative arthrosis
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| − | ===Nutritional diseases===
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| − | ====Hypervitaminosis A====
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| − | *See [[Bones Metabolic - Pathology#Hypervitaminosis A|metabolic diseases of bones]]
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| − | *May cause spondylosis of cervical vertebrae
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| − | *Mainly on dorsolateral surface
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| − | *Also in elbow and shoulder joints -> fixation of joint
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| − | *May resolve with changes of diet
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| − | ===Disc protrusion===
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| − | [[Image:Intervertebral disc degeneration.jpg|right|thumb|100px|<small><center>Intervertebral disc degeneration (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Occurs mainly in dogs
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| − | *Almost always '''dorsal''' protrusion due to eccentric position of [[Joints - normal#Fibrocartilagenous joints|''nucleus pulposus'']]
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| − | *Main sites are '''cervical and lumbar''' regions
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| − | **Thoracic vertebrae have [[Joints - normal#Fibrocartilagenous joints|conjugal ligaments]]
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| − | *Degeneration precedes protrusion (two patterns):
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| − | **'''Chondroid'''
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| − | ***In chondrodystrophic breeds
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| − | ***Concurrent calcification of [[Intervertebral disc degeneration|degenerated ''nucleus pulposus'']]
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| − | ***Progressive loosening and fragmentation of overlying ''annulus fibrosis'' fibres
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| − | ****Damaged by both compressive and rotational forces
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| − | ***Predisposing degeneration of the discs occurs by one year of age in most of the dogs
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| − | ***Protrusion usually occurs in males, 3-6 years of age
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| − | ***'''Sudden complete protrusion''' -> severe damage to spinal cord in the area
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| − | ***Widespread necrosis and haemorrhage
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| − | ***Extruded material is gritty, hemorrhagic or “cheesy”
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| − | **'''Fibroid'''
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| − | ***In non-chondrodystrophic breeds, horses, pigs
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| − | ***Usually occurs later in life
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| − | ***Pathogenesis:
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| − | ****Progressive dehydration and collagenisation of ''nucleus pulposus''
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| − | ****Fraying and fragmentation of lamellar ''annulus fibrosis'' fibres
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| − | **** -> Attempts to repair by fibrosis
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| − | **** -> Weak area in the annulus
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| − | **** -> '''Partial protrusion''' (rarely may calcify) of nucleus into spinal canal
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| − | *****May be dorsal or lateral
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| − | **** -> Pressure on spinal cord
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| − | **** -> Demyelination of white matter
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| − | **** -> Progressive weakness of structures innervated distally to the lesion
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| − | ***Disk material may enter blood vessels causing fibrocartilagenous embolism
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| − | ****May present without any disk symptoms
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| − | *'''Sudden protrusion''' can occur in any breed due to traumatic compression of spinal cord
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| − | ===Cervical spinal stenosis===
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| − | *Usually funnel-shaped
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| − | *Stenosis in dorso-ventral plane
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| − | *May occur at more than one site
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| − | *Predisposed in some breeds: Great Dane, Doberman, Basset Hound, Irish Wolfhound, Old English Sheepdog
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| − | *Clinical signs: cervical pain -> ataxia -> quadriplegia
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| − | ===Cervicospinal arthropathy===
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| − | * = "'''Wobbler'''" in horses
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| − | *Usually presents in first two years of life
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| − | *Mainly in fast growing thouroughbreds
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| − | *Most common site is C3-C4, can occur anywhere
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| − | *Abnormal laxity between the vertebrae + cervical vertebral malformation may be evident
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| − | *[[Musculoskeletal terminology|Osteophyte formation]] at edges of synovial components of joint
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| − | *Some due to stenosis of neural canal later in life (1-4 years of age)
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| − | *Clinical signs:
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| − | **Ataxia - hindlimbs more affected
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| − | *Presumed cause is rapid growth
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| − | ===Spondylosis===
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| − | [[Image:Spondylosis.jpg|right|thumb|100px|<small><center>Spondylosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Often in bulls and dogs, occurs also in horses, cats and pigs
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| − | *[[Musculoskeletal terminology|Osteophyte]] formation on ventral aspect of vertebrae
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| − | **Often around lumbar region
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| − | **Adjacent to intervertebral spaces
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| − | **Varies in size - small spurs -> 'bridges' between vertebrae
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| − | **May extend over few vertebrae
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| − | *Pathogenesis:
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| − | **Repeated abnormal movement between joints -> stress
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| − | ** -> Degeneration of [[Joints - normal#Fibrocartilagenous joints|''annulus fibrosis'']]
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| − | ** -> [[Musculoskeletal terminology|Osteophyte]] formation
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| − | *In dogs usually no symptoms
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| − | *In bulls may cause inability to mount
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| − | *In severe cases repeated damage may progress to recurrent posterior weakness and ataxia in conjuction with fractures of spondylitic and vertebral bone
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| − | ===Cranial cruciate ligament rupture===
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| − | *Autoantibodies against collagens seen in the joint fluid – no relationship to the disease (ie: not an autoimmune disease) – can be seen in any joint disease
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| − | ===Steroid arthropathy===
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| − | *From glucocorticoids injected into joint as antiinflammatories
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| − | *Injection sometimes causes rapid progression of degeneration
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| − | *Glucocortyicois suppress anabolic effect of chondrocytes -> reduction of cartilage matrix syhthesis -> proteoglycan depletion -> slower repair
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