Difference between revisions of "Joints Degenerative - Pathology"

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

Latest revision as of 16:07, 3 March 2011