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| − | ==Generalised==
| + | #REDIRECT[[:Category:Bones - Developmental Pathology]] |
| − | ===Proportionate dwarfism===
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| − | *Miniature breeds
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| − | *Due to growth factor deficit
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| − | ===Chondrodysplasia===
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| − | *Literally means “abnormal cartilage development”
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| − | *Defective cartilage growth at the physis
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| − | *Usually genetic cause
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| − | *Occurs in cattle, dogs, sheep, pigs and cats
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| − | *Leads to '''disproportionate dwarfism''' (contrast with miniature breeds)
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| − | **Generally, growth is disproportionate because only the growth of bones which form from cartilage models is retarded – growth of other bones is normal (i.e. long bones shorter than normal)
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| − | <u>In Dogs:</u>
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| − | *'''Localised''' forms occur in dogs (e.g. affecting skulls of Pekingese and Bulldogs or the limbs of Dachshunds and Bassett hounds)
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| − | *Occasionally seen in immature Beagles, Poodles, Alaskan Malamutes, Scottish Deerounds and Norwegian Elkhounds
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| − | <u>In Cattle:</u>
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| − | *'''Dexter cattle'''
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| − | **Are heterozygous for incompletely dominant gene
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| − | **When homozygous - lethal, producing 'buldog calf'
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| − | **Usually aborted prior to seven month of pregnancy
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| − | **Also occurs in Holstein, Jerseys and Charolais
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| − | **Grossly:
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| − | ***Limbs and vertebral column are short
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| − | ***Domed cranium
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| − | ***Protruding [[Tongue - Anatomy & Physiology|tongue]]
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| − | ***Absent hard palate
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| − | ***Large umbilical hernia with eventrated abdominal organs
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| − | **Histologically:
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| − | ***Proliferative and hypertrophic zones in the physes are irregularly separated by fibrovascular tissue
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| − | ***Chondrocytes are not properly arranged
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| − | ***Irregular ossification and mineralisation
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| − | *'''Telemark type'''
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| − | **Cattle of Norwegian origin
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| − | **Also seen in Jersey cows
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| − | **Calves born alive, unable to stand and die soon after birth
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| − | **Grossly:
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| − | ***Domed cranium
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| − | ***Brachygnatic face
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| − | ***Protruding [[Tongue - Anatomy & Physiology|tongue]]
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| − | ***Cleft palate
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| − | ***Short neck and limbs
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| − | *'''Brachycephalic 'Snorter' type'''
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| − | **Hereford and Aberdeen Angus
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| − | **Show nasal dyspnoea and chronic rumenal tympany
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| − | **Grossly:
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| − | ***Short, broad head
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| − | ***Prominent, laterally displaced eyes
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| − | ***Short and compressed vertebral column
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| − | ***Distal long bones shorter than proximal
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| − | **Histologically:
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| − | **Physes appear normal
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| − | **Pallisading chondrocytes fewer in number
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| − | **Less hypertrophy
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| − | <u>In Sheep:</u>
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| − | *'''Ancon type'''
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| − | **Short limbs due to premature closure of growth plates
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| − | **Now rare
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| − | *'''Spider lamb'''
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| − | **Hereditary (autosomal recessive) in Suffolk and Hampshire breeds in North America
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| − | **Long, thin, angular limbs
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| − | **May be born alive or dead, aborted or develop symptoms within a month of birth
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| − | **Grossly:
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| − | ***Fine bones, poor musculature, small heads, scoliosis
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| − | **Histologically:
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| − | ***Abnormal centres of [[Bones - normal#Bone development|endochondral ossification]]
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| − | ***Nodular cartilage hypertrophy
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| − | <u>In Pigs:</u>
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| − | *Occurs in Danish Landrace
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| − | *Autosomal recesive inheritance
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| − | *Dwarfs with short legs, forelegs shorter than hind legs
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| − | *Abnormal movement is noticable at weaning
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| − | *Sequel is [[Joints Degenerative - Pathology#Degenerative joint disease (DJD)|arthrosis]]
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| − | ===Osteopetrosis (Marble bone disease)===
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| − | *Occurs in sheep, dogs, cattle, horses
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| − | *Failure of resorption by osteoclasts -> failure of remodelling of [[Bones - normal#Bone organisation|cancellous bone]]
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| − | *Bones become thickened and dense but brittle
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| − | *Marrow cavites are full of unresorbed primary spongiosa
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| − | *Thickened intramembranous bones of skull -> altered shape of brain
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| − | *Associated with severe viral infections, e.g. '''FeLV''', [[Bovine Viral Diarrhoea Virus|BVD]]
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| − | *Hereditary in Angus cattle
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| − | ===Lysosomal storage disease===
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| − | *Excess accumulation of metabolites in lysosomes
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| − | *Affects mainly nervous system
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| − | *Also affects growth of cartilage
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| − | ===Osteogenesis Imperfecta===
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| − | *Cause of fragile bones in humans, very rarely in animals
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| − | *Reported in Holstein and Charolais calves
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| − | *Poor mineralisation of bones and teeth
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| − | *Fractures are often present at birth
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| − | ===Congenital hyperostosis of pigs===
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| − | [[Image:Hyperostosis.jpg|right|thumb|100px|<small><center>Hyperostosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Rare, genetic
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| − | *Diaphysial dysplasia
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| − | *Excessive periosteal intramembranous bone, particularly in long bones
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| − | *Grossly:
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| − | **Greatly thickened long bones
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| − | **Tense, shiny skin, closely adherent to tissues below
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| − | *Born dead or die soon after birth
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| − | ===Retention of elongated primary trabeculae===
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| − | *Happens due to impaired osteoclastic activity
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| − | *Primary trabeculae do not transform into secondary and tertiary
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| − | *Continue to elongate
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| − | *Form a dense band beneath growth plate - growth retardation lattice
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| − | *Dense spikules apparent on radiographs
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| − | *Can be caused by [[Paramyxoviridae#Canine Distemper Virus (CDV)|distemper virus]], [[Flaviviridae|bovine viral diarrhoea virus]]
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| − | ==Localised==
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| − | *'''Hemimelia''' - abscence of one of limb bones
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| − | *'''Syndactylia''' - fusion of toes
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| − | *'''Polydactylia''' - increased number of digits
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| − | *'''Ectrodactylia''' - cleft in paw extending to metacarpus of dogs and cats
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| − | ===Cervical Vertebral Stenotic Myelopathy (Wobblers)===
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| − | *Equine disease
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| − | *Narrowing of the vertebral canal due to malalignment or maldevelopment of the vertebrae
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| − | *Fast growing male TBs ranging from 8 months to 4 years
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| − | *Hind limb ataxia due to cord compression
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| − | ===Angular limb deformity===
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| − | *Lateral deviation of distal portion of limb (valgus)
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| − | *Medial deviation of distal portion of limb (varus) - more rare
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| − | *Most common in foals
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| − | **Carpal joint
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| − | **Tarsal joint
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| − | **Fetlock joint
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| − | *Congenital or acquired
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| − | *Due to:
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| − | **Malpositioning in utero
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| − | **Excessive joint laxity
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| − | **[[Hypothyroidism|Hypothyroidism]]
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| − | **Trauma
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| − | **Overnutrition
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| − | **Defective endochondral ossification
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| − | **Poor conformation
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| − | **Disruption of blood supply to one side of bone
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| − | **Secondary to [[Bones Developmental - Pathology#Physitis|physitis in horses]]
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| − | *Usually resolves spontaneously in one to two weeks of life
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| − | *More severe cases exceding compensatory capabilities will persisist
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| − | *[[Bones - normal#Bone development|Cartilage development]] is affected
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| − | ===Fibrous dysplasia===
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| − | *See [[Bones Hyperplastic and Neoplastic - Pathology#Fibrous dysplasia|Bones and Cartilage - hyperplastic and neoplastic]]
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| − | ===Physitis===
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| − | *In horses
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| − | *Often associated with [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]]
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| − | *Also called '''epiphysitis''' and '''physeal dysplasia'''
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| − | *Problem of [[Bones - normal#Bone development|endochondral ossification]]
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| − | *Two age groups
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| − | **Weanlings
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| − | **Yearlings in early training and two-year-olds
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| − | *May cause contracted tendons and flexural deformities
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| − | *Factors probably involved in its development:
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| − | **Genetically fast growth rate
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| − | **Large quantities of imbalanced, high energy feed
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| − | **Imbalanced weight-bearing on joints
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| − | **Excessive activity
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| − | **Growth spurts
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| − | *Histologically: (appearance similar to [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]])
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| − | **Lateral aspect of radius
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| − | ***Thickened metaphyseal part of physeal cartilage
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| − | ***-> Delay or disturbance of endochondral ossification
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| − | ***Compression
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| − | **Central part
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| − | ***No obvious deformity
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| − | **Medial aspect
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| − | ***Tension
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| − | ***-> Transverse [[Bones Fractures - Pathology|fractures]] and repair
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| − | **Laxity of periarticular attachements in young foals allows [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]]; not occuring in older foals and young horses
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| − | **(Sustained trauma produces similar lesions)
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| − | [http://www.omafra.gov.on.ca/english/livestock/horses/facts/info_congenital.htm#musculoskeletal Developmental abnormalities]
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| − | ==Test yourself with the Bone and Cartilage Pathology Flashcards==
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| − | [[Bones_and_Cartilage_Flashcards_-_Pathology|Bones and Cartilage Flashcards]]
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| − | [[Category:Musculoskeletal System - Pathology]]
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