Disorders of the Physis Flashcards
what are the parts of long bones?
epiphysis
physis
metaphysis
diaphysis
what is the epiphysis?
end of a long bone
secondary center of ossification
what are the two cartilagenous areas of long bones?
articular cartilage
physeal cartilage
what size and shape is physeal cartilage?
size and shape of diaphysis
how does longitudinal bone growth occur?
endochondral ossification
what is the reserve zone adjacent to?
epiphysis
what does the proliferative zone look like?
cells divide in a linear fashion
where are germinal cells?
adjacent to epiphysis
what do the cells look like in the hypertrophic zone?
broad, flat cells
what happens in the calcification zone?
matrix seeded with calcium phosphate
hydroxyappetite crystals form and calcify
what arteries supply the physeal blood supply?
epiphyseal artery
metaphyseal artery
what does disruptions of epiphyseal blood supply lead to?
necrosis of germinal cells and permanent cessation of growth
what does disruption of the metaphyseal blood supply result in?
reversible cessation of ossification
the cartilaginous physis is ___________ than the adjacent bone
weaker
what does salter-harris classification classify physeal fractures based on?
anatomic location and correlated with prognosis
what is a type VI fracture?
traumatically induced periosteal bridging resulting in an angular or rotational deformity
what does the salter-harris classification not take into account?
age of animal
specific bone involved or location
what does a salter-harris type I spare?
reserve zone of cartilage cells
what is a salter-harris type I?
fracture or separation through the hypertrophic zone
what is a salter-harris type II?
fracture or separation through portion of hypertrophic zone and the metaphysis
what is a salter-harris type III?
fracture or separation through a portion of the hypertrophic zone and the epiphysis
what is a salter-harris type IV?
fracture or separation through a portion of the hypertrophic zone, metaphysis, and epiphysis
what is a salter-harris type V?
crushing injury of the physis
what does a salter-harris type V result in?
necrosis of resting layer of cartilage cells and therefore cessation of bone growth
what is the most common site of a salter-harris type VI (not truly salter-harris)?
distal radius
where are retained cartilaginous cores most common?
distal ulnar physis and metaphysis
what does a retained cartilaginous core cause?
slowed growth of distal ulnar physis
who are angular limb deformities in horses most common in?
young foals
what is angular limb deformity in foals?
deviation from the normal axis in the frontal plane
what are some causes of angular limb deformity in young foals?
premature birth
twins
placentitis
trauma
soft tissue laxity
crushing of non-ossified cuboidal bones
what is the metaphysis of a long bone?
wider tapered section between epiphysis and diaphysis
what does the hypertrophic zone look like?
broad, flat cells
8x increase cell volume
decrease in extracellular matrix
where does a stress riser exist?
within the hypertrophic zone
where does a fracture occur with an overload applied to the physis?
hypertrophic zone due to stress concentration at this level
what does salter-harris not take into account?
age of animal
specific bone involved or location
what is the most common site of a salter-harris type II fracture?
distal femur
what is the most common site of a salter-harris type IV fracture?
distal humerus
what is the most common site of a salter-harris type V fracture?
distal ulna
what are some causes of angular limb deformity in older foals?
nutritional imbalance
excessive exercise
trauma
growth plate injury
what is the most common site for a salter-harris type I?
femoral capital physis
what is the most common site of a salter-harris “type VI”?
distal radius
