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Bone growth and abnormalities - Coggle Diagram
Bone growth and abnormalities
Early (fetal) bone development
Embryonic mesenchymal cells condense & form anlage (cartilage model of future bone)
Cells become chondroblasts & secrete matrix
Nutrient artery penetrates perichondrium
Osteogenic cells secrete
osteoid to form bone collar
Perichondrium becomes periosteum
Cartilage dies replaced by osteoblasts - primary ossification center (diaphysis)
Medullary cavity forms
Epiphyseal (2°) ossification centers form
Hyaline (articular) cartilage over epiphysis
(Epi)physeal growth plate forms
Bone Growth - Lengthening
Occurs at physeal plate
4 cartilage zones in plate:
Resting
Inactive cells
Anchored to epiphysis
Proliferation
rapidly dividing chondrocytes
Increases length
multiplying cells push resting zone toward epiphysis
Hypertrophy
Cells mature and enlarge
Increases length as lacunae expand
Calcification
Thin – old, dying cells
Matrix is calcified
Osteoclasts resorb calcium
Osteoblasts invade and deposit osteoid
summary
Proliferation
increase cell numbers
epiphysis is pushed away from diaphysis
Hypertrophy
cells enlarge
diaphysis lengthens
Large amounts of new osteoid replaces dying cells
solidifies resultant elongated bone
Continues until cells stop proliferating
physeal plate closes leaving a scar
Diaphyseal enlargement (bone widening)
Periosteum contains resting osteoblasts
Bone widening at periosteum and outer circumferential lamellae
Resting cells are activated and produce osteoid
New bone develops around periosteal vessels
vessel becomes encased in a tunnel of bone lined with resting
osteoblasts
More osteoblasts secrete more matrix & form lamellae & new osteon
Expands toward outer surface & widens bone
Cortical diameter increases as bone deposition occurs on the periosteal surface
Osteoclasts resorb bone on endosteal surfaces
Medullary cavity increases in diameter to maintain cortical thickness and mechanical properties
Angular limb deformities
Most common in sites with 2 parallel bones
Unequal bone lengthening causes angular deformity of limb
When do you treat??
cause functional problems
deformity greater than animal’s ability to compensate
shortening, rotational/angular deformities
abnormal stress and strain on joints
results degenerative joint disease
Surgical Correction
Depends on
Age/remaining growth potential
Severity of deformation
Site of deformation
Goals
Re-establish elbow congruency
Correct radial malalignment
Correct length discrepancies
Injuries to the physis
angular limb deformity
disparate growth rates between paired bones
distal ulna physis especially vulnerable
responsible for almost all antebrachial bone growth
Premature Closure of the Distal Ulnar Physis
most common ~85%
no known trauma
physis - conically shaped
compressive force
kills chondroblasts
premature physeal closure
two-bone system results in deformity
ulna bowstring
changes radial growth
cranial bowing
carpus valgus
depends on age/severity lameness
pain with elbow manipulation
valgus deformation
external rotation
Radiographic Signs
damaged anconeal process
flattened trochlear notch
fragmented coronoid process
cranial bowing
open radial physis
carpus valgus
damaged ulnar physis
gap between ulnar styloid and carpal
Ulnar Ostectomy
Distal Ulnar Ostectomy
young dog, mild incongruity
Correct while radius still growing
Removes bowstring effect
allows radial remodeling
Fat graft slows healing
Dynamic Proximal Ulnar Osteotomy (DPUO)
older dogs, more severe sublet
Marked elbow subluxation w/elbow pain
Short oblique cut
avoid joint and IO ligament
Pull of the triceps
+/- IM pin for alignment
Radial osteotomy
Radial deformities
Procurvatum
External rotation
Carpus valgus
Corrective osteotomy
Transverse
Oblique
Cuneiform
Opening wedge
Closing wedge
Reinserted wedge
Dome
Pes varus
rare
seen in Daschunds
Varus deformity of distal tibia
Caudal bowing of distal tibia
Slight internal rotation of distal tibia and pes
Medial cortex of tibias horter than lateral cortex
Surgery
Preplan
Measure angular deformation
Calculate size of wedge to correct
medial approach to tibia
Corrective osteotomy
Stabilize
external skeletal fixator
bone plate