Growth Plate or the physis has been divided into four zones:
- Germinal (Reserve)
- Proliferative
- Hypertrophic
- Provisional Calcification
The actively growing cartilage disc is called physis, situated between epiphysis and metaphysics
Most commonly injured physeal injury is Phalanges (37%)
4 Zones:
The Zone of Resting Cartilage(Germinal)
Adjacent to epiphysis
Collagen content is higher
Collagen fibre orientation= Horizontal, So strain observed is lower
Chrondocytes are of moderate size and scattered throughout the intercellular substance of cartilage
In some sites, cartilage is separated from the zone of epiphysis by space containing nutrient vessels
The Zone of Young proliferating Chondrocytes
Location of cellular proliferation
Collagen fibre orientation is Verticle, So strain observed is Higher
Made of thin wedge-shaped cells stacked in the column whose longitudinal axis is parallel to the main bone
Add progressively to the overall length of bone
The Zone of Maturing Chondrocytes
WEAKEST ZONE: The previous hypothesis, but when evaluated post-clinical trauma, in acute biopsy- fracture line can be anywhere
Extracellular matrix proliferation, cellular hypertrophy, apoptosis, extracellular calcification
Vascular invasion of lacunae
Collagen fibres orientation is Verticle, So, strain observed is higher
Still arranged in a column
larger, and gradually mature
Contains glycogen and alkaline phosphate
The Zone of Calcified Cartilage
Very thin
Cells are necrotic and calcified
Undergoes cavitation and dissolution
Capillary loops and accompanying osteogenic cells invade the tunnels formed by the disintegration of cell column-> Osteoblast line the remnants of calcified cartilages (diaphyseal sides)
Pathology of Growth Plate Injuries
Formation of dense cortical bone in physeal injury site. So, bone seems sclerotic
Pattern of arrest
- Central Arrest
- Peripheral Arrest
- Linear Arrest
Central Arrest
- Peripheral physis continues to growth
- Volcano effect
- Shortening
Peripheral Arrest
- Severe form
- Gives angular deformity
Linear Arrest
- Angular deformity + Shortening
- Type IV: Salter-Harris
Gold Standard for diagnosis is MRI
Factors contribute to the success
- Size: 30 %
- Age: Younger the better ( > 2 years of growth left)
- Duration of surgery: > 2 years since injury (poor)
- Etiology:
- Trauma (Good)
- Infection (Poor)
- Radiation (Poor)
Ideal candidates for resection
- Young
- Small bridge (< 30%)
- Trauma Origin
- Recent arrest
- Central and Linear bridge
See also: Slipped Capital Femoral Epiphysis
See also: Skeletal Dysplasia (Classifications)
See also: Growth modulation
