June 20, 2024

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:

Growth Plate or physis anatomy
Zone of physis

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

  1. Central Arrest
  2. Peripheral Arrest
  3. Linear Arrest
The pattern of Growth 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

  1. Young
  2. Small bridge (< 30%)
  3. Trauma Origin
  4. Recent arrest
  5. Central and Linear bridge

See also: Slipped Capital Femoral Epiphysis

See also: Skeletal Dysplasia (Classifications)

See also: Growth modulation

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