structure of physis
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1) The physis, also known as the growth plate, is located between the epiphysis and metaphysis of growing bones. It is responsible for the longitudinal growth of bones. 2) The physis contains several zones, including a germinal zone, proliferative zone, hypertrophic zone, and zone of provisional calcification. Blood is supplied to the physis from epiphyseal, perichondrial, and metaphyseal arteries. 3) Physeal injuries are classified using the Salter-Harris system. Type 1 and 2 fractures can usually be treated non-operatively, while more severe types often require open reduction and internal fixation.
structure of physis
- 1. STRUCTURE OF PHYSIS PRESENTER:DR.TARUN KUMAR JUNIOR RESIDENT DEPT OF ORTHOPAEDICS RLJH TAMAKA KOLAR
- 2. SPECIFIC LEARNING OBJECTIVES • At the end of the class , participants should be able to answer: • What is physis • What are zones of physis • Vascular supply of physis • Types of physeal injuries and management
- 3. PHYSIS • Physis is also known as Growth plate • The physis is a unique cartilaginous structure that varies in thickness depending on age and location • Located between epiphysis and metaphysis of growing bones • Responsible for longitudinal growth of the bones • Appears radiolucent on X ray
- 4. The cells on epiphyseal surface of the epiphyseal cartilage plate continously proliferate until growth in length is completed. • The mature cells on the diaphyseal surface of the epiphyseal cartilage plate degenerate and are replaced by bone from the diaphysis.
- 5. • When full growth is attained, the epiphyeal cartilage turns into bone and can longer be found. This occurs between 18 to 25 years.
- 7. • The peripheral margin of the physis consist of two specialized areas :- • ZONE OF RANVIER • It is a wedge-shaped group of germinal cells that is continous with the physis. • It consists of three cell types-osteoblast , chondroblast and fibroblast.
- 8. • Osteoblasts form the bony portion of the perichondrial ring at the metaphysis. • Chondroblasts contribute to the longitudinal growth • Fibroblasts circumcsribe the zone and anchor it to perichondrium above and below the growth plate.
- 9. • PERICHONDRIAL RING OF LACROIX • It is a fibrous structure that is continous with the fibroblasts of the zone of ranvier and the periosteum of the metaphysis. • Perichondrial ring of LaCroix provides strong mechanical support for the bone-cartilage junction of the growth plate.
- 11. 1.GERMINAL ZONE (RESERVE ZONE) Chondrocytes here are spherical and seperated by more matrix compared with cells in other zones. The cells contain many lipid vacuoles and abundant endoplasmic reticulum, which is indicative of protien production.
- 12. • ZONE OF PROLIFERATION • In the proliferative zone , chondrocytes are flattened and alinged in columns parallel to the long axis of the bone. • The oxygen tension is higher than in the other zones as is the cell metabolism, resulting in high concentration of cell metabolism. • The primary function of this zone is cellular proliferation, other functions include the formation of intracellular matrix, proteoglycan and collagen.
- 13. • ZONE OF HYPERTROPHY • The chondrocyte become spherical and, at the base of the zone, are five times the size of chondrocyte in the proliferative zone. • It has been found that insulin-like growth factor stimulates the hypertrophy of the chondrocytes in this zone, thus promoting longitudinal growth. • The oxygen tension inn this part of the hypertrophic zone is low, anaerobic metabolism develops, and lactate accumulates.
- 14. • ZONE OF PROVISIONAL CALCIFICATION • Very thin layer and adjoins directly to the diaphysis. • The cells are necrotic and the calcified substance undergoes cavitation and dissolution.
- 15. • HISTOLOGY OF PHYSIS
- 16. • VASCULAR SUPPLY OF PHYSIS • EPIPHYSEAL ARTERIES supply blood to the epiphysis via multiple branches to the growth plate, providing vascularization into the proliferative zone. • PERICHONDRIAL ARTERIES supply the fibrous structures of the growth plate.
- 17. NUTRIENT ARTERY provides four-fifths of the metaphyseal blood supply. METAPHYSEAL ARTERIES supply the remainder of the blood supply. The terminal branches of these vessels end in small vascular loops or capillary tufts below the last intact row of chondrocyte lacunae of growth plate.
- 18. VASCULAR SUPPLY OF PHYSIS
- 19. PHYSEAL INJURIES It has been estimated that 30% of fractures in children involve a physis and most heal with out any long-term complication. The hypertrophic zone has the lowest resistance to shear forces and thus is the most common anatomic site of physeal injuries. Ligaments in children are functionally stronger than the physis. Therefore a higher proportion of injuries that produce sprain in adults result in physeal fractures in children.
- 20. • ETIOLOGY OF PHYSEAL INJURIES • Trauma • Infection • Tumors • Vascular injuries • Repetitive stress
- 21. • CLASSIFICATION –SALTER AND HARRIS
- 22. • Type 1 fractures occur through the physis only , with or with out displacement. • It has good prognosis • Type 2 fractures have a metaphyseal spike attached to the seperated epiphysis with or with out displacemet. • It is the most common type
- 23. • Type 3 fractures occur through the physis and epiphysis into the joint with joint incongruity when the joint is displaced. • Poor prognosis as the proliferative and reserve zones are interrupted. • Type 4 fractures occur in the metaphysis and pass through the physis and epiphysis into the joint. Joint incongruity occurs with displaced fractures.
- 24. • Poor prognosis as the proliferative and reserve zones are interrupted. • Type 5 fractures, which are usually diagnosed only in retrospect, are compression or crush fractures of the physis , producing permanent damage and growth arrest. • It has worst prognosis
- 25. • MANAGEMENT: • TYPE 1 and 2 fractures can be treated non operatively by closed reduction and immobiliztion with cast or slab • Other types: open reduction and internal fixation
- 26. REFERENCES • Turek’s textbook of orthopedics • Campbell’s operative orthopedics
- 27. THANK YOU