HEREDITARY AND METABOLIC DISEASE OF BONE OSTEOMYELITIS

Hereditary and metabolic bone diseases are conditions that affect bone development and strength due to genetic defects or metabolic imbalances. Common hereditary disorders include Osteogenesis Imperfecta, characterized by brittle bones due to collagen defects, and Achondroplasia, leading to short stature from abnormal cartilage growth. Metabolic disorders like Rickets and Osteomalacia result from vitamin D deficiency, affecting bone mineralization, while Osteoporosis involves decreased bone mass and increased fracture risk. Paget’s disease causes abnormal bone remodeling, leading to enlarged, deformed bones. Osteomyelitis is a serious bone infection, often caused by Staphylococcus aureus, presenting with pain, swelling, fever, and may lead to chronic bone damage if untreated. Early diagnosis and a multidisciplinary approach, including physiotherapy, are essential for managing these conditions.

1. HEREDITARY AND METABOLIC DISEASE OF BONE OSTEOMYELITIS Sneha Thakur MPT (Orthopedics)

2. NORMAL STRUCTURE OF BONE The skeleton consists of cartilage and bone . Cartilage has a role in growth and repair of bone, and in the adults forms the articular skeleton responsible for movement of joints. Bone is a specialized form of connective tissue which performs the function of providing mechanical support and is also a mineral reservoir for calcium homeostasis. There are 206 bones in the human body, and depending upon their size and shape may be long, flat, tubular etc.

3. Cortical or compact bone Trabecular or cancellous bone

4. 1. Osteoblasts Osteoblasts are uninucleate cells found abundantly along the new bone-forming surfaces. They synthesize bone matrix. The serum levels of bone-related alkaline phosphatase (other being hepatic alkaline phosphatase) is a marker for osteoblastic activity. Its levels are raised at puberty during period of active bone growth and in pathologic conditions associated with high osteoblastic activity such as in fracture repair and Paget's disease of the bone.

5. 2. Osteocytes Osteocytes are those osteoblasts which get incorporated into the bone matrix during its synthesis. Osteocytes are found within small spaces called lacunae lying in the bone matrix. The distribution of the osteocytic lacunae is a reliable parameter for distinguishing between woven and lamellar bone.

6. 3. Osteoclasts Osteoclasts are large multinucleate cells of mononuclear-macrophage origin and are responsible for bone resorption. The osteoclastic activity is determined by bone- related serum acid phosphatase levels (other being prostatic acid phosphatase). Osteoclasts are found along the endosteal surface of the cortical (compact) bone and the trabeculae of trabecular (cancellous) bone.

7. HEREDITARY AND METABOLIC DISEASE- Hereditary metabolic bone diseases are characterized by genetic abnormalities in skeletal homeostasis and encompass one of the most diverse groups among rare diseases. Hereditary metabolic bone diseases comprise one of the most diverse groups among rare diseases. These disorders are characterized by genetic abnormalities in skeletal homeostasis with or without abnormal circulating calcium, phosphate, vitamin D metabolites and other markers.

8. INFECTIONS OF BONE—OSTEOMYELITIS The term "osteomyelitis" was coined in 1844 by Nelaton . Infection of the bone may involve any of its anatomical part, for e.g. Periosteum → Periostitis Cortex → Osteitis Medullary cavity → Osteomyelitis However, in practice the infection involves more than one part. So, the term osteomyelitis is used regardless of which part is affected. Thus, osteomyelitis is defined as inflammation of bone.

9. PATHOPHYSIOLOGY Microorganisms enter bone (Phagocytosis) Phagocyte contains the infection Release enzymes Lyse bone

10. Pyogenic osteomyelitis (Aetiology) Adults Staphylococcus aureus, 80-90% Escherichia coli Pseudomonas Klebsiella Mixed bacterial infection source: - Genitourinary tract I.V. drug abusers source: - Surgery. Open fracture Neonates Haemophilus influenzae Group B streptococci Salmonella infection —in patients with sickle disease

11. Pathogenesis

12. Morphology During surgical intervention the dead bone (sequestrum) is taken out so that the living bone (involucrum) can grow and repair the damage. Gross appearance The sequestrum grossly appears like a fragment of bone with ragged and blackish or brownish coloured margins. The surface is covered by pus.

13. COMPLICATIONS 1. Sinus formation 2. Suppurative arthritis -due to direct spread of infection to the joints. In infants and children below first year of age epiphyseal plate is vascularised so infection rapidly spreads to joints. However, in adults the cartilage plate resists bacterial invasion. Only when the infection is severe it spreads to adjacent soft tissue and from there to the joint.

14. 3 . Growth disturbances- due to damage of growth cartilage 4. Spread of infection: To soft tissue To the heart valve 5. Damage to articular cartilage causing ankylosis of joints. 6. Squamous cell carcinoma in recurrent sinus

15. 7. Sarcoma 8. Brodies abscess Sometimes osteomyelitis does not follow a spreading and destructive course. The initial infection is localised to a small area which becomes walled off to create a localised abscess. X-ray appears as an area of complete bone loss, surrounded by a zone of increased bone density. This is known as brodies abscess. Aetiology: It occurs due to: Inadequate therapy by drugs Infection by low grade pathogens

16. 9. Sclerosing osteomyelitis of Garre. It is a type of osteomyelitis which shows extensive new bone formation which obscures the underlying bone structure.

17. Clinical Picture Fever with chills Local, throbbing pain Soft tissue shows - redness, swelling and tenderness X-ray shows a focus of lytic bone surrounded by a zone of sclerosis.

18. Granulomatous osteomyelitis

19. Tuberculous osteomyelitis

20. Syphilitic osteomyelitis Syphilitic involvement of bone occur in: Secondary syphilis Tertiary syphilis Congenital syphilis Microscopic appearance Severe plasmacytic inflammation. Inflammatory cell infiltrate consists of plasma cells, lymphocytes and histiocytes. Granulation tissue formation Dead bone. Spicules of dead bone surrounded by inflammatory granulation tissue.

21. CLINICAL PICTURE Nose: Destruction of vomer gives rise to collapse of nasal bridge called saddle nose deformity. Lower leg: Periostitis of tibia causes excessive new bone formation on the anterior surface, giving rise to anterior bowing of leg - saber shin

22. REFERENCES Harsh Mohan. Textbook of Pathology, 8th Ed. 2010 AK Mandal & Sharmana Choudhary. Textbook of Pathology, 2nd Ed. 2021. Robbins & Kumar. Basic of Pathology, 11 th Ed. 2023.