Inflammatory Bone Diseases PDF

INFLAMMATORY BONE DISEASES Dr: Ahmed Roshdi; PhD/MD Professor of Pathology, Sohag University In this lecture:  Introduction  Pathology of osteomyelitis  Pott`s disease of vertebra  Healing of bone fracture Introduction (Trabecular) (Cortex)...

INFLAMMATORY BONE DISEASES Dr: Ahmed Roshdi; PhD/MD Professor of Pathology, Sohag University In this lecture:  Introduction  Pathology of osteomyelitis  Pott`s disease of vertebra  Healing of bone fracture Introduction (Trabecular) (Cortex) Introduction  Introduction Osteoid (prteins and minirals) Osteoclast Cells in normal bone  Introduction Diseases of bone Inflammatory Osteo- (Osteomyelitis) dystrophies Tumors OSTEOMYELITIS  Osteomyelitis (OM) Definition: OM is inflammation of bone and bone marrow Types: Acute  Acute pyogenic OM  Chronic non-specific: chronic suppurative OM Chronic  Chronic specific: tuberculosis of bone  Osteomyelitis (OM) Acute pyogenic OM Definition: Acute suppurative inflammation of bone and bone marrow Causative organism: Commonest is Staphylococcus aureus. Other organisms include streptococci, Escherichia coli, Pseudomonas Types  Acute hematgenous OM: blood born infection  Acute non hematgenous pyogenic OM: infection reaches bone by direct spread Pathological features of acute hematgenous OM Incidence: commonly affect children Rout of infection: Organism reaches bone by hematgenous rout Site: Affect metaphysis of lone bone - Metaphysis is a common site of minor trauma - Blood vessels show stasis at this site  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute hematgenous OM Pathogenesis: - Starts as a suppurative focus at metaphysis - Commonly affect femur and tibia. - Infection spreads to:  Medullary canal (so involve bone marrow)  Periosteum (so forms sub-periosteal abscess)  Joint space (less frequent) - Ischemia of bone due to:  Inflammatory thrombosis of blood vessels.  Compression of blood vessels by inflammatory exudate and subperiosteal abscess  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute hematgenous OM Pathogenesis: - Necrotic bone (due to ischemia) appears fragmented, thin and irregular (called sequestrum). - Periosteum is stimulated to deposit new bone trabeculae (called involucrum). - Spaces between involucrum allows pus is discharged through sinus tracts. (called cloaca) - Microscopically: fragmented bone trabeculae (sequestrum) with inflammatory exudate and infiltration by neutrophils, pus cells and macrophages.  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute hematgenous OM Pathogenesis:  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute hematgenous OM Pathogenesis:  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute hematgenous OM Microscopic picture:  Osteomyelitis (OM) Acute pyogenic OM Pathological features of acute NON hematgenous OM  Osteomyelitis (OM) Acute pyogenic OM Complications of pyogenic OM 1. Toxemia and septicemia. 2. Septic thrombophlebitis leading to systemic pyemia. 3. Direct spread of infection to joints leading to septic arthritis 4. Chronicity leading to chronic suppurative osteomyelitis. 5. Pathological fracture. 6. Alteration of growth rate due to affection of epiphyseal plate. 7. Secondary amyloidosis in chronic cases. 8. Malignancy (squamous cell carcinoma) may arise in sinus tract that becomes lined by squamous epithelium.  Osteomyelitis (OM) Chronic specific OM (TB of bone) - Definition: A chronic specific inflammation of bone (secondary TB) - Causative organism: Mycobacterium tuberculosis bacilli (human or bovine types) - Rout of infection:  Hematgenous: main rout. Infection comes by blood spread from TB of lung, intestine  Direct extension from adjacent infection of the joint or soft tissue - Site: Vertebrae are the main sites (called Pott`s disease) followed by and ends of long bones.  Osteomyelitis (OM) Chronic specific OM (TB of bone) - Pathological features:  Tuberculous infection first reaches Haversian canals and bone marrow spaces  The inflammation expands with formation of caseation necrosis.  The bone undergoes destruction and become replaced by caseous material.  Formation of multiple sinuses discharging caseating material through soft tissues and skin.  Involvement of joint spaces and intervertebral disc is common.  Periosteal new bone formation is minimal or absent.  Microscopically: granulomatous inflammation (epithelioid cells, lymphocytes, Langhan’s giant cells with caseation necrosis).  Osteomyelitis (OM) Pott`s disease of bone Definition: it is secondary tuberculous infection affecting vertebra Rout of infection: haematogenous spread from TB of the lung, intestine or elsewhere Sites:  Commonly affects lower thoracic and upper lumbar vertebrae.  The vertebral bodies and inter-vertebral discs are destroyed while transverse processes and spines are spared.  Intervertebral disc is avascular; so it is destroyed in Pott's disease but spared in cases of metastatic tumors (can be identified radiologically).  Osteomyelitis (OM) Pott`s disease of bone Pathological features: three main features of Pott's disease 1. Deformity: due to destruction of vertebral bone with subsequent collapse of vertebral bodies. Deformities include Kyphosis and Scoliosis.  Osteomyelitis (OM) Pott`s disease of bone Pathological features: three main features of Pott's disease 2. Cold abscess: caseous material collects under prevertebral fascia anteriorly and spread in various directions according to site of the lesion; – In Pott`s of cervical vertebra: cold abscess appears at retropharyngeal position or at posterior border of sternomastoid muscle. – In Pott`s of thoracic vertebra: cold abscess appears in posterior mediastinum. – In Pott`s of lumbar vertebra: cold abscess appear in lumbodorsal triangle or pass along the psoas sheath down to inguinal region. 3. Paraplegia: occurs due to compression on spinal cord (by inflammatory edema or cold abscess) or due to collapse of vertebra Healing of bone fracture  Healing of bone fracture Definition: A regenerative process to restore damaged bone to its integrity. Steps of healing of bone fracture (Pathogenesis) 1- Hematoma and inflammation: due to tear 2- Soft callus and provisional callus: of blood vessels at fracture site followed by Granulation tissue formation (soft acute inflammatory with scanty inflammatory callus) followed by deposition of exudate. Products of inflammation are then collagen and fibrocartilage (provisional removed by macrophages and osteoclasts. callus or woven bone)  Healing of bone fracture Healing of bone fracture is a regenerative process to restore damaged bone to its integrity. Steps of healing of bone fracture (Pathogenesis) 3- Lamellar bone formation: woven bone is 4- Remodeling of bone: Excess bone gradually removed by osteoclasts and cortex (external callus) or within medullary replaced by osteoid matrix and collagen canal (internal callus are removed by bundles that acquire lamellar arrangement osteoclasts followed by regeneration of bone and osteoid become calcified. marrow  Healing of bone fracture Causes of delayed or improper healing of bone 1. Faulty immobilization leads to fibrous union. 2. Infection at the site of fracture. 3. Impaired blood supply. 4. Interposition of soft tissues between the bony ends. 5. Nutritional disturbances of the body and old age. Link to this lecture: Good luck