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Metabolic bone disorders
Defnition (DISEASES ASSOCIATED WITH DECREASED BONE MASS)
Osteoporosis is a disease characterized by increased porosity of the skeleton resulting from reduced bone mass.
Localized to a bone - limb - entire skeleton
OSTEOPOROSIS
“PEAK” bone mass is early adulthood Normal decline, slow Osteoporosis is accelerated bone loss Factors:
AGE Physical activity Estrogen Nutrition (Ca++) Genetics
Categories of Generalized OsteoporosisPrimary Postmenopausal Idiopathic Senile Secondary Endocrine disorders Rheumatologic diseaseHyperparathyroidism DrugsHypo-hyperthyroidism Anticoagulants Hypogonadism Chemotherapy Pituitary tumors Corticosteroids Diabetes, type 1 Anticonvulsants Addison disease Alcohol Neoplasia MiscellaneousMultiple myeloma Osteogenesis imperfecta Carcinomatosis Immobilization Gastrointestinal Pulmonary disease Malnutrition, Malbs., Hepatic Insuf., Vit C,D Homocystinuria
Anemia
Diseases caused by OSTEOCLAST DYSFUNCTIONPaget Disease (Osteitis Deformans)
Matrix madness, Osteoblasts/-cytes gone wild C/b - Disordered bone85%
MONOSTOTIC, WHOLE BONE 15% POLY-OSTOTIC (skull, pelvis) “JIGSAW”, NOT LAMINAR, BONE
3 phrases:1) Increased osteoclast resorption2) Increased “hectic” bone formation (osteoblasts)3) Osteosclerosis
Histological features
Irregular trabecular woven bone rather than lamellar Areas of osteolysis with abnormally large
osteoclasts Serum calcium – normal Alkaline phosphatase- markedly elevated
Clinical features Most are asymptomatic - bone pain - deformities - fractures in osteolytic phase - nerve or spinal cord compression (bone
enlargement in the sclerotic stage) - deafness ( VII cranial nerve compression & distortion
of middle ear cavity) - osteosarcoma - heart failure ( bone in paget’s disease are extremely
vascular and blood flow markedly increased)
DISEASES ASSOCIATED WITH ABNORMAL MINERAL HOMEOSTASIS
Ricketts and OsteomalaciaVITAMIN D deficiency/dysfunction
Hyperparathyroidism, PRIMARY (PTH ADENOMA)
ENTIRE SKELETONOSTEITIS FIBROSIS CYSTICA (von
Recklinghausen’sdisease (of bone)“BROWN” TUMOR
Hyperparathyroidism, SECONDARY (RENAL) (NOT AS SEVERE AS 1º)
Renal Osteodystrophy = ANY bone disorder due to chronic renal disease
Primary hyperparathyroidism
OSTEITIS FIBROSA CYSTICA
“BROWN” “TUMOR’’
Renal osteodystrophy
Phoshate retention Hypophosphatemia Hypocalcemia Increased PTH Increased osteoclasts Metabolic acidosis release of
HYDROXYAPATITES from matrix
Osteomyelitis
Inflammation of bone and bone marrow Mode of spread
Hematogenous Contiguous Direct implantation
Aetiology Most common in children & adolescents- staph aureus bacteremia ( boil / skin infections
) Tuberculous & syphylitic Most common- before introduction of antibiotics Salmonella – children with sickle cell disease - diaphysis PDF – compound fractures when there is
extensive ulceration of overlying skin - Boil/skin infections
Pathogenesis Transient bacteraemia-eg: staph aureus
Foci of inflammation in the metaphysis of long bone Necrosis of bone fragments ( sequestrum )
Reactive new bone ( involucrum )
Untreated cases sinuses – drainage of pus through cloacae
Sequestrum
Inflammatory process in the Haversian canals of the cortical bone
Compression of the blood vessels
Necrosis of the bone ( sequestrum )
Metaphysis – part of shaft immediately adjacent to epiphyseal plate
- Rich capillary network & large venous channels - sluggish blood flow
Circulating micro-organisms deposit and grow here
Adults – epiphyseal plate is fused & no barrier to spread of infection from metaphysis to
joint
Children > 1 year- Epiphyseal plate blocks extension of infection
Spreads laterally into subperiosteal space or joints in which synovial reflections extend beyond
the epiphysis to metaphysis like sholder and hip joints.
Infants – small capillaries cross the epiphyseal growth plate extension of infection to epiphysis and joint.
Prognosis Age Onset of antibiotic treatment Presence of foreign material- - joint prostheses - internal fracture fixation devices bone infection associated with orthopaedic
surgery are more common than primary osteomyelitis in most of countries.
OSTEOMYELITISDX: X-ray, Bone scan
OSTEOMYELITIS Histology
POTT’s DISEASE