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