Bone disorders. Types of Bone Lamellar Forms the adult skeleton \\ Arrangement of collagen fibers...
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Transcript of Bone disorders. Types of Bone Lamellar Forms the adult skeleton \\ Arrangement of collagen fibers...
Bone disorders
Types of BoneLamellar
Forms the adult skeleton
\\ Arrangement of collagen fibers
Few osteocytes
Uniform osteocytes in lacunae // to long axis of collagen fibers
Woven
Irregular
Many osteocytes of various size and shape
In adults signifies always a pathologic condition
Cells
Osteoblasts: bone forming cells
Produce the protein
Osteoid
Osteocyte: bone maintaining cells
Osteoblast within bone in a lacuna
Osteoclast: bone eating cells
Multinucleated
Resorbs bone
Howship’s lacunae
Types of bone disorders
• Metabolic Conditions: Osteoporosis, Osteomalacia and rickets
• Hereditary and Congenital Disorders
• Inflammatory
• Neoplasms
Metabolic Conditions
1- Osteoporosis : The Silent Thief
- Osteoporosis is a metabolic bone disease characterized by
low bone mass and micro-architectural defect of the bone
tissue, with a consequent increase in bone fragility and
susceptibility to fracture
- Are of two types: primary and secondary
Amount of bone resorbed >>> Amount of bone formed by osteoclasts by osteoblasts
BONE LOSS
Primary OsteoporosisMost commonUncertain etiologyPostmenopausal womenElderly persons (senile)
Genetic: peak bone massEstrogens: decreasedAging Calcium intakeEnvironmental factors: smoking leads to estrogen
Secondary Osteoporosis
Corticosteroids
Inhibition of osteoblastic activity
Impair of vit. D dependant intestinal calcium absorption
Hematologic malignancies
Malabsorption: GI and liver diseases
Alcoholism
Inhibition of osteoblasts,
↓ absorption of calcium
Steroid-induced Osteoporosis
Majority of bone loss occurs in the beginning (10-20%)25% may experience a fracture4 fold increase in all fracturesUsually affects vertebrae, ribs, hipRisk higher in patients with higher dose, taking longer duration
Cause
Calcium Urinary Calcium Osteoblast absorption excretion formation and
function
2- Osteomalacia and rickets
Inadequate mineralization of newly formed bone matrix (osteomalacia)
Rickets: children, epiphyseal plates open; also problem with cartilage
Beaded appearance of costo-chondral junctions
Dental abnormalities
Vitamin D deficiency
Phosphate deficiency
Defects in mineralization process
3- Hyperparathyroidism
Parathyroid adenoma, hyperplasia, rare malignancy
Promotes excretion of phosphate in the urine and stimulates
osteoclastic activity resulting in hypercalcemia
Hereditary and Congenital Diseases
1- Osteogenesis imperfecta
Many types
Mutations of collagen type I gene
Multiple fractures (starting in utero)
Dental findings: Dentinogenesis imperfecta
2- Achondroplasia
80% new mutations
Most common form of inherited dwarfism
Absence or decreased area of proliferative
cartilage
Epiphyseal disorder (plate closes
prematurely preventing bone growth)
Head and torso are normal
Vertebral column and hip abnormality
Inflammatory and Non-Inflammatory
(Non-neoplastic) Disorders
1- OsteonecrosisAvascular, aseptic
Ischemic death of bone and marrow in absence of infection
Emboli: bone infarction
Trauma Corticosteroids
Radiation Alcoholism
Systemic diseases: sickle cell anemia, gout, metabolic diseases
Osteochondritis dissecans: dead piece of cartilage
Site specific: head of femur
2- Myositis Ossificans
Formation of reactive bone in muscle as a result of injury
More common in lower limbs
Diagnosis: radiographically and histologically
3- Osteomyelitis
Inflammation of bone caused by an infectious organism
Staphylococcus, streptococcus, neisseria gonorrhea,…..
Direct penetration
Wounds, fractures, surgery
Hematogenous
Bloodstream, teeth; metaphyses
Knee, ankle, hip
Complications of Osteomyelitis
Septicemia
Acute bacterial arthritis
Pathologic fractures
Squamous cell carcinoma
Chronic osteomyelitis
4- Osteoarthritis
Most common joint disease
Slow progressive degeneration of articular cartilage
Weight bearing joints
Fingers
Primary: defect in cartilage, not an inflammatory disease
Secondary: trauma, crystal deposits, infection
Interphalangeal joints, knees, hips, cervical and lumbar spine
Clinical picture
Narrowing of joint space (loss of disk)
Increased thickness of subchondral bone
Subchondral bone cysts
5- Rheumatoid arthritis
Systemic chronic inflammatory disease
Autoimmune disease
STARTS AS SYNOVIAL DISEASE
More common in women 3:1
Remissions and exacerbations
6- GoutIncrease in serum uric acid and deposition of urate crystals in the
joints and kidneys
Only 15% of patients with ↑ uric acid suffer from gout
Gout can result from:
Overproduction of purines
Augmented catabolism of nucleic acids
Decreased uric acid secretion
Primary gout
Secondary gout
Primary gout
Hyperuricemia in the absence of other disease
Asymptomatic hyperuricemia can precede gout
Impaired secretion by kidneys
Secondary gout
Tumors
Leukemias
Lymphomas
After chemotherapy
Alcoholism
Accelerated ATP catabolism
Clinical featuresAcute gouty arthritis
Painful
Involves one joint initially, then polyarticular
Podagra (painful, red metatarsophalangeal joint)
Tophaceous gout
Development of tophi
Chalky, cheesy, yellow-white, pasty deposits of
monosodium urate crystals
Bone Tumors
Bone Forming
Benign: Osteoma Osteoid Osteoma Osteoblastoma
Malignant: Primary and secondary osteosarcoma
Cartilagenous
Benign: Chodroma Osteochodroma
Malignant: Chodrosarcoma
Other
Giant cell tumor of bone Ewing sarcoma
Metastatic Tumors of the Jaws
• Most common form of cancer involving bone
• Breast and prostate carcinomas are most common
• Variety of symptoms: pain, swelling, loose teeth, …….
• Site from which tooth was removed for local pain or mobility
• Prognosis is poor; most patients die within a year