bone 1: non neoplastic

NON NEOPLASTIC CONDITIONS OF

THE BONE

NON NEOPLASTIC CONDITIONS OF

THE BONE

Dr. V. P. Sumathi

The Royal Orthopaedic Hospital

Woodlands, Birmingham

Vaiyapuri.sumathi@roh.nhs.uk

Dr. V. P. Sumathi

The Royal Orthopaedic Hospital

Woodlands, Birmingham

Vaiyapuri.sumathi@roh.nhs.uk

NORMAL BONE

FUNCTION

MECHANICAL

CHEMICAL

HAEMATOLOGICAL

TYPES OF

BONE

Trabecular

Compact

COMPOSITION OF BONE

Inorganic elements (65%) � Calcium hydroxyapotite

Organic matrix (35%) � Cells and Proteins. Type 1 collagen

Osteocalcin

BONE FORMING CELLS

OSTEOPROGENATOR CELLS

OSTEOBLASTS

OSTEOCLASTS

OSTEOCYTES

BASIC MULTICELLULAR UNIT

BMP

FGF

PDGF

TGF

CORTICAL BONE TRABECULAR BONE

LAMELLAR BONE WOVEN BONE

REGULATION OF OSTEOCLAST FORMATION

ABNORMALITIES IN BONE

DEVELOPMENTAL

(Genetic)ACQUIRED

• DEFECTS IN NUCLEAR PROTEIN

-Transcription factor (homeobox gene)–

dyostoses

localised abnormality

Craniorachischisis-failure of closure of spinal canal

and skull

• Defects in hormones and signal-dysplasia

-Transduction mechanism – Achondroplasia

ACHONDROPLASIA

� FGF3 inhibits cartilage proliferation in normal

� Mutation of FGFR3 gene on chromosome 4

� Substitution of arginine for glycine

� Symptoms such as bowlegs, large head, and limited

elbow extension

� Abnormal body proportions, short arms and legs,

normal torso size, reduced height, upper arms/thighs

more shortened than forearms/lower legs

� Homozygous infants have shorter life expectancy than

heterozygous infants

OSTEOGENESIS IMPERFECTA (OI)

BRITTLE BONE DISEASE

• Genetic disorder of type I collagen

• Four types Type I-IV

• Most are autosomal dominant mutation of

genes7&17

• 25% have spontaneous mutation

OSTEOGENESIS IMPERFECTA (OI)

• Affects all connective tissue

• Decreased osteoblasts

• Sparse cancellous bone

• Osteoporosis - prone for fracture

OI

Type I

60-80% of cases

Normal stature

Hyper-extendibility

Hearing loss

Average life expectency

OI

• Subtype B –dentinogenesis imperfecta

• abnormal dentin collagen –

• Affects primary and permanent teeth

• translucent discoloured teeth

• Enamel fracture

• Short roots

• Periapical lucencies

OI

Type II

Fatal perinatal or intrauterine

Abnormal extremities and skull

Blue black sclera

Defects in Metabolic Pathways

� Osteopetrosis (Marble bone disease/Albers-Schonberg disease)

Carbonic anhydrase II deficiency, enzyme required for

acidification and excretion of hydrogen ions.

Reduced osteoclast bone resorption

Characterised by systemic sclerosis

Diseases associated with decreased bone mass

OSTEOPOROSIS

PRIMARY

� Post menopausal

� Senile

�disuse

SECONDARY

� Hyperparathyroidism

� Hypothyroidism

� Multiple Myeloma

� Drugs

� Corticosteroids

� Anticoagulants

� Chemotherapy

PATHOGENESIS OF OSTEOPEROSIS

1. Reduced osteoblastic activity-low turnover

2. Reduced physical activity

3. Genetic factors-polymorphism of vit D receptor

4. Nutritional status

5. Hormonal influence

DISEASES CAUSED BY OSTEOCLAST

DYSFUNCTION

1. PAGET’S DISEASE

2. Pathogenesis – Paramyxovirus infection (IL6, M-CSF

Osteoclast activation)

Complications of Paget’s Disease

• Sarcoma (osteosarcoma, chondrosarcoma,

fibrosarcoma)

• Metastatic carcinoma

• Hematologic malignancies

• Giant-cell tumor

Diseases associated with abnormal mineral

homeostasis

� Vitamin D deficiency

Osteomalacia – poor calcification causing a delay

or failure of bone matrix mineralization usually

caused by Vitamin D deficiency or a disturbance in

its metabolism

Rickets – osteomalacia happening before the

epiphyses have fused

RICKETSTender /swollen joints, classically wrists

Deformed bones

Bone pain or tenderness

Fits or irritability

Breathing difficulties

Occurs during rapid growth

Bow legs or knock knees

Delayed walking or waddling gait

Rickety rosary

Tetany or convulsions

Apnoea or stridor

Impaired growth or delayed fontanelle closure

Delayed eruption of teeth or enamel hypoplasia

HYPERPARATHYROIDISM

PRIMARY: (increased parathormone production)

� ADENOMA (MEN 1,2)

� HYPERPLASIA

�Parathyroid carcinoma

SECONDARY: (compensatory overactivity of parathyroid glands)

� Chronic renal failure

OSTEOMYELITIS

• Infectious process of the bone(s)

• Classification based on Route of Entry

– Contiguous spread of adjoining soft tissue infection

– Direct inoculation secondary to trauma or surgery

– Hematogenous bacterial emboli lodging in the bone

• Children - primarily in the long bones (femur, tibia,

fibula, humerus)

• Adults (50-60s) - primarily vertebrae

• Neonates - have multiple bone infectious sites

Pain - predominant factor

– Fever

– Increased WBC (< 15,000)

– Edema, erythema, and

tenderness at the site of infection in 50%

of cases