Bone Disorders

Abnormalities of spinal curvature

Kyphosis: excessive outward curvature of the spine, causing hunching of the back

Lordosis: excessive inward curvature of the spine

Scoliosis: abnormal lateral curvature of the spine, congenital or developed from poor posture

Fractures

Fractures of bones are classified according to the pattern of the break and heal in a predictable manner.

Treatment: alignment of the bones back together, immobilisation with plaster/pins, stress relief
  1. Closed (simple) fracture: skin is not punctured by bone
  2. Open (compound) fracture: ends of broken bone tear through skin
  3. Compression fractures: collapse of a vertebrae (most commonly due to osteoporosis, primary tumours or infection)
Result: thrombotic or fat embolisms released into ruptured blood vessel → infarction and necrosis, infection (osteomyelitis), impaired fracture healing due to malunion

Diagnosis: X-ray, CT and MRI (for spinal fractures when testing spinal cord injury)

Symptoms: pain, tenderness and localised numbness, swelling and deformity, impaired sensation and function of associated tissues (if nerve damage occurs)

Risks: elderly person, lack of weight bearing exercise, malnutrition, primary or secondary bone diseases, drug use

How are fractures healed?

  1. Fresh fracture: formation of hepatoma (blood outside blood vessel)
  2. Inflammatory phase (days 2-7): inflammation, neovascularisation, early fibrosis → fibrotic plaque, initial appearance of woven bone (to bridge gap between fractured bones)
  3. Fibrotic callus (weeks 2-6): further inflammation and granulation tissue fade, cartilage appears, overproduction of woven bone → bulbous
  4. Reparative phase, bony callus (few months): overproduced woven bone is reduced by osteoclasts
  5. Remodelling phase (later months): dense lamellar compact bone appears, joins new bone to old
  6. Years later: bone is held

What about pathological fractures?

Occur after no or minimal trauma

Cause: underlying bone abnormality, e.g. osteoporosis, osteomalacia, Paget's disease, primary or metastatic tumours, local infection, bone cysts or congenital bone disorders, e.g. dwarfism

Osteoporosis

A decreased bone mass due to increased porosity of the skeleton.

Characteristics: imbalance in remodelling of bone (osteoclast activity > osteoblast activity), decreased no. of trabecules (also thinner)

Risk: familial history, lack of physical activity, poor nutrition, ageing, menopause

Site of osteoporosis: hip, spine, pelvis, upper arms, wrist and ribs

Symptoms: asymptomatic until fracture occurs → pain, deformity and disability

Site of osteoporosis-causing fractures: neck of femur, distal radius (colles fracture), vertebral fracture → kyphosis (dowager hump)

Diagnosis: dual energy x-ray absorptiometry (DXA) - measures bone mineral density using low radiation exposures, produces two x-ray beams (one high and one low intensity) to measure the amount passed through the bone → varies as bone thickness varies. The difference in absorption between two beams determines bone density.

Osteomalacia (Rickets in children)

Impaired mineralisation of osteoid, causing accumulation of under-mineralised matrix and thus softer bones.

Cause: vitamin D deficiency, calcium and phosphate deficiencies and drugs

Result: deformities and fractures

Symptoms: muscle weakness, achy bone pain

Osteomyelitis

Inflammation of bone and marrow as a result of infection (exogenous or endogenous).

Cause: pyogenic bacteria (staph. aureus most common) or mycobacterium tuberculosis

Site: in children → legs and upper arm bones, in adults → vertebrae, diabetics → feet (if foot ulcers)

Treatment: surgery or strong antibiotics (delivered intravenously) for 6 weeks

Bone Neoplasms

Metastatic cancers in bone are much more common than primary tumours, which would always be benign and affect persons under 30.

Age: elderly

Symptoms: extreme pain, functional impairment, pathological fracture

Diagnosis: X-ray and biopsy

The types of bone neoplasm are outlined below:

Osteoma

A bony tumour found on the bone surface, particularly at the head and neck of bones.

Age: middle-aged persons

Characteristics: slow growing, benign, solitary (existing alone)

Osteosarcomas (Primary Malignant Tumours)

Most common malignant primary bone neoplasm.

Age: under 20 (3rd most common childhood cancer)

Site: 60% around the knee

Origin: osteoblast or osteocyte origin

Result: hematogenous spread to lung

Prognosis: 2/3 chance of survival

Treatment: surgery and chemotherapy

Metastatic Bone Disease

Metastatic bone disease is most common derived from the prostate, breast, kidney and lung.

Site of metastasis: axial skeleton (head, trunk and vertebrae), proximal femur and humerus

Characteristics: multiple small lesions

Symptoms: pain that worsens at night

Result: pathological fracture, spinal cord compression, bone marrow failure

Paget's Disease of Bone (Osteitis Deformans)

The excessive bone remodelling (of one or more bones) with a net gain in bone mass.

Cause: unknown, genetic predisposition

Age group: over 50

Gender: more common in men

Result: deformities and fracture, fragile and misshapen bones, hearing loss, pinched spinal nerves

Site: pelvis, skull, spine and legs

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