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Osteomyelitis:

an infection in a bone and morrow cavity that results in inflammation and impacts the bone matrix.

Osteomyelitis  Risk factors:

-          Staphylococcus aureus

-          Circulation disorders (poorly controlled diabetes, peripheral arterial disease, sickle cell anaemia)

-          Recent injury or orthopaedic injury (bone fracture, surgery, hip replacement ect)

-          Problems requiring intravenous lines or catheters (dialysis machine tubing, urinary catheters, long term intravenous tubing)

Osteomyelitis Symptoms:

-          Localised bone pain

-          Reduced movement

-          Inflammation

-          Suppurlent exudate

-          Fever/chills

-          Irritability

-          Nausea

Osteomyelitis Pathogenesis:

-          Bacterial growth

-          Acute inflammation

-          Bone necrosis

-          Abscess formation

-          Spreads

-          Surrounding tissue damage

-          Draining sinus

Osteomyelitis Complications

-          Pathological fractures

-          Septic arthritis

-          Impaired growth

-          Skin cancer

-          Chronic infections

Osteomalacia and rickets:

disorders caused by defective bone mineralisation due to severe vitamin d deficiency

Osteomalacia:

adult form

Rickets:

occurs in infants and children

Vitamin D function:

-          Maintains calcium and phosphate balanced

-          Promotes calcium absorption in intestines and kidneys

-          Promotes bone mineralisation

-          Promotes osteoblast activation

-          Promotes osteoclast development

Vitamin d deficiency pathophysiology:

Vitamin d deficiency> hypocalcaemia> increased PTH release>:

-          Kidney calcium reabsorption

-          Phosphate excretion

-          Bone resorption

-          Increased intestinal calcium absorption

Vitamin d deficiency results:

-          Persistent hypophosphatemia

-          Poor bone mineralisation

-          Excess unmineralized osteoid

Osteomalacia risk factors:

-          Low vitamin d intake

-          Limited sunlight exposure

-          Frequent pregnancies

-          Elderly/nursing home residents

-          Malabsorption disorders

Rickets pathogenesis:

-          Thickened growth plate

-          Disorganised chondrocytes

-          Accumulation of osteoid

-          Bowing deformities due to weak bones

Rickets symptoms:

 

-          Bowed legs

-          Frontal bossing

-          Pigeon chest

-          Harrison groove

-          Craniotabes (soft skull)

Osteomalacia pathogenesis:

-          Newly formed osteoid fails to mineralise

-          Weak bones prone to fractures/microfractures

Osteomalacia symptoms:

-          Bone pain

-          Muscle weakness

-          Stress fractures

-          Waddling gait

Osteoporosis

bones with holes, more bone destruction than renewal, decrease in bone density, bone loses calcium

Common fracture sites of osteoporosis:

-          Hip

-          Wrist

-          Spine

Types of osteoporosis

-          Senile osteoporosis

-          Postmenopausal osteoporosis

Bone cells:

-          Osteoblasts: form bone tissue

-          Osteocytes: maintain bone tissue

-          Osteoclasts: bone resorption/ destruction

Osteoporosis pathogenesis:

-          Imbalance between osteoblasts and osteoclasts

-          Increased osteoclast activity

-          RANK/RANKL interaction

-          M-CSF involvement

-          OPG inhibits bone resorption

-          Dysregulation> osteoporosis

Bone mass changes:

-          Peak bone mass in young adulthood

-          Done decline begins 30-40s

-          Postmenopausal women at high risk

-          Oestrogen important for bone maintenance

Osteoporosis risk factors

-          Increasing age

-          Female gender

-          Reduced physical activity

-          Low calcium intake

-          Eating disorders

-          Thyroid disease

-          Steroid use

-          Smoking and alc

Osteoporosis early symptoms:

-          Receding gums

-          Weak grip

-          Brittle fingernails

Osteoporosis late symptoms:

-          Fractures

-          Loss of height

-          Compression fractures (spine)

-          Stooped posture

-          Back and neck pain

-          Pulmonary complication

Rheumatoid arthritis:

systemic, chronic inflammatory disease that attacks joints, proliferative synovitis, destruction of cartilage and bone, more common in women, peak incidence in 20-40yrs

RA risk factors:

-          Family history

-          HLA genes (DR4,DR1, DR10,DR140)

-          Possible infectious agents (EBV, borrelia etc)

RA joints affected:

-          Symmetrical arthritis

-          Hands

-          Feet

-          Ankles

-          Knees

-          Wrists

-          Elbows

-          Shoulders

RA pathogenesis:

-          Autoimmune process

-          Activated helper t cells

-          Cytokine release

-          Activation of neutrophils/macrophages

-          Synovial hyperplasia

-          B cell activation

-          Autoantibody production

-          Osteoclast activation

-          Joint destruction

RA Histology:

-          Chronic synovitis

-          Pannus formation

-          Synovial hyperplasia

-          Inflammatory infiltrates

-          Angiogenesis

-          Osteoclast bone erosion

-          Muscle atrophy

Rheumatoid nodules:

-           present in 1/4 patients

-          Firm non tender masses

-          Central fibrinoid necrosis

-          Surrounded by inflammatory cells

Rheumatoid factors:

-          IgM against Fc portion of IgG

-          Present in 80% of patients

-          Forms immune complexes

-          Deposits in joints

-          Causes inflammation

RA joint changes:

-          Ankylosis

-          Joint stiffness

-          Limited movement

-          Swan neck deformity

-          Boutonniere deformity

-          Ulnar deviation

RA clinical manifestations

-          Weakness

-          Malaise

-          Low grade fever

-          Aching joints

-          Morning stiffness

-          Enlarged joints

-          Progressive disability

-          Chronic relapsing, remitting course

Osteoarthritis:

degenerative joint disease rather than inflammatory disorder, common part of aging, degeneration and loss of articular cartilage

Osteoarthritis joints affected:

-          Hips

-          Knees

-          Lumbar vertebrae

-          Cervical vertebrae

-          Hands

-          Feet

Osteoarthritis gender differences:

-          Women: knees and hands

-          Men: hips

Osteoarthritis risk factors:

-          Wear and tear

-          Aging

-          Genetics

-          Increased bone density

-          Gender

-          Obesity

Normal articular cartilage:

-          Friction free movement with synovial fluid

-          Spreads load across weight bearing joints

-          Allows underlying bone to absorb weight

Articular cartilage extracellular matrix:

-          Proteoglycans: provide elasticity and stiffness

-          Ground substance: highly hydrated semisolid gel

-          Collagen: provide tensile strength

-          Chondrocytes: continually degrade and replace matrix

Osteoarthritis pathogenesis:

-          Cartilage contains more water and less proteoglycan

-          Collagen diminished

-          Increased chondrocyte apoptosis

-          Chondrocytes proliferate to repair damage

-          Reparative changes eventually fail

Osteoarthritis morphological changes:

-          Enlargement and disorganization of chondrocytes

-          Cartilage surface cracks

-          Synovial fluid enters cracks

-          Vertical clefts form

-          Articular cartilage erosion

-          Sclerotic underlying bone

-          Fibrous walled cysts

-          Synovial joint inflammation

Osteoarthritis x ray changes:

-          joint space narrowing

-          subchondral bony sclerosis

-          osteophyte/ bone spur formation

Osteoarthritis symptoms:

-          Deep aching pain

-          Pain worsening by use

-          Cracking, grating sensation

-          Limited joint movement

-          Joint instability

-          Radicular pain

-          Muscle spasms

-          Muscle atrophy