Bones and Joints - Final Exam Flashcards
How many bones to adult humans have?
206
How much body weight do the bones attribute?
12%
How much bone is replaced annually?
10%
Periosteum
Outer layer of fibrous tissue surrounding bone
Cortical bone
Hard layer of bone surrounding inner cancellous bone
Cancellous bone
Spongy bone
Medullary layer
Primarily in long bone
Inside cancellous bone
Reticular or lace formation
Supports bone marrow
Bone marrow
Makes blood cells
Cells of the bone (3)
- Osteoclast
- Osteoblast
- Osteocyte
Osteoid
Calcified type I collagen
Osteoclast
Used to remodel bone
Resorb osteoid
Osteoblast
Make osteoid and control mineralization of bone
Osteocyte
Osteoblasts that have surrounded themselves with bone
Involved in mineralization and sense mechanical forces
Epiphys
End of long bones, associated with cartilage cap and joint
Metaphysis
Contains growth plate
Changes radically during growth
Diaphysis
Central portion of bone
Two mechanisms of bone formation
Endochondral ossification
Intramembranous ossification
Endochondral ossification
Long bones
Cartilage makes bone bigger first, then turned into bone
Intramembranous ossification
Flat bones
Fibrous tissue is taken up and calcified
Functions of bones
Support muscles, facilitate movement
Protect organs
Site of bone marrow
Storage of calcium and phosphate
Vitamin D functions (3)
- Increased Ca absorption by intestine
- Resorption of Ca by kidneys
- Bone mineralization (calcification of osteoid)
Cause of Vitamin D deficiency (3)
- Lack of exposure to sunlight
- Inadequate intake
- Abnormal intestinal absorption
Vit D deficiency
Osteopenia (osteomalacia)
Osteopenia
Decreased mineralization of bone
Bones are soft, pliable
Increased fractures
Rickets in children
Osteoporosis
Reduction of bone mass Often multifactorial Cortical and medullary bone is lost Fracture risk increases (can be caused by body weight alone, vertebrae, hips and distal radius) Primary or secondary
Primary osteoporosis
Idiopathic
Older age, menopause, diet/lifestyle, low initial bone mass
Secondary osteoporosis (5)
Due to identifiable cause
- Hormone inbalances (menopausal women)
- Dietary insufficiency
- Drugs (steroids)
- Tumours (hormone production or direct bone destruction)
- Immobilization
Fractures
Disruption of bone structure
Usually due to trauma
Complete or incomplete
Simple, comminuted, open/compound, complicated, pathogenic
Complete fracture
Through entire thickness of bone
Incomplete fracture
Through partial thickness of bone
Simple fracture
One fracture
Comminuted fracture
Multiple fractures
Closed fracture
Skin intact
Open/compound fracture
Skin disrupted
Complicated fracture
Infected
Pathologic fracture
Due to abnormal bone (osteoporosis, tumour)
Fracture healing (4)
- Blood fills gap left by fracture and clots (hematoma)
- Inflammatory cell, fibroblasts, and new capillaries use clot framework and ingrow (granulation tissue)
- Soft tissue becomes woven bone (bony callus)
- Matures and subjected to physical/weight bearing stress - remodelling to become like regular bone, but only 70% of former strength
Osteomyelitis
Infection of bone
Usually bacterial (occasionally fungal, rarely viral)
Tries to wall off infection by making more bone, with necrotic tissue in center, can have sinus formation
Difficult to treat (surgery, amputation)
Causes of osteomyelitis (3)
- Direct inoculation/trauma (stabbed into bone)
- From adjacent joint (septic joint)
- Haematogenously (by blood)
Bone tumors
Rare
Benign (osteoma) or malignant (osteosarcoma)
Mainly in children or young adults
Each bone tumour has preferred site
Osteosarcoma
Most common primary bone malignancy
Occurs in children/adolescents
Common in metaphysis of long bones
Tumour of osteoblasts, making disorganized osteoid
Typically metastatic at presentation (lungs)
Treated with chemotherapy and surgery
60-70% live 5 years post-treatment
Joint
Connection between 2 or more bones
Allows movement, support and structure
Two types
Two types of joints
- Synarthroses - little to no movement
2. Synovial - allow movement
Synovial joints
Bones covered in cartilage
Non-boney surfaces covered with synovial cells that produce fluid
Surrounded by capsule made of connective tissue/tendons
May have meniscus (fibrous tissue that absorbs shock)
Osteoarthritis
Degenerative joint disease Affects weight bearing joints (knee) Increased incidence with age and weight Due to wear and tear Cartilage damage Many symptoms
Cartilage damage of osteoarthritis (5)
- Exposed bone
- Boney sclerosis (looks like ivory, called eburnation)
- Cysts form in bone (fibrosis in bone marrow spaces)
- New nodules of bone form, project into joint space and adjacent soft tissue
- Inflammation and welling
Eburnation
Boney sclerosis
Makes bone look like ivory
Osteophytes
New nodules of bone
Project into joint spaces and adjacent soft tissue
Symptoms of osteoarthritis (6)
- Pain
- Crepitus
- Swelling, inflammation
- Deformation
- Loss of mobility
- Stiffness ***improves with rest
Crepitus
Cartilage degeneration
Rheumatoid arthritis
Systemic autoimmume disease affecting synovial joints
May affect any age group
Synovium becomes markedly inflamed
Inflammatory cells and fluid expand joint pace (pannus formation)
Inflammation stimulates growth of vessels and proliferation of synovium, produce factors that induce injury to cartilage and bone
Bone fusion (ankyloses) can appear
Characteristic features of rheumatoid arthritis (3)
- Chronic, symmetric inflammation of joints
- Serologic evidence of autoimmune disorder
- Extra-articular manifestations (splenomegaly, skin nodules)
Symptoms of rheumatoid arthritis (5)
- Pain
- Joint deformity
- Limited mobility (scarred into place)
- Contractures
- Stiffness (improves with movement)
Pannus formation
Inflammatory cells and fluid expanding joint space
Ankyloses
Bone fusion
Gout
Disease due to hyperuricemia
Deposition of uric acid crystals in various body sites (big toe)
Primary or secondary
Uric acid crystals are insoluble in tissue
Lower temperatures encourage crystallization, which induce inflammation
Acute or chronic
Primary gout
Metabolic (increased uric acid production)
Renal (decreased uric acid excretion)
Secondary gout
Malignancy, chronic kidney disease
Acute gout
Pain, swelling, problems with mobility/walking, systemic symptoms
Last days
Chronic gout
Bone deformities Gouty tophi (tumour like masses)