chap 21 - disorders of the bones and joints Flashcards
skeletal system function
reservoir of minerals (calcium and phosphorus), protection, production of blood cells, movement, shape, rigid support
structure of skeletal system
bone is connective tissue, all bones have the same basic structure - cortex, trabeculae, and bone marrow
cortex
outlayer of compact bone
trabeculae
inner spongy layer of the bone
bone marrow
spaces between trabeculae consist of fat and blood-forming tissue
bone
dynamic living tissue, undergoing remodeling
- strength and thickness depend on activity
bone cells
osteoclasts, osteoclasts, osteocytes
bone growth
ossification
types: endochondral and intramembranous
endochondral ossification
lay down cartilage, laying down of bone, ossification at epiphyseal plate
intramembranous ossification
no cartilage phase occurs, typically occurs in flat bones
bone density
- amount of mineral per cm/bone
- indicator of fracture risk
factors influencing bone mineral density
diet(calcium, vitamin D, K+, magnesium,protein) , physical activity, hormones (calcitonin, parathyroid hormone, estrogen), age, sex
signs and symptoms
pain, decreased mobility, deformity
symptoms associated with arthritis
joint stiffness and decreased mobility
tests
diagnostic modalities
- radiography to visualize fractures and bony abnormalities
osteoblasts
secrete the matrix that will help build the bones
b = build
osteoclasts
ruffled membrane, causes bone resorption which is breaking down bone
osteocytes
cell of the bone, embedded in the matrix of the bone
osteoprogenitor
can become any bone cell
erythrocyte sedimentation rate
How long does it take for red blood cells to settle in a sample - shows systemic inflammation, increase in systemic inflammation causes the cells to be stickier and settle first, increase of erythrocyte settlement rate (could show arthritis because inflammation is one of the main manifestations of arthritis)
achondroplasia
- Plasia = division, chon = cartilage, chondrocytes, a=no → without chondrocyte dividing, important for bone formation, no laying down of cartilage, no laying down of bone
Leading cause of dwarfism
Causes mutation in fibroblast growth factor 3 (FGFR3) - Autosomal dominant
- Majority de novo mutations, de novo = new
- Most common risk is age of the father
Result in Faulty bone formation
Impaired growth of extremities and formation of skull bones
- Most common risk is age of the father
- Can lead to stenosis on the spinal cord due to malformation of foramen magnum in occipital bone
Causes dwarfism with disproportionately short limbs
osteogenesis imperfecta
“Brittle Bone” Disease = Thin and delicate bones easily broken
“Imperfect bone formation”
Mutation in genes resulting in abnormal collagen formation
- Collagen is of normal quality but is produced in insufficient quantities
- Collagen is part of the cartilage that is laid down prior to the bone
Autosomal Dominant
Increase susceptibility to bone fractures
May be in utero
Eight Types
- I-VIII
- Different types of collagen
Malformation of fingers and toes
Spinal curvature
Brittle teeth
Blue Sclera - thin because it is a connective tissue disorder and the sclera is connective tissue, so the veins are showing through
congenital clubfoot (talipes)
The most common congenital disorder of the legs
Not painful
Multifactorial inheritance - environment and genetic susceptibility
Treatment: manipulation and casts
fractures
Any disruption in continuity of bone
Most often caused by
Trauma
Pathologic fracture
Underlying disease of bone
Pain resulting from tearing of periosteum (covering of the bone)
- types: simple, comminuted, compound, pathologic, and greenstick
in order for a fracture to heal
- broken fragments must be close to each other, also must be stabilized
healing process: involves proliferation of
- osteoblasts from fracture margins - lay down new matrix which will be mineralized to make new bone, vascular channels from periosteum
- immature bone and cartilage gradually remodel into mature bone
osteomyelitis
Bacterial infection of bone and marrow
Organisms gain access to bone via
- Spread of infection from somewhere else
- Following trauma or surgery to bone itself
Manifestation
- Fever, local pain and tenderness
Diagnosis and treatment
- X-ray reveals changes in bone
- Antibiotics, possible surgery
Complications may include:
- Spread of infection
- Endocarditis, sepsis
Amputation
osteoporosis
Multifactorial disease characterized by absolute reduction of total bone mass
- Porous bones
- Bone histology is usually normal but lacks structural integrity
Age related: One third of population >85 have it
Women > men; especially after menopause
- Men have a slower decline
signs and symptoms of osteoporosis
Disease itself has no symptoms
Increased risk of fractures
- Mortality
- Loss of independent living
- Decreased Mobility
causes of osteoporosis
Primary
- Intrinsic to bone itself
- Age - age related bone loss (approx. 0.7%/yr) is a normal biological phenomenon
- Declining estrogen
Secondary
- Cortisol excess
- Cortisol breaks things down - stress hormone, so people who are under prolonged stress or take cortisol drugs
- Increase PTH
-Bone resorption
risk factors for osteoporosis
Age
Ethnicity - caucasian and asian women are more at risk
Genetics
- Allele for the vitamin D receptor molecule
Skeletal frame size
- Smaller frame - less bones - increased risk
Decreased levels of estrogen and testosterone
Decreased activity level
Excess intake of phosphorous, alcohol, nicotine
Inadequate levels of vitamins D, calcium, K+, or Mg++
clinical manifestations of osteoporosis
Vertebral fractures - vertebrae break down over time
Lumbar lordosis and kyphoscoliosis - excess curvature
Pulmonary embolism may result from overt fractures of the femoral neck, pelvis or spine
- Break the bone = bone marrow in the middle gets into the bloodstream and can travel and get lodged in pulmonary vein
diagnosis of osteoporosis
Plain radiographs cannot detect osteoporosis until 30-40% of bone mass is loss; thus specialized radiographic imaging techniques needed
- Not a very sensitive test
Dual energy x-ray absorptiometry (DEXA)
- More sensitive, much better at looking at small changes in loss of density
Can be used for screening in populations that are at risk
treatment of osteoporosis
irreversible
-Medication
Inhibition of osteoclasts(biphosphonate, boniva, fosamax), estrogen mimetic - don’t want to put women on hormone replacement therapy (evista), synthetic PTH (forteo)
osteopenia
BMD is lower than normal
- precursor to osteoporosis
osteomalacia and rickets
softening of bone
- poor mineralization
causes
- vitamin D deficiency
rickets in children and osteomalacia in adults
complications
- deformity - increased fracture risk
scoliosis
abnormal lateral and rotational curvature of spine
kyphosis
abnormal forward bending of upper spine
- produces hunched back
potential causes of scoliosis and kyphosis
arthritis, congenital, osteoporosis, idiopathic
complications of scoliosis and kyphosis
impairment of activity, breathing problems, back pain
neoplasms of bone
most common = metastatic tumors from prostate, breasts, other organs
- hematopoietic (40%) - myeloma, leukemia
bone tumor groups (excluding hematopoietic)
- bone - cartilage -fibrous - miscellaneous
tumors of bone
- benign cysts and tumors: osteoma
- primary malignant: osteosarcoma
osteoma
histology resembles normal bone
- generally slow-growing tumors of little clinical significance when they cause obstruction or produce cosmetic problems
- asymptomatic, often in facial bones
they do not undergo malignant change
osteosarcoma
the most common malignant tumor of bone in children
- 70% in patients younger than 20 years
symptoms
- bone pain, progressive enlarging mass, pathologic fractures
- more common in males, ends of long bones, metastasis is common
symptoms, signs, and tests of the joints
joint stiffness and decreased mobility, pain and inflammation
tests: arthroscopy to visualize joint space
osteoarthritis
degenerative joint disease, most common
- “wear and tear” = disease of old age
- affects weight-bearing big joints, small joints of hands and feet
classification
- primary: cause unknown or multifactorial
- secondary: related to another disease
etiology of osteoarthritis
cartilage becomes thin, bone surfaces rub against each other - produce bone cysts and osteophytes
- little inflammation until advanced stage
risk factors of osteoarthritis
increased age, joint trauma, long-term mechanical stress, endocrine disorders, drugs, obesity
rheumatoid arthritis
systemic autoimmune disease affecting connective tissues throughout the body, especially the joints
- produces chronic inflammation and thickening of synovial membrane
- often associated with rheumatoid factor
- autoantibody in blood and synovial tissues, produced by B lymphocytes directed against individuals own gamma globulin
- not age associated
- usually affects small joints of hands and feet
clinical course of rheumatoid arthritis
extremely variable
- begins with malaise, fatigue and generalized musculoskeletal pain and then joint pain
- small points are usually affected first
- involved joints are swollen, warm, painful and stiff on arising or following inactivity
arthritis: gout
disorders of purine metabolism
- disrupts the body’s control of uric acid production or excretion
- precipitation
gout manifests high levels of uric acid in the blood and other body fluids
- hyperuricemia
can also lead to uric acid kidney stones
crystals deposit in CT throughout the body
- 50% of the initial attacks occur in the metatarsophalangeal joint of the great toe
- heel, ankle, instep, knee, wrist or elbow
when these crystals occur in the synovial fluid, the inflammation is known as gouty arthritis
contributing factors of arthritis
age, male sex, obesity, high intake of alcohol, red meat, genetic predisposition
