Bone/Joint and Muscle Pathology Flashcards
Characteristics of bone
how much calcium is stored in them? they are the primary site of ____? influenced by what hormones?
- store 99% of the body’s calcium
- in adults, they are the primary site of hematopoiesis
- constantly remodeling under the influence of parathyroid hormone, vitamin D, and calcitonin
Description of medullary bone, cortical bone, periosteum, and woven bone.
- medullary bone: resists compression forces
- cortical bone: thick and resists bending forces
- periosteum: tough fibrous membrane that covers bone surfaces except at the joints; well-innervated and painful if injured
- woven bone: immature
osteogenesis imperfecta
- disease of abnormal bone matrix
- deficient or defective type 1 collagen –> too little bone
- generalized osteopenia (multiple fractures and bone deformities)
- malformed teeth (dentin deficiency)
achondroplastic dwarfism
- reduced function of epiphyseal growth plates (mostly affects long bones)
- has normal intelligence and normal life span
osteopetrosis
- defective osteoclasts
- bone is brittle and too dense
- can cause cranial nerve palsies
osteomalacia
- softening of the bone due to Vitamin D deficiency or kidney failure
- delayed eruption of teeth
- defects in dentin and enamel
- adult form of Ricketts
Albers-Schonberg disease
- impaired osteoclasts
- reduces bone resorption
- associated with anemia, bone fractures, blindness, deafness
osteitis deformans
- mixed stages of osteolysis and osteogenesis
acquired bone diseases
Scurvy (Vit. C deficiency)
Ricketts (osteomalacia in adults)
- Vit. D deficiency
- due to GI malabsorption syndrome or lack of sunlight
exposure
- lack of normal mineralization (usually kidney related)
Osteoporosis
- common in elderly women after menopause
Hyperparathyroidism
- constantly releasing Ca2+
- adenoma in parathyroid can be a cause
Causes of osteoporosis
- genetic: age, low estrogen, fair hair and skin, tall and thin
- behavior: inactivity, smoking/alcohol, malnutrition, medication (chronic corticosteroids)
incidence/burden of osteoporosis in the US
- 10 million people in the US, mostly women
- 1/3 women over 50 yrs have at least one osteoporotic hip fracture
- most hip fractures in women over 70 yrs (increases the likelihood of death in the next year…mechanism not understood)
disorders of bone instability
- kyphosis - abnormal forward curvature of spine
- scoliosis - abnormal lateral curvature of spine
types of fractrues
- complete
- closed (overlying tissue intact)
- compound (bone pieces in the skin)
- comminuted (bone splintered or crushed)
- displaced (fractured bone not aligned)
- pathological (associated with cancers)
osteomyelitis (and causes)
- inflammation of the bone/marrow
CAUSES: - blood-born or direct inoculation
- trauma from compound fractures
- pyogenic infections (staph aureus, salmonella)
- granulomatous (TB or fungal; “Pott Disease” when associated with TB and in the spine)
- diabetes (poor circulation in the extremities; if chronic, can form a drainage site and can even become osteosarcoma)
characteristics of oasteoarthritis
- degenerative joint disease
- loss of articular cartilage with secondary changes in bone
- presents to some degree is most persons older than 65 yrs; symptoms worsen with excessive use
- wear and tear (most common type of joint pain)
- no inflammatory changes
- boney swellings called “Heberden nodes”
characteristics of rheumatoid arthritis
- more systemic and bilateral
- joint swelling, pain, and tenderness
- extreme distortions of joints and surrounding bone (deforming and debilitating)
- may have systemic symptoms of fever, weakness, and malaise
- other areas also affected: ulcers, pulmonary nodules and fibrosis, carditis and pericarditis, vasculitis
- most have circulating anti-cyclic citullinated peptides (anti-CCP)…used a a lab test
incidence of rheumatoid arthritis
- autoimmune (1% prevalence; most common form of autoimmune disease)
- most common in caucasians; uncommon in asians
- onset age: 25-50 yrs
- 75% female
- can have juvenile RA
Other types of inflammatory arthritis
- psoriatic arthritis
- other autoimmune diseases (lupus, scleroderma)
- post-infectious (rheumatic fever)
- infectious (staph/strep, TB)
- gout (crystallized uric acid)
- lyme disease (tick-based spirochete; if not treated can lead to arthritis and neuro consequences)
Gout (characteristics and causes)
- primary cause: reduced renal excretion or purine
- primary treatment: allopurinol - decreases synthesis of purines
- symptoms: hot, swollen, pain in joints; progressive joint destruction –> gouty tophi (crystallized aggregates of uric acid)
- pseudo-gout: crystal deposits of calcium pyrophosphate
- treat with: colchicine, allopurinol, or indomethacin
ganglion cysts
- a cyst resulting from connective tissue around joints; often painful
Marfan syndrome
- hereditary connective tissue disease caused by a mutant fibrillin gene
- symptoms: spider-like fingers, tall growth, necrosis of the aorta
Malignant carcinomas spread to the bone most likely from to come from…
lungs, prostate, breast, thyroid, and kidneys
Tumors most likely seen in maxilla or mandible
- osteomas (immature bone)
- giant cell tumor (benign, but aggressive; mandible)
- fibrous dysplasia (not malignant, benign, medullary bone does not properly mature, often in jaws)
- osteosarcoma (adolescents or older patients)
- ewing sarcoma (10-20 yrs old, 2nd most frequent sarcoma after osteosarcoma)
incidence of osteosarcomas in US
8,000/yr
osteosarcoma
- malignant
- most frequent bone malignancy
- adolescents or geriatric patients most likely
- usually in long bones or sometimes mandible
osteochondrosarcoma
- malignancy of cartilage
incidence of soft tissue tumors in the US
12,000/yr
types of soft tissue tumors
- lipomas (very common, don’t usually require treatment
- liposarcoma (malignant)
- fibrous tumors (usually reactive)
- fibrosarcoma (malignant neoplasm of fibroblasts)
- rhabdomyosarcoma (skeletal muscle tumor, frequently in head and neck region; rare)
- leiomyoma (smooth muscle tumor, benign)
- leiomyosarcoma (malignant smooth muscle tumor, deep soft tissue)
muscular dystophy
- most common = Duchenne Muscular Dystonia
- symptoms: progressive weakness of voluntary muscles and breakdown of muscle tissue; can occur anytime/anywhere; represents a group of genetic diseases
congenital myopathies
- present with congenital hypotonia and weakness
rhabdomyolysis
- diffuse destruction of skeletal muscle
- acute: muscles are tender and swollen
- may develop with flu episode
- can be caused by some drugs such as “statins”
denervation diseases
- ALS or polio
- typically result in muscle degeneration
Myasthenia gravis
- inflammatory myopathy
- symptoms: weakness in skeletal muscles responsible for breathing and mobility; worsens with activity and improves with rest; often includes other skeletal muscles such as for eyelids, facial movement, chewing, swallowing, and talking
- cause: auto-antibodies kill ACh receptors (thymus may contribute to formation); not inherited
treatment of myasthenia gravis
- acetylcholinesterase inhibitors (pyridostigmine)
- immunosuppressants (prednisone, rituximab)
- prognosis usually good with proper treatment
