MSK Patho (Schoenwald) Flashcards
What are two types of metabolic bone disease?
Osteoporosis
Rickets
What is the cause of disease in osteoporosis?
Reduced mass of mineralized bone due to imbalance of bone metabolism resulting in Increased bone resorption
What is the cause of disease in Rickets?
Calcium metabolism (related to a vitamin D issue)
Is osteomyelitis infectious?
Yes
Is osteoarthritis infectious?
No
What is Paget disease?
Excessive osteoblastic bone formation with abnormal structure and instability
Osteoclasts are responsible for bone…
Bone resorption
Osteoblasts are responsible for bone…
Bone formation
What does microscopic pathology of osteoporosis show?
Symmetric thinning of trabecular and cortical bone (this results in increased risk of fracture of bone)
In primary osteoporosis, risk increases with…
Age
What is Type I osteoporosis?
Postmenopausal- due to estrogen loss (more typical form)
Causes an increase in osteoclastic activity
What is Type II osteoporosis?
Senile- decreased osteoblastic activity
What are the most common bones fractured in osteoporosis?
Hip
Compression fracture of vertebrae
Distal radius (FOOSH)
What are the risk factors for developing osteoporosis?
Aging and positive family history Smoking Alcoholism Decreased estrogen Low body mass index, low calcium diet, lack of weight bearing exercise
What is an endocrine-related secondary cause of osteoporosis?
Increased PTH, DM, Addison’s disease
What is a GI secondary cause of osteoporosis?
Malnutrition
What is a hematologic-related secondary cause of osteoporosis?
Blood cancers
What is a drug-related secondary cause of osteoporosis?
Long-term presnisone usage, heparin, some chemo agents
Which gender has a higher incidence of developing osteoporosis?
Females
What do patients with osteoporosis often present with?
Vertebral compression fractures, kyphotic
What is the textbook patient stereotype of someone with osteoporosis?
Thin, white female with a long term history of smoking, postmenopausal
What kind of test measures bone density?
DEXA scan
What 2 parameters does a DEXA scan report?
T score, Z score
What is a T score?
Reported by a DEXA scan
Bone density measurement compared to a healthy 30 year old’s bone mass (peak)
What is the normal values for a T score?
+1 to -1
What is a Z score?
The number of standard deviations above or below what is normally expected for same age, sex, weight, and ethnic or racial origin
What is an abnormal Z score?
-2 or lower
What does a T score of +1 to -1 indicate?
Healthy bone density
What does a T- score of -1 to -2.5 indicate?
Osteopenia
What does a T-score of -2.5 to -3.0 indicate?
Osteoporosis
What does a T score of -3.0 and lower indicate?
Severe osteoporosis
What is the difference between Rickets and Osteomalacia?
Same disease preocess but Rickets technically describes children and osteomalacia technically describes adults
What is the disease process in Rickets/osteomalacia?
Mineralization of osteoid is decreased while bone mass stays normal- results in bowing of legs
Vitamin D deficiency/ phosphate deficiency
What is Rickets?
Affects the growing bones of children
It is the inadequate mineralization of osteoid matrix leading to the overgrowth and distortion of epiphyseal cartilage
What does osteomalacia affect?
Newly formed bone matrix in adults
What is osteomyelitis?
Infection of the bone
How is osteomyelitis spread?
Hematogenous spread, contiguous spread
How is osteomyelitis more commonly spread in children?
Hematogenous
What is the most common causative agent in the hematogenous spread of osteomyelitis?
Staph aureus
How is osteomyelitis more commonly spread in adults?
More common to have contiguous spread in adults
Ex- diabetic foot wound, staph is common but can be polymicrobial
True or False osteomyelitis can be either chronic or acute
True- osteomyelitis can be chronic or acute
What are the clinical findings in osteomyelitis?
Pain, warmth of area affected
Fever can be present but is often absent
What labs are you going to see in osteomyelitis?
Elevated ESR, CRP
Elevated platelet count
What radiographic findings are you going to see in osteomyelitis?
Destruction of bone
Periosteal edema
How is the diagnosis of osteomyelitis made?
Blood cultures
Biopsy of bone
(Superficial cultures are not reliable)
What is the treatment for osteomyelitis?
Long term IV antibiotics targeted to organism +/- surgical debridement
How does osteomyeltitis result in ischemia of bone?
Infection lifts periosteum of bone, which impairs blood flow, resulting in ischemia
What is a sequestrum?
A dead bone fragment (in osteomyelitis)
What is an involucrum?
New bone growth around the sequestrum (in osteomyelitis)
What is a Brodie’s abscess?
Residual abscess surrounded by bone growth
Generally speaking, what is arthritis?
Inflammation of the joint
What can be done to help differentiate between infectious and inflammatory arthritis?
Synovial fluid anaylsis
What is the synovial fluid analysis going to indicate in a normal joint?
Clear appearance <200 WBCs <25 PMNs 95-100% serum glucose No crystals
What is a synovial fluid analysis going to indicate in a joint with non-nflammatory arthritis?
Appearance- clear <400 WBCs <25 % PMNs 95-100% serum glucose level No crystals
What is the synovial fluid analysis going to indicate in a joint with an acute gout attack?
Appearance- turbid 2000-5000 WBCs >75% PMNs 80-100% serum glucose level Negative birefringence needle-like crystals