Which bone graft substitue disappears the most quickly in vivo?
What is the rate of decay in bone mass after skeletal maturity?
After menopause in women?
0.3-0.5% per year after skeletal maturity
a further 2-3% for untreated women during the decade after menopause
Standard vs. MIPO plating has what effect on blood flow?
Decreased periosteal AND medullary blood flow
What kind of collagen is fibrocartilage?
same as bone
So scar = type 1 collagen
What cell type accounts for 90% of the adult skeleton?
rhBMP-2 is approved for what uses?
Single level ALIF from L2-S1 in DDD with a fusion device
open tibial shaft fratures stabilized with an IM N and treated with 14 days of initial injury
What is the bending rigidity of a plate proportional to?
What is false about osteocalcin?
1. It is the most abundant noncollagenous protein of bone
2. It is secreted by osteoclasts
3. It is involved in mediating calcium homeostasis
4. It has been used as a biochemical marker of bone formation
5. It is part of the organic matrix of bone
It is secreted by osteoBLASTS
What is the increase in mortality risk after a fragility fracture of:
Vertebral fragility fracture: 15% increase
Hip fragility fracture: 20% increase
How much devascularization does reaming cause?
It devascularizes 50-80% of the cortex
Muscle duration and speed of contraction are most dependent on what?
Type II (fast twitch) contract faster, stronger and fatigue quicker
What happens with removal of the AER?
AER controls longitudinal growth
Name the rare, but deadly, complication of Paget's
What is the prognosis?
secondary transformation into osteosarcoma > chondrosarcoma > spindle cell sarcoma
5 year survival <5%
Distraction osteogenesis - bone forms by what type of ossifciation?
intramembranous (primary) ossifciation
Name 4 results of joint immobilization on articular cartilage
reduced proteoglycan content
What's the role of collagen in artiular cartilage?
Prevent swelling of articular cartilage that would otherwise occur due to the effect of aggrecan in drawing in water
What is the mechanism of botox?
Inhibition of ACh release from presynaptic vesicles
How do local anesthetics works?
Interfere with conduction (depolarization)
Rate of decrease of vertebral fragility fractures after bisphosphonate treatment at 1 & 3 years?
1 year: 60% decrease
3 years: 40% decrease
Also decreased non-vertebral fraglity fractures 40%
Area of growth plate pathology in rickets
zone of provisional calcification
This is why there is a widening of physis on xray, bc the physis doesn't ossify!
3 radiographic findings in osteopetrosis
Rugger jersey spine
Erlenmeyer flask distal femur
Thickened cortex/lack of a IM canal
Phases of ligament healing
- neutrophils & macrophage mediated with growth factors involved
What happens to water content of cartilage with normal aging? in OA?
Decreases with normal aging
Increases with OA
What supplies the inner and outer parts of bone? (blood vessels)
Nutrient artery system supplies inner 2/3
is a high pressure system
Periosteal system supplies outer 1/3
is a low pressure system
50 year old DM patient comes in with sudden onset of unilateral leg weakness, absent reflexes on that side and weight loss of about 15 - 20 lbs. No history of radiculopathy or back issues. Diagnosis? 1 differential
Diabetic lumbosacral plexopathy (basically diabetic neuropathy)
Acute, stepwise onset of unilateral weakness
Associated with poor diabetic control, absent reflexes and weight loss (up to 40 lbs)
When does enchondral ossification occur in fracture healing (what stage)?
Why don't you want your anesthesiologist to use nitrous oxide as an inducin agent for spine or pelvic surgery?
Causes abdominal distension and makes fluoroscopy difficult to interpret
Descirbe direct insertion of ligament or tendon onto bone:
= fibrocartilagenous insertion
via 4 transition zones:
Zone 1: tendon or ligament
Zone 2: fibrocartilage
Zone 3: mieralized fibrocartilage
Zone 4: bone
Effect of tapping prior to screw insertion on pullout strength
The femur radiograph of a healthy 25-year-old female is compared to the femur radiograph of a healthy 85-year-old female:
What best describes the 25-year-old's femur in terms of cortical thickness and medullary canal volume?
Increased cortical thickness
Decreased medullary canal volume
As you age, you get thinner cortices and therefore larger canal volumes