Basic Science Flashcards
Fibular hemimelia?
Not an isolated entity. Can be associated w femur shortening
Where is the primary ossification centre?
Linea aspera of femur @ 1 year, but it’s present in all long bones
Syndactyly?
Failure of differentiation
Growth plate zones?
Resting, proliferative, hypertrophic, primary spongiosa, secondary spongiosa
Distal femur and proximal tibia growth cm per year?
0.9cm femur, 0.6cm tibia
What hormone regulates the process of growth plate closure?
Estrogen
Growth hormone - insulin growth factor
Most important for linear bone growth
Effects of juvenile hypothyroidism?
Delayed ossification, short stature, scfe
Vitamin d indirect and direct?
Indirect - absorption of calcium in intestine
Direct - on growth plate chondrocytes
Rickets is caused by?
Lack of calcium, vitamin d and phosphate
Heuter volkmann law?
Increased pressure on a physis stimulates growth
Skeletal dysplasia - 4 d’s
Dwarfism, dysmorphic features, deformities, disproportionate features
What zone of growth plate does achondroplasia affect?
Proliferative
Marfan’s syndrome?
A type of skeletal dysplasia, rule out cardiac and ocular complications, cartilage disorder characterised by hyper laxity
Diastrophic dysplasia? What thumb deformity?
Hitchhikers thumb. Different then the large space between 2nd and 3rd fingers you see in achondroplasia
Most common cause of teratologic DDH?
Arthrogryposis
How does varus/values deformity progress in children?
Genu varum until 1.5 then neutral. Progress to maximum valgus by age 3-4 then reach adult valgus at age 7.
If not either skeletal dysplasia or bone metabolic disease
Why is 8yo a critical age in ddh?
There is no capacity for hip to remodel beyond this age, so not the right answer to simply reduce a dislocated hip
Pathoanatomy in ddh - 6 things?
Inverted limbus, ligamentum teres, Iliopsoas, pulvinar, transverse acetabular ligament,
What “packaging problems” are associated w ddh?
Torticollis, metatarsus adductus
Three causes of ddh?
- Ligamentous laxity - females - Estrogen
- Mechanical causes - first born, oligohydramnious, cultural etc.
- Primary acetabular dysplasia
Why do we take a Pavlik harness off if it’s not working?
AVN Risk factors include No ossific nucleus High dislocation Extreme abduction in cast Acetabular inlet constriction
How do bisphosphonates work? Which type are more effective?
Inhibit osteoclast resorption of bone. Nitrogen containing 1000x
How do nitrogen containing bisphosphonates work?
Inhibit protein prenylation - block farnesyl pyrophosphate synthase leading to decrease GTPase
Osteoconductive matrix?
Scaffold or framework for bone growth
Osteoinductive factors?
Growth factors such as bmp that stimulate bone formation
Osteogenic cells?
Primitive mesenchymal cells, osteoblasts, osteoclasts
Hyperaemia in inflammatory arthritis activates?
Osteoclasts, periarticular osteopenia.
the inflammatory cells are called pannus
Gouty arthropathy? Fluid stains?
Needle like crystals, brightly birefringent
Pseudogout?
Episodic inflammation of joints. CPPD deposits. Positively birefringement
Uniform joint space narrowing is predictive of what type of arthritis?
Inflammatory arthritis
Erosion and joint space narrowing?
Spondyloarthropathy
If you have a sausage digit? What type of arthritis?
Spondyloarthropathy - reactive vs psoriatic
Cause is flexor tenosynovitis and entheslopathy
If a patient has polymyositis what do you need to rule out?
Malignancy
Osteoarthritis what type of joint space narrowing?
Asymmetrical jsn. (inflammatory is symmetrical)
Whats the difference between oncogene and tumour suppressor gene?
Both lead to cancer - oncogene cell function turned on. Tsg gene function turned off
Name 5 causes of an Erlenmeyer flask deformity as seen on xray.
Mnemonic CHONG
C- Craniometaphyseal Dysplasia (Pyle Disease)
H- Hemoglobinopathies (Thalassemia/Sickle Cell)
O- Osteopetrosis
N- Niemann Pick Disease
G- Gaucher’s Disease
Which disease is characterized by a hereditary deficiency of glucocerebrosidase?
Gaucher’s disease. Lysosomal storage disorder resulting in fatty deposits in many organs, especially bone marrow.
Name 7 molecules that stimulate bone resorption
RANKL PTH (activates adenylyl cyclase) IL-1 1-25 Dihydroxyvitamin D3 Prostaglandin E2 IL-6 (myeloma) MIP-1A (myeloma)
Name 5 molecules that inhibit bone resorption
Osteoprotegrin (binds RANKL) Calcitonin (direct binding of receptor on osteoclast) Estrogen TGF beta IL-10
PTH increases serum calcium and decreases serum phosphate. List three effects of PTH on the osteoblast. What does PTH do in the kidney? Where is PTH made?
Effects of PTH on Osteoblast:
- Increases synthesis of IL-1 and IL-6
- Increases synthesis of RANKL
- Increases M-CSF (macrophage colony stimulating factor; this promotes more osteoclasts)
PTH effect on kidney:
Causes 25-hydroxyvitamin D3 to be activated to 1,25dihydroxyvitamin D3 (this in turn increases absorption of calcium and excretion of phosphate)
PTH is made in the chief cells of the parathyroid gland.
Calcitonin: Where is it made? How does it influence bone resorption?
Made in C-cells of the thyroid gland.
It directly binds receptors on the osteoclast and decreases bone resorption by decreasing the number of osteoclasts and decreasing osteoclast activity.
List RFs for osteoporosis (10)
older age female gender early menopause fam hx of hip fracture low body weight smoking/etoh fair skinned low protein intake use of anticonvulsants/antidepressants use of glucocorticoids
Indirect ligament insertion (ie. MCL) occurs via Sharpey’s fibers. Describe zones of direct ligament insertion.
Bonus: give an example of a tendon which inserts via direct insertion.
Zone 1. Ligament.
Zone 2. Fibrocartilage
Zone 3. Mineralized fibrocartilage
Zone 4. Bone
Bonus: Supraspinatus
Effect of age on hyaline cartilage
Larger cells Fewer cells Less water Higher ratio of keratin sulfate to chondroitin sulfate Higher protein content Smaller proteoglycan size Stiffer (increased modulus of elasticity) Less elasticity
Effect of osteoarthritis on hyaline cartilage
Increased water Increased chondroitin sulfate Decreased PG content Decreased keratin sulfate Decreased collagen content Less stiff (Decreased modulus of elasticity)
Function of Type A and Type B synovial cells
A: phagocytosis
B: produce synovial fluid
List factors contributing to stability of an Ex Fix construct.
Bone ends in contact Larger pins (rigidity proportional to radius to 4th power) More pins Pins spaced further Bicortical pins Pins in different planes Rods closer to bone Thicker rods Multiple rods (ie. stacked rods) Rods in different planes
List 4 indications for use of a locked plate
Osteoporotic bone
Bridging comminuted fracture
Short articular segment with comminuted metaphysis
When anatomic constraints do not permit plating tension side.
List layers of physis
Reserve Proliferative Maturation (hypertrophic zone) Degeneration (hypertrophic zone) Provisional Calcification (hypertrophic zone) Spongiosa
List 9 indications and 2 contratindications for bisphosphonate use
Osteogenesis Imperfecta Polyostotic fibrous dysplasia Paget's disease Early AVN Osteoporosis Metastatic disease Multiple myeloma Malignant hypercalcemia CRPS
**DON’T use if severe renal disease or postop lumbar fusion
Outline the Lankford and Evans stages of CRPS
Differentiate between type I and II CRPS
Stage 1 (0-3mos from onset) Red, swollen, warm, sweaty, painful. Decreased ROM. Xray often normal.
Stage 2 (3-12 mos) Worse pain. Dry skin, maybe cyanosis. Stiffness. Osteopenia on xray.
Stage 3 (>12 mos) Pain diminished. Contractures and shiny skin. Extreme osteopenia on xray.
Type I: “RSD” no demonstrable nerve lesion
Type 2: “causalgia” has involved nerve dysfunction
Outline pharmacologic mgmt of CRPS
NSAIDS and alpha blockers.
Bisphosphonates
Antidepressants/Anticonvulsants
Outline non pharmacologic, non surgical mgmt of CRPS (3)
Gentle physiotherapy
Tactile discrimination training
Graded motor imagery
Outline surgical mgmt of CRPS
Sympathectomy
Which experiences more tourniquet damage - directly compressed tissue or distal ischemic tissue?
Both directly compressed muscle/nerve is more damaged than the distal ischemic tissue.
EMG changes with tourniquet use? How long?
Yes - in 62% of postop ortho patients.
Lasted 51 days
