Joints Flashcards
Rheumatoid arthritis is…
a T-cell mediated autoimmune disease.
Rheumatoid factor is…
an IgM autoantibody that targets IgG.
TNF alpha inhibitors
- Infliximab
- Etanercept
- Adalimumab
Surgical management of TNF alpha inhibitors
Hold 1 week prior to surgery and 2 weeks after
Rituximab
CD20 inhibitor (B cells)
Abatacept
fusion protein that inhibits T cells
Juvenile idiopathic arthritis
- less than 16 years old
- elevated ESR/ANA
- need opthamologic eval (slit lamp exam)
- can have atlantoaxial instability (like RA)
- treat with DMARDs (like RA)
Reiter’s syndrome
-arthritis, urethritis, conjunctivitis/uveitis
Which meds can be continued during surgery?
methotrexate, leflunomide, hydroxychloroquine
Timing of surgery with regards to rituximab
surgery 7 months after last dose
Volumetric wear
pi x r ^2 x w (where w is linear wear)
Polyethylene is best made by…
direct compression molding of powder
Crosslinking PE improves…
wear resistance (especially adhesive wear) but reduces mechanical properties (fracture toughness, tensile strength).
Sterilization of PE is done by…
irradiation in inert gas. Irradiation generates free radicalas which facilitate cross linking of PE and improve wear.
However, too many free radicals (irradiation in the presence of air) is bad bc they cause oxidative degradation of PE.
How to remove excess free radicals after irrradiation
remelting (heat PE past melting point) and annealing (heat PE close to melting point)
Effect of remelting and annealing on crystal formation of UHMWPE
- annealing increases
- remelting decrease
Which bearing surface provides the least volumetric wear?
ceramic on ceramic
Stripe wear
characteristic pattern of ceramic on ceramic bearings from lift off separation of femoral head coming into contact with the acetabular rim
Risk factors for stripe wear and thus liner fx
vertical cup
obesity
metal on metal hips produce
smaller wear particles than metal on PE
Pseudotumor is also known as…
aseptic, lymphocyte dominated vasculitis-associated lesion (ALVAL)
Urinary N telopeptide is…
a marker for osteolysis and a breakdown product of type I collagen.
Best predictor of pain w/ AVN is…
bone marrow edema on MRI.
What Kerboul angle poses a high risk for femoral head collapse?
> 240
In sickle cell, the natural history of AVN is..
progressive loss of sphericity of the femoral head
Hip OA cartilage characteristics
increased water content
decrease proteoglycan content
In hip OA, IL-1, IL-6 and TNF-alpha increase…
MMP activity leading to cartilage degeneration.
In OA, indian hedgehog (Ihh) mediates..
activation of chondrocyte differentiation –> osteophyte formation (pathologic activation of endochondral ossification).
Bleeding under the transverse acetabular ligament is from…
the obturator artery.
What is most effective at reducing EBL during THA?
spinal anesthesia (and therefore transfusion requirement)
Pseudotumor is generally caused by…
fretting and corrosion reaction from taper.
After THA, safe to return to driving after…
2 weeks.