Wear and Osteolysis Basic Science Flashcards
Volumetric Wear
directly related to square of radius of head
V=Pie9 (rSquared) w
Therefore head size is most determiant factor is number of parcile generated
UHMWPE
Less wear particles, smaller wear particles, less mechanical properties
Osteoclast activation and Osteolysis
Via the RANKL Pathway
Denosumab Inhibits?
RANKL- Therefore inhibits Osteoclastogeneisis
Enteracept inhibits/Counteracts
TNF a (which is pro-inflammatory)
Tocilizumab inhibits?
Monoclonal antibody to IL-6
UHMWPE Mechanical Pitfalls
Decrease Ductility
Decreased Fracture Propagation Prevention
Decreased Tensile Strength
Biologic Response to PE wear productes is directly proportional to ______
Number of particles
N-Telopeptide breaker marker of What?
Type I Collagen
Aseptic Loosening of Implants Thinks secreted by macrophages
IL-6, IL-1, PDGF, PGE2
UHMWPE wear rates are independent of head size between sized ___ and ___
22–>46
___ wear rate AND____ wear rate contribute to osteolysis
Liner and VOlumetric
Wear Rates with increased risk of osteolysis ?
> 0.1mm/year
Osteoprotegrin binds to what structure to decrased osteolysis ?
RANKL
Acetabular Bone Loss Grading?
AAOS I- Segmental II Caavitary (volumetric III: combined iV: pelvic discontinuity V: arthrodesis
Acetabular Bone Lone Paprosky
I; Minimal deformity, intact rim 2A: Superior bone loss 2B- Superior lateral bone loss 2C: Central bone loss 3A: Involving columbs 3B: pelvic Discontinuity
MObile bearing desing of PE on tibial base plate does what
- decrease poly wear (theorectical) NOT proven
- Same survivorship
- increase spit out in flexion space
Stand-alone revision acetabular liner replacement has high increased incidence of ?
post-op dislocation
Contraindications for femoral head resurfacings?
femoral head cyst >1cm
Coxa Vara (poor outcomes)
Acetabular dysplasia or loss of bone stock
What is the Kerbooul Angle?
Hip Osteonecrosis
- Measuring the necrotic angle wedge on AP and LAT and combining the two angle sums
Low risk <190
Mod Risk 190-240
High Risk >240
Ficat mod of Stienberg Classification
- Hip osteonecrois
o- normal Xray, Normal MR I; norma xray, abdnormal MR (dark on t1) II; cystic or scleoriss changes III- crescent sign (subchondral collapse) IV: femoral head flattening V: Narrowing of joint VI: advnaced degen
Vancouver Type b3 treatemnt
Younger?
Older?
young- Allograft composite replacement
Older: cemented segmental replacement, proximal femoral replacemnet
What should normal Lateral Center Edge Angle be?
> 25
What should vertical center edge angle be and on what view?
> 25
on False Profile view
What shoulder the normal Tonnis agnle be?
<13
What femoral alpha angles seen on lateral xray are suspicious for CAM lesion?
> 42 d
Top three causes of of TKA failure?
1> aseptic loosening
- Septic failure
- Instability
Anderson TKA femoral bone loss classificaiton
1
2A; loss on one femoral of tibial condyle
2B: Loss on both condyles
3 Massive loss- bulk allographfts,
cavitary defect <1cm cement, >1 cm sleeves, cones
What mediator is found to be responsible in partical mediated osteolysis?
TNF-Alpha
releated to number no exacly size of particles
Cross-Linking
Oxidation removal
- Radiation Gamma, inert air
- Heating, melting
What type of allergy class is allergy to metal?
Type IV hypersensitivity RXN,
What amount of acetabular component uncoverage is acceptable ?
< 30%
Titanium tibial baseplate versus all poly
No difference in functional status
- poly version is cheaper
Dose for HO radiation?
Preop within 24 hours
Post op within 72 hours
HAS TO BE 700cGY
