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
