Recon Flashcards
Lateral center edge angle for acetabular dysplasia.
Less than 20 deg.
Anterior center edge angle for acetabular dysplasia.
Less than 20 deg.
Anterior center edge angle measured on this radiograph.
False profile.
Definition of alpha angle in FAI.
Angle between center of head to head-neck junction and center of neck midline.
Alpha angle with pistol grip deformity.
Greater than 40 degrees.
Energy expenditure with unilateral hip arthrodesis.
Increased by 30%.
Hip arthrodesis positioning.
Neutral abduction, 20-25 deg flexion.
Most common indication for hip arthrodesis conversion to THA.
Back pain.
Hip function after fusion conversion to THA most dependent on this.
Integrity of abductor complex.
This test needed prior to takedown of hip fusion to THA.
Gluteus medius EMG.
___% of cases of osteonecrosis have bilateral involvement.
50%
These drugs reduce risk of collapse in femoral head AVN.
Bisphosphonates.
Method to reduce cement porosity in TJA.
Vacuum mixing.
Optimal pore size for bone ingrowth.
50-150 micrometers.
Main cause of proximal femur stress shielding.
Modulus of elasticity mismatch between femur and stem.
Femoral stem breakage is caused by this.
Cantilever bending.
Bone deficiency defined as loss of cancellous bone without compromise of main structural bone support.
Cavitary deficiency.
Bone deficiency defined as loss of main bony support.s
Segmental deficiency.
Standard cup for revision THA.
Hemispheric porous cup with screw fixation.
Amount of rim needed for fixation of cup in revision THA.
Two-thirds
Acetabular safe zone for screw fixation.
Posterior superior.
Most common complication after modular bearing exchange after THA.
Dislocation.
Most important bearing wear mechanism.
Adhesive bearing wear.
Factors and cytokines release by activated macrophages in osteolysis (6).
- TNF-alpha
- IL-1
- TGF-beta
- IL-6
- PDGF
- RANKL
Main determinant of number of polyethylene particles generated.
Volumetric wear.
Volumetric wear approximates this shape.
A cylinder.
Linear wear rates in excess of ____ mm/yr are associated with osteolysis.
0.1 mm/yr
Hallmark radiographic finding of osteolysis.
Femoral endosteal scalloping.
Why most late periprosthetic hip fractures occur at stem tip.
Area of greatest modulus mismatch.
Most common reason for intra-op periprosthetic acetabular fracture.
Underreaming.
Most common complication of hip resurfacing.
Fracture.
Treatment of failed hip resurfacing.
Convert to total hip arthroplasty.
Most common mechanism of nerve injury after THA.
Compression.
Sciatic nerve travels closest to acetabulum at level of the _____.
Ischium.
Treatment of postoperative hematoma causing sciatic nerve palsy.
Hematoma evacuation.
Lengthening of leg more than ____ cm increases risk for foot drop.
3.5cm
Psoritatic arthritis is associated with increase risk of this.
Infection.
Superior gluteal nerve located ___ cm superior to tip of the greater trochanter.
5 cm
Zirconia ceramic in vivo undergoes this.
A phase transformation.
Zirconia ceramic phase transformation and its implication.
Yttrium-stabilized tetragonal crystal phase changes to monoclinic crystal phase. Monoclinic phase has increased surface roughness.
Why avoid titanium femoral heads.
Scratch easily.
Transfer of metal to surface of ceramic femoral head.
Metal smearing.
Polyethylene manufacturing process with best wear characteristics.
Direct compression molding.
The additive needed for ram bar extrusion method of polyethylene manufacturing.
Calcium stearate.
Irradiated and re-melted polyethylene produces low or high crystallinity.
low
Which polyethylene manufacturing process produces the strongest product irriadiated and melted or annealed?
Annealed.
Which has higher oxydation potential irriadated and melted or annealed polyethylene?
Annealed.
Polyethylene sterilization method that produces the lowest amount of free radicals.
Ethylene oxide and gas plasma.
Most important factor influencing on the shelf polyethylene oxidation.
Packaging material.
Asperities on each bearing surface do not make contact in this type of lubrication.
Hydrodynamic.
Asperities on each bearing surface always contact in this type of lubrication.
Boundary lubrication.
Stripe line is caused by metal smear effect true or false?
False.
Stripe line wear must be detected in this manner.
Microscopically.
Size of particles generated in metal-on-metal wear.
0.015-0.12 micrometers.
Absolute number of particles generated in polyethylene wear or metal-on-metal wear?
Metal-on-metal.
Metal debris from metal-on-metal bearing processed by this cell.
T-cell lymphocyte.
Two types of biologic response to metal wear (2).
- Hypersensitivity (immediate)
2. Particulate-induced T-cell response (seen after 3-5 years)
Metal hypersensitiivty usually related to this metal.
Nickel
ALVAL
Aseptic lymphocytic- and vasculitic-associated lesion.
Women or men more likely to be affected by particulate-induced T-cell response to metal implant.
Women.
Metal ions cross placenta true or false?
True.
Metal-on-metal implants increase the risk of cancer true or false?
False.
Polyethylene bearing placement after ceramic-cermamic bearing fracture results in this.
Rapid polyethylene wear due to third body abrasion.
Best type of patient for osteotomy about the knee.
Young active patient under age of 50.
Contraindications to valgus-producing knee osteotomy (7).
- Inflammatory arthritis
- Limited flexion (< 90 deg)
- Flexion contracture > 10 deg
- Ligament instability
- Lateral tibia subluxation > 1 cm
- Medial compartment bone loss
- Lateral compartment joint space narrowing
Extent of valgus angle about the knee that can be offloaded with varus-producing osteotomy.
15 degrees.
Contraindications to unicompartment knee arthroplasty (6).
- Inflammatory arthritis
- Significant fixed deformity (must be able to correct to normal alignment manually)
- Previous meniscectomy in opposite compartment
- ACL deficiency (absolute contraindication in mobile bearing)
- Flexion contracture greater than 10 deg
- Tricompartmental arthritis
Treatment of choice in older patient with significant patellofemoral arthritis.
Total knee arthroplasty.
When are full-length lower extremity plain films needed prior to TKA (3).
- Angular deformity present
- Short stature (< 60 inches)
- Tall stature (> 75 inches)
When peroneal palsy is identified postoperatively after TKA what is initial management.
Remove compressive wrap and flex knee.
Treatment for intraoperative MCL injury.
Repair if possible and convert to M/L constraint prosthesis.
Treatment of extensor mechanism disruption with TKA.
Allograft reconstruction (fresh frozen allograft preferred).
Manipulation of stiff postoperative TKA done during this time.
4-6 weeks postop.
Arthrotomy with scar resection and reduction of modular polyethylene thickness for late TKA arthrofibrosis.
Not recommended.
Femoral rollback.
Progressive posterior change in femoral-tibial contact point as knee moves into flexion.
Excess PCL recession in CR TKA results in this.
Late failure with flexion instability.
Maximum joint line elevation in TKA.
8 mm
Indications for posterior stabilized (versus CR) TKA (3).
- Patellectomy
- Inflammatory arthritis
- PCL deficiency
Spine level of pain about the knee.
L4
Metal hypersensitivity reaction diagnosis made by.
Lymphocyte T-cell proliferation test.
Skin patch test for nick hypersensitivity good for diagnosing metal hypersensitivity true or false.
False.
Thickness of patella needed for revision of patellar component.
12mm
Minimum polyethylene insert thickness to prevent catastrophic wear in TKA.
8mm
Why sliding wear occurs in TKA.
Due to ACL sacrifice.
Sliding of tibia on femur most pronounced on CR or PS designs?
CR
A tight flexion or extension gap hastens sliding-wear effect in TKA?
Flexion.
Machining of polyethylene in TKA causes this.
Stretching of polyethylene chains, making them more susceptible to oxidation.
