Adult Reconstruction Flashcards
What coronal deformity results in cartilage loss on the posterior aspect of the femur and tibial plateau?
What XR view shows this?
Valgus knees
Obtain a Rosenberg View (PA Flexion)
Increased radionuclide activity in bone may be a normal postoperative finding for how long after fracture repair or TKA?
6-12 months
What is the leading cause of revision TKA?
Aseptic loosening
How much penetration is recommended for cement penetration?
3-4 mm where if less than 1.5 is associated with radio-lucencies and 5-10 mm is concerning for thermal necrosis
For acetabular dysplasia, there is an acetabular index that is greater than how many degrees?
5 degrees
For acetabular dysplasia, the lateral CE angle is less than how many degrees?
20 degrees (vertical line and line from femoral head center to acetabular edge)
The crossover sign signifies what in the acetabulum?
That it is retroverted
How do you measure the femoral alpha angle?
On an AP of the hip, draw a line from the center of the femoral head down the middle of the neck and form an angle with another line from the center of the femoral head to the head/neck junction
Normal is 40 degrees or less
What is the Ficat stage for symptomatic osteonecrotic hip with crescent sign?
Stage 3
Treatment of the following necrotic hips:
-Small lesion, no crescent sign
-Medium/Large lesion, no crescent sign, less than 40
-Medium/Large lesion, no crescent sign, less than 40
-Crescent sign
- Core decompression (Do NOT offer if on chronic steroid treatment)
- Vascularized Fibular strut graft
- THA
- THA
What is the preferred optimal pore size for bony ingrowth for THA?
50-200 micrometers
The grab distance between the implant and bone in a press fit THA must be less than what?
50 micrometers
In a THA, fibrous fixation occurs when micromotion exceeds what?
150 micrometer fixation
What is the formula for hydroxyapatite?
Ca10(PO4)6(OH)2
High cobalt levels 5 times more than chromium, what am I worried about?
Trunnionosis
What head/shell combo in THA has the lowest wear?
Ceramic head on ceramic poly (but there is a fracture risk and squeaking)
What is the percentage of neurologic complications in THA?
1% (Often the sciatic nerve and the result of compression (hematoma))
HO is most common with that THA approach?
Lateral
PPX: 700 cGY (centigray) 24 hrs preop or up to 48 hrs postop or indocin
Pain and weakness with resisted hip flexion after a THA, what is the diagnosis?
Iliopsoas impingment
Tx: Conservative, injections
If fail conservative and cup is not prominent more than 8 mm, iliopsoas tenotomy. If cup is prominent anterior 8 mm then revise the cup
What is the number one reason for long term THA revisions?
Aseptic loosening
What is the name of the classification for proximal femoral bone loss in THA?
Paprosky
1 - metaphysis intact
2 - metaphysis loss
3. diaphysis
4. No support, both metaphysis and diaphysis not intact
Where is the zone of death in the acetabulum to avoid placing screws and what is at risk?
Anterior-Superior
External iliac artery and vein
(Also avoid anterior inferior which targets the obturator n/a/v)
What is the safest zone for acetabulum screws?
Superior posterior
Alpha defensin is released by what cell?
Neutrophils
Which method removes all free radicals for polyethylene? Is it annealing or melting
Melting (as a result decreases mechanical properties)
What is the best form of PE implant manufacturing? Is it ram bar extrusion, sheet molding, compression molding or direct compression molding?
Direct compression molding
Blood supply to the adult femoral head comes from ?
Medial femoral circumflex artery
What is left intact in a Bernese PAO?
Posterior column
What size mantle of cement do you want for cemented femoral stem?
2 mm
I should build more retroversion for a THA in a patient with what type of spine?
Flatback (stuck sitting)
What is yearly mortality rate for femoral neck fracture?
20-30 percent
What bearing has the highest young’s modulus?
Ceramic
What bearing has the young’s modulus closest to cortical bone?
Titanium
What kind of wear is most important for PE particle generation?
Adhesive wear
What is the osteolysis threshold?
0.1 mm/year
(The large the head the higher the volumetric wear rate which is why small heads were initially chosen but HCLPE has such low rates of wear that we are now able to tolerate larger heads)
For THA, drive reaction time normalizes at what time postop?
4-6 weeks
What muscle originates from the AIIS?
Rectus femoris
Hip resurfacing requires what kind of bearing?
Metal on Metal (MoM)
What is the most common early complication for hip resurfacing?
Femoral neck fracture
What vessel is at risk of bleeding with a DAATHA?
Ascending branch of lateral femoral circumflex vessel
What is the incidence of dislocation in THA and revision THA?
1-2%
5-7%
A vertical cup results in what direction dislocation risk?
Posterior superior
What is the most common legal reason for suing after a THA?
Nerve injury
What angle is a good method to asses risk of collapse in osteonecrotic hips?
Kerboul angle
190-240 medium risk
Who has a higher dislocation rate: THA or Hip resurfacing?
THA because hip resurfacing has a large femoral component
What is my osteotomy option for a varus knee malalignment?
Valgus producing proximal tibia osteotomy
What is my osteotomy option for a valgus knee malalignment?
Due to a lateral femoral condyle hypoplasia so do a varus producing supracondylar femoral osteotomy
What patella deformity can result from close or open wedge proximal tibia osteotomy?
Patella Baja
The distal femur cut is made perpendicular to what axis?
The mechanical axis (line from femoral head through knee center to the ankle center
The maximum alteration of the joint line in TKA is how much?
8 mm but avoid 4 mm
What is the biggest predictor of postoperative TKA ROM?
Pre-operative ROM
What degrees is the joint line cut for mechanical versus kinematic alignment?
0 degrees to mechanical and 3 degrees varus for kinematic
As a knee goes into extension, how does the tibia behave?
It externally rotates
The flexion gap is controlled by what three things?
Posterior femoral cut
Tibial cut
PCL
The extension gap is controlled by what three things?
Distal femur cut
Tibial cut
Posterior capsule
Which nerve block is both motor and sensory for TKA? (Femoral or Adductor Nerve Block)
Femoral nerve block
What area of the knee is not covered by both femoral and adductor nerve blocks?
Posterior knee
What maneuver will cause a fracture if there is notching with a TKA?
Bending
Where does the large arterial contribution to the patella come from?
Inferomedial
What is the minimum thickness of the patella required for a TKA?
13 mm
Postoperative manipulation of a TKA should occur when?
4-12 weeks postop
For a TKA, the most common site for ostelysis is where?
Behind the posterior femoral condyle
What is the distance from the joint line for the following in mm:
Lateral Femoral Condyle
Medial Femoral Condyle
Fibular Head
Medial Condyle: 28 mm
Lateral Condyle: 23 mm
Fibular Head: 14 mm
Compared to manual UKA, robotic UKA provides what?
Better implant positoning and shorter hospital stay
CR knees should be avoided if varus more than what and valgus more than what?
Varus more than 10 degrees and valgus more than 15 degrees
Patient with hyper extension instability requires what type of TKA?
Hinge knee
Most common cause of TKA loosening at:
<2 yrs
>2 yrs
PJI for < 2 yrs
Aseptic loosening >2 yrs
What makes up the Insall-Salvati ratio?
Patellar tendon length / Length of the patella bone
Normal is 1:1`
Patella clunk is unique to what TKA design?
PS Knee
Adductor blocks what nerve?
Saphenous nerve
What symptoms can be seen with metal toxicity?
Cardiomyopathy, hypothyroidism, polycythemia, neuropathy
Alpha defensin can be falsely positive in what hip condition?
Pseudotumor (metal on metal hip)
How can I measure true leg length?
Draw line from ASIS to Medial Malleolus
Dislocation and Early revision are seen more with what? THA or Hemi?
THA
What neurovascular structure is closest to the posterior capsule of the knee?
Popliteal Artery
What knee approach has led to rotation malpositioning?
Quad sparring approach
Post polio syndrome require what kind of TKA?
Hinge knee
What inflammatory marker has the highest correlation to PJI?
IL-6
What is the most common postoperative complication after surgical dislocation of the hip?
Heterotopic ossification