THA

Question 1

How does anterior approach compare to posterior approach?

What is the main con of each?

Answer 1

Anterior slightly better/faster at rehab -> NO DIFF after 3 months
Anterior - high rate of femoral failure
Posterior - higher rate of dislocation

Question 2

What is the average failure rate %/year of THA?

Answer 2

1%/year

Question 3

In what scenario should you consider cementing a cup?

Answer 3

Previously irradiated

Question 4

What should the average size be for the following to have good bone ingrowth:

1. ) Metal porosity %
2. ) Depth of pores
3. ) Gap

Answer 4

Rules of 50’s!

1. ) 50%
2. ) 50-150 microns
3. ) < 50 microns

Question 5

What is the consequence of wear rate of modern PE (UHMWPE) with use of larger femoral heads?

Answer 5

NO consequence of bigger femoral heads!
(typically with old poly the larger femoral heads led to higher volumetric wear and small heads led to high linear wear)

Question 6

What is the main type of wear that occurs with ceramic on poly THA bearings - contributes MOST to osteolysis?

Answer 6

Adhesive wear

Question 7

What is the osteolytic threshold (that is the wear rate under which osteolysis is not seen)?

Answer 7

< 0.1 mm/year

Question 8

What are the main molecules/mediators involved in osteolysis?

Answer 8

TNF-alpha
IL1-beta
IL-6

Question 9

What technical error is particularly bad for MoM/hip resurfacing?

Answer 9

Vertical cup placement -> edge loading!!

Question 10

What is the main mediator cell for:

1. ) Osteolysis due to PE
2. ) ALVAL

Answer 10

1. ) Macrophage
2. ) Lymphocyte (delayed Type IV hypersensitivity)
   * *Realize that ALTR (which is the condition and ALVAL is the histologic dx) can result in XR with signs of osteolysis! PE is not the only thing that causes osteolysis!

Question 11

What is the best study to look at pseudotumor in MoM hips?

Answer 11

MARS MRI

Question 12

What is the cause of trunionosis?

What is the treatment?

Answer 12

Micromotion at modular head/neck jxn of metal head w/ trunion -> fretting corrosion = corrosion due to small cyclic motion disrupting the protective oxide layer. See Co:Ch levels 4-5:1
Treatment is revision w/ placement of Ceramic head w/ titanium sleeve

Question 13

What bad consequence can happen due to destruction from metallosis (MoM or trunionosis)? And what is the revision surgery typically needed?

Answer 13

Loss of abductors

Constrained liner

Question 14

If a patient has footdrop postop and you think it is due to hematoma what is the first thing that you do?

Answer 14

TAKE THEM BACK TO OR AND DECOMPRESS IT!

Don’t order any imaging studies if you know from presentation!

Question 15

What are the two possible HO ppx treatments? And when should they be given?

Answer 15

1. ) Indomethacin (variable dosing) given for 1-6 weeks postop (look out for people w/ kidney issues and AVOID this!)
2. ) Radiation - 7 Gy to be given 24 hrs preop or 48 hrs postop (very small risk of cancer!)
   * *There is NO role for late use of these - if they form HO…just wait for it to mature and take out later

Question 16

What is the cause of most LLD postop?

Answer 16

Perceived! -warn the patients that they may feel long b/c they have been living short!
Tx -> observe, stretch and let tissue accommodate

Question 17

What is a possible cause of anterior hip pain after THA? And what are the possible tx’s?

Answer 17

Iliopsoas impingement/tendonitis.
Can verify w/ injection
1.) Get crosstable lateral XR to eval for cup overhang -> if overhand > 8 mm revise!
2.) Tenotomy

Question 18

In the case of performing a revision for PE wear w/ osteolysis and lytic defects behind a well-fixed, well-positioned cup what should you do?

Answer 18

LEAVE THE CUP!!! EVEN IF BIG OSTEOLYTIC DEFECT BEHIND IT!! (High morbidity if you do this!)…..if the poly locking mechanism doesn’t exist b/c it’s an old cup -> CEMENT IN THE LINER

Question 19

What is the #1 cause for THA revision longterm?

Answer 19

Aseptic loosening

Question 20

What is the Paprosky definition of femoral bone loss? And what implant should be used for each?

Answer 20

Type 1: Intact metaphysis (any primary implant)
Type 2: Metaphyseal bone loss (cementless diaphyseal engaging stem)
Type 3A: > 4 cm diaphysis remaining
Type 3B: < 4 cm diaphysis remaining
(cementless diaphyseal engaging)
Type 4 -> Nonsupportive diaphysis (DFR or APC)

Question 21

In a revision THA on the acetabular side, how much acetabulum do you need to use a hemispherical cup w/ screws?

Answer 21

> 2/3 rim intact

> 50% acetabular bone stock

Question 22

What do you do if there is an intraop calcar fracture?

Answer 22

1.) Expose fracture!
If limited to calcar/metaphysis -> cable and keep same stem. WBAT!
If extends to diaphysis -> switch to a diaphyseal engaging stem!

Question 23

What is the most common cause of acute PJI?

What is the most common cause of chronic PJI?

Answer 23

Acute -> Staph aureus

Chronic -> Staph epi (aka coagulase negative Staph)

Question 24

What is MoA of TXA?

Who is it contraindicated in?

Answer 24

Competitively inhibits plasminogen (antifibrolytic) by binding to the lysine binding site
Contraindicated in renal failure and pt w/ active VTE
**NO evidence that it increases the risk of VTE…but decrease intraop blood loss and need for transfusion!

Question 25

What is the largest predictor of progression of femoral head osteonecrosis?

Answer 25

SIZE and LOCATION of the lesion!

Question 26

What are the normal ranges for the LCEA and Tonnis angle?

Answer 26

LCEA: 25-30 | Tonnis < 10

Question 27

Who should you consider acetabular osteotomy for? Which acetabular osteotomy should we choose for the test and what are some of its pros?

Answer 27

DDH in young pt, no arthritis/intact cartilage (okay if have labral tear), shallow socket PAO = Bernese Periacetabular Osteotomy Pros: High degree of correction, posterior column stays intact/ NV structures somewhat protected

Question 28

What 2 hips should you never scope?

Answer 28

Dysplastic or arthritic hip!

Question 29

In a Crowe IV hip that you are doing THA on, what additional surgery do you need to think about doing?

Answer 29

Subtrochanteric osteotomy if you are going to lengthen > 2-4 cm OR ~10% of length of the femur

Question 30

``` Hip Biomechanics (look a diagram and see my notes on this!). What does medializing the hip COR do to abductors and JRF? What does lateralizing the hip COR do to abductors and JRF? ```

Answer 30

Decreases the work of abductors Decreases JRF Increases work of abductors Increases JRF

Question 31

If your abductors are weak what happens to pelvis tilt and body tilt w/ single leg stance? Choose example of left hip w/ weak abductors What can help this?

Answer 31

During single leg stance on left hip the right hemipelvis will drop - and to compensate the upper body/trunk will lean toward the left side to balance and decrease the BW moment. Can help by putting cane in CONTRALATERAL (right for above example) hand - will help level pelvis and REDUCE JRF through hip by 50%!

Question 32

What common problems do these groups get postop? 1. ) Sickle cell 2. ) Psoriatic arthritis 3. ) Ankylosing Spondylitis 4. ) Parkinsons 5. ) Dialysis

Answer 32

1. ) Early loosening, infection 2. ) Infection 3. ) HO 4. ) Dislocation, mortality 5. ) Infection, loosening

Question 33

What do you do with a draining wound at 10-14 days?

Answer 33

URGENT I&D!... don't need to wait for cultures, etc! Want to clean it out before has chance to form biofilm so can retain componenets.

Question 34

What are the MoA for the following VTE ppx meds? 1. ) Aspirin 2. ) LMWH 3. ) Dabigatran 4. ) Fondaparinux 5. ) Rivaroxaban/Apixaban 6. ) Warfarin

Answer 34

1. ) COX inhibitor 2. ) Activates anti-thrombin III and inhibits Xa 3. ) Thrombin inhibitor 4. ) Indirect Xa inhibitor 5. ) Direct Xa inhibitors 6. ) Vit K antagonist (Factors II, VII, IX, X)

Question 35

What is the typical presentation of transient hip osteoporosis/who does it present in? What does imaging look like? What is tx?

Answer 35

MC in middle-aged men or women (esp in 3rd trimester of preg). XRs are typically negative but MRI shows diffuse edema in the femoral head Tx: TTWB to protect from stress fx - resolves in 6-8 months

Question 36

Other than abductor dysfunction/damage, what is they other main indication on the test for constrained liner?

Answer 36

Pt s/p bariatric surgery and large weight loss who has hip instability/dislocations w/ well-fixed, well positioned implants! We know these patient's are prone to this!