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Adult Recon > Miller's Review Adult Recon > Flashcards

Miller's Review Adult Recon Flashcards

Ortho Adult Recon Review

1
Q

Biomechanical moment that contributes to knee osteoarthritis

A

Increased knee adductor moment (tibia and ankle adducted relative to the knee). Increased medial compartment overload -> OA.

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2
Q

Kellgren Lawrence Classification, when is TKA indicated?

A

TKA indicated K-L 4. 1 = small osteophytes, 2 = definite osteophytes normal joint space, 3 = moderate joint space reduction, 4= complete joint space loss and bone deformity

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3
Q

AAOS 2021 strong recommendations for knee OA

A

Recommended: patient exercise programs (supervised and self-managed), topical/oral NSAIDs and APAP.

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4
Q

AAOS 2021 moderate recommendations for knee OA

A

Recommended: cane, brace, neuromuscular training, corticosteroid injections, weight loss, partial meniscectomy in mild/moderate OA in select patients.

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5
Q

AAOS 2021 inconsistent/limited recommendations for knee OA

A

Supplements, massage, laser, acupuncture, electrical/magnetic stimulation, shock wave, PRP, denervation and HTO

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6
Q

AAOS 2021 consensus recommendations for knee OA

A

Dry needling and free-floating interpositional spacers (no)

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7
Q

HTO contraindications

A

Inflammatory OA, flexion <90, flexion contracture >10, ligament instability (especially varus thrust), coronal subluxation >1cm, medial bone loss, lateral compartment narrowing (confirm w/stress radiographs)

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8
Q

Open wedge HTO complications

A

Patella baja (most common), loss of correction secondary to collapse of osteotomy, non-union, harvest site pain

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9
Q

Closing wedge HTO complications

A

Patella baja (most common), loss of posterior slope, nerve injury

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10
Q

Rate of conversion from HTO to TKA at 6 years

A

13%. Requires longer OR time and more frequent use of revision implants

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11
Q

DFO valgus anglulation indication

A

12+ degree valgus deformity

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12
Q

Contraindications to DFO

A

Inflammatory OA, flexion <90, flexion contracture >10, ligament instability (especially valgus thrust), coronal subluxation >1cm, prior medial meniscectomy, medial compartment narrowing (confirm w/stress radiographs)

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13
Q

DFO complications

A

Nonunion, loss of correction, residual patellofemoral maltracking

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14
Q

Best DFO for future TKA

A

Crescentic dome, allows for instrumentation of the femur and use of stem later on

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15
Q

UKA benefits over TKA

A

Faster recovery, fewer complications, better knee function and less post-operative pain

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16
Q

UKA contraindications

A

Inflammatory OA, fixed varus/valgus deformity, prior contralateral meniscectomy, flexion contracture >10, tricompartmental OA, ACL deficient (absolute contraindication if mobile bearing), patellofemoral disease is controversial

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17
Q

UKA complications

A

Tibial stress fracture, mobile bearing dislocation, overcorrection and contralateral disease progression, undercorrection and implant failure due to overload, implant subsidence

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18
Q

Management of tibial stress fracture after UKA

A

Rest, NWB if stable. If tibial component compromised -> ORIF vs long stem revision to TKA

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19
Q

Risks for UKA tibial tray implant subsidence

A

Large resection, tray not on cortical rim, osteoporosis

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20
Q

Recommended treatment for the ABOS I for end stage isolated patellofemoral osteoarthritis

A

Superior functional results in TKA compared to patellectomy or patellofemoral arthroplasty

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21
Q

DMARDs to continue periop

A

MTX, sulfasalazine, hydroxychloroquine, leflunomide, doxycycline

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22
Q

Periop management of corticosteroids

A

No loading dose, continue regular dose in patients up to 16mg/day

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23
Q

Surgery timing for biologic immune inhibitors

A

Stop all biologic agents prior to surgery. Plan surgery at the end of dosing cycle of that drug (2 week dosing cycle, operate week 3)

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24
Q

When to stop tofacitinib (Xeljanz) prior to surgery?

A

7 days, this has a very short 1 day half life

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25
Q

When to restart biologic agents after TKA?

A

14 days after surgery as long as wound healed and staples/sutures are out

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26
Q

Severe SLE patients with organ involvement should continue these medications preoperatively? What about moderate disease?

A

Mycophenoloate mofetil

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27
Q

Management of periop abx in PCN allergic patient

A

Pre-op test dose is normal in 97% of patients. Bone penetration is best in Ancef and infection rates are higher if Ancef is not given.

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28
Q

How does your valgus distal femoral cut angle change with patient height?

A

Hip offset remains similar despite patient height. Consequently, short patients need a greater valgus cut and tall patients need a smaller valgus cut.

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29
Q

Maximum alteration of knee joint line in TKA

A

8mm. Raising or lowering the joint line beyond 8mm alters the timing of collateral ligament tension in the flexion-extension arc of motion

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30
Q

Medial releases in varus knee undergoing TKA

A

1) osteophytes 2) deep MCL and capsule complex to 1.5cm distal to joint line 3) posteromedial corner 4) sMCL

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31
Q

Consequence of posteromedial corner contracture in OA

A

Fixed internal rotation of tibia, releasing this allows external rotation of the tibia

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32
Q

Different releases of sMCL for varus knee balancing

A

Posterior oblique portion of MCL released if tight in extension, anterior portion of sMCL released if tight in flexion

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33
Q

Lateral releases in valgus knee undergoing TKA

A

1) Osteophytes 2) Lateral capsule (ALL resists IR of tibia) 3) popliteus (tight in flexion) vs IT band (tight in extension) 4) LCL (tight in flexion and extension)

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34
Q

Next step if inadvertent isolate cut of popliteus tendon

A

Does not alter static stability 0-90 degrees, PS bearing is fine, more constraint not needed

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35
Q

Indications for concomitant osteotomy with TKA

A

Coronal deformity within distal ¼ of femur, proximal ¼ of tibia and >20 degrees. Do closed wedge or dome osteotomy + diaphyseal press fit stem to provide rotation stability

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36
Q

Releases for tight flexion gap

A

1) Osteophytes 2) Posterior capsule 3) PCL if CR knee 4) Gastroc. Can also adjust cuts (slope, posterior femoral cut)

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37
Q

How many degrees correction of flexion contracture do you get with 2mm more resection of the distal femur?

A

10 degree correction for each 2mm of resection

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38
Q

Balancing knee that is normal in extension and loose in flexion

A

Upsize poly and either take 2mm more distal femur or release more posterior capsule

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39
Q

Balancing knee that is loose in extension and normal flexion

A

Distalize femur with screws or augments. Or, upsize poly and recess PCL or cut more tibial slope.

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40
Q

Tourniquet vs non-tourniquet TKA

A

Less blood loss and increased short term pain scores with tourniquet use.

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41
Q

AAOS strong recommendations for not using what 3 things intra-op?

A

Navigation, patient specific instrumentation and a drain

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42
Q

AAOS strong recommendation for using __ in TKA

A

TXA decreases blood loss and transfusions, periarticular anesthetic + peripheral nerve block decreases pain and opioid use

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43
Q

3 AAOS strong recommendations post-op TKA

A

CPM doesn’t improve outcomes, therapy same day of TKA decreases length of hospital stay, do not perform routine duplex /us after TKA

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44
Q

AAOS strong recommendations for implant design in TKA

A

No difference in CR/PS, all poly vs modular tibia, patellar resurfacing and cement vs cementless.

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45
Q

AAOS strong recommendation for pre-op risk factors in TKA

A

Patients with obesity have less improvement after TKA

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46
Q

TXA mechanism of action

A

Stops breakdown of fibrin clot. It is a lysine analogue that reversibly binds to 4-5 lysine receptors on plasminogen, preventing activation to plasmin with a half life of 3 hours.

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47
Q

How is TXA excreted

A

95% renal

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48
Q

TXA contraindications

A

Anaphylaxis, active VTE, florid renal failure and seizure disorder (lysine competes with glycine CNS receptors and can activate seizure disorder when lysine binding sites are blocked)

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49
Q

AAOS strong recommendations for anesthesia and analgesia

A

No increased risk of complications with APAP. Early pre/post op NSAIDs reduce pain. Pregabalin reduces postop pain, neuropathic pain and opioid consumption (gabapentin does not, pregabalin is 2-4x stronger than gabapentin). Opioid administered immediately prior to surgery reduces 72 hour pain scores, but may increase complications.

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50
Q

Area of knee not covered in femoral and adductor canal nerve blocks

A

Posterior knee, can develop pseudo DVT symptoms

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51
Q

AAOS recommendation for DVT ppx after TKA

A

Mechanical + pharmacologic recommended, no agent superior than the other. No change in length of anticoagulation needed if factor V Leiden deficiency.

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52
Q

Management of immediate post op flexion contracture after TKA when knee was well balanced in OR

A

Therapy for hamstring contracture and spasms. No pillows under the knee.

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53
Q

Risk for fracture if femur is notched in TKA

A

No risk in torsion. Highest risk is in bending (avoid MUA in notched TKA)

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54
Q

When to consider bypass femoral stem in notched femur

A

More than 3mm depth of notching

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55
Q

Knee deformity that pre-disposes to post-op palsy

A

Valgus and flexion.

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56
Q

Management of post-op foot drop after TKA

A

Remove compressive wraps, flex knee, AFO, observe for 3 months of neurapraxia, then explore if no return.

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57
Q

Risk for patella AVN after TKA

A

Lateral release disrupts the last remaining blood supply to the patella from the lateral superior geniculate artery

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58
Q

Minimum thickness of patella before increasing risk of fracture

A

13mm

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59
Q

Management of patella fractures after TKA

A

No lag, stable implant = brace -> self-directed ROM

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60
Q

Periprosthetic distal femur fracture management in elderly osteoporotic patient with or without stable implant

A

DFR allows immediate full weight bearing, mobilization and more likely to preserve ambulation. Can consider plate-nail combo if younger patient with comminution and osteoporosis

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61
Q

Management of periprosthetic tibial shaft fracture after TKA?

A

Can do IMN around tibial baseplate, board answer likely closed reduction and casting

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62
Q

Acceptable management options for intra-op MCL injury

A

Revision to high post varus/valgus contrained or primary MCL repair with brace x 6 weeks

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63
Q

Management of extensor disruption at tibial tubercle

A

Direct repair and non-op do not work, must perform extensor reconstruction with allograft (recreates native mechanics, maximizes extensor efficiency, bulky, can non-unite or get infected) or mesh (low profile = better for wound healing; however, no patella = residual lag, must have good bone on tibial side.)

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64
Q

Complication of late TKA MUA

A

Supracondylar femur fracture

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65
Q

Operative indication for management of arthrofibrosis s/p TKA

A

No improvement with MUA out to 12 weeks, identified problem with implant alignment, sizing or component position.

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66
Q

Top metallergies

A

1) Nickel 2) Cobalt 3) Chromium

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67
Q

Skin patch testing for metallergy prior to TKA

A

No correlation with internal allergy and joint pain. True test is lymphocyte T-cell proliferation test (LTT) to see if live T-cells react against metal and/or PMMA

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68
Q

Metallergy hypersensitivity type

A

T-cell mediated type IV delayed hypersensitivity

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69
Q

CR knee pros/cons

A

Pros: bone conserving, better at maintaining joint line because flexion gap stays small with PCL intact

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70
Q

Problem in patient s/p CR TKA with inability to get up out of a low chair or okay going up stairs, but not going down stairs

A

Late PCL failure = midflexion instability

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71
Q

PS knee pros/cons

A

Pros: easier balancing of severe deformity, controlled rollback

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72
Q

Causes of cam jump

A

Over release of popliteus, over release of anterior portion of sMCL, anterior translation of femur in anterior referencing technique

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73
Q

Causes of patella clunk

A

Inadequate synovectomy, wide/tall box, small patella component, over-resected patella, patella baja and increased posterior condylar offset (pulls patella distal into box), prior surgery

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74
Q

Causes of anterior polyethylene post wear in PS TKA

A

Hyperextension, flexed femoral component, excess posterior tibial slope and anterior translation of tibial component

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75
Q

Why is there a higher risk of joint line elevation in PS TKA?

A

PCL resection opens the flexion gap, then you chase it by resecting more distal femur and can elevate the joint line significantly

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76
Q

Absolute indications for PS knee

A

Patellectomy, inflammatory OA and PCL insufficiency

77
Q

Pros/cons of AS

A

Pros: No box, easy to switch from CR if PCL deficient intraop

78
Q

Management of mobile bearing dislocation in TKA

A

Open reduction, the medial side may be reduced and lateral side spun out, can’t close reduce these. Also revision for loose flexion gap

79
Q

Modular vs all poly tibia

A

Modular has more backside wear and osteolysis, no clinical differences through

80
Q

Causes of aseptic loosening

A

Cementless = occurs within 1-5 years due to failure of integration. Cemented early = poor cementing technique. Cemented late = breakage of cement mantle

81
Q

Radiographic findings in aseptic loosening vs osteolysis vs infection

A

Aseptic loosening = smooth radiolucent lines, pedestal, eccentric stem. Osteolysis = round lytic lesions. Infection = erosions.

82
Q

What causes osteolysis in TKA?

A

Submicron particle digested by macrophage, magrophage releases TNFa, IL1, IL-6, osteoblasts produce RANK-L, osteoclasts differentiate and resorb bone

83
Q

Definition of a constrained knee?

A

A construction that limits rotation to less than 1.5 degrees. PS is not a constrained knee. Varus/valgus constrained knee with high post is the first constrained knee, then hinge on rotating platform.

84
Q

Indications for rotating hinge TKA

A

Global instability (trauma or infection), hyperextension instability (polio, knee dislocation), endoprosthesis (tumor, fracture), severe MCL deficiency, Charcot arthropathy

85
Q

Hinge TKA function is largely dependent on:

A

Functional extensor mechanism, otherwise it buckles

86
Q

Most common missed diagnosis of a painful TKA?

A

Missed hip osteoarthritis. Other causes include the spine, allodynia, CRPS, loosening, osteolysis, malpositioning/malalignment, instability, metallergy, infection.

87
Q

1 reason for revision TKA within first 2 years of primary surgery

A

Infection

88
Q

How to choose your incision on revision total knee with prior incisions

A

Try to stay 7cm away, pick the most lateral incision because blood supply comes from medial to lateral. Cross transverse incisions at 90 degrees, no less than 60 degree, you see necrosis at 30 degrees. Keep deep fascia layer with the skin flap.

89
Q

Indication for TTO in revision TKA

A

Stiff TKA (<90 degrees flexion) with patella baja

90
Q

Landmark for joint line in revision TKA

A

1.5cm proximal to fibular head. Set joint line with tibia first, then build femur down to it, extension gap 1st, then close flexion gap with augments.

91
Q

Management of failed total knee due to patellar maltracking

A

Rule out infection, then revision TKA to correct malaligned components, not an isolated lateral release.

92
Q

Correctable risk factors for TKA PJI

A

Smoking cessation > 30 days prior, A1c <7, albumin >3.5, BMI >35, immunosuppressant, dental hygiene

93
Q

Non-modifiable risk factors for TKA PJI

A

Post-traumatic knee OA w/stiffness (<90 deg), age >70, autoimmune disease, immunodeficiency, blood transfusion

94
Q

Most common biofilm forming bacteria in TKA

A

S. epi

95
Q

How does biofilm form

A

Bacterial inoculation by planktonic cells -> quorum sensing molecules make them senescent (persister cells in G0) as more bacteria clump together and they produce biofilm which is a highly rigorous extracellular polymeric substance (EPS) that prohibits infection eradication by limiting antimicrobial agent penetration and decreasing function of macrophages and other immune cells

96
Q

Metals with high -> bacterial adherence

A

Titanium alloy -> stainless steel -> pure titanium -> tantalum

97
Q

What puts bacteria in the biofilm into persister state?

A

Antibiotic levels above MIC, nutrient depletion, metabolic stress all put the bacteria into dormant G0 phase. They then resume normal wild type growth when the stressor is removed.

98
Q

Most common cause of recurrent PJI?

A

Retained implant/cement pieces and suture = retained biofilm

99
Q

Definition of surgical site infection in PJI

A

Infection occurring within 1 year of implantation

100
Q

Major criteria for diagnosing PJI

A

2 or more positive cultures with same organism or draining sinus tract communicating with the prosthesis

101
Q

Minor criteria for diagnosing PJI

A

CRP >10/D-dimer>860, ESR>30, synovial WBC>3k/++LE/a-defensin>1, synovial PMN >70%, single + cx, 5+ PMNs/hpf intra-op, intra-op purulence

102
Q

CRP values and timing in TKA

A

Values peak days 2-3, return to normal in 2-3 weeks. Re-elevation can be due to SSI, PJI, DVT, URI, PNA, UTI, ileus and constipation

103
Q

Indications for DAIR procedure

A

<3 weeks duration of infection, non-fungal infection

104
Q

Risk of PJI for every day of wound drainage after 5 days

A

42% in hips, 29% in knees

105
Q

Indication for arthrodesis instead of second stage

A

Loss of functional tissue and extensor mechanism. May consider AKA if neuropathic and significant leg length discrepancy due to bone loss

106
Q

Next step in positive intra-operative culture after presumed aseptic revision

A

Complete revision -> 6 weeks IV abx

107
Q

Proven methods to prevent PJI

A

Abx within 30 minutes of incision, vertical laminar flow (not horizontal, creates vortex flow straight into wound), abx cement in high risk patients

108
Q

How does adding 1g of abx powder to PMMA change it’s mechanical properties?

A

1g abx/40g bag PMMA weakens the cement by 10%. Premixed are better than hand mixed.

109
Q

Blood supply to main option for soft tissue coverage about the knee

A

Medial gastroc flap = medial sural artery. Lateral gastroc flap is only used for far lateral defects because there is little excursion and can cause peroneal nerve palsy

110
Q

Imaging hallmark of fugal PJI

A

Marginal erosions into bone, especially at ligament insertions

111
Q

Most common fungal organism in fungal PJI

A

Candida

112
Q

Mechanism of action in “azole” antifungals

A

P450 inhibitor via ianosterol 14a-demethylase (azole ring). This disrupts the cell wall synthesis in fungi.

113
Q

Antifungal preferred in PJI

A

Triazole agents because they have good oral absorption, good patient tolerance and good tissue penetration. Remember patients may need to be on these for months to years.

114
Q

Only azole anti-fungal that does not need drug level testing to evaluate efficacy

A

Fluconazole

115
Q

Mechanism of action of polyene antifungals

A

Has hydrophilic and lipophilic ends on a long chain that makes the cell wall more crystalline resulting in cell lysis. Amphotericin B is a polyene and has many toxic side effects.

116
Q

Most frequent complication in TKA

A

Patella maltracking

117
Q

Techniques to minimize patellar maltracking in TKA

A

Neutral mechanical axis (valgus increases Q-angle), IR of femoral and/or tibal component, medialization of tibial and/or femoral component, medialize the patella, don’t overstuff (increases lateral retinacular tension)

118
Q

Technique to NOT use when planning your posterior femoral cut in a valgus knee

A

Posterior condylar axis referencing. The lateral femoral condyle hypoplasia will make you IR the femur.

119
Q

Revision solution for this problem?

A

This is impingment in a patient with patella baja. The treatment is to lower the joint line, redo the patella in a more proximal position, transfer the tibial tubercle more proximally, patellectomy (would need to convert to PS)

120
Q

Absolute indication for patella resurfacing

A

Inflammatory arthritis, patellar bone deformity, primary indication for surgery is patellofemoral arthritis

121
Q

Risk of revision surgery in patients with unresurfaced patella

A

4x greater than in resurfaced patella

122
Q

Definition of catrostrophic wear TKA

A

Macroscopic poly failure in intermediate lifecycle of implant, leads to metallosis if untreated…not due to osteolysis

123
Q

Minimum allowable thickness of polyethylene insert

A

8mm

124
Q

Development techniques to minimize HXLPE wear

A

Maximize contact area, minimize contact load

125
Q

Best method for manufacturing polyethylene

A

Direct compression molding, gamma irradiation in inert environment to cross link PE, reheat/anneal +/- Vit E to get rid of free radicals and sterilize in ethylene oxide or gas plasma

126
Q

SPONK etiology

A

Mechanical overload (malalignment, osteoporosis, meniscal tear) -> micrfracture of subchondral bone -> fluid ingress increases intraosseous pressure and disrupts blood flow -> cell necrosis and collapse

127
Q

SPONK treatment

A

Pre-collapse: non-op if <45% condyle width, scope only if mechanical symptoms, HTO for younger pts w/<45% condyle width involved

128
Q

Secondary osteonecrosis of the knee etiology

A

Ischemia, idiopathic, atraumatic, corticosteroids. Typically seen younger age, diffuse involvement with multiple areas involved, lateral femoral condyle more commonly involved

129
Q

Secondary osteonecrosis of the knee treatment

A

Non-op if subchondral bone not affected. Pre-collapse = core decompression if done prior to crescent sign (subchondral collapse), arthroscopy if mechanical symptoms. Post-collapse = TKA preferred, outcomes lower than those with OA.

130
Q

Post-arthroscopy osteonecrosis of the knee etiology

A

Mechanical compression of the cartilage

131
Q

Post-arthroscopy osteonecrosis of the knee treatment

A

Same as SPONK. Non-op if pre-collapse, <45% condyle, scope if mechanical sx, osteotomy if young. UKA/TKA if >50% condyle and older with collapse.

132
Q

Anterior hip approach superficial and deep intervals

A

Sartorius (fem) & TFL (SGN), then recture (fem) & G. medius (SGN)

133
Q

Cons to anterior hip approach

A

LFCN nerve injury and challenging femoral exposure

134
Q

Anterolateral approach interval

A

Between TFL (SGN) and glut medius (SGN)

135
Q

Cons to anterolateral hip approach

A

Femoral exposure, TFL denervation, need to take down some of glut medius

136
Q

Con to direct lateral approach

A

Abductor limp, not proximally extensile (SGN 5cm proximal to greater troch tip)

137
Q

Most stable approach to hip

A

Direct lateral

138
Q

Arteries to avoid in posterior approach when not doing THA

A

IGA along piriformis and MFCA near quadratus

139
Q

Cons of posterior approach to hip

A

Instability, partial denervation of gluteus maximus

140
Q

Anterior vs posterior approach

A

No differences at 3 months, higher dislocation rate posterior, 5 day faster recovery anterior, higher rate of femoral failure anterior

141
Q

Cement vs uncemented femoral stems in THA? Acetabular cup?

A

Cement and cementless femoral stems equivalent in primary THA, cement favored in fracture.

142
Q

Creep

A

Progressive deformation over time

143
Q

Sir Kobe Steals Tricks

A

Decreasing order of Young’s modulus of elasticity: “Siramic”, “Kobalt” chrome, stainless “steel”, “T”itanium, cortical bone, PMMA, UHMWPE, cancellous bone

144
Q

Mechanism of failure in this stem

A

Cantilever bending

145
Q

Charnley all-polyethylene acetabular shell failure rate

A

Add 1% per year they ask about

146
Q

Requirements for bony ingrowth

A

1) Live host bone 2) 40-80% porosity, 50-150 microns deep, gaps <50 microns 3) No motion, fibrous ingrowth if >150 microns of motion

147
Q

Bone ongrowth

A

Not porous, plasma spray or grit blast allows bone to grow into divots, implant roughness gives it initial fixation strength

148
Q

Formula for hydroxyapatite

A

Ca10(PO4)6(OH)2

149
Q

HA use in THA implants

A

Osteoconductive, optimal thickness is 50-75 microns, must be applied onto rough surface or it can delaminate

150
Q

Mean femoral head penetration into THA high cross linked polyethylene

A

0.005mm/yr

151
Q

Equation for volumetric wear

A

V = 3.14 * radius of head^2 * linear wear

152
Q

Optimal femoral head size with respect to wear rates when using highly crosslinked poly?

A

Head size does not affect wear rates

153
Q

Abrasive wear

A

Wear when there is a difference in hardness between two surface or when a third body is trapped between two surfaces

154
Q

Adhesive wear

A

Chemical bonds between two surface are broken everytime movement occurs, can release sub-micron size particle and induce osteolysis

155
Q

Wear threshold per year that leads to osteolysis

A

0.1mm/year

156
Q

Types of artificial joint lubrication

A

Boundary: asperities on each surface contact each other, fluid film: articulating surfaces are separated by the fluid film layer, mixed: surface just barely separated enough to prevent severe wear (in MoM hips, wear decreased with increasing head size due to increased fluid entrapment)

157
Q

Edge wear

A

Maximum area of wear crosses over the edge of the cup, lubrication breaks down and contact pressures increase. Can be caused by impingement, microseparation and edge loading (vertical cup).

158
Q

How does ALTR occur in MoM hips?

A

Dose-related toxicity of Co and Cr with B & T lymphocyte mediated allergic response

159
Q

What gender does worse in MoM hips?

A

Females did worse with resurfacing. Males did worse with MoM THA.

160
Q

Why do you need a manual cell count when evaluating hip aspiration of MoM hips?

A

The ALTR creates necrotic debris and clumps of debris that get miscounted by the automated cell counter.

161
Q

Labs in Trunnionosis

A

Cobalt > chromium 2:1 to 5:1

162
Q

Corrosion associated with trunnionosis

A

Mechanically assisted chemical (crevice) corrosion, small amount of motion at the trunnion disrupts the protective oxide layer

163
Q

Passivation

A

Formation of protective oxide coat in the body (seen instantly with titanium)

164
Q

Fretting corrosion

A

Cyclic motion <100um between two surfaces at any modular junction disrupts the protective oxide layer

165
Q

Crevice corrosion

A

Crevices create local conditions that increase oxidation

166
Q

Galvanic corrosion

A

Two different metals

167
Q

Concerning ion levels in MoM hip vs. metal on PE hip?

A

MoM > 7, metal on PE >1

168
Q

THA complications in sickle cell

A

Early loosening and infection

169
Q

THA complications in inflammatory arthritis

A

Infection

170
Q

THA complications in ankylosing spondylitis

A

HO, stiffness

171
Q

THA complications in Parkinsons

A

Dislocation, higher mortality

172
Q

THA complications in dialysis patients

A

Highest risk for infection, loosening

173
Q

THA complication in post-XRT patients

A

Loosening with cementless implants

174
Q

THA approach with highes incidence of HO

A

Direct lateral

175
Q

HO prophylaxis treatment

A

700cGy 24 hours pre-op or 48 hours post op,nothing outside of that window, Indocin can be given with 1-6 weeks

176
Q

Indications for HO excision

A

Mature HO (~2 years out) and symptomatic

177
Q

Leg lengthening threshold when we get worried about nerve injury

A

2-4cm

178
Q

Indication for cup revision with iliopsoas tendinitis

A

Failure of conservative management, cup 8+mm prominent -> revise cup, if cup doesn’t need revision, then can do psoas tenotomy

179
Q

Option for head liner exchange in well fixed acetabular cup that you don’t have a liner for?

A

Cement in a liner

180
Q

Patients at highest risk for THA dislocation

A

Post-traumatic conversion THA (prior femoral neck ORIF)

181
Q

Indications for and problems with constrained liners for revision THA

A

Reserved for abductor insufficiency. Problem is high failure rate with failure of cup to ingrow and reduced ROM to impingement

182
Q

1 cause of long term THA revision

A

Aseptic loosening

183
Q

Paprosky classification and treatment for femoral bone loos

A

I) intact metaphysis – primary THA 2) metaphyseal bone loss – diaphyseal engaging stem 3A) >4cm diaphsis intact – diaphyseal engaging setm 3B) <4cm diaphyseal bone loss – diaphyseal engaging stem 4) nonsupportive diaphysis - megaprosthesis

184
Q

Acetabular requirements to get a well fixed cup without augments/cages

A

2/3 acebular rim intact and 50% acetabular bone stock

185
Q

What makes up biofilm?

A

15% bacteria, 85% glycocalyx

186
Q

Synovial aspirate cut offs for acute vs chronic PJI

A

Acute WBC >10k and/or 90% PMNs. Chronic >3k and/or 80% PMNs.

187
Q

AAOS guideline for VTE ppx in patients with high risk of bleeding (cirrhosis)

A

Mechanical ppx only

188
Q

AAOS Hip OA CPG strong recommendations

A

For NSAIDs, PT, intra-articular steroid. Against hyaluronic acid

189
Q

Low risk vs high risk prediction of femoral head collapse in AVN?

A

Low risk = Kerboul <190, high risk >240

Adult Recon (1 decks)

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