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.
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
3
Q
AAOS 2021 strong recommendations for knee OA
A
Recommended: patient exercise programs (supervised and self-managed), topical/oral NSAIDs and APAP.
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.
5
Q
AAOS 2021 inconsistent/limited recommendations for knee OA
A
Supplements, massage, laser, acupuncture, electrical/magnetic stimulation, shock wave, PRP, denervation and HTO
6
Q
AAOS 2021 consensus recommendations for knee OA
A
Dry needling and free-floating interpositional spacers (no)
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)
8
Q
Open wedge HTO complications
A
Patella baja (most common), loss of correction secondary to collapse of osteotomy, non-union, harvest site pain
9
Q
Closing wedge HTO complications
A
Patella baja (most common), loss of posterior slope, nerve injury
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
11
Q
DFO valgus anglulation indication
A
12+ degree valgus deformity
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)
13
Q
DFO complications
A
Nonunion, loss of correction, residual patellofemoral maltracking
14
Q
Best DFO for future TKA
A
Crescentic dome, allows for instrumentation of the femur and use of stem later on
15
Q
UKA benefits over TKA
A
Faster recovery, fewer complications, better knee function and less post-operative pain
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
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
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
19
Q
Risks for UKA tibial tray implant subsidence
A
Large resection, tray not on cortical rim, osteoporosis
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
21
Q
DMARDs to continue periop
A
MTX, sulfasalazine, hydroxychloroquine, leflunomide, doxycycline
22
Q
Periop management of corticosteroids
A
No loading dose, continue regular dose in patients up to 16mg/day
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)
24
Q
When to stop tofacitinib (Xeljanz) prior to surgery?
A
7 days, this has a very short 1 day half life
25
When to restart biologic agents after TKA?
14 days after surgery as long as wound healed and staples/sutures are out
26
Severe SLE patients with organ involvement should continue these medications preoperatively? What about moderate disease?
Mycophenoloate mofetil
27
Management of periop abx in PCN allergic patient
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.
28
How does your valgus distal femoral cut angle change with patient height?
Hip offset remains similar despite patient height. Consequently, short patients need a greater valgus cut and tall patients need a smaller valgus cut.
29
Maximum alteration of knee joint line in TKA
8mm. Raising or lowering the joint line beyond 8mm alters the timing of collateral ligament tension in the flexion-extension arc of motion
30
Medial releases in varus knee undergoing TKA
1) osteophytes 2) deep MCL and capsule complex to 1.5cm distal to joint line 3) posteromedial corner 4) sMCL
31
Consequence of posteromedial corner contracture in OA
Fixed internal rotation of tibia, releasing this allows external rotation of the tibia
32
Different releases of sMCL for varus knee balancing
Posterior oblique portion of MCL released if tight in extension, anterior portion of sMCL released if tight in flexion
33
Lateral releases in valgus knee undergoing TKA
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)
34
Next step if inadvertent isolate cut of popliteus tendon
Does not alter static stability 0-90 degrees, PS bearing is fine, more constraint not needed
35
Indications for concomitant osteotomy with TKA
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
36
Releases for tight flexion gap
1) Osteophytes 2) Posterior capsule 3) PCL if CR knee 4) Gastroc. Can also adjust cuts (slope, posterior femoral cut)
37
How many degrees correction of flexion contracture do you get with 2mm more resection of the distal femur?
10 degree correction for each 2mm of resection
38
Balancing knee that is normal in extension and loose in flexion
Upsize poly and either take 2mm more distal femur or release more posterior capsule
39
Balancing knee that is loose in extension and normal flexion
Distalize femur with screws or augments. Or, upsize poly and recess PCL or cut more tibial slope.
40
Tourniquet vs non-tourniquet TKA
Less blood loss and increased short term pain scores with tourniquet use.
41
AAOS strong recommendations for not using what 3 things intra-op?
Navigation, patient specific instrumentation and a drain
42
AAOS strong recommendation for using __ in TKA
TXA decreases blood loss and transfusions, periarticular anesthetic + peripheral nerve block decreases pain and opioid use
43
3 AAOS strong recommendations post-op TKA
CPM doesn’t improve outcomes, therapy same day of TKA decreases length of hospital stay, do not perform routine duplex /us after TKA
44
AAOS strong recommendations for implant design in TKA
No difference in CR/PS, all poly vs modular tibia, patellar resurfacing and cement vs cementless.
45
AAOS strong recommendation for pre-op risk factors in TKA
Patients with obesity have less improvement after TKA
46
TXA mechanism of action
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.
47
How is TXA excreted
95% renal
48
TXA contraindications
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)
49
AAOS strong recommendations for anesthesia and analgesia
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.
50
Area of knee not covered in femoral and adductor canal nerve blocks
Posterior knee, can develop pseudo DVT symptoms
51
AAOS recommendation for DVT ppx after TKA
Mechanical + pharmacologic recommended, no agent superior than the other. No change in length of anticoagulation needed if factor V Leiden deficiency.
52
Management of immediate post op flexion contracture after TKA when knee was well balanced in OR
Therapy for hamstring contracture and spasms. No pillows under the knee.
53
Risk for fracture if femur is notched in TKA
No risk in torsion. Highest risk is in bending (avoid MUA in notched TKA)
54
When to consider bypass femoral stem in notched femur
More than 3mm depth of notching
55
Knee deformity that pre-disposes to post-op palsy
Valgus and flexion.
56
Management of post-op foot drop after TKA
Remove compressive wraps, flex knee, AFO, observe for 3 months of neurapraxia, then explore if no return.
57
Risk for patella AVN after TKA
Lateral release disrupts the last remaining blood supply to the patella from the lateral superior geniculate artery
58
Minimum thickness of patella before increasing risk of fracture
13mm
59
Management of patella fractures after TKA
No lag, stable implant = brace -> self-directed ROM
60
Periprosthetic distal femur fracture management in elderly osteoporotic patient with or without stable implant
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
61
Management of periprosthetic tibial shaft fracture after TKA?
Can do IMN around tibial baseplate, board answer likely closed reduction and casting
62
Acceptable management options for intra-op MCL injury
Revision to high post varus/valgus contrained or primary MCL repair with brace x 6 weeks
63
Management of extensor disruption at tibial tubercle
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.)
64
Complication of late TKA MUA
Supracondylar femur fracture
65
Operative indication for management of arthrofibrosis s/p TKA
No improvement with MUA out to 12 weeks, identified problem with implant alignment, sizing or component position.
66
Top metallergies
1) Nickel 2) Cobalt 3) Chromium
67
Skin patch testing for metallergy prior to TKA
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
68
Metallergy hypersensitivity type
T-cell mediated type IV delayed hypersensitivity
69
CR knee pros/cons
Pros: bone conserving, better at maintaining joint line because flexion gap stays small with PCL intact
70
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
Late PCL failure = midflexion instability
71
PS knee pros/cons
Pros: easier balancing of severe deformity, controlled rollback
72
Causes of cam jump
Over release of popliteus, over release of anterior portion of sMCL, anterior translation of femur in anterior referencing technique
73
Causes of patella clunk
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
74
Causes of anterior polyethylene post wear in PS TKA
Hyperextension, flexed femoral component, excess posterior tibial slope and anterior translation of tibial component
75
Why is there a higher risk of joint line elevation in PS TKA?
PCL resection opens the flexion gap, then you chase it by resecting more distal femur and can elevate the joint line significantly
76
Absolute indications for PS knee
Patellectomy, inflammatory OA and PCL insufficiency
77
Pros/cons of AS
Pros: No box, easy to switch from CR if PCL deficient intraop
78
Management of mobile bearing dislocation in TKA
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
Modular vs all poly tibia
Modular has more backside wear and osteolysis, no clinical differences through
80
Causes of aseptic loosening
Cementless = occurs within 1-5 years due to failure of integration. Cemented early = poor cementing technique. Cemented late = breakage of cement mantle
81
Radiographic findings in aseptic loosening vs osteolysis vs infection
Aseptic loosening = smooth radiolucent lines, pedestal, eccentric stem. Osteolysis = round lytic lesions. Infection = erosions.
82
What causes osteolysis in TKA?
Submicron particle digested by macrophage, magrophage releases TNFa, IL1, IL-6, osteoblasts produce RANK-L, osteoclasts differentiate and resorb bone
83
Definition of a constrained knee?
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
Indications for rotating hinge TKA
Global instability (trauma or infection), hyperextension instability (polio, knee dislocation), endoprosthesis (tumor, fracture), severe MCL deficiency, Charcot arthropathy
85
Hinge TKA function is largely dependent on:
Functional extensor mechanism, otherwise it buckles
86
Most common missed diagnosis of a painful TKA?
Missed hip osteoarthritis. Other causes include the spine, allodynia, CRPS, loosening, osteolysis, malpositioning/malalignment, instability, metallergy, infection.
87
#1 reason for revision TKA within first 2 years of primary surgery
Infection
88
How to choose your incision on revision total knee with prior incisions
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
Indication for TTO in revision TKA
Stiff TKA (<90 degrees flexion) with patella baja
90
Landmark for joint line in revision TKA
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
Management of failed total knee due to patellar maltracking
Rule out infection, then revision TKA to correct malaligned components, not an isolated lateral release.
92
Correctable risk factors for TKA PJI
Smoking cessation > 30 days prior, A1c <7, albumin >3.5, BMI >35, immunosuppressant, dental hygiene
93
Non-modifiable risk factors for TKA PJI
Post-traumatic knee OA w/stiffness (<90 deg), age >70, autoimmune disease, immunodeficiency, blood transfusion
94
Most common biofilm forming bacteria in TKA
S. epi
95
How does biofilm form
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
Metals with high -> bacterial adherence
Titanium alloy -> stainless steel -> pure titanium -> tantalum
97
What puts bacteria in the biofilm into persister state?
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
Most common cause of recurrent PJI?
Retained implant/cement pieces and suture = retained biofilm
99
Definition of surgical site infection in PJI
Infection occurring within 1 year of implantation
100
Major criteria for diagnosing PJI
2 or more positive cultures with same organism or draining sinus tract communicating with the prosthesis
101
Minor criteria for diagnosing PJI
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
CRP values and timing in TKA
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
Indications for DAIR procedure
<3 weeks duration of infection, non-fungal infection
104
Risk of PJI for every day of wound drainage after 5 days
42% in hips, 29% in knees
105
Indication for arthrodesis instead of second stage
Loss of functional tissue and extensor mechanism. May consider AKA if neuropathic and significant leg length discrepancy due to bone loss
106
Next step in positive intra-operative culture after presumed aseptic revision
Complete revision -> 6 weeks IV abx
107
Proven methods to prevent PJI
Abx within 30 minutes of incision, vertical laminar flow (not horizontal, creates vortex flow straight into wound), abx cement in high risk patients
108
How does adding 1g of abx powder to PMMA change it’s mechanical properties?
1g abx/40g bag PMMA weakens the cement by 10%. Premixed are better than hand mixed.
109
Blood supply to main option for soft tissue coverage about the knee
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
Imaging hallmark of fugal PJI
Marginal erosions into bone, especially at ligament insertions
111
Most common fungal organism in fungal PJI
Candida
112
Mechanism of action in “azole” antifungals
P450 inhibitor via ianosterol 14a-demethylase (azole ring). This disrupts the cell wall synthesis in fungi.
113
Antifungal preferred in PJI
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
Only azole anti-fungal that does not need drug level testing to evaluate efficacy
Fluconazole
115
Mechanism of action of polyene antifungals
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
Most frequent complication in TKA
Patella maltracking
117
Techniques to minimize patellar maltracking in TKA
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
Technique to NOT use when planning your posterior femoral cut in a valgus knee
Posterior condylar axis referencing. The lateral femoral condyle hypoplasia will make you IR the femur.
119
Revision solution for this problem?
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
Absolute indication for patella resurfacing
Inflammatory arthritis, patellar bone deformity, primary indication for surgery is patellofemoral arthritis
121
Risk of revision surgery in patients with unresurfaced patella
4x greater than in resurfaced patella
122
Definition of catrostrophic wear TKA
Macroscopic poly failure in intermediate lifecycle of implant, leads to metallosis if untreated…not due to osteolysis
123
Minimum allowable thickness of polyethylene insert
8mm
124
Development techniques to minimize HXLPE wear
Maximize contact area, minimize contact load
125
Best method for manufacturing polyethylene
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
SPONK etiology
Mechanical overload (malalignment, osteoporosis, meniscal tear) -> micrfracture of subchondral bone -> fluid ingress increases intraosseous pressure and disrupts blood flow -> cell necrosis and collapse
127
SPONK treatment
Pre-collapse: non-op if <45% condyle width, scope only if mechanical symptoms, HTO for younger pts w/<45% condyle width involved
128
Secondary osteonecrosis of the knee etiology
Ischemia, idiopathic, atraumatic, corticosteroids. Typically seen younger age, diffuse involvement with multiple areas involved, lateral femoral condyle more commonly involved
129
Secondary osteonecrosis of the knee treatment
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
Post-arthroscopy osteonecrosis of the knee etiology
Mechanical compression of the cartilage
131
Post-arthroscopy osteonecrosis of the knee treatment
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
Anterior hip approach superficial and deep intervals
Sartorius (fem) & TFL (SGN), then recture (fem) & G. medius (SGN)
133
Cons to anterior hip approach
LFCN nerve injury and challenging femoral exposure
134
Anterolateral approach interval
Between TFL (SGN) and glut medius (SGN)
135
Cons to anterolateral hip approach
Femoral exposure, TFL denervation, need to take down some of glut medius
136
Con to direct lateral approach
Abductor limp, not proximally extensile (SGN 5cm proximal to greater troch tip)
137
Most stable approach to hip
Direct lateral
138
Arteries to avoid in posterior approach when not doing THA
IGA along piriformis and MFCA near quadratus
139
Cons of posterior approach to hip
Instability, partial denervation of gluteus maximus
140
Anterior vs posterior approach
No differences at 3 months, higher dislocation rate posterior, 5 day faster recovery anterior, higher rate of femoral failure anterior
141
Cement vs uncemented femoral stems in THA? Acetabular cup?
Cement and cementless femoral stems equivalent in primary THA, cement favored in fracture.
142
Creep
Progressive deformation over time
143
Sir Kobe Steals Tricks
Decreasing order of Young’s modulus of elasticity: “Siramic”, “Kobalt” chrome, stainless “steel”, “T”itanium, cortical bone, PMMA, UHMWPE, cancellous bone
144
Mechanism of failure in this stem
Cantilever bending
145
Charnley all-polyethylene acetabular shell failure rate
Add 1% per year they ask about
146
Requirements for bony ingrowth
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
Bone ongrowth
Not porous, plasma spray or grit blast allows bone to grow into divots, implant roughness gives it initial fixation strength
148
Formula for hydroxyapatite
Ca10(PO4)6(OH)2
149
HA use in THA implants
Osteoconductive, optimal thickness is 50-75 microns, must be applied onto rough surface or it can delaminate
150
Mean femoral head penetration into THA high cross linked polyethylene
0.005mm/yr
151
Equation for volumetric wear
V = 3.14 * radius of head^2 * linear wear
152
Optimal femoral head size with respect to wear rates when using highly crosslinked poly?
Head size does not affect wear rates
153
Abrasive wear
Wear when there is a difference in hardness between two surface or when a third body is trapped between two surfaces
154
Adhesive wear
Chemical bonds between two surface are broken everytime movement occurs, can release sub-micron size particle and induce osteolysis
155
Wear threshold per year that leads to osteolysis
0.1mm/year
156
Types of artificial joint lubrication
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
Edge wear
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
How does ALTR occur in MoM hips?
Dose-related toxicity of Co and Cr with B & T lymphocyte mediated allergic response
159
What gender does worse in MoM hips?
Females did worse with resurfacing. Males did worse with MoM THA.
160
Why do you need a manual cell count when evaluating hip aspiration of MoM hips?
The ALTR creates necrotic debris and clumps of debris that get miscounted by the automated cell counter.
161
Labs in Trunnionosis
Cobalt > chromium 2:1 to 5:1
162
Corrosion associated with trunnionosis
Mechanically assisted chemical (crevice) corrosion, small amount of motion at the trunnion disrupts the protective oxide layer
163
Passivation
Formation of protective oxide coat in the body (seen instantly with titanium)
164
Fretting corrosion
Cyclic motion <100um between two surfaces at any modular junction disrupts the protective oxide layer
165
Crevice corrosion
Crevices create local conditions that increase oxidation
166
Galvanic corrosion
Two different metals
167
Concerning ion levels in MoM hip vs. metal on PE hip?
MoM > 7, metal on PE >1
168
THA complications in sickle cell
Early loosening and infection
169
THA complications in inflammatory arthritis
Infection
170
THA complications in ankylosing spondylitis
HO, stiffness
171
THA complications in Parkinsons
Dislocation, higher mortality
172
THA complications in dialysis patients
Highest risk for infection, loosening
173
THA complication in post-XRT patients
Loosening with cementless implants
174
THA approach with highes incidence of HO
Direct lateral
175
HO prophylaxis treatment
700cGy 24 hours pre-op or 48 hours post op,nothing outside of that window, Indocin can be given with 1-6 weeks
176
Indications for HO excision
Mature HO (~2 years out) and symptomatic
177
Leg lengthening threshold when we get worried about nerve injury
2-4cm
178
Indication for cup revision with iliopsoas tendinitis
Failure of conservative management, cup 8+mm prominent -> revise cup, if cup doesn’t need revision, then can do psoas tenotomy
179
Option for head liner exchange in well fixed acetabular cup that you don’t have a liner for?
Cement in a liner
180
Patients at highest risk for THA dislocation
Post-traumatic conversion THA (prior femoral neck ORIF)
181
Indications for and problems with constrained liners for revision THA
Reserved for abductor insufficiency. Problem is high failure rate with failure of cup to ingrow and reduced ROM to impingement
182
#1 cause of long term THA revision
Aseptic loosening
183
Paprosky classification and treatment for femoral bone loos
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
Acetabular requirements to get a well fixed cup without augments/cages
2/3 acebular rim intact and 50% acetabular bone stock
185
What makes up biofilm?
15% bacteria, 85% glycocalyx
186
Synovial aspirate cut offs for acute vs chronic PJI
Acute WBC >10k and/or 90% PMNs. Chronic >3k and/or 80% PMNs.
187
AAOS guideline for VTE ppx in patients with high risk of bleeding (cirrhosis)
Mechanical ppx only
188
AAOS Hip OA CPG strong recommendations
For NSAIDs, PT, intra-articular steroid. Against hyaluronic acid
189
Low risk vs high risk prediction of femoral head collapse in AVN?
Low risk = Kerboul <190, high risk >240
