Recon

Question 1

What is the most common cause of early revision in hip resurfacing?

Answer 1

periprosthetic fracture

most common

Question 2

What linear wear rate has been associated with osteolysis and loosening?

Answer 2

> 0.1 mm/year

Question 3

5 variables leading to PE wear characteristics

Answer 3

PE thickness:

• should be >8mm

Articular surface design:

• higher congruity/contact surface area leads to lower contract stress and better wear characteristics

Kinematics:

• ie knee kinematics. Change them to get most congruous implant

PE sterilization:

• Gamma radiation Sterilization in oxygen depleted environment is best
• Then package in vacuum, argon or nitrogen environment

PE machining

• Best is with direct-compression molding

Question 4

4 complications of free fibula vascularized bone graft?

Answer 4

1. sensory deficit
2. motor weakness
3. FHL contracture
4. tibial stress fracture from side graft is taken

Question 5

5 Considerations in sickle cell in arthroplasty

Answer 5

Pre-op

Check for osteomyelitis

Avoid sickle cell crisis (lots of fluids, oxygenate, avoid acidosis)

CHF often present with chronic anmeia

pre-op transfusion/plasmaphoresis

Intraop

Protrusio

Widened canal (marrow hyperplasia)

poor bone quality

osteonecrosis

Postop

Higher infection rates (no salmonella)

Do NOT need to cover for salmonella

Higher rates of dislocation

Question 6

Techniques to reduce nerve injury in THR for DDH?

Answer 6

1. good pre-operative planning
2. limb lengthening
3. subtrochanteric osteotomy
4. intra-operative wake-up test
5. neurophysiologic intraoperative monitoring
6. downsizing implant components if presenting with deficits peri-operatively

Question 7

On an AP xray, what landmarks are most useful for assessing acetabular cup position?

Answer 7

1. medial border of cup should approximate the ilioischial line and lie close to the teardrop
2. inferior border of cup should be at level of inferior teardrop line

Question 8

Postpartum female with hip pain - what do you think of?

Answer 8

transient osteoporosis of hip

Question 9

5 ways to avoid failure of cemented femoral stem.

Answer 9

1. smooth stem
2. > 2 mm mantle
3. rigid stem
4. centralized stem
5. No defects of mantle

Question 10

Two main contraindications to hip osteotomy?

Answer 10

Restricted hip motion

Advanced OA

Question 11

List 4 devices available for fixation of a TKA periprosthetic femoral fracture

Answer 11

condylar buttress plate (non-locking)

locking supracondylar plate

blade plate

dynamic compression screw

Question 12

Most common nerve injury with hip scope?

Answer 12

Pudendal from traction

Question 13

Describe femoral rollback

Answer 13

Lateral condyle has a larger curvature of radius so as you flex & extend the knee, the lateral condyle will pivot about the medial side

Question 14

Conceptually, what is the ideal patient to use constrained components in THA?

Answer 14

In patients with a soft tissue insufficiency not amenable to repair or augmentation

it is NOT to correct for malalignment

Question 15

Saggital balancing:

Flexion: Loose

Extension: Tight

What do you do?

Answer 15

resect femur + thicker poly

or

release capsule posteriorly and thicker poly

Question 16

Differentiate adhesive, abrasive, and third body wear.

Answer 16

adhesive wear

most important in osteolytic process

microscopically PE sticks to prosthesis and debris gets pulled off

abrasive wear

cheese grater effect of prosthesis scraping off particles

third body wear

particles in joint space cause abrasion and wear

Question 17

Indications for a hinged knee prosthesis?

Answer 17

1. global instability
2. massive bone loss in a neuropathic joint
3. oncologic procedures
4. hyperextension instability

Question 18

3 benefits of increasing offset?

Answer 18

1. increased soft-tissue tension
2. decreased impingement
3. decreased joint reaction force

Question 19

Risks of patellar periprosthetic fracture

Answer 19

patellar osteonecrosis

asymmetric resection of patella

inappropriate thickness of patella

implant related

• central single peg implant
• uncemented fixation
• metal backing on patella
• inset patellar component

Question 20

General workup algorithm for MoM patients

Answer 20

Yearly assessment (x-ray, blood levels)

If high risk: get advanced imaging (MARS MRI)

Revision if:

Symptomatic, osteolysis, poor cup abduction angle, increasing metal ion level, pseudotumour

Question 21

5 risks of HO in TKA

Answer 21

Periosteal stripping of anterior femur

Male

Obesity

Post-traumatic

Hypertropic osteophystes preop

Arthropathy (DISH, AS)
Paget’s

Cementless components

Approach: iliofemoral > Kocher > II

Manipulation post op

(NOT RA)

Question 22

in DDH THA, name 3 ways to decrease sciatic nerve palsy

Answer 22

Visualize/palpate for tension

lengthen 4cm or 15-20% of length (some say

Neuromonitoring

Question 23

Risk factors for Hip OA

Answer 23

Modifiable

Articular cartilage

Muscle weakness

Heavy physical stress at work

High impact sporting activities

Non-modifiable

Female

Increased age

Genetics

Developmental/acquired deformities

Hip dysplasia

SCFE

LCP

Question 24

2 ways of testing for nickel sensitivity?

Answer 24

1. patch testing
2. lymphocyte transformation test (LST)

Question 25

2 indications for chronic suppressive antibiotics in periprosthetic infection

Answer 25

Patient too sick to undergo surgery Complex arthroplasty with huge revision needed

Question 26

Name 8 risks of AVN of the hip (or of anything)

Answer 26

"ASEPTIC" Alcoholism/AIDS/Immnosuppressed Steroids/Sickle cell Erlenmeyer flask (Gaucher) Pancreatitis Trauma Idiopathic Caissons (The Bends) Hypercoaguable state

Question 27

Risks for knee OA

Answer 27

_Modifiable_ Articular trauma Occupation: repetitive knee bending Muscle weakness Large body mass Metabolic syndrome * Central (abdominal obesity) * Dyslipidemia (high triglycerides & high LDLs) High BP Elevated fasting glucose _Non-modifiable_ Female Increased age Genetics Race African american males are the least likely to receive total joint replacement when compared to whites and Hispanics

Question 28

What procedure has the lowest reoperation rates for patients with unicompartmental OA?

Answer 28

TKA

Question 29

3 surgical options for AVN femoral head in post-collapse:

Answer 29

Rotational osteotomy (may be done precollapse). Only if small lesion Resurfacing THA Arthrodesis

Question 30

Describe a differential MCL release in varus TKA

Answer 30

Posterior oblique tight in extension: release if tight in extension Anterior portion tight in flexion: release if tight in flexion

Question 31

(Small/large) head:neck ratios in THA ______ dislocation risk by increasing ______ distance

Answer 31

Large decreases Jump

Question 32

5 risk factors for squeaking with ceramic bearings?

Answer 32

1. edge loading 2. impingement and acetabular malposition 3. third-body wear 4. loss of fluid film lubrication 5. thin, flexible (titanium) stems

Question 33

What is the main determinant for number of wear particles created?

Answer 33

Volumetric wear V=3.14r^2 \* w (the circular area of the head times the rate at which it penetrates medially) w = linear wear rate

Question 34

Optimal micromotion in biologic fixation?

Answer 34

_Rule of 50's_ * pore size 50-300um * preferably 50-150um * porosity of 40-50% * gaps \<50um * micromotion \<150um

Question 35

What type of inflammatory response does MoM create?

Answer 35

Lymphocytic (it's a hypersensitivity response) vs. macrophage for PE

Question 36

What is the mechanism of failure for fracture of cemented femoral stems?

Answer 36

Cantilever bending. Cemented stems are thinner and more prone to breaking.

Question 37

3 causes of TKA periprosthetic femoral fractures

Answer 37

poor bone quality Mechanical stress riser Neurologic disorders

Question 38

Name 5 risk factors for dislocation after THA

Answer 38

female Treatment for AVN of femoral head Treatment for acute fracture inflammatory arthritis age \> 70

Question 39

What is a complication unique to cermaic bearings and what is the cause?

Answer 39

stripe wear occurs during lift-off separation of the head during gait (edge loading)

Question 40

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: glucosamine and chondroitin

Answer 40

STRONG evidence AGAINST

Question 41

Two risks with not resurfacing patella in THR?

Answer 41

Higher risk of anterior knee pain Higher risk of secondary resurfacing (No difference in complications such as AVN, fracture, ect)

Question 42

Well fixed cup with a broken locking mechanism, what is the best option?

Answer 42

Bone graft acetabular defects and cement in a new liner

Question 43

patella baja in setting of Revision TKA. What do you do for exposure?

Answer 43

Tibial tubercle osteotomy so that you can realign patella at same time

Question 44

5 complications of hip resurfacing?

Answer 44

periprosthetic femoral neck fracture implant loosening (aseptic) HO increased metal ion level Pseudotumour

Question 45

5 Risks of supracondylar fracture post TKA

Answer 45

Rheumatoid arthritis chronic steroid therapy Parkinson's disease osteopenia female gender

Question 46

Surgical options for a stiff TKA (4)

Answer 46

MUA arthroscopic or open adhesiolysis +/- MUA quadricepsplasty component revision.

Question 47

By how much does a hip fusion decrease efficiency of gait?

Answer 47

50%

Question 48

Femoral rollback clinically improves what?

Answer 48

improves quadriceps function and range of knee flexion by preventing posterior impingement during deep flexion

Question 49

3 indications for ETO as per JAAOS 2013 (Paprosky)

Answer 49

Significant varus remodeling a well fixed uncemented implant a long column of cement below the stem

Question 50

What effect does osteoprotegrin have on bone turnover?

Answer 50

Inhibits RankL thereby inhibitng bone turnover.

Question 51

4 ways to decrease free radicals in polyethylene production

Answer 51

Vitamin E Mechanical deformation Low doses of radiation alternated with annealing Final sterilization in ethylene oxide gas

Question 52

How long do ESR and CRP take to return to normal following surgery?

Answer 52

CRP = 21 days ESR = 90 days

Question 53

4 risks for creating stress shielding

Answer 53

stiff femoral stem: (most important risk factor) large diameter stem extensively porous coated stem greater preoperative osteopenia

Question 54

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: **rehabilitation, education and wellness activity**

Answer 54

STRONG evidence FOR

Question 55

POsition of hip arthrodesis

Answer 55

20-35 degrees of flexion 0-5 degrees adduction 5-10 degrees ER (equal to contralateral) Avoid abudction as it creates pelvic obliquity and increased back pain

Question 56

How thich do you want a cement mantle?

Answer 56

At least 2 mm thick

Question 57

3 complications unique to ceramic heads?

Answer 57

1. fracture 2. sqeaking 3. stripe wear

Question 58

hydroxyapatite coating is what kind of agent? What effect on biologic fixation does it have?

Answer 58

osteoconductive Allows more rapid closure of gaps shorter time to biologic fixation (in animals, and in humans in some studies)

Question 59

What are the five goals of revision total knee surgery?

Answer 59

1. extraction of components with minimal bone loss and destruction 2. restoration of bone deficiencies 3. restoration of joint line 4. balance knee ligaments 5. stable revision implants

Question 60

Surgeon wants to use extramedullary referencing for tibia cuts in a total knee arthroplasty. If he ignores the rotational mismatch between the ankle and the tibial tubercle, what will the result? a. No coronal malalignment b. Varus malalignment on coronal c. Valgus malalignment on coronal d. Increase posterior slope cut into tibia

Answer 60

b. Varus malalignment on coronal

Question 61

What type of arthroplasty will worsen your golf game?

Answer 61

TKA: increases handicap THA: no change

Question 62

Name 6 tools to have on hand during revision arthroplasty (Paprosky Jaaos 2013)

Answer 62

Manufacturere specific explant tools flexible osteotomes trephines high speed burrs ultrasonic cement removal instruments universal extraction tools

Question 63

Risk factors for dislocation following THR?

Answer 63

1. prior hip surgery (greatest risk factor) 2. female sex 3. \>70-80 years of age 4. posterior surgical approach * repairing capsule and reconstructing external rotators brings dislocation rate close to anterior approach 5. malpositioning of components * ideal positioning of acetabular component is 40 degrees of abduction and 15 degrees anteversion give or take 10 degrees in each position * in general, excessive anteversion increases risk of anterior hip dislocation; excessive retroversion increases risk of posterior hip dislocation 6. spastic or neuromuscular disease (Parkinson's) 7. drug or alcohol abuse 8. decreased offset (decreases tissue tension and stability) 9. decreased femoral head to neck ratio

Question 64

2 risks for increased MoM serum ion levels

Answer 64

Smaller component size Cup abduction angle \>55

Question 65

In sciatic nerve injury post-THA, what percentage fully recover?

Answer 65

80% remain symptomatic

Question 66

What do you do for intra-operative calcar fracture during THR?

Answer 66

stem removal, cable wiring of the calcar, and re-insertion of the primary stem

Question 67

Options for cartilage defects in an adult without end stage OA and no major coronal deformity. (List By Size)

Answer 67

_femoral condyle defect_ correct malaligment, ligament instability, meniscal deficiency measure size \< 4 cm2 = microfracture or osteochondral autograft transfer (pallative if older/low demand) \> 4 cm2 = osteochondral allograft transplantation or autologous chondrocyte implantation _patellofemoral defect_ address patellofemoral maltracking and malalignment measure size \< 4 cm2 = microfracture or osteochondral autograft transfer \> 4 cm2 = autologous chondrocyte implantation (microfracture if older/low demand)

Question 68

List 4 options for a Vancouver B2 periprosthetic fracture

Answer 68

Cylindrical, distally fitted monoblock stem (old gold standard) Modular, distally fitted, tapered stem (Wagner style - new gold standard) Cemented stem Allograft-prosthetic composite Tumour replacement

Question 69

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: NSAIDS

Answer 69

STRONG evidence FOR

Question 70

2 contraindications for TT osteotomy

Answer 70

## Footnote Osteolysis Proximal tibial osteoporosis

Question 71

How do you deal with the mechanical axis when doing a UKA?

Answer 71

Undercorrect the mechanical axis by 2-3 degrees do NOT want it to be in neutral or varus as these are associated with poor outcomes

Question 72

MCL rupture during TKA. What are 2 options?

Answer 72

Suture repair + PS/CR + hinged knee brace x 6 weeks Unhinged constrained knee (VVC)

Question 73

Elevation of the joint line by how much will lead to motion problems?

Answer 73

8mm

Question 74

What is the effect of the routine use of antbiotic loaded cement in TKA?

Answer 74

Increased risk of aseptic loosening

Question 75

6 risks of femoral neck fracture in hip resurfacing

Answer 75

notching of the femoral neck osteoporotic bone large areas of preexisting osteonecrosis femoral neck impingement (from malaligned acetabular component) female sex varus positioning of femoral component

Question 76

6 risk factors for nerve injury in THR?

Answer 76

1. developmental dysplasia of the hip 2. revision surgery 3. female gender 4. limb lengthening 5. posttraumatic arthritis 6. surgeon self-rated procedure as difficult

Question 77

disruption of medial & lateral inferior geniculate arteries will results in what perioperatively during TKA?

Answer 77

patellar tendon rupture Superior geniculate artery for quad tendon

Question 78

7 techniques for femoral revision

Answer 78

1. Primary total hip components – minimal loss of metaphyseal bone 2. Extensively porous coated stems – metaphyseal bone loss with intact diaphysis 3. Monoblock calcar revision stems 4. Modular tapered diaphyseal fit stems 5. Impaction grafting 6. Allograft prosthetic composites 7. Modular oncology stem

Question 79

Fracture of ceramic on ceramic THA. What must you do at revision?

Answer 79

Replace with another ceramic component. Despite thorough I&D, there will be ceramic debris left over that will cause massive 3rd body wear of any other type of component

Question 80

Name the three most common hip scope portals, their landmarks and associated nerve injuries.

Answer 80

* Anterior = LCFN * Intersection between superior GT and ASIS * Anterolateral = SGN * 2 cm anterior, 2 cm superior to AS aspect of GT * Established first * Posterolateral = Sciatic * 2 cm posterior to tip of GT

Question 81

Correction of what deformity has the highest rate of peroneal nerve palsy in TKA

Answer 81

valgus & flexion

Question 82

Do you need to cover for salmonella after arthroplasty in sickle cell?

Answer 82

No While there are increased infection rates overall, there were no salmonella infections

Question 83

What is the most common complication of THA performed for salvage of a failed internal fixation for pathologic proximal femur fracture?

Answer 83

Deep joint infection

Question 84

4 indications for constained liner in THR.

Answer 84

1) cases with no identifiable cause for instability 2) abductor deficiency 3) patients with neuromuscular disorders 4) recurrent instability with well positioned components

Question 85

Contraindications to CR knee (3)?

Answer 85

1. varus deformity \> 10 degrees 2. valgus deformity \> 15 degrees 3. No PCL

Question 86

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: Viscosupplementation

Answer 86

STRONG evidence AGAINST

Question 87

4 surgical techniques to treat a recurrant dislocator (hip) in revision setting.

Answer 87

* 1 realign components * indicated if malalignment explains dislocatio * 2 head enlargement * optimize head-neck ratio * (Dual mobility is similar option) * 3 trochanteric osteotomy and advancement * places abductor complex under tension which increases hip compression force * 4 conversion to a constrained acetabular component

Question 88

What is the proposed benefit of a mobile bearing knee?

Answer 88

Tibial poly rotates on the baseplate. This creates a larger surface area for contact and thought to decrease contact pressure and reduce wear.

Question 89

5 indications for knee fusion?

Answer 89

1. painful ankylosis after infection or trauma 2. neuropathic arthropathy 3. tumor resection 4. salvage for failed TKA (most common) 5. loss of extensor mechanism

Question 90

Order of release in flexion contacture in TKA

Answer 90

osteophytes posterior capsule gastrocnemius

Question 91

Risks of blood loss & allogenic transfusion in TKA (4)

Answer 91

Slower physical recovery higher rates of postoperative infection increased length of hospital stay increased morbidity and mortality

Question 92

5 causes of sciatic nerve injury in THR?

Answer 92

* compression (most common) due to * hematoma * retraction * tight bandages * direct trauma * heat from polymethylmethacralate polymerization * stretch * unknown (40%)

Question 93

Ficat Classification of femoral head AVN

Answer 93

I: normal II: sclerotic or cystic lesions IIa: no crescent sign IIb: subchondral collapse (crescent sign) without flatterning of femoral head III: flattening of femoral head IV: OA with decreased joint space with articular collapse \*Note: some use the Steinberg classification (see picture), which is a modification of Ficat

Question 94

3 signs of prosthetic infection on radiographs.

Answer 94

1. periosteal reaction 2. scattered patches of osteolysis 3. generalized bone resorption without implant wear

Question 95

How do you deal with MCL injury intra-operatively?

Answer 95

**_MCL transection/deficiency_** * suture repair or suture anchor reattachment, use of either CR or PS implant, hinged knee brace for 6 weeks postoperatively * use of unlinked constrained prosthesis **_Both MCL and LCL_** * revision to an hinged knee (linked constrained prosthesis)

Question 96

How do you get an antibiotic spacer to elute more abx?

Answer 96

Increase porosity (hand mix instead of vacuum) increase concentration of antibiotic Increase surface area of cement (antibiotic beads)

Question 97

4 variables that affect THA stability?

Answer 97

1. component design (i.e. head size, skirts) 2. component position (version/abduction) 3. soft-tissue tensioning (offset) 4. soft tissue function

Question 98

Risk factor for sciatic nerve injury in THA (4) What percentage of patients have subclinical injury What percentage of patients with a clinical nerve injury have persistent injury

Answer 98

Female Revision surgery DDH 70% have subclinical injury 80% of patients with nerve injury hae persistent neurologica dysfunction

Question 99

In a loose femoral component (cemented \> uncemented), how does the proximal femur remodel?

Answer 99

varus and retroversion

Question 100

4 risks of iliopsoas impingement post THA

Answer 100

Retained cement Malposition acetabular component LLD Excessive length of screws

Question 101

After THA for CDH, patient has sciatic nerve palsy not responsive to conservative measures. What are 2 surgical options?

Answer 101

SUbtroch osteotomy downsizing components

Question 102

T/F? sterilization in argon/nitogen creates free radicals

Answer 102

True: free radicals are needed to create cross-linking HOWEVER, sterilization in oxygen causes unacceptably high levels of free radicals, leading to a brittle PE with higher rates of failure

Question 103

4 signs of a well fixed femoral component?

Answer 103

* spot-welds * new endosteal bone that contacts porous surface of implant * absence of radiolucent lines around porous portion of femoral stem * proximal stress shielding in extensively-coated stems * absence of stem subsidence on serial radiographs

Question 104

3 contraindications to MoM implants

Answer 104

Pregnant women Renal disease (metal ions excreted by kidneys) Metal hypersensitivity due to metal ions

Question 105

5 considerations for hemophiliac in arthroplasty

Answer 105

Replace factors to 100% preop Abnormal morphology: valgus, flattened femorla head, acetabuluar dysplasia (like LCP) Increased infection rates Higher rate of failure (no effect on HO)

Question 106

What does stripe wear indicate?

Answer 106

Impingement and excursion that occurs during dislocation of component stripe wear is cuased by edge loading and recurrent subluxation during gait

Question 107

What is the general cutoff for metal ion levels that indicates further workup?

Answer 107

7ppb of cobalt or chromium

Question 108

Contraindications to UKA

Answer 108

inflammatory arthritis ACL deficiency absolute contraindication for mobile-bearing UKA and lateral UKA controversial for medial fixed-bearing **fixed varus deformity \> 10 degrees** **fixed valgus deformity \>5 degrees** restricted motion arc of motion flexion contracture of \> 5-10° previous meniscectomy in other compartment tricompartmental arthritis (diffuse or global pain) younger high activity patients and heavy laborers overweight patients (\> 82 kg) grade IV patellofemoral chondrosis (anterior knee pain)

Question 109

AAOS classification for femoral bone loss

Answer 109

attached

Question 110

Bone marrow edema in femoral head AVN is predictive of what 2 things:

Answer 110

pain eventual collapse

Question 111

Outcomes (success rate) of 2 stage revision for infected arthroplasty?

Answer 111

70-90% in delayed (after 4-6 week abx) reimplantation vs. 35% for early 2nd stage reimplantation

Question 112

In setting of multiple revision TKA with multiple lateral scars. Where do you make your incision?

Answer 112

At the most lateral scar Blood supply comes from medial so you want to preserve blood supply to lateral skin as much as possible

Question 113

## Footnote How does the Anderson Orthopedics Bone Loss Classification help decision making in revision TKR?

Answer 113

Type 1 – metaphyseal bone is intact and supportive of prosthesis – contained defects can be filled with graft or cement Type 2 – Deficiency of metaphyseal bone compromises implant support – need to use a extended stem and combine this with either structural bone graft or a modular prosthesis that allows for augmentation Type 3 – deficiency of metaphyseal region – Tumor prosthesis

Question 114

Saggital balancing: Flexion: Tight Extension: Ok What do you do?

Answer 114

Downsize femur or Slope tibia

Question 115

Two features that antibiotic must have to be used in cement (ie for a spacer)

Answer 115

Heat stable Water soluble

Question 116

Decreasing offset does what to JRF in THA?

Answer 116

Increases it b/c it weakens abductors

Question 117

2 surgical treatments for Psoas impingment post-THR and what is indication for each?

Answer 117

1) Psoas release/tenotomy --\> well positioned cup 2) Acetabular revision --\> excessive anterior cup overhang

Question 118

What is the minimum number of THA cases a surgeon must perform per year to have a base level of competence (decreased complications)

Answer 118

35

Question 119

TT osteotomy techniqe (for TKR exposure)?

Answer 119

1. 6-10 cm bone fragment cut from medial to lateral 2. fixed with screws or wires

Question 120

Contraindications to hip fusion?

Answer 120

active infection severe limb-length discrepancy greater than 2.0 cm. bilateral hip arthritis adjacent joint degenerative changes * lumbar spine * contralateral hip * ipsilateral knee severe osteoporosis degenerative changes in lumbar spine contralateral THA increased failure rate (40%) in THA when there is a contralateral hip arthrodesis

Question 121

Treatment of acetabular bone loss by poprovsky grade?

Answer 121

* Type 1: Minimal deformity, intact rim * Type 2A: Superior bone lysis with intact superior rim * Type 2B: Absent superior rim, superolateral migration * Type 2C: Localized destruction of medial wall * Type 3A: Significant bone loss, superolateral cup migration * Type 3B: Significant bone loss, pelvic discontinuity Sheth et al. reviewed acetabular bone loss in revision total hip arthroplasty. They state that Paprosky Type 1 and 2 defects can usually be managed with porous-coated hemisphere cup secured with screws. Type 3 defects require reconstruction cages to protect with cups and structural augments or custom triflange implants.

Question 122

What are the 4 steps of osteolysis?

Answer 122

1. particulate debris formation 2. macrophage activated osteolysis 3. prosthesis micromotion 4. particulate debris dissemination

Question 123

Name two types of surface wear and two types of fatigue wear.

Answer 123

Surface = adhesive or abrasive Fatigue = delamination or pitting

Question 124

What is the go -to osteotomy for a valgus knee?

Answer 124

Varus producing distal femoral osteotomy

Question 125

Most accurate and precise way to measure polyethylene wear

Answer 125

radiostereometric analysis

Question 126

What single test must you order before converting a hip fusion to a THR?

Answer 126

EMG to assess gluteus medius. If non-functional then you need to use a constrained liner.

Question 127

3 ways to decrease post-op pain in TKA?

Answer 127

Per-articular injection Peripheral nerve blockage Not using tourniquet AAOS CPG 2015

Question 128

5 risk factors for neurovascular injury in TKA

Answer 128

1. severe valgus or flexion defromity 2. pre-operative neuropathy 3. tourniquet longer than 120 min 4. post op hematoma 5. use of epidural anesthesia

Question 129

Most important type of wear in the osteolytic process?

Answer 129

adhesive wear PE sticks to prosthesis and debris gets pulled off

Question 130

Why is it a bad idea to use posterior referencing in valgus knee?

Answer 130

Hypoplastic lateral condyle will lead to increased IR of the femoral component if unrecognized

Question 131

What two things happen (biologically) with a chronic (\>4 week) infection that necessitates explant instead of just I&D with a poly exchange?

Answer 131

bacteria forms a biofilm bacteria invades bone-implant interface

Question 132

5 Risk factors for developing motor nerve palsies post THA:

Answer 132

developmental dysplasia of the hip revision surgery female gender limb lengthening posttraumatic arthritis surgeon self-rated procedure as difficult Uncemented components

Question 133

Other than instability, what is an important risk of valgus contracture release in TKR?

Answer 133

Peroneal nerve injury

Question 134

Three technical methods to avoid wound complication in revision TKA

Answer 134

1. Use most lateral incision 2. dont cross incisions at angles less than 6o degrees 3. 5-6 cm skin bridges

Question 135

Name 4 options for extensor mechanism repair post rupture post TKA

Answer 135

Priamry repair Autograft/Allograft reconstruction Synthetic material Gastrocs rotation flap

Question 136

Optimal porosity in biologic fixation:

Answer 136

50% _rule of 50's_ * pore size 50-300um preferably 50-150um porosity of 40-50% gaps \<50um micromotion \<150um

Question 137

What is a Kerboul angle and what does it predict?

Answer 137

Combination of angles of involved areas of AVN on AP and Lateral xray. Higher the number higher the chance for progression.

Question 138

Patient with PS knee suffers acute pain and inability to move knee. Diagnosis and management?

Answer 138

Cam jump Reduce using anterior drawer maneuver

Question 139

What are the MSIS criteria for periprosthetic Joint Infection

Answer 139

1. There is a sinus tract communicating with the prosthesis; or 2. A pathogen is isolated by culture from at least two separate tissue or fluid samples obtained from the affected prosthetic joint; or 3. Four of the following six criteria exist: Elevated serum erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) concentration, Elevated synovial leukocyte count, Elevated synovial neutrophil percentage (PMN%), Presence of purulence in the affected joint, Isolation of a microorganism in one culture of periprosthetic tissue or fluid, or Greater than five neutrophils per high-power field in five high-power fields observed from histologic analysis of periprosthetic tissue at ×400 magnification.

Question 140

When do you treat post-operative LLD?

Answer 140

Wait 6 months for soft tissue tension to settle.

Question 141

Should you routinely used navigated or patient specific TKA?

Answer 141

No strong evidence against *routine* use no difference in outcomes vs. conventional AAOS CGP 2015

Question 142

Use of a closed suction drain (hemavac, JP etc) post TKA gives a risk of what?

Answer 142

Increased risk of transfusion

Question 143

Post-TKA - when should you start PT?

Answer 143

POD 0 - same day of surgery Leads to better outcomes AAOS CPG 2015

Question 144

PAO - why can patient weight bear right away?

Answer 144

Posterior column remains intact

Question 145

Unresurfaced patella vs. resurfaced patella in TKA will have: (2)

Answer 145

Higher risk of anterior knee pain Higher risk of secondary resurfacing

Question 146

What amount of femoral lengthening leads to increased rates of sciatic nerve palsy?

Answer 146

4 cm

Question 147

Optimal position of hip fusion?

Answer 147

* 20-35° of flexion * 0°-5° adduction * 5-10° external rotation

Question 148

In a simplified acetabular bone loss classification, what amount of bone loss suggests an incompetent vs. compentent rim?

Answer 148

\>2/3 of rim remaining is competent

Question 149

During TKA, implants are perfect but patella still maltracks. What is your first move?

Answer 149

DEFLATE THE TOURNIQUET

Question 150

Three ways to change offset through femoral component selection.

Answer 150

1. choosing a stem with more or less offset 2. choosing a stem with a different neck-shaft angle 3. modifying the length of the femoral neck

Question 151

3 stages of the TKA Su classification of periprosthetic femoral fractures

Answer 151

I: fracture proximal to femoral component II: # originates at proximal aspect of femoral component and extends proximally III: any part of # line distal to upper edge of anterior flange of femoral component

Question 152

Location of popliteal artery in relation to tibial plateau in flexion/extension

Answer 152

Extension: 1cm posterior Flexion: 2cm posterior

Question 153

5 contraindications to knee fusion.

Answer 153

1. active infection 2. bilateral knee arthrodesis 3. contralateral leg amputation 4. significant bone loss 5. ipsilateral hip or ankle DJD

Question 154

Complication of free-fibular transfer resulting in leg pain?

Answer 154

Tibial stress fracture

Question 155

What is lambda in terms of arthroplasty?

Answer 155

Defines lubrication of MoM components Lambda ratio = thickness of fluid film to the composite root mean square of surface roughness * severe mixed lubrication * Abrasive wear occurs via direct contact of the two bearing surface \>3: * fluid film lubrication is sufficient to substantially reduce effect of load and minimze friction and wear

Question 156

Name the nerve at risk with each hip portal: a) anterior b) Anterolateral c) Posterolateral

Answer 156

a) LCFN b) SGN c) sciatic

Question 157

5 types of wear

Answer 157

_Adhesive:_ * most important * PE sticks to prosthesis and gets pulled off _Abrasive:_ * cheese greater effect _3rd body_ _volumetric:_ * main determinant of # of particles created _Linear_

Question 158

2 Complications specific to UKA

Answer 158

Tibial stress fracture (under baseplate) tibial component collapse (tibial side gets messed up)

Question 159

What is the most commonly injured division of the sciatic nerve in THA?

Answer 159

peroneal division of sciatic

Question 160

What type of antibiotic spacer elutes more antibiotics?

Answer 160

Static Although eradication rates for mobile vs. static are the same!

Question 161

Describe the Poprovsky acetabular bone loss classification.

Answer 161

## Footnote Type I Minimal deformity, intact rim Type IIA Superior bone lysis with intact superior rim Type IIB Absent superior rim, superolateral migration Type IIC Localized destruction of medial wall Type IIIA Bone loss from 10am-2pm around rim, superolateral cup migration Type IIIB Bone loss from 9am-5pm around rim, superomedial cup migration

Question 162

Name 6 risk factors for peroneal nerve palsy post THA

Answer 162

Hip dysplasia posterior approach extreme lengthening post-traumatic arthritis uncemented femoral component surgeon self-rating the surgery as difficult

Question 163

Risk factors for periprosthetic fracture

Answer 163

osteolysis and loosening trauma age gender osteoporosis index diagnosis revision surgery technique type of implant used (JAAOS 2014 - periprosthetic fractures)

Question 164

You do a cup/cage for pelvic discontinuity. You find the hip to be unstable and don't want to revise the femoral component. What is an option to decrease instability?

Answer 164

Trochanteric advancement. DO NOT use a constrained liner. It puts too much strain on the acetabular revision and it will fail. You can use a constrained liner if boney ingrowth has already occured.

Question 165

4 Options for treating Paprosky 4 femoral bone loss

Answer 165

Incompetent isthmus Allograft prosthetic composite Long cemented stem Impaction grafting + long cemented stem Modular oncology components (femoral replacement)

Question 166

Allogenic Transfusion triggers in TKA (JAAOS 2014)

Answer 166

DO NOT transfuse if \>8g/dL Absolutely transfuse if Beween 6-8g/dL, depends on symptoms This corresponds with the American Association of Blood Banks CPG that has a trigger of 8g/dL

Question 167

Paprosky 1 femoral bone loss. Outcomes of revision with primary, monobloc stems. What should you do?

Answer 167

Poor: revision rates of 20% at 8 years Use SROM instead. Revision rate of 1.5% at 7 years. JAAOS 2013 (Paprosky - Femoral bone loss) They say you can use monobloc stems in paprosky 1 but many have reported poor results and have moved towards distally fitted stems

Question 168

Position of knee fusion if pre-existing LLD of \> 2 cm?

Answer 168

Full extension because leg will be able to clear the ground during gait.

Question 169

## Footnote 3 Methods to mobilize extensor mechanism for better exposure in revision TKR

Answer 169

1. Lateral release 2. Remove retro-patellar adhesions 3. Subperiosteal dissection of superomedial tibia

Question 170

What's the issue with arthrocentesis for culture in periprosthetic joint infection?

Answer 170

Low sensitivity (28%) Therefore careful how you use it Same with gram stain

Question 171

Risk factor for nonunion in ORIF of periprosthetic TKA fracutre of distal femur

Answer 171

Extensile lateral approach (vs. submuscular approach) Use submuscular (MIPO)

Question 172

What is the important structure at risk during a lateral retinacular release?

Answer 172

Superior geniculate artery Can lead to extensor mechanism rupture or patellar fracture

Question 173

5 complications to using constrained liner

Answer 173

Acetabular loosening dissociation of the constrained liner from the shell material fatigue disengagement of the constraining ring excessive wear

Question 174

Three patient facors necessary for PAO?

Answer 174

1. symptomatic dysplasia in an adolescent or young adult 2. concentrically reduced hip 3. mild-to-moderate arthritis

Question 175

Lowest WBC & PMN from prosthetic joint apsirate that indicates infection?

Answer 175

WBC: \>1100 cells/mm² PMN: \>64% Both above: PPV 98.6% Both below: NPV 98.2% (Ghanem & Parvizi JBJS 2008)

Question 176

TKA: Outcomes of All cemented vs. All uncemented

Answer 176

Same AAOS CPG 2015

Question 177

Two bail out options for repeat total hip dislocators once revision options exhausted?

Answer 177

Convert to hemi with large head Resection arhtroplasty

Question 178

What is the success rate of I and D + liner exchange for acute infection?

Answer 178

50-55%

Question 179

Describe the Hartofilikadis classification.

Answer 179

## Footnote **Hartofilakidis Classification** Dysplasia (Type A) Femoral head within acetabulum despite some subluxation. Segmental deficiency of the superior wall. Inadequate true acetabulum depth. Low dislocation (Type B) Femoral head creates a false acetabulum superior to the true acetabulum. There is complete absence of the superior wall. Inadequate depth of the true acetabulum. High dislocation (Type C) Femoral head is completely uncovered by the true acetabulum and has migrated superiorly and posteriorly. There is a complete deficiency of the acetabulum and excessive anteversion of the true acetabulum.

Question 180

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: Acupuncture

Answer 180

STRONG evidence AGAINST

Question 181

6 factors that influence success of revision TKR (think local factors) (pre-op factors)

Answer 181

1. Pre-surgical diagnosis and extent of reconstruction required 2. ROM 3. extensor mechanism function 4. collateral ligament sufficiency 5. Quality of skin and soft tissues 6. remaining bone stock

Question 182

Name 5 complications unique to THA

Answer 182

Sciatic nerve injury HO Osteolysis Pseudotumour squeaking Dislocation LLD Iliopsoas tendon impingement

Question 183

What are the driving recomendations post TKR?

Answer 183

1. 4 weeks after a right total knee 2. less than 4 weeks after a left total knee

Question 184

Medial compartment OA. Outcomes of valgus HTO vs. Uni knee?

Answer 184

No difference Moderate evidence AAOS CPG 2015

Question 185

What is the biggest risk for requiring postop blood transfusion post THA?

Answer 185

Low Pre-ob Hb

Question 186

Saggital balancing: Flexion: Good Extension: Loose What do you do?

Answer 186

Augment femur or Downsize femur + thicker poly

Question 187

AVN hip: what factor determines whether you can do hip preservation vs. arthroplasty?

Answer 187

Kerboul angle Kerboul angle \>200 = arthroplasty

Question 188

How does CPM effect outcomes following primary TKA?

Answer 188

Continuous passive motion (CPM) devices have not demonstrated superior clinical outcomes in multiple level 1 studies.

Question 189

5 Risks of HO post THA

Answer 189

Prolonged surgical time Hypertrophic subtype of OA Handling soft tissues during surgery Previous HO DISH Paget's Ankylosing Sponlylitis

Question 190

Complications with TJA in hemophiliacs

Answer 190

Increased infection increased risk of hematoma Inreased stiffness/arthrofibrosis (not instability)

Question 191

In what position should you close the knee after TKA?

Answer 191

Flexion, to avoid overtightening the extensor mechanism that leads to stiffness

Question 192

6 risk factors for intra-operative acetabular fracture during THR?

Answer 192

1. underreaming \>2mm 2. elliptical modular cups 3. osteoporosis 4. cementless acetabular components 5. dysplasia 6. radiation

Question 193

5 things that maximize biologic fixation in arthroplasty

Answer 193

_Rule of 50's_ * pore size **50-300um** (preferably **50-150um**) * porosity of 40-**50%** * gaps **50um** * micromotion 1**50um** * Maximal contact with bone

Question 194

highyl cross-linked UHMPE has lower rates of what kinds of wear?

Answer 194

Adhesive and abrasive wear

Question 195

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: Weight Loss

Answer 195

MODERATE evidence FOR

Question 196

Saggital balancing: Flexion: Tight Extension: Tight What do you do?

Answer 196

Thinner poly (min is 6 mm) or Resect tibia

Question 197

What is the recommended femoral, acetabular and combined version in THA

Answer 197

Femoral: 10-15 degrees anteverted Acetabular: 5-25 degrees anteverted Combined: 37 degrees anteverted

Question 198

2 options for treating Paprosky 3B femoral bone loss

Answer 198

Modular tapered stem with antirotational splines (Wagner style) - preferred Impaction grafting + cemented stem

Question 199

Cavitary defects in TKA. What do you use to fill a defect 1cm?

Answer 199

\>1cm: augment or structural bone allograft

Question 200

What differentiates osteonecrosis from transient osteoporosis on MRI?

Answer 200

Presence of a double density sign

Question 201

Where is the peroneal nerve in relation to the lateral capsule What do you have to do in TKA to protect it?

Answer 201

When doing a lateral capsular release, make sure you stay on bone (tibia) and use cautery

Question 202

Describe the Paprovsky femoral bone loss classification.

Answer 202

## Footnote Paprosky Classification of Femoral Bone Loss Type I Minimal metaphyseal bone loss Type II Extensive metaphyseal bone loss with intact diaphysis Type IIIa Extensive metadiaphyseal bone loss, minimum of 4 cm of intact cortical bone in the diaphysis Type IIIb Extensive metadiaphyseal bone loss, less than 4 cm of intact cortical bone in the diaphysis Type IV Extensive metadiaphyseal bone loss and a nonsupportive diaphysis

Question 203

Contrast 1st to 3rd generation cementing techniques.

Answer 203

**_1st generation_** * hand-mixed cement * finger packed cement * no canal preparation or cement restrictor **_2nd generation_** * cement restrictor placement * cement gun * femoral canal preparation * brush and dry **_3rd generation_** * vacuum-mixing to reduce cement porosity * cement pressurization * femoral canal preparation * pulsatile lavage

Question 204

What is an advantage and disadvantage of zirconia compared to alumnia for bearing surfaces?

Answer 204

1. Zirconia is tougher and less prone to fracture 2. Zirconia can undergo phase transformation of tetragonal to monoclinic crystals that makes the surface rough and leads to wear.

Question 205

What do spot welds mean for biologic fixation?

Answer 205

A well fixed component represents new endosteal bone that contacts porous surface of implant

Question 206

Contra-indications to using subvastus type incisions for TKR?

Answer 206

1. ROM 2. obese patient 3. hypertrophic arthritis 4. previous HTO 5. Previous arthrotomy 6. Revision TKR

Question 207

How do you employ radiation to reduce HO formation?

Answer 207

600-800 cGy (6Gy) administered ideally within 24-48 hours following procedure

Question 208

Describe the ratio for mixing antibiotic cement for vano and tobra.

Answer 208

In a 40 g bag of cement: 3 g of vanco 4 g of tobra (gent may be substituted for tobra)

Question 209

What is the most common complication after isolated PE liner exchange in THA?

Answer 209

Dislocation

Question 210

AAOS classification for acetabulr bone loss

Answer 210

see image

Question 211

What cytokine released by macrophages activates RankL during the osteolysis process?

Answer 211

TNF-Alpha

Question 212

4 ways to treat patella baja in TKA

Answer 212

Superior placement of patellar component with resection of inferior pole Lower joint line Tibial tubercle transfer to cephalad position Patellectomy

Question 213

Saggital balancing: Flexion: Ok Extension: Tight What do you do?

Answer 213

Resect femur or Release posterior capsule

Question 214

Risks for early failure of HTO? Which is most important?

Answer 214

Delayed or nonunion - most important Presence of tibial lateral thrust (b/c lax LCL) Age \>50 BMI \>25 Insufficient valgus correction Pre-op flexion Previous arthroscopic debridement

Question 215

Treatment of a) proximal wound necrosis and b) distal wound necrosis with TKR?

Answer 215

a) local wound care and skin graft b) Muscle flap coverage to protect extensor mechanism

Question 216

What is the difference between Tc and In bone scans?

Answer 216

Tc-99m (technetium) detects inflammation and In-111 (indium) detects leukocytes

Question 217

Define q angle

Answer 217

Angle between: ASIS and center of patella (pull of extensor mech) Center of patella and tibial tubercle (long axis of patellar lig) Normal is 11 ± 7 deg Remember this picture to figure out what causes patella instability

Question 218

Contrast the femur and tibia cuts made in classic versus anatomic cuts for TKR

Answer 218

## Footnote Classic technique – 5-6 degree valgus femoral cut and neutral tibia cut Anatomic technique – 9 degree valgus femur and 3 degree varus tibia

Question 219

Describe the 3 types of ideal candidates for hip resurfacing according to Matta

Answer 219

* patients with proximal femoral deformity making total hip arthroplasty difficult * patients with high risk of sepsis due to prior infection or immunosuppression * patients with a neuromuscular diagnosis

Question 220

What percentage of patients recover full strength after a sciatic nerve palsy in THA?

Answer 220

Only 35-40%

Question 221

AVN of one hip, what must you investigate for?

Answer 221

AVN of contralateral hip Bilateral disease 80% of the time ±multifocal disease (3%)

Question 222

5 complications of knee osteotomy.

Answer 222

* Compartment syndrome * Non or mal union * Over or under correction * Peroneal nerve injury * Patella baja

Question 223

Order of release for varus deformity in coronal plane balancing

Answer 223

1. osteophytes, meniscus & its capsular ttachments 2. deep MCL & capsule 3. posteromedial corner * semimembranosus & capsule 4. Superficial MCL * do not fully release. Perform either * subperiosteal elevation or * differential release: posterior oblique if tight in extension, anterior portion if tight in flexion 5. PCL

Question 224

Equipment on hand for a femoral stem removal?

Answer 224

To facilitate stem removal, the following instruments should be on hand: * manufacturer-specific explant tools * flexible osteotomes * trephines * high-speed burrs (eg, pencil tip, carbide tip, metal cutting wheel) * ultrasonic cement removal instruments * universal extraction tools that allow attachment to the stem or taper

Question 225

3 patient contraindications for MoM bearings?

Answer 225

1. pregnant women 2. renal disease 3. metal hypersensitivity due to metal ions

Question 226

What is the outcome of cryotherapy and CPM machines post TKA?

Answer 226

No improvement in outcome for either

Question 227

What prevents collapse in hip AVN?

Answer 227

bisphosphonates | (more than core decompression)

Question 228

Hip and knee Arthroplasty: Low virulence infection in immunocompromised patient, within minimal increase in ESR, CRP. What type of infection should you suspect?

Answer 228

Fungal Candida most common

Question 229

5 risk factors for nerve injury in TKR?

Answer 229

1. preoperative valgus and/or flexion deformity 2. tourniquet time \> 120 min 3. postoperative use of epidural analgesia 4. aberrant retractor placement 5. preoperative diagnosis of neuropathy (centrally or peripherally)

Question 230

Downside of using tourniquet in TKA? Does it affect outcome

Answer 230

Incrased post-op pain No effect on outcome AAOS CPG 2015

Question 231

List 2 absolute and 3 relative contraindications for hip resurfacing

Answer 231

_absolute_ * bone stock deficiency of the femoral head or neck (e.g., cystic degeneration of the femoral head) * abnormal acetabular anatomy (small) _relative_ * coxa vara (increased risk for neck fractures) * significant leg length discrepancies (resurfacing does not allow for leg length corrections) * female gender (controversial)

Question 232

5 causes of late instability of THR?

Answer 232

1. polyethylene wear 2. component malpositioning or loosening 3. trauma 4. infection 5. deterioration in neurological status of the patient

Question 233

What is the role or arthroscopy and lavage in knee OA?

Answer 233

No role AAOS CPG

Question 234

5 indications for PS TKA

Answer 234

Indicated whenever there is risk of AP laxity If also valgus/varus laxity - consider constrained Inflammatory arthritis PCL deficiency/Functionally absent PCL Previous patellectomy Varus deformity \>10 degrees Valgus deformity \>15 degrees

Question 235

Order of release in Varus TKA deformity

Answer 235

Osteophytes, meniscus and capsular attachments Deep MCL Capsule Posteromedial corner (semimembranosus & capsule) Superficial MCL PCL \*My CORR Recon instructor said it doesn't matter your order, as long as have you have one and it makes sense (ie don't start with PCL) \*\* MY CORR Recon instructor could beat up YOUR CORR Recon instructor

Question 236

How will leg length be affected by placing the femoral center of rotation above/below the acetabular center of rotation?

Answer 236

_Femoral above acetabular:_ * increased leg length _Femoral below acetabular:_ * decrease leg length

Question 237

What is the primary indication for conversion to a constrained acetabular component?

Answer 237

recurrent instability with a well positioned acetabular component due to soft tissue deficiency or dysfunction

Question 238

4 risk factors for wear in a tibial baseplate sterilized in air?

Answer 238

1. Increasing shelf age 2. younger age 3. male gender 4. rough tibial baseplate

Question 239

5 ways to increase offset in THA

Answer 239

increasing length of femoral neck decreasing neck-shaft angle medializing the femoral neck while increasing femoral neck length trochanteric advancement alteration of the acetabular liner (lateralized liner)

Question 240

Describe Tonnis arthritis grade

Answer 240

0: no signs of OA 1: sclerosis of the joint minimal joint space narrowing & osteophyte formation 2: small cysts in the femoral head or acetabulum Moderate joint space narrowing 3: Advanced arthritis large cysts in femoral head/acetabulum Joint space obliteration and severe deformity of the femoral head

Question 241

2 methods of polyethylene production and which is better?

Answer 241

1) Compression moulding - better 2) Machining - Inferior because machining shear forces lead to cracking and delamination

Question 242

grit blasted surfaces allow for what kind of biologic fixation?

Answer 242

ongrowth

Question 243

Imaging to assess for pseudotumor?

Answer 243

MRI with metal subtraction.

Question 244

A 58-year-old man has significant pain and stiffness after undergoing right total knee arthoplasty 6 months ago. ESR is 45mm/hr (normal 0-20) and a CRP is 13.5 mg/l(normal

Answer 244

Repeat aspiration Best step in equivocal aspirate is re-aspiration

Question 245

In general, how do posteromedial knee structures affect flexion vs. extension gaps in TKA?

Answer 245

Posteromedial knee structures affect extension fap (ie semimembranosus)

Question 246

Preferred approach to hip arthrodesis?

Answer 246

Lateral approach with trochanteric osteotomy or Anterior approach Must preserve abductors

Question 247

4 advantages of articulating antibiotic spacer

Answer 247

Decreased reimplantation exposure time Better maintenance of joint space and motion Decreased quad shortening Better patient satisfaction

Question 248

## Footnote 4 Technical methods to avoid patellar mal-tracking

Answer 248

1. ER femoral component 3 degrees 2. Lateralize the femoral component 3. ER tibial component 4. Patella button on superomedial patella

Question 249

Comparison of Warfarin, LMWH, Rivaroxaban in VTE prophylaxis (general)

Answer 249

Rivaroxaban \> LMWH \> Warfarin at preventing clots Rivaroxaban \> LMWH \> Warfarin in bleeding risk

Question 250

Position of knee fusion?

Answer 250

5-7 valgus 15 flexion

Question 251

Classification of patellar periprosthetic fractures

Answer 251

Goldberg Type I: not involving implant/cement interface of quads mechanism Type II: involving implant/cement interface or quads Type III A: inferior pole fracture with patellar ligament rupture B: Inferior pole fracture without patellar ligament rupture Type IV: all types of fracture dislocations

Question 252

Which classification is this?

Answer 252

AAOS Classification of Acetabular Bone Loss

Question 253

List 4 options to deal with patella Baja during TKR.

Answer 253

1. Place patellar button superior and trim inferior osteophytes (mild baja) 2. Lower joint line (moderate) 3. Tibial tubercle cephalad transfer (moderate) 4. Patellectomy (severe)

Question 254

3 methods of increasing exposure after medial parapatellar approach and mobilization of extensor mechanism.

Answer 254

Rectus snip Vy turndown TT osteotomy

Question 255

Asymptomatic AVN of hip ID'ed on MRI, what percentage of patients will go on to collapse? What if they have Sickle cell?

Answer 255

33% 75% in patients with sickle cell

Question 256

5 Risks of intraoperative periprosthetic femur fracture

Answer 256

Female Technical errors Cementless implants osteoporosis Revision Cementless press-fit technique Compromised bone stock Impaction grafting technique * Prophylactive cerclage wires and cortical onlay strut allografts are recommended to help reduce the risk Mimimally invasive technique

Question 257

4 Risk factors for HO in THR?

Answer 257

1. prolonged surgical time 2. excessive soft tissue handling during procedure 3. hypertrophic osteoarthritis 4. male gender

Question 258

What 5 technical factors will lead to patellar maltracking in TKA?

Answer 258

IR of femoral component medialization of femoral component IR of tibial component Medialization of the tibial component Placing patellar component on the lateral side of patella

Question 259

in MoM components, what causes seizing?

Answer 259

No enough clearance (difference in diameter between acetabular and femoral components) Clearance 100-200um maximizes fluid thickness Too much clearance: wear as fluid is allowed to leak out between components Too little clearance: not enough fluid in between components Clamping/equatorial seizing

Question 260

Cement mantle how thick leads to increased risk of fracture?

Question 261

How are metal ions excreted?

Answer 261

Renal

Question 262

Risk of patellar prosthesis failure

Answer 262

* Metal backed components * poor ingrowth * peg failure * dislocation of poly * component fracture • poor surgical technique * asymmetric resection (not achieving equal facet thickness) * excessive patellar resection (not maintaining native patellar height) * overstuffing PF joint * not maintaining vascular supply * poor patellofemoral tracking

Question 263

Lab test with highest correlation to periprosthetic infection?

Answer 263

IL-6

Question 264

Kerboul classification of femoral head AVN

Answer 264

Gives cross sectional area of AVN as a combined angle 190-240^o: 50% chance of collapse \>240^o: 100% risk of collapse

Question 265

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: HTO

Answer 265

LIMITED evidence FOR

Question 266

Contrast the timing of post-operative femur periprosthetic fractures for cemented versus cementless?

Answer 266

Cemented = usually \> 5 years out, occurs at the tip Cementless = Usually within first 6 months due to stress riser created during broaching. Tapered stems fracture in metaphysis, extensive coated stems fracture more distally.

Question 267

Name risk factors for periprosthetic infection There are 17 (THINK: ADRIAN BLOWS MONKEYs)

Answer 267

_Preoperative_ * Malnutrition * DM * Obesity (BMI \> 40kg/m2) * Male * Post-traumatic arthritis * inflammatory arthritis * Colonization with MRSA _Intraoperative_ * Inadequate Skin prep * Surgical gowns and gloves (no difference between space-suits, but both and gloves are highly contaminated) * Regular cement * OR configuration/traffic * Wound closure * Longer OR time _Postop_ * Retention of foley \> 1 day * Blood transfusions * Prolonged wound Drainage * Dental Procedures

Question 268

What is the best predictor of ambulatory status following conversion of hip fusion to THR?

Answer 268

Gluteus medius function.

Question 269

5 techniques for acetabular revision

Answer 269

1. Hemispherical cup – 1. need 50% bone stock, use 2 mm larger than last reamer, augment with screws 2. Jumbo cup – usually 6-10 mm larger than previous cup 3. High hip center 2. Impaction grafting with a cemented cup 3. Structural allograft 4. Cup cage – no posterior wall, significant loss of superior bone, discontinuity. 5. Tantalum cup with augments

Question 270

6 risk factors for femoral neck fracture following hip resurfacing.

Answer 270

1. notching of the femoral neck 2. osteoporotic bone 3. large areas of preexisting osteonecrosis 4. femoral neck impingement (from malaligned acetabular component) 5. female sex 6. varus positioning of femoral component

Question 271

3 factors that affect risk of AVN after hip dislocation

Answer 271

Amount of initial displacement reduction decompression of hematoma (maybe)

Question 272

Most common complication after revision THA in the setting of pelvic discontinuity?

Answer 272

dislocation

Question 273

2 forms of prophylaxis in HO

Answer 273

NSAIDs Radiation therapy 700cGy (7 Gy) (THA) 24-48hrs post op

Question 274

How do you re-establish the correct joint line in revision TKR?

Answer 274

Revise tibial side first. Tibial joint line should be 1.5 to 2 cm above head of fibula. Can also compare to other knee with xray.

Question 275

3 major common complications of PAO?

Answer 275

Anterior overcorrrection NV injury Intra-articular fracture

Question 276

What is the most common reason for THA revision?

Answer 276

Instability

Question 277

What does heating do in the process of making polyethylene?

Answer 277

Decreases free radicals

Question 278

DORR classification

Answer 278

Measurement of IM canal width at the LT and width of IM canal 10cm below Measurement at diaphysis divided by measurement at LT _Dorr A:_ * Ratio * Cortices seen on both AP & Lateral * Amenable to uncemented _Dorr B:_ * Ratio 0.5 - 0.75 * Thinning of posterior cortex on lateral * Still ok for uncemented _Dorr C:_ * Ratio \>0.75 * Thinning on both views * Stovepipe femur * Use cemented

Question 279

What is a differential release of the superficial MCL?

Answer 279

Release in 2 parts: Posterior oblique: tight in extension, so release if tight in extension ANterior portion: release if tight in flexion

Question 280

Contraindication to using extensively porous coated stem for revision of a type 3 femur?

Answer 280

IIIB defects with canals \>19 mm in diameter

Question 281

Two technical factors that increase MoM wear rates?

Answer 281

Abduction \> 55 and smaller head size

Question 282

Define Contact pitch to rim distance

Answer 282

in MoM components Distance between point of application of the JRF and the rim of the acetabular component in standing position Inverse relationship between CPR and wear

Question 283

What is the first step if the patella lateralizes during ROM with trial implants in place?

Answer 283

Deflate tourniquet and try again.

Question 284

Name two types of antibiotic spacers and a benefit/drawback for each.

Answer 284

Dynamic - Better patient function and satisfaction, however less effective at eluting antibiotics. Static - No ROM and poorer satisfaction, much better abx elution. \*No difference in eradication rates between mobile/static spacers

Question 285

7 steps to optimize cement fixation

Answer 285

_limited porosity of cement_ * leads to reduced stress points in cement _cement mantle \> 2mm_ * increased risk of mantle fractures if _stiff femoral stem_ * flexible stems place stress on cement mantle _stem centralization_ * avoid malpositioning of stem to decrease stress on cement mantle _smooth femoral stem_ * sharp edges produce sites of stress concentration _absence of mantle defects_ * defined as any area where the prosthesis touches cortical bone with no cement between * creates an area of higher concentrated stress and is associated with higher loosening rates _proper component positioning within femoral canal_ * varus or valgus stem positioning increases stress on cement mantle

Question 286

Contra-indication to using a extensively porous coated long stem postethis for Pop Type IIIb defects?

Answer 286

Canal diameter greater than 19 mm.

Question 287

What is run-in wear?

Answer 287

Increased wear for 1st million cycles (~1 year) in MoM components A steady state of wear follows

Question 288

Valgus Deformity order of release in coronal plane balancing

Answer 288

1. osteophytes 2. lateral capsule 3. ITB (if tight in extension) * perform Z-plasty or release off Gerdy's tubercle 4. Popliteus 5. LCL * some release LCL first if tight in both flexion and extnesion * Cannot do full release or will get varus laxity- pie crust.

Question 289

wear rate of non and highly cross-linked UHMPE

Answer 289

non-crosslinked UHMPE: 0.1-0.2mm/yr crosslinked: 0.003mm/yr Smaller particles and more resistant (but worse mechanical properties)

Question 290

Stratgies for minimizing blood loss in TKA

Answer 290

JAAOS 2014

Question 291

2 necessary pieces of equipment for removing a well fixed cup

Answer 291

flexible osteotomes and size specific removal tools

Question 292

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: lateral wedge insoles

Answer 292

Moderate Evidence Against

Question 293

AAOS, for or against: Viscoelastic supplementation glucosamine & chondroitin acupuncture lateral wedge insoles Needle lavage

Answer 293

All against

Question 294

Post op TKA Now stiff 9 causes

Answer 294

* **Poor compliance with postoperative rehabilitation** * **Postoperative complication (wound dehiscence, DVT, CRPS)** * **Overstuffing of the patello-femoral joint** * **Oversized components (femur)** * Failure to restore native tibial slope (insufficient tibial posterior slope) * Incomplete osteophyte resection * Mismatch of flexion and extension gaps (inappropriate balancing (PCL too tight) * Component Malposition * Elevation of the joint line

Question 295

Technical Risk factors for TKA periprosthetic femoral fractures (3)

Answer 295

- anterior femoral notching (debatable) - mismatch of elastic modulus between metal implant and femoral cortex - rotationally strained components

Question 296

Which femoral condyle is bigger? What does this produce in terms of kinematics?

Answer 296

Lateral is larger Creates medial pivot point during flexion

Question 297

Give the paprosky classification for acetabular bone loss

Answer 297

see image

Question 298

What is reccomended combined anteversion?

Answer 298

37 degrees

Question 299

Approach to extensor disruption in TKR?

Answer 299

1. Partial quads tear = 6 weeks zimmer 2. Complete quads tear or partial patellar avulsion from TT = Direct repair 3. Complete patellar tear with good tissues = primary repair with allograft 4. Complete tear with poor tissues = extensor mechanism allograft (this sounds crazy)

Question 300

Post posterior approach THA in an ankylosing spondylitis patient, what are they at risk of?

Answer 300

Anterior dislocation Due to pre-existing lumbo-pelvic angulation

Question 301

3 stages of the TKA Lewis and Rorabeck classification of periprosthetic femoral fractures

Answer 301

I: Non-displaced; component intact II: Displaced; component intact III: Displaced; component loose or failing

Question 302

Neuropathic joint: what kind of TKA shoud you use?

Answer 302

Hinged

Question 303

3 prognostic indicators for collapse in hip AVN (radiographic)

Answer 303

Kerboul angle \>190 * 190 - 240: 50% * \>240: 100% AVN of \> 2/3 of the weight bearing surface of femoral head Medium to large lesions (\>30% in Steinberg classification) * 30-50%: 46% collapse * \>50%: 85% collapse Bone marrow edema in proximal femur JAAOS 2014

Question 304

What is an advantage and disadvantage of poly insert/metal tray compared to all poly tibias?

Answer 304

1) Intra-operative modularity is the advantage 2) Drawbacks are backside wear and expense

Question 305

Order of release in valgus TKA

Answer 305

Osteophytes capsule IT Band Popliteus LCL \*May release LCL first if tight in both flexion & extension \*Consider constrained prosthesis if you release LCL

Question 306

In an asymptomatic patient with a recalled MoM prosthesis, should you perform revision surgery?

Answer 306

No Risk of revision not justified if they are asymptomatic (JAAOS 2015)

Question 307

3 advantages and disadvantages of antibiotic spacers?

Answer 307

**_Advantages:_** 1. reduce dead space 2. provide stability 3. deliver high dose antibiotics **_Disadvantages:_** 1. local/systemic allergic reactions 2. antibiotic resistance 3. can only use heat stable antibiotics

Question 308

What is the standard magnification on an xray?

Answer 308

20%

Question 309

Disadvantages of HCLPE:

Answer 309

Decreased toughness Decreased ductility Decreased fatigue strength Decreaed ultimate tensile strength Increased cost

Question 310

How much knee flexion do you need for: a) Swing phase of gait b) ADLs c) Getting out of chair

Answer 310

a) 65 degrees b) 90 degrees c) 105 degrees

Question 311

46 yo who had Perthes at age 6, treated with abduction bracing, now has hip pain, failed all non-op measures, flat mushroom shaped femoral head, well contained. Best treatment

Answer 311

valgus extension femoral osteotomy b/c well contained, valgus will: 1. Corrects LLD 2. Improves ROM (especially abduction) Indications late or salvage procedure, hinge abduction, medial dye pool

Question 312

clinical presentation of aseptic acetabular and femoral loosening

Answer 312

Acetabular: buttock/groin pain Femoral: thigh pain, startup pain

Question 313

Describe typical findings of osteonecrosis on MRI.

Answer 313

double density appearance T1: dark (low intensity band) T2: focal brightness (marrow edema)

Question 314

What three factors are important when deciding between hip preserving or arthroplasty options for hip AVN?

Answer 314

1. Is etiology reversible (i.e. steroids) 2. Stage of AVN (particularly is collapse present) 3. Age of patient

Question 315

5 risk factors for THA dislocation

Answer 315

Prior hip surgery: Greatest risk factor Female sex \>70-80 years of age Posterior surgial approach * Repairing capsule and reconstructing ER brings dislocation rate close to anterior approach Malpositioning of components * Ideal positioning of acetabular component: 40 degrees abduction, 15 degrees anteversion Spastic or neuromusular disease (Parkinsons') Drug or alcohol ause Decreased offset (decreases tension and stability) Decreased femoral head neck ratio AVN of femoral head Inflammatory arthritis Fracture treated with THA

Question 316

Optimal pore size in biologic fixation:

Answer 316

50-150um optimal 50-300um acceptable _rule of 50's_ pore size 50-300um preferably 50-150um porosity of 40-50% gaps micromotion

Question 317

Name 2 non-operative management modalities of AVN femoral head:

Answer 317

Bisphosphonates pre-collapse: will prevent collapse (in some studies) Electromagnet stimulation Shockwave therapy Hyperbaric osygen

Question 318

5 factors that lead to increased wear rates in THA?

Answer 318

1. poly thickness 2. malalignment of components 3. patients 4. men 5. higher activity level

Question 319

What is the most common complication after proximal tibial osteotomy?

Answer 319

Patella baja

Question 320

Saggital balancing: Flexion: Tight Extension: Loose What do you do?

Answer 320

Downsize femur, thicker poly

Question 321

Can't reduce a THR post implantation? Name some soft tissue releases that may help.

Answer 321

Adductor release. Gluteal release. Rectus release.

Question 322

indications for PAO (5)

Answer 322

* Near congruent DDH deformity * Young patient ( * No advanced OA * Adequate motion * Correctible deformity

Question 323

Effects of an increased offset in THA (5)

Answer 323

increased soft-tissue tension Decreased dislocation decreased impingement/increased ROM decreased joint reaction force Decreased wear

Question 324

3 variables effecting elution of antibiotics from cement.

Answer 324

1. cement porosity 2. surface area 3. concentration of abx

Question 325

5 Risks of Squeeking in THA

Answer 325

impingement edge loading component malposition loss of fluid film lubrication third body particles thin, flexible (titanium) femoral stem

Question 326

Two reasons to use a cemented acetabular cup

Answer 326

Poor bone stock Irradiated bone

Question 327

What are paprosky type 1-5 acetabular peri-prosthetic fractures? (Don't worry about sub-types)

Answer 327

1. intraoperative fracture - component insertion 2. intraoperative fracture - component removal 3. traumatic fracture 4. spontaneous fracture 5. pelvic discotinuity

Question 328

Risk factors for periprosthetic fracture

Answer 328

poor bone quality due to * age * steroid use * rheumatoid arthritis * stress-shielding mechanical stress-risers due to: * screw holes * local osteolysis * stiffness neurological disorders, including: * epilepsy * Parkinson's disease * cerebellar ataxia * myasthenia gravis * polio * cerebral palsy

Question 329

AVN vs. Post-traumatic arthritis. Wich one is more likely to get nerve injury and which is more likely to get instability after THR?

Answer 329

AVN = Instability Post-traumatic = Nerve Injury

Question 330

3 Contraindications to Ganz PAO

Answer 330

* Significant anterior cartilage wear (will end up in WB zone) * Combined Cam and Pincer * Excessive posterior wall coverage (will lead to extension impingement)

Question 331

6 causes of post-op foot drop in THA

Answer 331

Posterior retractor (retraction) Increased leg length/traction (traction) Laceration Hematoma Scarring/HO Entrapment sutures Anesthesia Seroma Heat form cement Idiopathic

Question 332

Patient with patellectomy. what kind of TKA does he need?

Answer 332

PS

Question 333

T/F? oxidation of PE occurs regardless of sterilization procedure?

Answer 333

True However some ways accelerate it (ie in oxygen)

Question 334

How can you quantify bone turnover in the osteolysis process? (A lab test)

Answer 334

N-telopeptide urine level

Question 335

T/F? Sterilization in oxygen causes free radicals

Answer 335

True: free radicals are needed to create cross-linking HOWEVER, sterilization in oxygen causes unacceptably high levels of free radicals, leading to a brittle PE with higher rates of failure Best to sterilize in nitrogen or argon or vacuum. These create the right amount of free radicals to make a cross-linked, wear resistant PE

Question 336

What kind of femoral stem (cemented vs. uncemented) should you use in revision THA?

Answer 336

UNcemented cemented his lower success rates

Question 337

Most common intraoperaitve fracture in TKA

Answer 337

meidal femoral condyle

Question 338

Best test for periprosthetic infection?

Answer 338

PET scan 98% sensitive 98% specific

Question 339

How much can you lengthen femur before sciatic nerve palsy sets in?

Answer 339

4cm (or 20% length of limb)

Question 340

What are anterior precautions?

Answer 340

avoid : * bridging * extension * extreme external rotation * adduction past body's midline

Question 341

## Footnote Heat stable antibiotics (4):

Answer 341

1. Tobramycin 2. Vancomycin 3. Gentamycin 4. Amphotericin B

Question 342

5 risk factors for post-operative periprosthetic supracondylar femur fractures.

Answer 342

1. Rheumatoid arthritis 2. Parkinson's disease 3. Chronic steroid therapy 4. Osteopenia 5. Female gender

Question 343

Treatment options for TKA periprosthetic femoral #

Answer 343

Antegrade IM nail Retrograde IM nail ORIF with fixed angle device Revision to long-stem prosthesis Distal femoral replacement

Question 344

Indication for flexion, IR proximal femoral osteotomy?

Answer 344

post- SCFE

Question 345

What do you look for as a marker for increase bone turnover/osteolysis?

Answer 345

Urine N-telopeptide

Question 346

Describe two abnormalities of the femoral head and acetabulum with adult hip dysplasia.

Answer 346

Femoral head: 1. decreased sphericity 2. decreased head:neck offset Acetabulum 1. increased retroversion (Crossover sign) 2. acetabular protrusio

Question 347

3 options for operative management of stiff TKA

Answer 347

MUA Arthroscopic/open lysis of adhesions Revision TKA

Question 348

Who is at greatest risk for developing pelvic discontinuity following THA?

Answer 348

RA patients

Question 349

7 intraoperative methods to prevent infection in arthroplasty

Answer 349

Perioperative adminstration of abx shorter OR time Appropriate skin preparation before surgical incision Frequent glove changes use of antibiotic-impregnated cement Limiting operating room traffic Wound closure with sutures or staples Laminar flow rooms

Question 350

What patients are candidates for hip resurfacing with adult hip dysplasia?

Answer 350

Crowe 1-2 (also male, adequate femoral bone stock, ect)

Question 351

What are posterior precautions?

Answer 351

avoid: * flexion past 90 degrees * extreme internal rotation * adduction past body's midline

Question 352

5 factors leading to higher wear rates?

Answer 352

PE Thickness malalignment of components Patients men higher activity level \*femoral head size 22-46mm does NOT affect wear of UHMPE

Question 353

Osteoarthritis of the Knee AAOS Guidelines Level of Evidence for: needle lavage

Answer 353

Moderate evidence AGAINST

Question 354

MSIS criteria for periprosthetic joint infection:

Answer 354

_Definitely present when:_ * There is a sinus tract communicating with prosthesis or * A pathogen is isolated by culture from 2 separate tissue or fluid samples obtained from the affected joint or _4 out of 6 of the following are present:_ * increased ESR & CRP * Increased synovial WBC * Elevated percentage of PMNs * Purulence in the affected joint * Isolation of a pathogen in 1 culture of periprosthetic tissue or fluid * \>5 neutrophils/hpf at 400x magnification

Question 355

Position of hip fusion?

Answer 355

30-5-10 30 flexion 5 adduction 10 ER

Question 356

When is urine/serum metal concentration highest after MoM THR?

Answer 356

12-24 months. This is because MoM has an intitial period of increased wear during the first year called the "run in" phase.

Question 357

Risk factors for extensor mechanism rupture after TKA

Answer 357

Systemic disease (RA) revision surgery previous patellar realignment surgery previous HTO

Question 358

5 risk factors to wound complications post TKA

Answer 358

_Systemic factors:_ * Diabetes * Vascular disease * RA * Medications * Tobacco * Poor nutritional status * Albumin * Total lymphocyte count * Perioperative anemia * Obesity _Local factors_ * Previous incision * Skin bridges should be 5-6cm * Avoid crossing previous skin incisions at acute angles * Knee deformity * Skin adhesions * Poor local blood supply _Technique_ * Large subcutaneous flaps * Not preserving subcutaneous fat layer _Post-operative_ * Hematoma * Infection

Question 359

3 indications for a cemented femoral component?

Answer 359

1. Dorr C femur - Stovepipe 2. Severe osteopenia (elderly patient) - cement peentrates well into osteopenic bone 3. Irradiated bone - wont ingrow

Question 360

Patient post-op arthroplasty (past the acute period) presenting with pain. What is your next step?

Answer 360

Rule out infection Pain = suspect infection PT only if purely mechanical symptoms

Question 361

Name the main nerves to the lower extremity as they relate to the Psoas in the pelvis.

Answer 361

_Lateral: (3)_ * Iliohypogastric n * Ilioinguinal n * LFCN _Medial: (2)_ * Obturator * Lumbosacral trunk _Between psoas & iliacus (1)_ * Femoral _Piercing then lying anterior to psoas (aka through) (1)_ * Genitofemoral

Question 362

Best option for dealing with a loose cemented cup?

Answer 362

Remove and revise to a cementless cup

Question 363

Describe the Crowe classification.

Answer 363

## Footnote **Crowe Classification** Grade Proximal displacement Femoral head subluxation I Less than 10% • Less than 50% II 10-15% • 50-75% III 15-20% • 75-100% IV Greater than 20% • Greater than 100%

Question 364

3 tricks for extensile exposure in TKA

Answer 364

Quadriceps snip V-Y turndown Tibial tubercle osteotomy

Question 365

Name 3 ways to restore/modify offset

Answer 365

choosing a stem with more or less offset choosing a stem with a different neck-shaft angle modifying the length of the femoral neck

Question 366

List 2nd/3rd generation cementing techniques (AKA the ones we use now)

Answer 366

_2nd generation_ * cement restrictor placement * cement gun * femoral canal preparation (brush and dry) _3rd generation_ * vacuum-mixing to reduce cement porosity * cement pressurization * femoral canal preparation: pulsatile lavage

Question 367

What are the mechanical factors of highly cross-linked UHMPE vs. conventional?

Answer 367

decreased toughness, ductility, tensile strength, and fatigue strength It has better wear properties, but worse biomechanical properties

Question 368

Give the Paprosky classification for femoral bone loss

Answer 368

see image

Question 369

What are the differences in functional outcomes between dynamic and static antibiotic spacers?

Answer 369

No difference in functional outcomes

Question 370

Porous coated metallic surfaces allow for what kind of biologic fixation?

Answer 370

ingrowth

Question 371

5 techniques to increase offset?

Answer 371

1. increasing length of femoral neck 2. decreasing neck-shaft angle 3. medializing the femoral neck while increasing femoral neck length 4. trochanteric advancement 5. alteration of the acetabular liner (lateralized liner)

Question 372

What is the role of MMPs?

Answer 372

* matrix metalloproteases * proteolytic enzymes * responsible for cartilage matrix digestion

Question 373

Classification of tibial periprosthetic fracutre (TKA)

Answer 373

Felix & Associateds Type I: fracture of tibial plateau Type II: fracures adjacent to tibial stem Type III: Fracture of tibial shaft, distal to component Type IV: fracture of tibial tubercle

Question 374

3 alternatives to posterior referencing in valgus TKA?

Answer 374

anterior referencing Whitesides line transepicondylar axis custom knee? Navigation?

Question 375

4 radiographic signs of well fixed femoral component (biologic fixation)

Answer 375

spot welds absence of radiolucent lines around porous portion of stem proximal stress sheilding in extensively coated stems absence of stem subsidence on serial x-rays

Question 376

When is it appropriate to perform an isolated popliteus release in TKA?

Answer 376

valgus & tight in flexion

Question 377

Name a prosthetic option for each poprosky type of femoral deficiency in revision femur surgery. (give a safe answer for each)

Answer 377

1. Metaphyseal porous coated 2. Extensively porous coated cylindrical stem 3a. Extensively porous coated cylindrical stem 3b. Modular tapered stem (i.e. distal press fit) / Wagner 4. APC (allograft prosthetic composite) or tumor prosthesis

Question 378

3 Indications for the use of a constrained acetabular component

Answer 378

1) recurrent dislocations due to unrepairable soft-tissue insufficiency from lack of abductor function or capsular attenuation 2) severe cognitive disorders 3) late dislocations with well positioned components.

Question 379

in TKA, which is better, neuraxial or general anesthetic?

Answer 379

Neuraxial Decreased overall complications AAOS CPG 2015

Question 380

5 indications and 3 contraindications to hip fusion.

Answer 380

* Indications * * High activity * Severe pain * Post traumatic or post infectious * Normal adjacent joints * Contra indications * Abnormal adjacent joints * Active infection * LLD \> 2 cm

Question 381

What is the maximum depth of osteochondroplasty to limit risk of femoral neck fracture?

Answer 381

30% of diamter of femoral neck

Question 382

Sensitivity & specificity of gram stain in diagnosing periprosthetic joint infections?

Answer 382

Sensitivity: 0-23% Specificity: 100% Sensitivity too low. DO NOT use alone

Question 383

Options for Knee Fusion Fixation

Answer 383

1. Wichita (hinged) nail 2. Longe antegrade nail 3. External Fixation * unilateral external fixation * Ilizarov * Taylor Spatial Frame 4. Plate Fixation

Question 384

Indications for MUA in stiff TKA:

Answer 384

* Timing is controversial but definitely do NOT do MUA after 12 weeks

Question 385

What is the role of hydroxyapatite (HA) in THR?

Answer 385

* osteoconductive agent used as an adjunct to porous-coated and grit blasted surfaces * has shown shorter time to biologic fixation in animal models, but no advantage clinically in humans

Question 386

What is the difference between resurfacing the patella or not resurfacing with respect to the following outcomes: 1) pain 2) function 3) re-operation rates

Answer 386

1) pain = **No Difference** 2) function = **No Difference** 3) re-operation rates = **Higher with _non-resurfaced_**

Question 387

Name 2 surgical interventions for AVN femoral head for early (precollapse) disease

Answer 387

Core decompression Non-vascularized bone grafting Vascularized bone graft (not really done anymore)

Question 388

What is the gold standard treatment for chronic periprosthetic infection?

Answer 388

2 stage revision IV abx 4-6 weeks in between

Question 389

wear rate of of MoM

Answer 389

2.5-5um per year

Question 390

wear rate of of ceramic on ceramic and ceramic on PE

Answer 390

C on C: 0.5-2.5um per year (not mm) C on PE: 0-150um per year

Question 391

Saggital balancing: Flexion: loose Extension: loose What do you do?

Answer 391

Thicker Poly

Question 392

does femoral head size affect wear

Answer 392

Not for sizes beween 22-46mm in highly crosslinked UHMWPE for the old non-crosslinked it does

Question 393

What treatment is indicated for proximal versus distal skin necrosis following TKR?

Answer 393

1) Skin necrosis of the proximal wound including the area over the patella can be treated by local wound care and skin grafting 2) Skin necrosis over the tibial tubercle or patellar tendon requires muscle flap coverage to prevent extensor mechanism disruption and deep infection

Question 394

What does patella baja cause?

Answer 394

Inability to fully flex knee Due to mechanical block as patella impinges on tibia in extreme flexion Patella descends during knee flexion. if it's already low, then it will impinge on tibia prior to full flexion

Question 395

what is the mechanism of osteolysis in implant wear?

Answer 395

RANKL mediated bone resorption (via osteoclasts)

Question 396

2 ways to decrease blood loss in TKA as per AAOS CGP 2015?

Answer 396

Tranexemic acid tourniquet

Question 397

5 risks of periprosthetic joint infection:

Answer 397

Immune suppression * Drugs: steroids, DMARDs * Conditions: HIV Perioperative surgical site infection Poor wound healing RA Psoriasis Diabetes Smoking Obesity Table is for TKA specifically, JAAOS 2015

Question 398

what is the linear wear rate that is associated with osteolysis and subsequent component loosening?

Answer 398

\>0.1mm/yr

Question 399

What is your choice of knee prosthesis with moderate bone loss in the setting of neuropathic arthropathy?

Answer 399

VVC (\*\* Rotating hinge if MASSIVE bone loss)

Question 400

List 3 nonoperative management modalities that has strong evidence for in knee OA

Answer 400

NSAIDs or tramadol (strong) Combined supervised and self monitored home exercise program (strong) weight loss program (moderate)

Question 401

After how many months do the risks of MUA out weight the potential beenfits in a stiff TKR?

Answer 401

3 months

Question 402

How far is the popliteal artery from the posterior tibial cortex at 90 degrees flexion?

Answer 402

9 mm

Question 403

What is the current reccomendation for use of ABX cement in TKR?

Answer 403

1. Reccomended for revisions 2. No good evidence for primaries. Don't use routinely because it compromises the strength and can lead to higher rates of asceptic loosening.

Question 404

Main cause of metal hypersensitivity in arthroplasty

Answer 404

Nickel (it is found in Cobalt-chromium alloys)

Question 405

What material of THA has the best wear characteristics but the worst biomechanical characteristics?

Answer 405

Ceramic

Question 406

Two causes of CAM jump on PS knee and what is reduction maneouver?

Answer 406

1. Hyperextension or loose flexion gap 2. anterior drawer

Question 407

6 (proposed) advantages of UKA over TKA?

Answer 407

* faster rehabilitation and quicker recovery * less blood loss * less morbidity * less expensive * preservation of normal kinematics * theory is that retaining ACL, PCL and other compartments leads to more normal knee kinematics * smaller incision * less post-operative pain leading to shorter hospital stays

Question 408

What is the most common problem in TKA?

Answer 408

Abnormal patellar tracking

Question 409

Treatment algorithm for AVN femoral head

Answer 409

See image

Question 410

Outcomes for rectus snip comapred to standard medial parapatellar approach in revision TKA?

Answer 410

No difference

Question 411

In what position do you perform your posterior release in TKA?

Answer 411

90 deg of knee flexion to protect popliteal artery

Question 412

Saggital balancing: Flexion: Loose Extension: Ok What do you do?

Answer 412

Resect femur + thicker poly or Posterior releases + thicker poly

Question 413

What is the recommended theta (abduction) angle in THA?

Answer 413

30-50 degrees

Question 414

What is the normal relationship between the posterior condylar axis and the transepicondylar axis?

Answer 414

3 deg IR in TKA, must make femoral cut in 3 deg ER to make it parallel to transepicondylar axis

Question 415

2 absolute and 3 relative contraindications for hip resurfacing?

Answer 415

Absolute: Poor femoral neck bone stock Abnormal acetabular anatomy Relative: Female LLD Coxa Vara

Question 416

Describe the method for preventing non-union of TT osteotomy

Answer 416

Long osteotomy maintain attachment of anterior compartment muscles to the fragment.

Question 417

Optimal gap space in biologic fixation

Answer 417

_rule of 50's_ * pore size 50-300um preferably 50-150um porosity of 40-50% gaps micromotion

Question 418

5 contraindications to constrained liners in THA

Answer 418

malposition component loosening insufficiency of bone acute infection skeletal immaturity neurologic spasm

Question 419

3 signs of well biologically fixed acetabular component

Answer 419

lack of migration of serial x-rays lack of progressive radiolucent lines intact acetabular screws

Question 420

5 properties of antibiotics that can be used in cement:

Answer 420

Heat stable water soluble bactericidal Targeted Good elution properties Non-allergenic Favourable side effect profile Cheap

Question 421

Name 4 things that can help you with bony defects in TKA

Answer 421

Cement Allograft Autograft Metaphsyeal sleeves Cones Stems

Question 422

4 signs of loose cemented femoral components

Answer 422

Subsidence Break in cement lucency in cement/bone interface or cement/implant interface pedestal formation

Question 423

5 risk factors for peroneal nerve injury following THR?

Answer 423

1. preoperative diagnosis of developmental dysplasia of the hip 2. posttraumatic arthritis 3. the use of a posterior approach 4. lengthening of the extremity 5. use of an uncemented femoral implant

Question 424

What is the position for fusion of the knee?

Answer 424

15 degrees flexion 5-10 degrees ER