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3. OrthoBullets (General Knowledge) > Recon > Flashcards

Recon Flashcards

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1
Q

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

A

periprosthetic fracture

most common

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2
Q

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

A

> 0.1 mm/year

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3
Q

5 variables leading to PE wear characteristics

A

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
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4
Q

4 complications of free fibula vascularized bone graft?

A
  1. sensory deficit
  2. motor weakness
  3. FHL contracture
  4. tibial stress fracture from side graft is taken
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5
Q

5 Considerations in sickle cell in arthroplasty

A

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

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6
Q

Techniques to reduce nerve injury in THR for DDH?

A
  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
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7
Q

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

A
  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
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8
Q

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

A

transient osteoporosis of hip

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9
Q

5 ways to avoid failure of cemented femoral stem.

A
  1. smooth stem
  2. > 2 mm mantle
  3. rigid stem
  4. centralized stem
  5. No defects of mantle
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10
Q

Two main contraindications to hip osteotomy?

A

Restricted hip motion

Advanced OA

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11
Q

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

A

condylar buttress plate (non-locking)

locking supracondylar plate

blade plate

dynamic compression screw

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12
Q

Most common nerve injury with hip scope?

A

Pudendal from traction

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13
Q

Describe femoral rollback

A

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

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14
Q

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

A

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

it is NOT to correct for malalignment

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15
Q

Saggital balancing:

Flexion: Loose

Extension: Tight

What do you do?

A

resect femur + thicker poly

or

release capsule posteriorly and thicker poly

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16
Q

Differentiate adhesive, abrasive, and third body wear.

A

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

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17
Q

Indications for a hinged knee prosthesis?

A
  1. global instability
  2. massive bone loss in a neuropathic joint
  3. oncologic procedures
  4. hyperextension instability
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18
Q

3 benefits of increasing offset?

A
  1. increased soft-tissue tension
  2. decreased impingement
  3. decreased joint reaction force
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19
Q

Risks of patellar periprosthetic fracture

A

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
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20
Q

General workup algorithm for MoM patients

A

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

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21
Q

5 risks of HO in TKA

A

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)

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22
Q

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

A

Visualize/palpate for tension

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

Neuromonitoring

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23
Q

Risk factors for Hip OA

A

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

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24
Q

2 ways of testing for nickel sensitivity?

A
  1. patch testing
  2. lymphocyte transformation test (LST)
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25
Q

2 indications for chronic suppressive antibiotics in periprosthetic infection

A

Patient too sick to undergo surgery

Complex arthroplasty with huge revision needed

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26
Q

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

A

“ASEPTIC”

Alcoholism/AIDS/Immnosuppressed

Steroids/Sickle cell

Erlenmeyer flask (Gaucher)

Pancreatitis

Trauma

Idiopathic

Caissons (The Bends)

Hypercoaguable state

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27
Q

Risks for knee OA

A

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

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28
Q

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

A

TKA

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29
Q

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

A

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

Resurfacing

THA

Arthrodesis

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30
Q

Describe a differential MCL release in varus TKA

A

Posterior oblique tight in extension: release if tight in extension

Anterior portion tight in flexion: release if tight in flexion

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31
Q

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

A

Large

decreases

Jump

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32
Q

5 risk factors for squeaking with ceramic bearings?

A
  1. edge loading
  2. impingement and acetabular malposition
  3. third-body wear
  4. loss of fluid film lubrication
  5. thin, flexible (titanium) stems
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33
Q

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

A

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

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34
Q

Optimal micromotion in biologic fixation?

A

Rule of 50’s

  • pore size 50-300um
  • preferably 50-150um
  • porosity of 40-50%
  • gaps <50um
  • micromotion <150um
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35
Q

What type of inflammatory response does MoM create?

A

Lymphocytic (it’s a hypersensitivity response)

vs. macrophage for PE

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36
Q

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

A

Cantilever bending.

Cemented stems are thinner and more prone to breaking.

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37
Q

3 causes of TKA periprosthetic femoral fractures

A

poor bone quality

Mechanical stress riser

Neurologic disorders

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38
Q

Name 5 risk factors for dislocation after THA

A

female

Treatment for AVN of femoral head

Treatment for acute fracture

inflammatory arthritis

age > 70

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39
Q

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

A

stripe wear

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

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40
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

glucosamine and chondroitin

A

STRONG evidence AGAINST

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41
Q

Two risks with not resurfacing patella in THR?

A

Higher risk of anterior knee pain

Higher risk of secondary resurfacing

(No difference in complications such as AVN, fracture, ect)

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42
Q

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

A

Bone graft acetabular defects and cement in a new liner

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43
Q

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

A

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

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44
Q

5 complications of hip resurfacing?

A

periprosthetic femoral neck fracture

implant loosening (aseptic)

HO

increased metal ion level

Pseudotumour

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45
Q

5 Risks of supracondylar fracture post TKA

A

Rheumatoid arthritis

chronic steroid therapy

Parkinson’s disease

osteopenia

female gender

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46
Q

Surgical options for a stiff TKA (4)

A

MUA

arthroscopic or open adhesiolysis +/- MUA

quadricepsplasty

component revision.

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47
Q

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

A

50%

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48
Q

Femoral rollback clinically improves what?

A

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

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49
Q

3 indications for ETO as per JAAOS 2013 (Paprosky)

A

Significant varus remodeling

a well fixed uncemented implant

a long column of cement below the stem

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50
Q

What effect does osteoprotegrin have on bone turnover?

A

Inhibits RankL thereby inhibitng bone turnover.

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51
Q

4 ways to decrease free radicals in polyethylene production

A

Vitamin E

Mechanical deformation

Low doses of radiation alternated with annealing

Final sterilization in ethylene oxide gas

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52
Q

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

A

CRP = 21 days

ESR = 90 days

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53
Q

4 risks for creating stress shielding

A

stiff femoral stem: (most important risk factor)

large diameter stem

extensively porous coated stem

greater preoperative osteopenia

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54
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

rehabilitation, education and wellness activity

A

STRONG evidence FOR

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55
Q

POsition of hip arthrodesis

A

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

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56
Q

How thich do you want a cement mantle?

A

At least 2 mm thick

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57
Q

3 complications unique to ceramic heads?

A
  1. fracture
  2. sqeaking
  3. stripe wear
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58
Q

hydroxyapatite coating is what kind of agent?

What effect on biologic fixation does it have?

A

osteoconductive

Allows more rapid closure of gaps

shorter time to biologic fixation (in animals, and in humans in some studies)

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59
Q

What are the five goals of revision total knee surgery?

A
  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
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60
Q

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

A

b. Varus malalignment on coronal

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61
Q

What type of arthroplasty will worsen your golf game?

A

TKA: increases handicap

THA: no change

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62
Q

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

A

Manufacturere specific explant tools

flexible osteotomes

trephines

high speed burrs

ultrasonic cement removal instruments

universal extraction tools

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63
Q

Risk factors for dislocation following THR?

A
  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
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64
Q

2 risks for increased MoM serum ion levels

A

Smaller component size

Cup abduction angle >55

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65
Q

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

A

80% remain symptomatic

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66
Q

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

A

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

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67
Q

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

A

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)

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68
Q

List 4 options for a Vancouver B2 periprosthetic fracture

A

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

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69
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

NSAIDS

A

STRONG evidence FOR

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70
Q

2 contraindications for TT osteotomy

A

Osteolysis

Proximal tibial osteoporosis

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71
Q

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

A

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

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72
Q

MCL rupture during TKA. What are 2 options?

A

Suture repair + PS/CR + hinged knee brace x 6 weeks

Unhinged constrained knee (VVC)

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73
Q

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

A

8mm

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74
Q

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

A

Increased risk of aseptic loosening

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75
Q

6 risks of femoral neck fracture in hip resurfacing

A

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

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76
Q

6 risk factors for nerve injury in THR?

A
  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
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77
Q

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

A

patellar tendon rupture

Superior geniculate artery for quad tendon

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78
Q

7 techniques for femoral revision

A
  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
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79
Q

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

A

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

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80
Q

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

A
  • 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
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81
Q

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

A

valgus & flexion

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82
Q

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

A

No

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

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83
Q

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

A

Deep joint infection

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84
Q

4 indications for constained liner in THR.

A

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

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85
Q

Contraindications to CR knee (3)?

A
  1. varus deformity > 10 degrees
  2. valgus deformity > 15 degrees
  3. No PCL
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86
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

Viscosupplementation

A

STRONG evidence AGAINST

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87
Q

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

A
  • 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
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88
Q

What is the proposed benefit of a mobile bearing knee?

A

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

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89
Q

5 indications for knee fusion?

A
  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
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90
Q

Order of release in flexion contacture in TKA

A

osteophytes

posterior capsule

gastrocnemius

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91
Q

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

A

Slower physical recovery

higher rates of postoperative infection

increased length of hospital stay

increased morbidity and mortality

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92
Q

5 causes of sciatic nerve injury in THR?

A
  • compression (most common) due to
  • hematoma
  • retraction
  • tight bandages
  • direct trauma
  • heat from polymethylmethacralate polymerization
  • stretch
  • unknown (40%)
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93
Q

Ficat Classification of femoral head AVN

A

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

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94
Q

3 signs of prosthetic infection on radiographs.

A
  1. periosteal reaction
  2. scattered patches of osteolysis
  3. generalized bone resorption without implant wear
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95
Q

How do you deal with MCL injury intra-operatively?

A

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)
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96
Q

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

A

Increase porosity (hand mix instead of vacuum)

increase concentration of antibiotic

Increase surface area of cement (antibiotic beads)

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97
Q

4 variables that affect THA stability?

A
  1. component design (i.e. head size, skirts)
  2. component position (version/abduction)
  3. soft-tissue tensioning (offset)
  4. soft tissue function
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98
Q

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

A

Female

Revision surgery

DDH

70% have subclinical injury

80% of patients with nerve injury hae persistent neurologica dysfunction

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99
Q

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

A

varus and retroversion

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100
Q

4 risks of iliopsoas impingement post THA

A

Retained cement

Malposition acetabular component

LLD

Excessive length of screws

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101
Q

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

A

SUbtroch osteotomy

downsizing components

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102
Q

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

A

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

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103
Q

4 signs of a well fixed femoral component?

A
  • 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
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104
Q

3 contraindications to MoM implants

A

Pregnant women

Renal disease (metal ions excreted by kidneys)

Metal hypersensitivity due to metal ions

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105
Q

5 considerations for hemophiliac in arthroplasty

A

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)

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106
Q

What does stripe wear indicate?

A

Impingement and excursion that occurs during dislocation of component

stripe wear is cuased by edge loading and recurrent subluxation during gait

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107
Q

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

A

7ppb of cobalt or chromium

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108
Q

Contraindications to UKA

A

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)

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109
Q

AAOS classification for femoral bone loss

A

attached

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110
Q

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

A

pain

eventual collapse

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111
Q

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

A

70-90% in delayed (after 4-6 week abx) reimplantation

vs.

35% for early 2nd stage reimplantation

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112
Q

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

A

At the most lateral scar

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

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113
Q

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

A

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

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114
Q

Saggital balancing:

Flexion: Tight

Extension: Ok

What do you do?

A

Downsize femur

or

Slope tibia

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115
Q

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

A

Heat stable

Water soluble

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116
Q

Decreasing offset does what to JRF in THA?

A

Increases it

b/c it weakens abductors

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117
Q

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

A

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

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118
Q

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

A

35

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119
Q

TT osteotomy techniqe (for TKR exposure)?

A
  1. 6-10 cm bone fragment cut from medial to lateral
  2. fixed with screws or wires
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120
Q

Contraindications to hip fusion?

A

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

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121
Q

Treatment of acetabular bone loss by poprovsky grade?

A
  • 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.

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122
Q

What are the 4 steps of osteolysis?

A
  1. particulate debris formation
  2. macrophage activated osteolysis
  3. prosthesis micromotion
  4. particulate debris dissemination
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123
Q

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

A

Surface = adhesive or abrasive

Fatigue = delamination or pitting

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124
Q

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

A

Varus producing distal femoral osteotomy

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125
Q

Most accurate and precise way to measure polyethylene wear

A

radiostereometric analysis

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126
Q

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

A

EMG to assess gluteus medius.

If non-functional then you need to use a constrained liner.

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127
Q

3 ways to decrease post-op pain in TKA?

A

Per-articular injection

Peripheral nerve blockage

Not using tourniquet

AAOS CPG 2015

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128
Q

5 risk factors for neurovascular injury in TKA

A
  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
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129
Q

Most important type of wear in the osteolytic process?

A

adhesive wear

PE sticks to prosthesis and debris gets pulled off

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130
Q

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

A

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

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131
Q

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

A

bacteria forms a biofilm

bacteria invades bone-implant interface

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132
Q

5 Risk factors for developing motor nerve palsies post THA:

A

developmental dysplasia of the hip

revision surgery

female gender

limb lengthening

posttraumatic arthritis

surgeon self-rated procedure as difficult

Uncemented components

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133
Q

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

A

Peroneal nerve injury

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134
Q

Three technical methods to avoid wound complication in revision TKA

A
  1. Use most lateral incision
  2. dont cross incisions at angles less than 6o degrees
  3. 5-6 cm skin bridges
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135
Q

Name 4 options for extensor mechanism repair post rupture post TKA

A

Priamry repair

Autograft/Allograft reconstruction

Synthetic material

Gastrocs rotation flap

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136
Q

Optimal porosity in biologic fixation:

A

50%

rule of 50’s

  • pore size 50-300um

preferably 50-150um

porosity of 40-50%

gaps <50um

micromotion <150um

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137
Q

What is a Kerboul angle and what does it predict?

A

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

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138
Q

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

A

Cam jump

Reduce using anterior drawer maneuver

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139
Q

What are the MSIS criteria for periprosthetic Joint Infection

A
  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.

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140
Q

When do you treat post-operative LLD?

A

Wait 6 months for soft tissue tension to settle.

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141
Q

Should you routinely used navigated or patient specific TKA?

A

No

strong evidence against routine use

no difference in outcomes vs. conventional

AAOS CGP 2015

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142
Q

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

A

Increased risk of transfusion

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143
Q

Post-TKA - when should you start PT?

A

POD 0 - same day of surgery

Leads to better outcomes

AAOS CPG 2015

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144
Q

PAO - why can patient weight bear right away?

A

Posterior column remains intact

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145
Q

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

A

Higher risk of anterior knee pain

Higher risk of secondary resurfacing

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146
Q

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

A

4 cm

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147
Q

Optimal position of hip fusion?

A
  • 20-35° of flexion
  • 0°-5° adduction
  • 5-10° external rotation
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148
Q

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

A

>2/3 of rim remaining is competent

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149
Q

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

A

DEFLATE THE TOURNIQUET

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150
Q

Three ways to change offset through femoral component selection.

A
  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
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151
Q

3 stages of the TKA Su classification of periprosthetic femoral fractures

A

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

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152
Q

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

A

Extension: 1cm posterior

Flexion: 2cm posterior

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153
Q

5 contraindications to knee fusion.

A
  1. active infection
  2. bilateral knee arthrodesis
  3. contralateral leg amputation
  4. significant bone loss
  5. ipsilateral hip or ankle DJD
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154
Q

Complication of free-fibular transfer resulting in leg pain?

A

Tibial stress fracture

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155
Q

What is lambda in terms of arthroplasty?

A

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
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156
Q

Name the nerve at risk with each hip portal:

a) anterior
b) Anterolateral
c) Posterolateral

A

a) LCFN
b) SGN
c) sciatic

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157
Q

5 types of wear

A

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

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158
Q

2 Complications specific to UKA

A

Tibial stress fracture (under baseplate)

tibial component collapse

(tibial side gets messed up)

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159
Q

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

A

peroneal division of sciatic

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160
Q

What type of antibiotic spacer elutes more antibiotics?

A

Static

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

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161
Q

Describe the Poprovsky acetabular bone loss classification.

A

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

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162
Q

Name 6 risk factors for peroneal nerve palsy post THA

A

Hip dysplasia

posterior approach

extreme lengthening

post-traumatic arthritis

uncemented femoral component

surgeon self-rating the surgery as difficult

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163
Q

Risk factors for periprosthetic fracture

A

osteolysis and loosening

trauma

age

gender

osteoporosis

index diagnosis

revision surgery

technique

type of implant used

(JAAOS 2014 - periprosthetic fractures)

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164
Q

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?

A

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.

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165
Q

4 Options for treating Paprosky 4 femoral bone loss

A

Incompetent isthmus

Allograft prosthetic composite

Long cemented stem

Impaction grafting + long cemented stem

Modular oncology components (femoral replacement)

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166
Q

Allogenic Transfusion triggers in TKA (JAAOS 2014)

A

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

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167
Q

Paprosky 1 femoral bone loss.

Outcomes of revision with primary, monobloc stems.

What should you do?

A

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

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168
Q

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

A

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

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169
Q

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

A
  1. Lateral release
  2. Remove retro-patellar adhesions
  3. Subperiosteal dissection of superomedial tibia
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170
Q

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

A

Low sensitivity (28%)

Therefore careful how you use it

Same with gram stain

171
Q

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

A

Extensile lateral approach (vs. submuscular approach)

Use submuscular (MIPO)

172
Q

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

A

Superior geniculate artery

Can lead to extensor mechanism rupture or patellar fracture

173
Q

5 complications to using constrained liner

A

Acetabular loosening

dissociation of the constrained liner from the shell

material fatigue

disengagement of the constraining ring

excessive wear

174
Q

Three patient facors necessary for PAO?

A
  1. symptomatic dysplasia in an adolescent or young adult
  2. concentrically reduced hip
  3. mild-to-moderate arthritis
175
Q

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

A

WBC: >1100 cells/mm2

PMN: >64%

Both above: PPV 98.6%

Both below: NPV 98.2%

(Ghanem & Parvizi JBJS 2008)

176
Q

TKA: Outcomes of All cemented vs. All uncemented

A

Same

AAOS CPG 2015

177
Q

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

A

Convert to hemi with large head

Resection arhtroplasty

178
Q

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

A

50-55%

179
Q

Describe the Hartofilikadis classification.

A

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.

180
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

Acupuncture

A

STRONG evidence AGAINST

181
Q

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

(pre-op factors)

A
  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
182
Q

Name 5 complications unique to THA

A

Sciatic nerve injury

HO

Osteolysis

Pseudotumour

squeaking

Dislocation

LLD

Iliopsoas tendon impingement

183
Q

What are the driving recomendations post TKR?

A
  1. 4 weeks after a right total knee
  2. less than 4 weeks after a left total knee
184
Q

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

A

No difference

Moderate evidence

AAOS CPG 2015

185
Q

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

A

Low Pre-ob Hb

186
Q

Saggital balancing:

Flexion: Good

Extension: Loose

What do you do?

A

Augment femur

or

Downsize femur + thicker poly

187
Q

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

A

Kerboul angle

Kerboul angle >200 = arthroplasty

188
Q

How does CPM effect outcomes following primary TKA?

A

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

189
Q

5 Risks of HO post THA

A

Prolonged surgical time

Hypertrophic subtype of OA

Handling soft tissues during surgery

Previous HO

DISH

Paget’s

Ankylosing Sponlylitis

190
Q

Complications with TJA in hemophiliacs

A

Increased infection

increased risk of hematoma

Inreased stiffness/arthrofibrosis (not instability)

191
Q

In what position should you close the knee after TKA?

A

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

192
Q

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

A
  1. underreaming >2mm
  2. elliptical modular cups
  3. osteoporosis
  4. cementless acetabular components
  5. dysplasia
  6. radiation
193
Q

5 things that maximize biologic fixation in arthroplasty

A

Rule of 50’s

  • pore size 50-300um (preferably 50-150um)
  • porosity of 40-50%
  • gaps 50um
  • micromotion 150um
  • Maximal contact with bone
194
Q

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

A

Adhesive and abrasive wear

195
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

Weight Loss

A

MODERATE evidence FOR

196
Q

Saggital balancing:

Flexion: Tight

Extension: Tight

What do you do?

A

Thinner poly (min is 6 mm)

or

Resect tibia

197
Q

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

A

Femoral: 10-15 degrees anteverted

Acetabular: 5-25 degrees anteverted

Combined: 37 degrees anteverted

198
Q

2 options for treating Paprosky 3B femoral bone loss

A

Modular tapered stem with antirotational splines (Wagner style) - preferred

Impaction grafting + cemented stem

199
Q

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

A

>1cm: augment or structural bone allograft

200
Q

What differentiates osteonecrosis from transient osteoporosis on MRI?

A

Presence of a double density sign

201
Q

Where is the peroneal nerve in relation to the lateral capsule

What do you have to do in TKA to protect it?

A

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

202
Q

Describe the Paprovsky femoral bone loss classification.

A

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

203
Q

Contrast 1st to 3rd generation cementing techniques.

A

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
204
Q

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

A
  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.
205
Q

What do spot welds mean for biologic fixation?

A

A well fixed component

represents new endosteal bone that contacts porous surface of implant

206
Q

Contra-indications to using subvastus type incisions for TKR?

A
  1. ROM
  2. obese patient
  3. hypertrophic arthritis
  4. previous HTO
  5. Previous arthrotomy
  6. Revision TKR
207
Q

How do you employ radiation to reduce HO formation?

A

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

208
Q

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

A

In a 40 g bag of cement:

3 g of vanco

4 g of tobra (gent may be substituted for tobra)

209
Q

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

A

Dislocation

210
Q

AAOS classification for acetabulr bone loss

A

see image

211
Q

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

A

TNF-Alpha

212
Q

4 ways to treat patella baja in TKA

A

Superior placement of patellar component with resection of inferior pole

Lower joint line

Tibial tubercle transfer to cephalad position

Patellectomy

213
Q

Saggital balancing:

Flexion: Ok

Extension: Tight

What do you do?

A

Resect femur

or

Release posterior capsule

214
Q

Risks for early failure of HTO?

Which is most important?

A

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

215
Q

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

A

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

216
Q

What is the difference between Tc and In bone scans?

A

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

217
Q

Define q angle

A

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

218
Q

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

A

Classic technique – 5-6 degree valgus femoral cut and neutral tibia cut

Anatomic technique – 9 degree valgus femur and 3 degree varus tibia

219
Q

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

A
  • 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
220
Q

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

A

Only 35-40%

221
Q

AVN of one hip, what must you investigate for?

A

AVN of contralateral hip

Bilateral disease 80% of the time

±multifocal disease (3%)

222
Q

5 complications of knee osteotomy.

A
  • Compartment syndrome
  • Non or mal union
  • Over or under correction
  • Peroneal nerve injury
  • Patella baja
223
Q

Order of release for varus deformity in coronal plane balancing

A
  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
  1. PCL
224
Q

Equipment on hand for a femoral stem removal?

A

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
225
Q

3 patient contraindications for MoM bearings?

A
  1. pregnant women
  2. renal disease
  3. metal hypersensitivity due to metal ions
226
Q

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

A

No improvement in outcome for either

227
Q

What prevents collapse in hip AVN?

A

bisphosphonates

(more than core decompression)

228
Q

Hip and knee Arthroplasty:

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

A

Fungal

Candida most common

229
Q

5 risk factors for nerve injury in TKR?

A
  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)
230
Q

Downside of using tourniquet in TKA?

Does it affect outcome

A

Incrased post-op pain

No effect on outcome

AAOS CPG 2015

231
Q

List 2 absolute and 3 relative contraindications for hip resurfacing

A

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)
232
Q

5 causes of late instability of THR?

A
  1. polyethylene wear
  2. component malpositioning or loosening
  3. trauma
  4. infection
  5. deterioration in neurological status of the patient
233
Q

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

A

No role

AAOS CPG

234
Q

5 indications for PS TKA

A

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

235
Q

Order of release in Varus TKA deformity

A

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

236
Q

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

A

Femoral above acetabular:

  • increased leg length

Femoral below acetabular:

  • decrease leg length
237
Q

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

A

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

238
Q

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

A
  1. Increasing shelf age
  2. younger age
  3. male gender
  4. rough tibial baseplate
239
Q

5 ways to increase offset in THA

A

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)

240
Q

Describe Tonnis arthritis grade

A

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

241
Q

2 methods of polyethylene production and which is better?

A

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

242
Q

grit blasted surfaces allow for what kind of biologic fixation?

A

ongrowth

243
Q

Imaging to assess for pseudotumor?

A

MRI with metal subtraction.

244
Q

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

A

Repeat aspiration

Best step in equivocal aspirate is re-aspiration

245
Q

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

A

Posteromedial knee structures affect extension fap (ie semimembranosus)

246
Q

Preferred approach to hip arthrodesis?

A

Lateral approach with trochanteric osteotomy

or

Anterior approach

Must preserve abductors

247
Q

4 advantages of articulating antibiotic spacer

A

Decreased reimplantation exposure time

Better maintenance of joint space and motion

Decreased quad shortening

Better patient satisfaction

248
Q

4 Technical methods to avoid patellar mal-tracking

A
  1. ER femoral component 3 degrees
  2. Lateralize the femoral component
  3. ER tibial component
  4. Patella button on superomedial patella
249
Q

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

A

Rivaroxaban > LMWH > Warfarin at preventing clots

Rivaroxaban > LMWH > Warfarin in bleeding risk

250
Q

Position of knee fusion?

A

5-7 valgus

15 flexion

251
Q

Classification of patellar periprosthetic fractures

A

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

252
Q

Which classification is this?

A

AAOS Classification of Acetabular Bone Loss

253
Q

List 4 options to deal with patella Baja during TKR.

A
  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)
254
Q

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

A

Rectus snip

Vy turndown

TT osteotomy

255
Q

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

A

33%

75% in patients with sickle cell

256
Q

5 Risks of intraoperative periprosthetic femur fracture

A

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

257
Q

4 Risk factors for HO in THR?

A
  1. prolonged surgical time
  2. excessive soft tissue handling during procedure
  3. hypertrophic osteoarthritis
  4. male gender
258
Q

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

A

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

259
Q

in MoM components, what causes seizing?

A

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

260
Q

Cement mantle how thick leads to increased risk of fracture?

A
261
Q

How are metal ions excreted?

A

Renal

262
Q

Risk of patellar prosthesis failure

A
  • 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
263
Q

Lab test with highest correlation to periprosthetic infection?

A

IL-6

264
Q

Kerboul classification of femoral head AVN

A

Gives cross sectional area of AVN as a combined angle

190-240o: 50% chance of collapse

>240o: 100% risk of collapse

265
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

HTO

A

LIMITED evidence FOR

266
Q

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

A

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.

267
Q

Name risk factors for periprosthetic infection

There are 17

(THINK: ADRIAN BLOWS MONKEYs)

A

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
268
Q

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

A

Gluteus medius function.

269
Q

5 techniques for acetabular revision

A
  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
270
Q

6 risk factors for femoral neck fracture following hip resurfacing.

A
  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
271
Q

3 factors that affect risk of AVN after hip dislocation

A

Amount of initial displacement

reduction

decompression of hematoma (maybe)

272
Q

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

A

dislocation

273
Q

2 forms of prophylaxis in HO

A

NSAIDs

Radiation therapy

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

274
Q

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

A

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.

275
Q

3 major common complications of PAO?

A

Anterior overcorrrection

NV injury

Intra-articular fracture

276
Q

What is the most common reason for THA revision?

A

Instability

277
Q

What does heating do in the process of making polyethylene?

A

Decreases free radicals

278
Q

DORR classification

A

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
279
Q

What is a differential release of the superficial MCL?

A

Release in 2 parts:

Posterior oblique: tight in extension, so release if tight in extension

ANterior portion: release if tight in flexion

280
Q

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

A

IIIB defects with canals >19 mm in diameter

281
Q

Two technical factors that increase MoM wear rates?

A

Abduction > 55 and smaller head size

282
Q

Define Contact pitch to rim distance

A

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

283
Q

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

A

Deflate tourniquet and try again.

284
Q

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

A

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

285
Q

7 steps to optimize cement fixation

A

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
286
Q

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

A

Canal diameter greater than 19 mm.

287
Q

What is run-in wear?

A

Increased wear for 1st million cycles (~1 year) in MoM components

A steady state of wear follows

288
Q

Valgus Deformity order of release in coronal plane balancing

A
  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.
289
Q

wear rate of non and highly cross-linked UHMPE

A

non-crosslinked UHMPE: 0.1-0.2mm/yr

crosslinked: 0.003mm/yr

Smaller particles and more resistant (but worse mechanical properties)

290
Q

Stratgies for minimizing blood loss in TKA

A

JAAOS 2014

291
Q

2 necessary pieces of equipment for removing a well fixed cup

A

flexible osteotomes and size specific removal tools

292
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

lateral wedge insoles

A

Moderate Evidence Against

293
Q

AAOS, for or against:

Viscoelastic supplementation

glucosamine & chondroitin

acupuncture

lateral wedge insoles

Needle lavage

A

All against

294
Q

Post op TKA

Now stiff

9 causes

A
  • 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
295
Q

Technical Risk factors for TKA periprosthetic femoral fractures (3)

A
  • anterior femoral notching (debatable)
  • mismatch of elastic modulus between metal implant and femoral cortex
  • rotationally strained components
296
Q

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

A

Lateral is larger

Creates medial pivot point during flexion

297
Q

Give the paprosky classification for acetabular bone loss

A

see image

298
Q

What is reccomended combined anteversion?

A

37 degrees

299
Q

Approach to extensor disruption in TKR?

A
  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)
300
Q

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

A

Anterior dislocation

Due to pre-existing lumbo-pelvic angulation

301
Q

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

A

I: Non-displaced; component intact

II: Displaced; component intact

III: Displaced; component loose or failing

302
Q

Neuropathic joint: what kind of TKA shoud you use?

A

Hinged

303
Q

3 prognostic indicators for collapse in hip AVN (radiographic)

A

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

304
Q

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

A

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

305
Q

Order of release in valgus TKA

A

Osteophytes

capsule

IT Band

Popliteus

LCL

*May release LCL first if tight in both flexion & extension

*Consider constrained prosthesis if you release LCL

306
Q

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

A

No

Risk of revision not justified if they are asymptomatic (JAAOS 2015)

307
Q

3 advantages and disadvantages of antibiotic spacers?

A

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
308
Q

What is the standard magnification on an xray?

A

20%

309
Q

Disadvantages of HCLPE:

A

Decreased toughness

Decreased ductility

Decreased fatigue strength

Decreaed ultimate tensile strength

Increased cost

310
Q

How much knee flexion do you need for:

a) Swing phase of gait
b) ADLs
c) Getting out of chair

A

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

311
Q

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

A

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

312
Q

clinical presentation of aseptic acetabular and femoral loosening

A

Acetabular: buttock/groin pain

Femoral: thigh pain, startup pain

313
Q

Describe typical findings of osteonecrosis on MRI.

A

double density appearance

T1: dark (low intensity band)

T2: focal brightness (marrow edema)

314
Q

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

A
  1. Is etiology reversible (i.e. steroids)
  2. Stage of AVN (particularly is collapse present)
  3. Age of patient
315
Q

5 risk factors for THA dislocation

A

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

316
Q

Optimal pore size in biologic fixation:

A

50-150um optimal

50-300um acceptable

rule of 50’s

pore size 50-300um

preferably 50-150um

porosity of 40-50%

gaps

micromotion

317
Q

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

A

Bisphosphonates

pre-collapse: will prevent collapse (in some studies)

Electromagnet stimulation

Shockwave therapy

Hyperbaric osygen

318
Q

5 factors that lead to increased wear rates in THA?

A
  1. poly thickness
  2. malalignment of components
  3. patients
  4. men
  5. higher activity level
319
Q

What is the most common complication after proximal tibial osteotomy?

A

Patella baja

320
Q

Saggital balancing:

Flexion: Tight

Extension: Loose

What do you do?

A

Downsize femur, thicker poly

321
Q

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

A

Adductor release.

Gluteal release.

Rectus release.

322
Q

indications for PAO (5)

A
  • Near congruent DDH deformity
  • Young patient (
  • No advanced OA
  • Adequate motion
  • Correctible deformity
323
Q

Effects of an increased offset in THA (5)

A

increased soft-tissue tension

Decreased dislocation

decreased impingement/increased ROM

decreased joint reaction force

Decreased wear

324
Q

3 variables effecting elution of antibiotics from cement.

A
  1. cement porosity
  2. surface area
  3. concentration of abx
325
Q

5 Risks of Squeeking in THA

A

impingement

edge loading

component malposition

loss of fluid film lubrication

third body particles

thin, flexible (titanium) femoral stem

326
Q

Two reasons to use a cemented acetabular cup

A

Poor bone stock

Irradiated bone

327
Q

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

A
  1. intraoperative fracture - component insertion
  2. intraoperative fracture - component removal
  3. traumatic fracture
  4. spontaneous fracture
  5. pelvic discotinuity
328
Q

Risk factors for periprosthetic fracture

A

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
329
Q

AVN vs. Post-traumatic arthritis.

Wich one is more likely to get nerve injury and which is more likely to get instability after THR?

A

AVN = Instability

Post-traumatic = Nerve Injury

330
Q

3 Contraindications to Ganz PAO

A
  • Significant anterior cartilage wear (will end up in WB zone)
  • Combined Cam and Pincer
  • Excessive posterior wall coverage (will lead to extension impingement)
331
Q

6 causes of post-op foot drop in THA

A

Posterior retractor (retraction)

Increased leg length/traction (traction)

Laceration

Hematoma

Scarring/HO

Entrapment sutures

Anesthesia

Seroma

Heat form cement

Idiopathic

332
Q

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

A

PS

333
Q

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

A

True

However some ways accelerate it (ie in oxygen)

334
Q

How can you quantify bone turnover in the osteolysis process?

(A lab test)

A

N-telopeptide urine level

335
Q

T/F? Sterilization in oxygen causes free radicals

A

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

336
Q

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

A

UNcemented

cemented his lower success rates

337
Q

Most common intraoperaitve fracture in TKA

A

meidal femoral condyle

338
Q

Best test for periprosthetic infection?

A

PET scan

98% sensitive

98% specific

339
Q

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

A

4cm

(or 20% length of limb)

340
Q

What are anterior precautions?

A

avoid :

  • bridging
  • extension
  • extreme external rotation
  • adduction past body’s midline
341
Q

Heat stable antibiotics (4):

A
  1. Tobramycin
  2. Vancomycin
  3. Gentamycin
  4. Amphotericin B
342
Q

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

A
  1. Rheumatoid arthritis
  2. Parkinson’s disease
  3. Chronic steroid therapy
  4. Osteopenia
  5. Female gender
343
Q

Treatment options for TKA periprosthetic femoral #

A

Antegrade IM nail

Retrograde IM nail

ORIF with fixed angle device

Revision to long-stem prosthesis

Distal femoral replacement

344
Q

Indication for flexion, IR proximal femoral osteotomy?

A

post- SCFE

345
Q

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

A

Urine N-telopeptide

346
Q

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

A

Femoral head:

  1. decreased sphericity
  2. decreased head:neck offset

Acetabulum

  1. increased retroversion (Crossover sign)
  2. acetabular protrusio
347
Q

3 options for operative management of stiff TKA

A

MUA

Arthroscopic/open lysis of adhesions

Revision TKA

348
Q

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

A

RA patients

349
Q

7 intraoperative methods to prevent infection in arthroplasty

A

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

350
Q

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

A

Crowe 1-2

(also male, adequate femoral bone stock, ect)

351
Q

What are posterior precautions?

A

avoid:

  • flexion past 90 degrees
  • extreme internal rotation
  • adduction past body’s midline
352
Q

5 factors leading to higher wear rates?

A

PE Thickness

malalignment of components

Patients

men

higher activity level

*femoral head size 22-46mm does NOT affect wear of UHMPE

353
Q

Osteoarthritis of the Knee

AAOS Guidelines Level of Evidence for:

needle lavage

A

Moderate evidence AGAINST

354
Q

MSIS criteria for periprosthetic joint infection:

A

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
355
Q

Position of hip fusion?

A

30-5-10

30 flexion

5 adduction

10 ER

356
Q

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

A

12-24 months.

This is because MoM has an intitial period of increased wear during the first year called the “run in” phase.

357
Q

Risk factors for extensor mechanism rupture after TKA

A

Systemic disease (RA)

revision surgery

previous patellar realignment surgery

previous HTO

358
Q

5 risk factors to wound complications post TKA

A

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
359
Q

3 indications for a cemented femoral component?

A
  1. Dorr C femur - Stovepipe
  2. Severe osteopenia (elderly patient) - cement peentrates well into osteopenic bone
  3. Irradiated bone - wont ingrow
360
Q

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

A

Rule out infection

Pain = suspect infection

PT only if purely mechanical symptoms

361
Q

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

A

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
362
Q

Best option for dealing with a loose cemented cup?

A

Remove and revise to a cementless cup

363
Q

Describe the Crowe classification.

A

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%

364
Q

3 tricks for extensile exposure in TKA

A

Quadriceps snip

V-Y turndown

Tibial tubercle osteotomy

365
Q

Name 3 ways to restore/modify offset

A

choosing a stem with more or less offset

choosing a stem with a different neck-shaft angle

modifying the length of the femoral neck

366
Q

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

A

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
367
Q

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

A

decreased toughness, ductility, tensile strength, and fatigue strength

It has better wear properties, but worse biomechanical properties

368
Q

Give the Paprosky classification for femoral bone loss

A

see image

369
Q

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

A

No difference in functional outcomes

370
Q

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

A

ingrowth

371
Q

5 techniques to increase offset?

A
  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)
372
Q

What is the role of MMPs?

A
  • matrix metalloproteases
  • proteolytic enzymes
  • responsible for cartilage matrix digestion
373
Q

Classification of tibial periprosthetic fracutre (TKA)

A

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

374
Q

3 alternatives to posterior referencing in valgus TKA?

A

anterior referencing

Whitesides line

transepicondylar axis

custom knee?

Navigation?

375
Q

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

A

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

376
Q

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

A

valgus & tight in flexion

377
Q

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

A
  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
  3. APC (allograft prosthetic composite) or tumor prosthesis
378
Q

3 Indications for the use of a constrained acetabular component

A

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.

379
Q

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

A

Neuraxial

Decreased overall complications

AAOS CPG 2015

380
Q

5 indications and 3 contraindications to hip fusion.

A
  • Indications
      • High activity
    • Severe pain
    • Post traumatic or post infectious
    • Normal adjacent joints
  • Contra indications
    • Abnormal adjacent joints
    • Active infection
    • LLD > 2 cm
381
Q

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

A

30% of diamter of femoral neck

382
Q

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

A

Sensitivity: 0-23%

Specificity: 100%

Sensitivity too low. DO NOT use alone

383
Q

Options for Knee Fusion Fixation

A
  1. Wichita (hinged) nail
  2. Longe antegrade nail
  3. External Fixation
    • unilateral external fixation
    • Ilizarov
    • Taylor Spatial Frame
  4. Plate Fixation
384
Q

Indications for MUA in stiff TKA:

A
  • Timing is controversial but definitely do NOT do MUA after 12 weeks
385
Q

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

A
  • 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
386
Q

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

A

1) pain = No Difference
2) function = No Difference
3) re-operation rates = Higher with non-resurfaced

387
Q

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

A

Core decompression

Non-vascularized bone grafting

Vascularized bone graft (not really done anymore)

388
Q

What is the gold standard treatment for chronic periprosthetic infection?

A

2 stage revision

IV abx 4-6 weeks in between

389
Q

wear rate of of MoM

A

2.5-5um per year

390
Q

wear rate of of ceramic on ceramic and ceramic on PE

A

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

C on PE: 0-150um per year

391
Q

Saggital balancing:

Flexion: loose

Extension: loose

What do you do?

A

Thicker Poly

392
Q

does femoral head size affect wear

A

Not for sizes beween 22-46mm in highly crosslinked UHMWPE

for the old non-crosslinked it does

393
Q

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

A

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

394
Q

What does patella baja cause?

A

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

395
Q

what is the mechanism of osteolysis in implant wear?

A

RANKL mediated bone resorption (via osteoclasts)

396
Q

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

A

Tranexemic acid

tourniquet

397
Q

5 risks of periprosthetic joint infection:

A

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

398
Q

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

A

>0.1mm/yr

399
Q

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

A

VVC

(** Rotating hinge if MASSIVE bone loss)

400
Q

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

A

NSAIDs or tramadol (strong)

Combined supervised and self monitored home exercise program (strong)

weight loss program (moderate)

401
Q

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

A

3 months

402
Q

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

A

9 mm

403
Q

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

A
  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.
404
Q

Main cause of metal hypersensitivity in arthroplasty

A

Nickel (it is found in Cobalt-chromium alloys)

405
Q

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

A

Ceramic

406
Q

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

A
  1. Hyperextension or loose flexion gap
  2. anterior drawer
407
Q

6 (proposed) advantages of UKA over TKA?

A
  • 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
408
Q

What is the most common problem in TKA?

A

Abnormal patellar tracking

409
Q

Treatment algorithm for AVN femoral head

A

See image

410
Q

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

A

No difference

411
Q

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

A

90 deg of knee flexion

to protect popliteal artery

412
Q

Saggital balancing:

Flexion: Loose

Extension: Ok

What do you do?

A

Resect femur + thicker poly

or

Posterior releases + thicker poly

413
Q

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

A

30-50 degrees

414
Q

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

A

3 deg IR

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

415
Q

2 absolute and 3 relative contraindications for hip resurfacing?

A

Absolute:

Poor femoral neck bone stock

Abnormal acetabular anatomy

Relative:

Female

LLD

Coxa Vara

416
Q

Describe the method for preventing non-union of TT osteotomy

A

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

417
Q

Optimal gap space in biologic fixation

A

rule of 50’s

  • pore size 50-300um

preferably 50-150um

porosity of 40-50%

gaps

micromotion

418
Q

5 contraindications to constrained liners in THA

A

malposition

component loosening

insufficiency of bone

acute infection

skeletal immaturity

neurologic spasm

419
Q

3 signs of well biologically fixed acetabular component

A

lack of migration of serial x-rays

lack of progressive radiolucent lines

intact acetabular screws

420
Q

5 properties of antibiotics that can be used in cement:

A

Heat stable

water soluble

bactericidal

Targeted

Good elution properties

Non-allergenic

Favourable side effect profile

Cheap

421
Q

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

A

Cement

Allograft

Autograft

Metaphsyeal sleeves

Cones

Stems

422
Q

4 signs of loose cemented femoral components

A

Subsidence

Break in cement

lucency in cement/bone interface or cement/implant interface

pedestal formation

423
Q

5 risk factors for peroneal nerve injury following THR?

A
  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
424
Q

What is the position for fusion of the knee?

A

15 degrees flexion

5-10 degrees ER

3. OrthoBullets (General Knowledge) (20 decks)

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