Arthroplasty

Question 1

RFs for PJI in THA?

Answer 1

Patient factors: Obesity, DM, steroids, EtOH use, CLD, post-traumatic OA<div>Surgical factors: prolonged OR time, Wound drainage, hematoma, revision surgery</div>

Question 2

MSIS Criteria for PJI?

Answer 2

Major (need 1)<div>-sinus tract communicating with joint</div><div>-pathogen isolated by culture from 2 separate tissue/fluid samples</div><div><br></br></div><div>Minor (need 4/6)</div><div>-serum: ESR>30 or CRP>10</div><div>-aspirate</div><div> -purulence on aspirate</div><div> -WBC>1,100cells/uL knees, >3k hips</div><div> -Neuts >64% knees, 80% hips</div><div> ->5 Neuts/HPF X5</div><div> -isolation of organism in 1 culture</div><div><br></br></div>

Question 3

X-ray Findings of FAI?

Answer 3

CAM<div>-pistol grip</div><div>-Head neck offset <8mm</div><div>-Alpha angle>55-60 deg</div><div><br></br></div><div>Pincer</div><div>-Overcoverage: CEA>40, tonnis<0, downsloping sourcil, coxa profunda, acetabulum protrusio</div><div>-Acetab retroversion: cross-over sign, ischial spine sign, PW sign</div>

Question 4

Coxa profunda vs Acetab Protrusion

Answer 4

Coxa profunda: deep socket - acetabular fossa medial to ilioischial line<div><br></br></div><div>Acetab Protrusion: deep head - femoral head medial to ilioischial line</div>

Question 5

3rd gen cement techinque?

Answer 5

porosity reduction (<b>vacuum assisted - but not necessary</b>)<div>cement pressurization</div><div>pulsatile lavage for canal prep</div><div>cement plug</div><div>retrograde filling</div>

Question 6

Advantages of HXPE vs UHMWPE

Answer 6

<b>decreased wear</b><div>decreased fracture</div><div>decreased oxidization</div><div><br></br></div><div><b>increased cost</b></div>

Question 7

THA Modes of wear?

Answer 7

Mode 1 – primary bearing surface to primary bearing surface (1x1) - <b><u>most common</u></b><div>Mode 2 – primary x secondary (2x1=2)</div><div>Mode 3 – 3rd body</div><div>Mode 4 – Wear between 2 non bearing surfaces, ie. 2 secondary surfaces (such as backside wear or neck socket impingement) (secondary surface x secondary surface – 2x2=4)<br></br></div>

Question 8

Properties of PMMA

Answer 8

<div><b>strongest in compression (not tension)</b></div>

exothermic to 75 deg<div>does not have adhesive properties (its a grout)</div><div>porosity reduction increases strength by 15%</div>

Question 9

Tantalum properties?

Answer 9

“-Young’s modulus approximates that of bone compared to other metals<div>- more ingrowth pores</div><div>-greater friction and bone-metal interface</div><div>-<b>similar biocompatibility to other metals</b></div>”

Question 10

Advantages of high off set stem?

Answer 10

-improved ROM<div>-improved stability</div><div>-improved joint reactive forces-> decrease wear/loosening</div><div>-decrease GT impingement</div><div>-improved abductor tension -> decr tren gait</div>

Question 11

Complications for mal-positioned cup

Answer 11

Dislocation, instability<div>Increased wear/osteolysis</div><div>Aseptic loosening</div><div>Impingement</div><div>LLD</div><div>Decreased ROM</div>

Question 12

RFs for hip AVN

Answer 12

Patient factors<div>-SLE, post-transplant</div><div>-hem disorder, (<b>not hemophilia)</b></div><div>-radiation tx</div><div>-dysbarism</div><div>Drugs: EtOH, Steroids</div><div>Trauma: fracture, dislocation, surgery</div>

Question 13

Treatment options for hip AVN?

Answer 13

Non-op: ?bisphosphonates<div>Core decompression</div><div>Core decompression + augment (fib, tantalum rod)</div><div>Vascularized FG</div><div>Rotational osteotomy</div><div>THA</div>

Question 14

Technical Considerations for Crowe 4 hip THA?

Answer 14

Acetabulum: anteversion, identifying and restoring true hip centre, anterosuperior bone deficiency<div><br></br></div><div>Femur: increased anteversion, valgus neck shaft, small diameter canal</div><div>-Options: Wagner cone, SROM, cemented polished</div><div><br></br></div><div>Soft-tissue: tensioning of sciatic nerve (subtroch shortening), deficient contracted abductors</div>

Question 15

Modular neck in THA leads to?

Answer 15

Increased corrosion

Question 16

RFs for HO post THA?

Answer 16

Male > <b>Female</b><div>Pagets</div><div>Ank Spon</div><div>Cementless implants</div><div><br></br></div><div>OA: post-traumatic, hypertrophic</div><div>DISH</div><div>Extended iliofem>kocher>ilioinguinal</div>

Question 17

RFs for HO (in general)?

Answer 17

“Arthropathies: DISH, Ank Spon, hypertrophic OA<div>Others: Paget’s<br></br><div>Surgeries: THA, TKA</div><div>Approach: iliofemoral</div><div>Trauma: polytrauma, SCI (20%), TBI (11%), burn</div><div><br></br></div></div>”

Question 18

THA and hemophilia?

Answer 18

“<b>infection rate higher than normal pop’n</b><div>coxa valga</div><div>should replace factors to 100% 2 hrs pre-op</div><div>HO decreased</div>”

Question 19

RFs for Fem Neck # with BHR

Answer 19

Patient: BMI, female, low BMD, inflamm arthropathy<div><br></br></div><div>Surgical:</div><div>varus implant <130 deg</div><div>femoral neck notching</div><div>femoral neck cysts</div><div>improper implant seading</div><div><br></br></div>

Question 20

Indications/Contraind for BHR?

Answer 20

Indications: male, <65, active, large fem head<div><br></br></div><div>Contra-indications</div><div>-Absoulte: CKD, women of childbearing age</div><div>-Relative: female, >65 years, low demand, Obese, AVN, Dysplasia, LLD</div>

Question 21

Poor Px factors for PAO in Adult Dysplasia?

Answer 21

Patient: advanced age, morbid obesity<div>X-ray factors</div><div>-Tonnis Grade 2/3 OA (sclerosis/cysts)</div><div>-CEA<0</div><div>-Os acetabuli</div><div>-incongruent van rosen (Ab IR) view</div>

Question 22

Signs of loosening femoral stem?

Answer 22

<div><ul> <li>Cemented (Harris Criteria)</li> <ul> <li>Definite --> subsidence, fractured stem, fractured cement mantle</li> <li>Probably --> continuous radiolucent line at interface, >2mm space at any point</li> <li>Possible --> any radiolucent line that is >50% of interface</li> </ul> </ul> <ul> <li>Uncemented:</li> <ul> <li>Subsidence, reactive line around implant, pedestal formation</li> <li>**stem geometry/Corail</li> </ul></ul></div>

<div><br></br></div>

<div>Cemented (Harris Criteria)<br></br></div>

<div>-subsidence</div>

<div>-fractured stem</div>

<div>-fractured cement mantle</div>

<div>-continuous radiolucent line</div>

<div><br></br></div>

<div>Uncemented</div>

<div>-subsidence</div>

<div>-reactive line around implant</div>

<div>-pedestal formation</div>

Question 23

Components of Paprosky Acetabular Bone Loss?

Answer 23

location of hip centre (ie migrated)<div>ischial osteolysis</div><div>integrity of Kohlers (ilioschial) line</div><div>teardrop destruction</div>

Question 24

Paprosky components of Femoral Bone Loss?

Answer 24

Proximal Metaphysis - intact or basent<div>Diaphysis -</div><div>-intact: extensively poorous coated</div><div>->4cm vs <4cm isthmus: modular <u>tapered</u> stem</div><div>-absent: allograft prosthetic composite</div>

Question 25

Components of Vancouver classification

Answer 25

Fracture location, implant stability, bone stock<div><br></br></div><div>A - GT/LT</div><div>B1 - stem, stable -> ORIF</div><div>B2 - unstable, good bone stock -> long stem revision</div><div>B3 - unstable, poor stock –> APC, PFR</div><div>C - below -> ORIF</div>

Question 26

RFs for instability post THA

Answer 26

Patient: Female, neuro impairment (dementia, cant comply with restrictrions, NM disease), no pre-op stiffness (AVN, fracture), high ASA, obesity<div><br></br></div><div>Surgical</div><div>-Approach: PL</div><div>-Soft tissue: Abductor integrity/tensioning</div><div>-Component position (Acetab 40 abd, 15 ante)</div><div>-Components Used:smaller head</div>

Question 27

Surgical tx options for recurrent THA instability

Answer 27

-component positioning!<div>-increase offset, trochanteric advancement</div><div>-constrained liner</div><div>-bipolar prosthesis</div><div>-resection arthroplasty</div>

Question 28

Releases to balance a varus knee?

Answer 28

medial osteophytes<div>joing capsule</div><div>POL</div><div>sMCL</div><div>semiM</div><div>pes anserine</div><div>PCL</div><div>MHG</div><div>deep MCL</div><div><br></br></div><div>lateral tightening</div>

Question 29

Releases to balance Valgus knee?

Answer 29

Osteophytes<div>Posterolateral capsule</div><div>Popliteus (flex)</div><div>ITB (extension)</div><div>LHG</div><div>PCL</div><div>LCL</div><div><br></br></div>

Question 30

Causes of post-op TKA stiffness?

Answer 30

“Patient factors<div>-poor pre-op ROM</div><div>-preop baja</div><div>-poor compliance with rehab</div><div>-poor pain control</div><div>-HO</div><div>-infection</div><div>-hematoma</div><div><br></br></div><div>Surgical factors</div><div>-component malalignment, malposition</div><div>-gap imbalance</div><div>-PF overstuffing</div><div>-cement extravasation posteriorly</div><div>-joint line elevation (patella baja)</div><div><br></br></div><div>Factors that don’t affect ROM</div><div>-obesity</div><div>-previous OR</div><div>-keloid scar</div><div>-age</div><div>-sex</div><div>-bilateral TKA</div><div>-multiple joint involvement</div><div><br></br></div>”

Question 31

Cyclops lesion?

Answer 31

anterior arthrofibrosis -><b>block to extension (not flexion)</b><div><b><br></br></b></div>

Question 32

hemophiliac TKA postop complaint?

Answer 32

stiffness, <b>not laxity</b>

Question 33

Methods to improve flexion gap during TKA?

Answer 33

<div>Bony: downsize femoral component, increase tibial slope</div>

resect PCL<div>posterior capsule</div><div>gastrocs</div><div>posterior corners (popliteus)</div><div>sMCL</div><div>pes anserine</div>

Question 34

Methods to prevent PF maltracking?

Answer 34

ER and Lateralization of tibial and femoral components<div>Medialization of Patellar component</div>

Question 35

CR vs PS knees?

Answer 35

-CR knees have better survival<div><b>-PS slightly better ROM with sacrificing –> but not clinically significant</b></div><div>-All patients getting arthroplasty have slight elevation of joint line, but no difference between implant types (do not raise joint line >8mm –> assx with worse outcome)</div>

Question 36

TKA: decrease infx risk

Answer 36

-shorter OR time<div>-lower BMI</div><div>-irrigation</div><div>-<b>not antiobiotic loaded cement</b></div>

Question 37

Surgical Management for revision TKA - bone loss?

Answer 37

-cementation augment<div>-allograft: structural vs morselized</div><div>-trabecular metal cones</div><div>-metaphyseal sleeves</div><div>-stems</div><div>-constraint</div><div>-salvage:</div><div> -megaprosthesis</div><div> -fusion: 30 deg flexion, 5-10 deg ER, neut varus/valgus</div><div> -amputation</div>

Question 38

RFs for HO post-TKA

Answer 38

MUA post-op<div>hypertrophic OA</div><div>femoral notching</div><div><br></br></div><div><b>not RA</b></div>

Question 39

release of semimembranous affects what in TKA?

Answer 39

-helps for varus knee<div>-especially in <b>extension</b></div>

Question 40

With the EM alignment rod placed at the ankle -> what is the result of the tibial cut?

Answer 40

<b>Varus malalignment</b><div>-ankle joint is ER cf to tibial</div><div><br></br></div><div><div>To avoid tibial malalignment, it is important to first place the extramedullary alignment guide at right angles to the proximal tibial anteroposterior axis and then the distal end of the extramedullary guide should be placed at the center of the ankle joint</div></div>

Question 41

Increasing articular congruitry of poly in fixed bearing TKA leads to?

Answer 41

decrease contact stress in poly

Question 42

HIT?

Answer 42

heparin induced thrombocytopenia<div>-can be caused by UFH or LMWH</div><div><b>-presents 5-10days after start</b></div><div>-tx: plts, change anti-coag</div>

Question 43

RF for MI during TKA

Answer 43

Patient factors!<div>-age>65</div><div>-obesity</div><div>-cardiac: HTN, CAD, prev MI, CHF</div><div>-renal: ESRD</div><div>-resp: COPD</div>

Question 44

Causes of snapping hip

Answer 44

Intra-art: labrum, loose body<div>Internal: iliopsoas over iliopectineal eminence (snaps from hip ext to flex)</div><div>External: IT over GT (flex to ext)</div><div><br></br></div><div><b>not hamstring or rectus</b></div>

Question 45

Hip Impingement?

Answer 45

-FAI<div>-Ischiofemoral: narrowing b/t ischial tuberosity and LT–> QF gets pinched</div><div>-Sub-AIIS spine: contact b/t AIIS and prox femur</div><div>-iliopsoas impingment: thicked/taut psoas at acetabular rim/hip capsule</div>

Question 46

Tx for Patellar Tendon rupture after TKA

Answer 46

-repair - poor outcomes<div><b>-autograft reconstruction with semitendinosus</b></div><div>-allograft reconstruction with Achilles tendon or entire Ext Mech graft</div><div>-synthetics</div>

Question 47

Knee fusion position

Answer 47

Flex 0-20 deg<div>ER 5-10 deg (CL side!)</div><div>Slight valgus</div>

Question 48

Classification for TKA peripros #s (not RC Q)

Answer 48

“<div> <div> <div> <div>Su classification of femoral side</div> <div>Type 1: proximal to component</div> <div>Type 2: anterior flange and proximal</div> <div>Type 3: distal to anterior flange</div> <div></div> <div><img></img></div><div><br></br></div><div><br></br></div><div><div><img></img></div> <div>Type 4 - Tibial Tubercle Fracture</div></div><div><br></br></div> </div> </div></div>”

Question 49

considerations in arthroplasty in patients with pagets?

Answer 49

<ul> <li>THA Considerations:</li> <ul> <li>Mixed sclerotic/soft bone</li> <li>Need for acetabular grafting</li> <li>Acetabular protrusio</li> <li>Coxa vara</li> <li>Trochanteric alignment</li> <li>Abnormal ingrowth, challenging cement mantle</li> </ul> <li>TKA Considerations:</li> <ul> <li>Angular deformity</li> <li>Extensive bone loss/cysts</li> <li>Tight collaterals</li> <li>Difficult exposure</li> <li>Unable to use intra-medullary guides</li></ul></ul>

<ul> <li>Complications:</li> <ul> <li>HO (23-52%)</li> <li>Bleeding</li> <li>Osteolysis</li> <li>Non-union</li> <li>Continued bone pain following arthroplasty</li> <li>Malignant transformation</li> </ul></ul>

Question 50

Methods to address Patella Baja in TKA

Answer 50

<div> <div> <div> <div>Joint Line Management:</div> <ul> <li>References for a Normal Joint Line:</li> <ul> <li>1.5cm above fibular head</li> <li>Epicondyles</li> <li>Physeal Scar</li> </ul> </ul> <div></div> <ul> <li>Elevation of Joint Line (>8mm is problematic)</li> <ul> <li>Mid flexion instability</li> <li>PF tracking problems</li> <li>Patella baja equivalent</li> </ul> </ul> <div></div> <ul> <li>Depression of Joint Line:</li> <ul> <li>Lack of full extension</li> <li>Flexion Instability</li> </ul> </ul> <div></div> <div>Methods to address Patella Baja in TKA (Orthobullets)</div> <ul> <li>Place patella component superiorly</li> <li>Lower joint line (more tibial cut, need to add distal femur augment)</li> <li>TT transfer proximally</li> <li>Patellectomy</li> </ul> </div> </div></div>

Question 51

Principles of TKA Revision?

Answer 51

<ul> <li>Know reason for revision, obtain previous records</li> <li>Approach: lateral incision, extensile (quads snip, VY, TTO)</li> <li>Removal of components: implant extraction set, preserve bone, leave patella if possible</li> <li>Bone defects: address with bone graft, metal augments, cones, sleeves</li> <li>Salvage</li> <ul> <li>Megaprosthesis</li> <li>Fusion: 20 deg flex, 5-10 deg ER (match CL side), slight valgus</li> <li>Amputation</li> </ul></ul>

Question 52

Algorithm for stiff knee postop?

Answer 52

“RMR:<div>MUA <12 weeks</div><div>if >12 weeks - do lysis of adhesions, consider revision</div><div><br></br></div><div><img></img><br></br></div>”

Question 53

NEJM 2018: ASA vs Rivaroxaban

Answer 53

-5 days of NOAC then randomized<div>-No difference in rates of symptomatic VTE (primary outcome) in THA and TKA</div><div>-no difference in complications either</div>

Question 54

<div>Acetabulum landmarks for reaming in hip dysplasia?</div>

Answer 54

fovea<div>confluence of ischium and pubis (teardrop)</div><div>TAL<br></br></div>

Question 55

ddh stems?

Answer 55

<ul> <li>Narrow diaphyseal-fixed cone-type tapered stems: Wagner Cone</li> <li>Modular, Proximal Fitting, Diaphyseal Stabilized Cynlindrical Stem (S-ROM)</li> <li>Narrow Cemented stems: Exeter</li></ul>

Question 56

subtroch shortening osteotomy?

Answer 56

“<ul> <li><img></img><br></br></li><li>Prepare femur - ream/broach for proximal fit</li> <li>Cut osteotomy </li> <li>Trial femoral component into proximal fragment</li> <li>Reduce hip</li> <li>Judge required amount of shortening</li> <li>Use resected bone as an onlay autograft</li> <li>Uncemented modular implants allow control of femoral version</li> <li>Fully porous-coated or diaphyseal stems are useful</li> <ul> <li>But not in very small diameter femurs (fracture risk)</li> </ul></ul>”

Question 57

Ficat Staging for Hip AVN

Answer 57

“<img></img>”

Question 58

Classify loosening of implants?

Answer 58

inadequate initial fixation<div>mechanical loss of fixation</div><div>biological loss (Osteolysis)<br></br></div>

Question 59

Paprosky classification elements for acetabular bone loss?

Answer 59

“<div><img></img><br></br></div><img></img>”

Question 60

OPtions for persistently unstable THA?

Answer 60

-constraint cup<div>-bipolar hemi</div><div>-resection arthroplasty</div>

Question 61

Radiation dose for HO prophylaxis?

Answer 61

7Gy (5.5-20) preop to avoid pain with early post-op ROM<div>Indomethacin 75mg dailyX6/52</div>

Question 62

MSIS criteria?

Answer 62

“<img></img>”

Question 63

Fusion positions for hip/knee

Answer 63

“Hip: 20 deg flex, 10 deg ER, 0 deg abd/add<div><img></img><br></br><div>Knee: 10 deg flex, 10 deg ER, 5 deg valgus</div></div><div><img></img><br></br></div>”

Question 64

Pathoanatomy and Radiographic features of Adult Hip Dysplasia

Answer 64

“<ul> <li>Acetabular: Anterolateral uncoverage</li><ul><li>Acetabular retroversion in 20-33%</li></ul></ul> <ul> <li>Femur :</li> <ul> <li>Increased anteversion and coxa valga</li> <li>Short femoral neck</li> <li>Narrow femoral canal</li></ul></ul><ul><ul> </ul><li><b><u>Radiographs</u></b></li><li>Lateral center edge angle <20o </li> <li>Anterior center edge angle <20o</li> <li>Acetabular index > 25o</li> <li>Tonnis angle- abnormal is greater than 10 degrees</li> <div><img></img></div></ul><div><br></br></div>”

Question 65

Kerboul angles AVN?

Answer 65

“<ul> <li>Use Kerboul method on MRI to measure arc of femoral surface involved on midcoronal and midsaggital images</li> <ul> <li>Sum of angles calculated</li> <ul> <li>Grade 1: <200 degrees (low risk of progression)</li> <li>Grade 2: 200-245 degrees</li> <li>Grade 3: 250-299 degrees</li> <li>Grade 4: 300+ degrees</li> </ul> </ul> </ul> <div></div> <div><img></img></div> <div>Kerboull angle = 247o</div> <div></div> <ul> <li>Ha (JBJS 2006)</li> <ul> <li>Prospective evaluation of 37 hips with pre-collapse osteonecrosis</li> <ul> <li><190degrees = 0/4 hips collapse</li> <li>190-240 degrees = 4/8 hips collapsed</li> <li>>240 degrees - all 25 hips collapsed</li> </ul> </ul></ul>”

Question 66

osteolysis vs aseptic loosening?

Answer 66

<div>-osteolysis: BIOLOGIC LOSS of fixation</div>

<div>--Mediated by macrophages --> phagocytosis of debris --> release of cytokines --> osteoclast induction</div>

<div>--Stimulation greater with small particles (<1microns) than with large particles (>10microns)</div>

<div><br></br></div>

-aseptic loosening: MECHANICAL LOSS of fixation

Question 67

DDx acetabular protrusio? Tx?

Answer 67

“<ul> <li>Infection</li> <li>Idiopathic - Otto Pelvis</li> <li>Inflammatory –> RA, AS, JRA, Psoriatic, Reiter</li> <li>Neoplasm –> hemangioma, mets, NF, radiation ON</li> <li>Metabolic –> Paget’s, OI, Ochronosis, Osteomalacia, Hyperparathyroidism, Acrodyostosis</li> <li>Traumatic –> post-acetabular fracture</li> <li>Genetic –> Trisomy 18, Sickle Cell, Marfan, Ehlers-Danlos, Stickler syndrome, Trichorhinophalangeal syndrome</li> <li>Iatrogenic –> post-arthroplasty (chronic or acute)</li></ul><div><ul> <li>Pediatric:</li> <ul> <li>Tri-radiate closure</li> <li>Valgus inter-trochanteric osteotomy</li></ul></ul> <ul> <li>Adults:</li> <ul> <li>Medial bone grafting vs cup-cage</li> </ul></ul></div>”

Question 68

Flexion/Extension Balancing in TKA - what is only combo that you can do ++ things in?

Answer 68

“<img></img>”

Question 69

Uni knees: indications, contraindications?

Answer 69

<ul> <li>Kozinn and Scott:</li> <ul> <li>Unicompartmental arthritis</li> <li>Age > 60 with low demand</li> <li>Weight < 82kg</li> <li>Minimal rest pain</li> <li>ROM > 90o with < 5o flexion contracture</li> <li>Angular deformity < 15o</li> <li>** intact ACL (with mobile bearing)</li> <li>mechanical axis deviation <10 degrees from neutral in varus or 5 degrees in valgus</li> </ul> <li>Contra-indications:</li> <ul> <li>Inflammatory arthritis</li> <li>Age < 60</li> <li>High activity level</li> <li>Rest pain</li> <li>PF pain</li> </ul></ul>

Question 70

contraindications to hip fusion?

Answer 70

<ol><ol><li>Active infection</li> <li>Knee fusion </li> <li>Bone stock</li> <li>Scoliosis</li> <li>Bilateral</li> </ol></ol>

Question 71

ceramic fracture/failure - tx/revision plan?

Answer 71

complete synovectomy<div>revision to ceramic on poly or ceramic on ceramic.</div><div><br></br></div><div>(DO NOT REVISE TO METAL ON POLY AS CERAMIC SHARDS WILL MELT AWAY METAL)</div>

Question 72

types of seronegative arthritis?

Answer 72

“<img></img>”

Question 73

how to reduce a dislocated TKA (femur anterior)

Answer 73

hyperflexion, then anterior drawer

Question 74

RFs for failure of DAIR (debriement, antibiotics, implant retention)

Answer 74

<ul> <li>presence of sinus</li> <li>immunocompromised patient</li> <li>delay between onset of infection and debridement procedure</li> <li>Staph infection (esp MRSA)</li> <li>multiple debridement procedures</li> <li>retention of exchangeable components</li> <li>short antibiotic duration</li></ul>

Question 75

Contents of Sciatic Notch - greater and lesser?

Answer 75

“<img></img><br></br><div><div>The following structures pass through the lesser sciatic foramen:</div><ul><li>Tendon of obturator internus</li><li>Nerve to obturator internus</li><li>Internal pudendal vessels</li><li>Pudendal nerve</li></ul></div>”

Question 76

A 72-year-old man with a past medical history of hypertensionis scheduledfor cemented total knee arthroplasty. What is the current recommendation for bone cement additive for this patient?<div>A. No antibiotics added</div><div>B. Premixed gentamicin</div><div>C. Premixed tobramycin</div><div>D. Hand-mixed vancomycin</div>

Answer 76

For routine cemented total knee arthroplasty, the current Food and Drug Administration recommendation is to use plain bone cement without premixed or hand-mixed antibiotics. The addition of antibiotics to bone cement is approved only for use in revision knee arthroplasty. The theoretical advantage of having antibiotics in bone cement to help reduce the incidence of infection following primary total knee arthroplasty has yet to be proven in the literature.

Question 77

“<div>For the implant shown in Figures 1 and 2, what is the predominant cell type that is responsible for cell-mediated wear?</div><div><img></img><img></img><br></br></div><div><br></br></div><div>A. Macrophage</div><div>B. Lymphocyte</div><div>C. Histiocyte</div><div>D. Mast cell</div><div><br></br></div>”

Answer 77

In the implant shown in Figures 1 and 2, the hip resurfacing arthroplasty has a metal-on-metal articulation, which generates metal ions into the local soft tissues. Lymphocytes are responsible for the local soft-tissue reactions. Macrophages are associated with metal-on-polyethylene wear-associated bone resorption. Histiocytes and mast cells are associated with anaphylactic reactions.

Question 78

Paprosky Classification of Femoral Bone Loss

Answer 78

Type I:There is <b>sufficient proximal bone to support any implant and therefore a primary stem (metaphyseal ingrowth) is sufficient</b> (using a double wedge taper design which provides the best proximal fill), altought there may still be compromised rotational stability and thus many surgeons elected for a fully porous stem (diaphyseal ingrowth). <div><br></br></div><div>Type II:there is insufficient metaphyseal bone stock to support the stem, thus the implant must have some diaphyseal porous coating for ingrowth.</div><div><br></br></div><div>Type IIIA:no metaphyseal bone stock, some deficient proximal diaphyseal bone stock.Requires diaphyseal fixation. While standard fully coated stem is an option, good results have also been shown with the Modular stem designs.</div><div><br></br></div><div>Type IIIB:even less diaphyseal bone stock (<b>< 4 cm intact diaphysis</b>) yet the femoral isthmus remains supportive. The Modular stem designs are the best option</div><div><br></br></div><div>Type IV:without any supportive diaphysis, there is no way to obtain initial press-fit to allow for bony ingrowth. Therefore these cases are incredibly challenging and typically require a total femoral replacement or APC (allograft-prosthetic composite).</div>

Question 79

“A 68-year-old man undergoes outpatient arthroplasty. He has a body mass index (BMI) of 31, is acurrent smoker, and is diabetic, with a hemoglobin (Hb)A1c score of 6.3. Given the patient’s history, what is his greatest risk factor for infection and readmission following outpatient arthroplasty?<div><br></br></div><div>A. Age</div><div>B. BMI</div><div>C. Smoking</div><div>D. Diabetes mellitus</div>”

Answer 79

“C. Smoking<div>Outpatient arthroplasty is becoming more common, and readmission can be a problem through improper patient selection. Smoking remains one of the most important risk factors for perioperative infection and readmission within the 90-day global period. Because this patient’s BMI is less than 35, the risk of infection is not elevated. <b>Age over 70 has been associated with an increased readmission risk</b>. <b>Although diabetes remains a risk factor for infection, having an HbA1c score less than 8 is not associated with an increased risk for readmission.</b><br></br></div>”

Question 80

What is the most common indication for revision THA? (BJJ 2016)

Answer 80

Instability

Question 81

What is the definition of early and late dislocators?

Answer 81

Early dislocator<div>- Within 2 years of surgery</div><div>- One study showed 59% of dislocations in first 3 months, 77% within first year</div><div><br></br></div><div>Late dislocator</div><div>- Beyond 2 years</div>

Question 82

How do the etiologies of instability differ in early vs. late dislocations?

Answer 82

Early: most commonly due to malposition<div><br></br></div><div>Late</div><div>- Eccentric liner wear</div><div>- Implant loosening (subsidence/migration or rotation of the cup)</div><div>- Abductor muscle damage</div><div>- GT disruption (due to osteolysis)</div>

Question 83

THA Dislocation Risk Factors (JAAOS 2004)

Answer 83

Patient factors<div>- Female (2x more common than men)</div><div>- Neuromuscular and cognitive disorders (CP, muscular dystrophy, parkinsons, psychosis, dementia, alcoholism)</div><div>- THA for management of fracture</div><div>- History of surgery on the same hip (for any indication)</div><div>- Patient non-compliance with activity restrictions</div><div><br></br></div><div>Surgical factors</div><div>- Surgeon inexperience</div><div>- Surgical approach - posterior approach</div><div>- Soft-tissue tension (capsule repair reduces risk, restoration of abductor tension reduces risk - offset and neck length, GT non-union or abductor avulsion increases risk)</div><div>- Component position (acetabulum, femur)</div><div>- Impingement (bone, implant, soft-tissue)</div><div><br></br></div><div>Reducing impingement: increase head:neck ratio (head diameter:neck diameter) - note: increasing head size increases jump distance. Avoid skirts. Clear acetabular osteophytes, extruded cement, HO. Increase femoral offset.</div>

Question 84

What are indications for constrained devices in THA?

Answer 84

1. Recurrent instability (3 or more dislocations)<div>2. Previous failed attempts at surgical stabilization</div><div>3. Lack of identifiable cause of instability that could be corrected</div><div>4. CNS disorders</div><div>5. Previous failure of a constrained device</div><div>6. Prophylaxes in revision procedures in patients with deficient soft tissues</div><div>7. Alcohol abuse</div><div>8. Multidirectional instability pre-operatively</div><div>9. Substantial abductor muscular deficiency</div><div>10. Presence of an internal fixation device</div><div>11. Extensive femoral or acetabular bone loss</div><div>12. Inability to repair the GT</div><div>13. Revision after arthrodesis or resection arthroplasty</div><div>14. Revision after periprosthetic fractures</div><div>15. Cognitive impairment preventing adherence to precautions</div><div>16. Prophylaxis in the revision of MoM with sustantial soft tissue defents after debridement of tissue granulomas or necrotic tissue</div>

Question 85

What are complications associated with dual-mobility components?

Answer 85

1. Increased poly volumetric wear<div>2. Osteolysis</div><div>3. Intraprosthetic dislocation</div>