Arthroplasty Flashcards
RFs for PJI in THA?
Patient factors: Obesity, DM, steroids, EtOH use, CLD, post-traumatic OA<div>Surgical factors: prolonged OR time, Wound drainage, hematoma, revision surgery</div>
MSIS Criteria for PJI?
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>
X-ray Findings of FAI?
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>
Coxa profunda vs Acetab Protrusion
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>
3rd gen cement techinque?
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>
Advantages of HXPE vs UHMWPE
<b>decreased wear</b><div>decreased fracture</div><div>decreased oxidization</div><div><br></br></div><div><b>increased cost</b></div>
THA Modes of wear?
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>
Properties of PMMA
<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>
Tantalum properties?
“-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>”
Advantages of high off set stem?
-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>
Complications for mal-positioned cup
Dislocation, instability<div>Increased wear/osteolysis</div><div>Aseptic loosening</div><div>Impingement</div><div>LLD</div><div>Decreased ROM</div>
RFs for hip AVN
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>
Treatment options for hip AVN?
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>
Technical Considerations for Crowe 4 hip THA?
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>
Modular neck in THA leads to?
Increased corrosion
RFs for HO post THA?
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>
RFs for HO (in general)?
“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>”
THA and hemophilia?
“<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>”
RFs for Fem Neck # with BHR
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>
Indications/Contraind for BHR?
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>
Poor Px factors for PAO in Adult Dysplasia?
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>
Signs of loosening femoral stem?
<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>
Components of Paprosky Acetabular Bone Loss?
location of hip centre (ie migrated)<div>ischial osteolysis</div><div>integrity of Kohlers (ilioschial) line</div><div>teardrop destruction</div>
Paprosky components of Femoral Bone Loss?
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>
Components of Vancouver classification
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>
RFs for instability post THA
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>
Surgical tx options for recurrent THA instability
-component positioning!<div>-increase offset, trochanteric advancement</div><div>-constrained liner</div><div>-bipolar prosthesis</div><div>-resection arthroplasty</div>
Releases to balance a varus knee?
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>
Releases to balance Valgus knee?
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>
Causes of post-op TKA stiffness?
“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>”
Cyclops lesion?
anterior arthrofibrosis -><b>block to extension (not flexion)</b><div><b><br></br></b></div>
hemophiliac TKA postop complaint?
stiffness, <b>not laxity</b>
Methods to improve flexion gap during TKA?
<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>
Methods to prevent PF maltracking?
ER and Lateralization of tibial and femoral components<div>Medialization of Patellar component</div>
CR vs PS knees?
-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>
TKA: decrease infx risk
-shorter OR time<div>-lower BMI</div><div>-irrigation</div><div>-<b>not antiobiotic loaded cement</b></div>
Surgical Management for revision TKA - bone loss?
-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>
RFs for HO post-TKA
MUA post-op<div>hypertrophic OA</div><div>femoral notching</div><div><br></br></div><div><b>not RA</b></div>
release of semimembranous affects what in TKA?
-helps for varus knee<div>-especially in <b>extension</b></div>
With the EM alignment rod placed at the ankle -> what is the result of the tibial cut?
<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>
Increasing articular congruitry of poly in fixed bearing TKA leads to?
decrease contact stress in poly
HIT?
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>
RF for MI during TKA
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>
Causes of snapping hip
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>
Hip Impingement?
-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>
Tx for Patellar Tendon rupture after TKA
-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>
Knee fusion position
Flex 0-20 deg<div>ER 5-10 deg (CL side!)</div><div>Slight valgus</div>
Classification for TKA peripros #s (not RC Q)
“<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>”
considerations in arthroplasty in patients with pagets?
<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>
Methods to address Patella Baja in TKA
<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>
Principles of TKA Revision?
<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>
Algorithm for stiff knee postop?
“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>”
NEJM 2018: ASA vs Rivaroxaban
-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>
<div>Acetabulum landmarks for reaming in hip dysplasia?</div>
fovea<div>confluence of ischium and pubis (teardrop)</div><div>TAL<br></br></div>
ddh stems?
<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>
subtroch shortening osteotomy?
“<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>”
Ficat Staging for Hip AVN
“<img></img>”
Classify loosening of implants?
inadequate initial fixation<div>mechanical loss of fixation</div><div>biological loss (Osteolysis)<br></br></div>
Paprosky classification elements for acetabular bone loss?
“<div><img></img><br></br></div><img></img>”
OPtions for persistently unstable THA?
-constraint cup<div>-bipolar hemi</div><div>-resection arthroplasty</div>
Radiation dose for HO prophylaxis?
7Gy (5.5-20) preop to avoid pain with early post-op ROM<div>Indomethacin 75mg dailyX6/52</div>
MSIS criteria?
“<img></img>”
Fusion positions for hip/knee
“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>”
Pathoanatomy and Radiographic features of Adult Hip Dysplasia
“<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>”
Kerboul angles AVN?
“<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>”
osteolysis vs aseptic loosening?
<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
DDx acetabular protrusio? Tx?
“<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>”
Flexion/Extension Balancing in TKA - what is only combo that you can do ++ things in?
“<img></img>”
Uni knees: indications, contraindications?
<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>
contraindications to hip fusion?
<ol><ol><li>Active infection</li> <li>Knee fusion </li> <li>Bone stock</li> <li>Scoliosis</li> <li>Bilateral</li> </ol></ol>
ceramic fracture/failure - tx/revision plan?
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>
types of seronegative arthritis?
“<img></img>”
how to reduce a dislocated TKA (femur anterior)
hyperflexion, then anterior drawer
RFs for failure of DAIR (debriement, antibiotics, implant retention)
<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>
Contents of Sciatic Notch - greater and lesser?
“<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>”
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>
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.
“<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>”
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.
Paprosky Classification of Femoral Bone Loss
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>
“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>”
“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>”
What is the most common indication for revision THA? (BJJ 2016)
Instability
What is the definition of early and late dislocators?
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>
How do the etiologies of instability differ in early vs. late dislocations?
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>
THA Dislocation Risk Factors (JAAOS 2004)
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>
What are indications for constrained devices in THA?
- 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>
What are complications associated with dual-mobility components?
- Increased poly volumetric wear<div>2. Osteolysis</div><div>3. Intraprosthetic dislocation</div>
