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>
- THA Considerations:
- Mixed sclerotic/soft bone
- Need for acetabular grafting
- Acetabular protrusio
- Coxa vara
- Trochanteric alignment
- Abnormal ingrowth, challenging cement mantle
- TKA Considerations:
- Angular deformity
- Extensive bone loss/cysts
- Tight collaterals
- Difficult exposure
- Unable to use intra-medullary guides
- Complications:
- HO (23-52%)
- Bleeding
- Osteolysis
- Non-union
- Continued bone pain following arthroplasty
- Malignant transformation
- References for a Normal Joint Line:
- 1.5cm above fibular head
- Epicondyles
- Physeal Scar
- Elevation of Joint Line (>8mm is problematic)
- Mid flexion instability
- PF tracking problems
- Patella baja equivalent
- Depression of Joint Line:
- Lack of full extension
- Flexion Instability
- Place patella component superiorly
- Lower joint line (more tibial cut, need to add distal femur augment)
- TT transfer proximally
- Patellectomy
- Know reason for revision, obtain previous records
- Approach: lateral incision, extensile (quads snip, VY, TTO)
- Removal of components: implant extraction set, preserve bone, leave patella if possible
- Bone defects: address with bone graft, metal augments, cones, sleeves
- Salvage
- Megaprosthesis
- Fusion: 20 deg flex, 5-10 deg ER (match CL side), slight valgus
- Amputation
- Narrow diaphyseal-fixed cone-type tapered stems: Wagner Cone
- Modular, Proximal Fitting, Diaphyseal Stabilized Cynlindrical Stem (S-ROM)
- Narrow Cemented stems: Exeter
- Prepare femur - ream/broach for proximal fit
- Cut osteotomy
- Trial femoral component into proximal fragment
- Reduce hip
- Judge required amount of shortening
- Use resected bone as an onlay autograft
- Uncemented modular implants allow control of femoral version
- Fully porous-coated or diaphyseal stems are useful
- But not in very small diameter femurs (fracture risk)
- Acetabular: Anterolateral uncoverage
- Acetabular retroversion in 20-33%
- Femur :
- Increased anteversion and coxa valga
- Short femoral neck
- Narrow femoral canal
- Radiographs
- Lateral center edge angle <20o
- Anterior center edge angle <20o
- Acetabular index > 25o
- Tonnis angle- abnormal is greater than 10 degrees
- Use Kerboul method on MRI to measure arc of femoral surface involved on midcoronal and midsaggital images
- Sum of angles calculated
- Grade 1: <200 degrees (low risk of progression)
- Grade 2: 200-245 degrees
- Grade 3: 250-299 degrees
- Grade 4: 300+ degrees
- Ha (JBJS 2006)
- Prospective evaluation of 37 hips with pre-collapse osteonecrosis
- <190degrees = 0/4 hips collapse
- 190-240 degrees = 4/8 hips collapsed
- >240 degrees - all 25 hips collapsed
- Infection
- Idiopathic - Otto Pelvis
- Inflammatory --> RA, AS, JRA, Psoriatic, Reiter
- Neoplasm --> hemangioma, mets, NF, radiation ON
- Metabolic --> Paget's, OI, Ochronosis, Osteomalacia, Hyperparathyroidism, Acrodyostosis
- Traumatic --> post-acetabular fracture
- Genetic --> Trisomy 18, Sickle Cell, Marfan, Ehlers-Danlos, Stickler syndrome, Trichorhinophalangeal syndrome
- Iatrogenic --> post-arthroplasty (chronic or acute)
- Pediatric:
- Tri-radiate closure
- Valgus inter-trochanteric osteotomy
- Adults:
- Medial bone grafting vs cup-cage
- Kozinn and Scott:
- Unicompartmental arthritis
- Age > 60 with low demand
- Weight < 82kg
- Minimal rest pain
- ROM > 90o with < 5o flexion contracture
- Angular deformity < 15o
- ** intact ACL (with mobile bearing)
- mechanical axis deviation <10 degrees from neutral in varus or 5 degrees in valgus
- Contra-indications:
- Inflammatory arthritis
- Age < 60
- High activity level
- Rest pain
- PF pain
- Active infection
- Knee fusion
- Bone stock
- Scoliosis
- Bilateral
- presence of sinus
- immunocompromised patient
- delay between onset of infection and debridement procedure
- Staph infection (esp MRSA)
- multiple debridement procedures
- retention of exchangeable components
- short antibiotic duration
- Tendon of obturator internus
- Nerve to obturator internus
- Internal pudendal vessels
- Pudendal nerve
