PANCE Review: Rheumatology and Orthopaedics(Musculoskeletal System)

2011-10-01

Orthopaedics

2011-03-28

Orthopaedics flashcards, third year clerkship

paediatrics-ortho

2010-11-19

paeds orth lecture

UH/TAMC Ortho Approaches

2010-11-13

Intervals and risks for common orthopedic surgical approaches

UH/ TAMC Millers Foot and Ankle

2010-11-05

OITE Review. Millers F/A Chapter

UH/ TAMC Millers Rehabilitation

2010-11-05

OITE Review

UH/ TAMC Millers Pediatrics

2010-11-02

OITE Review: Millers Peds

UH/ TAMC Millers Pediatrics

2010-11-02

OITE Review: Millers Peds

UH/ TAMC Millers Adult Reconstruction

2010-10-31

Best bearings for hard-soft couple Co-Cr-PE Best bearings for ceramic components Alumina best. Zirconia bad- undergoes phase transformation -->changes surface roughness Hip lubrication type in hard-soft bearings Boundary (synovial fluid can't separate asperites) Indication for Ti alloy THA components Nickel allergy Best technique for polyethylene manufacturing direct compression molding Effects of calcium stearate on polyethylene Creates areas w/ unfused PE particles--> dec mechanical properties Advantages of PE cross-linking improves resistance to adhesive and abrasive wear Disadvantages of PE cross-linking Decreased: tensile strength/fatigue strength/fracture toughness/ ductility Effects of PE oxidation molecular chain scission. Accelerated PE wear/failure. Effects of crystallinity on cross-linking Only amorphous areas cross-link. If crystallinity over 70% then higher failure rates Particles generated hard-hard bearings more particles. Much smaller (0.015-0.12 micron). Run in period during first million cycles. Cleared locally via lymph. Lubrication type hard-hard bearings Mixed (boundary/hydrodynamic-completely separated). Hydrodynamic phase d.o. head size >38mm/velocity/roughness. Smoothness of bearings Ceramic>metal>>>PE Radial clearance Difference in radius of head and cup. Bigger head--> equatorial contact. Smaller head-->polar contact. Optimal <150 micron clearance- w/ polar contact with high bearing conformity. Stripe wear Seen w/ hard on hard bearings. Assoc w/ edge loading. Represents surface wear. Positions associated with hip edge loading heel strike/ stair climbing/rising from chair Third generation cement preparation Vacuum-->dec porosity. Pressurized cement. Precoated stem. Rough surface finish. Stem centralizer. Cement mantle 2mm suggested. 2/3 rule: 2/3 canal filled w/ stem- 1/3 filled w/ cement. NO contact bet femoral stem and cortex Femoral component design cemented THA Stiffer preferred (elastic-->transfers stress to cement). Precoating--> no difference. Medial flange--> no difference. Porous coated components Bony ingrowth. Pore size 50-350 microns. Porosity 40-50%. Gaps < 50 microns XR findings of stem fixation Spot weld: inc bone density surrounding distal extent of porous coating (well fixed). Intramedullary pedestal: e/o loose components. Prime factor contributing to stress shielding Stem stiffness Factors affecting stem stiffness 1. 4th power of stem radius. 2. metal (Co-Cr stiffer than Ti). 3. Geometry Incidence of dislocation 1-2% primary. 26% revision. Highest in elderly with THA post failed femoral neck fx fixation Main determinant of primary arc head-neck ratio Excursion distance Distance head must travel to dislocate (1/2 diameter of femoral head) Ideal acetabular alignment 15-30deg anteversion. 35-45deg coronal tilt Need for revision post dislocation 2/3 treated succesfully nonop. 1. if dislocates within functional range post-reduction. 2. after >2 dislocations Treatment total hip w/ loss of greater troch attachment Reattachment not succesfull. Tx: larger head +/- constrained liner Most common cause of THA revision Cemented: failure of acetabular component. Non-cemented: failure of femoral component (osteolysis) Most common complication hip resurfacing Femoral head fracture- risk: notching/osteoporosis/osteonecrosis/misplaced acetabular cup--> impingement Acetabular revision Porous coated hemisphere cup w/ screws best. Can use hemisphere cup if 2/3 rim remains. Cavitary defects filled w/ graft. Structural allograft- high failure rate (secondary to graft resorption/component migration). Recon cage: for segemental defects. Fail 2/2 abduction pullout. Acetabular component screw placement Posterosuperior: safe- risk: sciatic n/superior gluteal a/v. Anterosuperior: risk: external iliacs. Posteroinferior: safe if <20mm. Risk: sciatic/inferior gluteals/internal pudendals. Anteroinferior: risk: anterior inferior obturator n/a/v. Femoral stem revision noncemented/extensively coated porous coated/long-stem. Pass 2-3cm below original or 2 shaft diameters below defect. Timing of periprosthetic fractures non-cemented: <6 months- stress risers . Cemented: 5yrs ave @ stem tip/distally- cortical defects Tx periprosthetic greater troch fracture nonoperative HO after THA higher risk: contralateral HO/ direct lateral approach/prior fusion. Reop only if severe dec ROM/pain. Nonop tx not effective. Prevention: 600-750cGy w/in 48hrs (shield noncemented parts). Indomethacin 75mg x6wks Nerve injury post THA peroneal div sciatic most common- closest to acetabulum at ischium. Usually 2/2 retractors. Risk: lengthening over 3.5cm Balancing varus deformity 1. osteophytes. 2. deep MCL. 3. posteromedial corner. 4. sup MCL. 5. PCL- rare Balancing valgus deformity 1. osteophytes. 2. lateral capsule. 3. IT if tight in extension/ popliteus if tight in flexion. 4. LCL Balancing sagittal plane deformities Symmetric: adjust tibia. Asymmetric: adjust femur Indications for cruciate substituting design previous patellectomy/ inflammatory arthritis/ PCL deficiency TKA component alignment- patellofemoral balancing Femur: ER/medialize. Tibia: ER/center over medial 1/3 tubercle. Patella: medialize/central. Femoral condyle size Medial larger than lateral Addressing pateall baja during TKA Lower joint line. Patella: small dome placed superiorly. Cut but don't resurface or patellectomy if severe PE thickness TKA Thinnest portion larger than 8mm. Effects of PE machining shearing forces--> stretch subsurface 1-2mm-->sensitize to oxidation (white band of subsurface oxidation) Flexion closure assoc w/ quicker flexion recovery. Avoids need for CPM Manipulation arthrofibrosis post TKA 4-6wks postop ideal. Inc risk supracondylar fx if wait longer or femoral notching. Patellar clunk syndrome PS knees only. Tissue on posterior quad above sup pole of patella- catches in box at 35-40deg- pops back out--> clunk Rectus snip oblique transverse cut medial--> lateral quad tendon- risk diastasis of repair--> extensor lag Indications for constrained non-hinged TKA MCL attenuation/ LCL deficiency/ flexion gap laxity. Controversial for MCL deficiency- high stress Indications for constrained hinged knee global ligament deficiency/hyperextension instability/ s/p joint resection. Must have medullary stems and rotating platform. Location of knee joint line 1.5-2cm above fibular head Tx nondisplaced supracondylar periprosthestic fx cast/brace Tx supracondylar periprosthetic fx extends distal to flange/ comminuted revision TKR w/ medullary stem Flap coverage TKA medial gastroc flap (off medial sural artery)--> medial/lateral. Lateral gastroc flap only useful for lateral wounds.-- risk common peroneal palsy from flap traction UKA vs TKA faster early recovery/rehab. Fewer short term complications. Smaller incision. Worse long term complications. Contraindications UKA 1. ACL deficiency. 2. fixed varus. 3. knee flexion less than 90deg. 4. inflammatory arthritis. 5. highly active patient/laborer. Correction varus deformity w/ UKA correct to 1-5deg valgus Failure UKA fixed bearing: mechanical loosening. Mobile bearing: disease progression Most common complication TSA approach axillary nerve injury Most common reason for failure of TSA glenoid loosening Glenoid bone stock and TSA Can't proceed of glenoid wear to coracoid. Relative retroversion common 2/2 OA Humerus positioning TSA 20-30 deg retroversion. Instability s/p TSA anterior- 2/2 subscap pull-off TSA s/p 4 part humeral fx Anatomic positioning tuberosities key to function. Nonunion--> instability Rotator cuff arthropathy tx 1. reverse TSA. 2. hemi w/ large head--> 40-70 deg elevation. 3. RTC reconstruction- combine w/ resurfacing. Must retain CA ligament- avoid superoanterior escape. Wiberg angle lateral center edge angle (>20deg nml) Lequesne angle anterior center edge angle (>20deg nml) Acetabular index >5deg nml (Tonnis angle) Crossover sign e/o acetabular retroversion THA s/p DDH Place head into native acetabulum. May need subtroch osteotomy for shortening to realign. Lengthening over 3.5cm--> risk sciatic nerve injury. Advantages of ganz periacetabular osteotomy 1. multiplanar. 2. allows large corrections. 3. medializes joint. 4. inherent stability (post column intact). 5. avoids hip abductors Subtrochanteric osteotomy for DDH Correction of coxa valga and excessive femoral anteversion. Do not use closing wedge for flexion (compromises future THA) Contraindications HTO for knee OA 1. lateral tibial subluxation >1cm. 2. bone loss medial compartment. 3. flexion contracture >10deg. 4. Knee flexion less than 90deg. 5. Varus >10 deg. Poor prognostic indicators HTO Unable to obtain 8-10 deg valgus/ overweight patient-- if both then 60% failure @ 3yrs Proximal tibia lateral closing wedge osteotomy- complication Main complication: recurrence, loss of posterior tibial slope, patella baja Proximal tibia opening wedge osteotomy- complication nonunion, collapse of opening wedge. Better at maintaining posterior slope than closing wedge Distal femoral varus-producing osteotomy Goal: produce horizontal joint line w/ tibiofemoral angle of 0 deg. Most common complication after converting to TKA is inability to restore anatomic valgus Hip arthrodesis Indication: <35yo w/ severe post-traumatic arthritis. Requires 30% more energy. DJD 15-25yrs postop in lumbar spine (55-100%)>ipsilateral and contralateral knee>contralateral hip. Position: 0 add/0-15 ER/20-25 flexion. Conversion hip arthrodesis to THA concern abductor function: consider EMG/NCS of gluteus medius preop. If absent then conversion contraindicated. Knee arthrodesis Indication: most common- failed TKR. Position: 5 valgus/ 0-10 ER/ 0-15 flexion. IM fixation preferred if bone loss. Shoulder arthrodesis Contraindicated if ipsilateral elbow arthodesis. Position: 30/30/30. Rotation most critical in optimal function. Mechanism osteolysis Particles ingested by macrophages--> activated macrophages release TNF-alpha/IL-1/IL-6/PG/hydrogen peroxide/acid phosphatase-->activate osteoclasts Tx osteolysis around acetabular screw if cup well fixed: poly exchange, debride and bone graft osteolytic lesion. Revise cup if not well fixed Early postoperative infection- total joint within 3wks of implantation. Tx: poly exchange/ I&D/ abx x 4-6wks Hematogenous infection- total joint Seeding well established implant. Tx: poly exchange/I&D/ abx x 4-6wks. Implant exchange if recurrent. Chronic infection- total joint infection present >3wks. Usually coag - staph aureus. Tx: implant exchange Dental prophylaxis s/p arthroplasty First 2yrs. Lifetime if immunocompromised/immunosuppressed (RA/SLE/DM/previous total joint infection) Core decompression osteonecrosis Indications: early ON before collapse. Effects: pain relief. Poorer results if steroid induced Rotational osteotomy for osteonecrosis Indications: small lesion in weight-bearing area (<50%). Goals: rotate affected area out of weight-bearing area. CI if over 50% involvement. Vascularized bone graft for osteonecrosis Indication: early stage ON. CI if whole head involvement. Goal: prevent subchondral collapse.

UH/ TAMC Millers Sports

2010-10-31

OITE Review: Millers Sports

UH/ TAMC Millers Spine

2010-10-31

OITE Review: Millers Spine Chapter

UH/ TAMC Millers Basic Science 1

2010-10-31

OITE Review Millers Basic Science

UH/ TAMC Millers Hand

2010-10-31

OITE Review Millers Hand Chapter

UH/ TAMC Millers Basic Science 2

2010-10-31

OITE Review Millers Basic Science Chapter

orthopaedics Flashcards

PANCE Review: Rheumatology and Orthopaedics(Musculoskeletal System)

Orthopaedics

paediatrics-ortho

UH/TAMC Ortho Approaches

UH/ TAMC Millers Foot and Ankle

UH/ TAMC Millers Rehabilitation

UH/ TAMC Millers Pediatrics

UH/ TAMC Millers Pediatrics

UH/ TAMC Millers Adult Reconstruction

UH/ TAMC Millers Sports

UH/ TAMC Millers Spine

UH/ TAMC Millers Basic Science 1

UH/ TAMC Millers Hand

UH/ TAMC Millers Basic Science 2