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88 Cards in this Set
- Front
- Back
% acute traumatic knee arthrosis w full-thickness chondral injury?
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5-10%
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Zones of articular cartilage organization?
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1) Superficial
2) Middle (transitional) 3) Deep (radial) 4) calcified cartilage |
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Superficial zone cartilage?
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-forms gliding surface
-thin collagen fibrils parallel to surface -Elongated chondrocytes parallel to surface -Proteoglycan content=lowest -Water content=highest(~80%) |
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Middle/Transitional zone articular cartilage?
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-larger diamete collagen fibrils
-less apparent organization -chondrocytes rounded in appearance |
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Deep Zone articular cartilage?
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-Proteoglycan content=highest
-water content=lowest -larger diameter collagen fibers organized perpendicular to joint surface |
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Zone of Calcified (articular) Cartilage?
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-Separated from Deep Zone by Tidemark
-Separates hyaline cartilage from subchondral bone -Small round chondrocytes in matrix |
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"Tide Mark"?
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-Wavy blue line on H&E
-separarates deep zone from calcified cartilage |
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Fluid phase caritlage?
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Water and electrolytes
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Solid phase cartilage?
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collagen, proteoglycans, and other proteins
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type II collagen?
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-90-95% of hyaline cart collagens
-distributed throughout matrix -quarter-staggered array |
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Type VI Collagen?
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-localized to pericellular capsule of chondrons
-may be important in tethering chondrocyt to pericellular matrix |
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Type IX Collagen?
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-Interruptions in triple helical domains
-does not form fibrillar structures on its own -Stabilizes collagen network by linking Type II collagen fibrils |
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Type X Collagen?
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-Appears to exist extracellularly in form of fine fibrous mats
-localized to deep calcified zones of mature joints -may play role in mineralization process above subchondral bone |
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Type XI Collagen?
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-Forms thinner fibrils
-links to itself as part of network |
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Major types of proteoglycans in articular cartilage?
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Chondroitin Sulfate (55-90%)
Keratan Sulfate (25-50%) Dermatan Sulfate |
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General characteristics of Proteoglycans?
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-10-20% cartilage
-chondroitin and keratin sulfate on protein core via link protein on hyaluronate backbone -high affinity for water -stiffness and strength -provides compressive strength |
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Increased age is accompanied by an increase in which GAG?
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Keratan Sulfate
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primary nutrition for articular cartilage?
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diffusion from synovial fluid
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Chondrocyte metabolism?
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-synthesize and maintain matrix
-Decreased metabolic rate w age -rarely divide after skeletal maturity -anaerobic metabolism |
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Why articular cart healing diff than other tissue?
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-avascular
-chondrocyt unable to migrate to defect |
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Artic cart response to partial thickness injury?
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-brief increase in matrix synthesis from adjacent chondrocytes
-no significant healing |
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Full thickness artic cart injury healing response?
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-defect is filled with fibrin clot and undifferentiated mesenchymal cells
-reparative tissue develops into 'hyaline-like" tissue -by 6-12 months fibrocartilage is present, which develops surface fibrillation with time. |
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Cart injury and repair process if subchondral bone is penetrated?
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-reparative response w fibrin clot,m cell migration from bone marrow, vascular ingrowth.
-fibrocatrilage formed w Type I collagen, less organized and vore vascular and biomechanically different than hyaline cartilage. Mechanically less durable and more likely to degenerate **mesenchymal stem cells come from bone marrow.** |
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What MRI setting look for articular cartilage injuries?
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T2 (T1 will not show articular cart injuries)
-*need proton density imaging of thin sections and T2-weighted imaging with fat suppression sequencing. -high relolution gradient echo/fast spin echo -Gadolinium enhances matris/GAG imaging |
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Outerbridge classification chondromalacia?
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-I Softening
-II Fibrillation -III Fissuring (but does not go down to subchondral bone) -IV Complete loss with exposed bone |
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Articular cart indications for surgery?
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-traumatic, nondegen lesion active pt <55yo
-lesion <1cm -symptomatic Gr IV lesions -symptomatic OCD in adolescents -symptomatic OCD in adults |
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Microfx technique?
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-best for contained, small, Gr 4 lesions
-3-4mm perforations separated by 5mm -need to debride (curette) calcified cartilage -NWB x 6 wks -CPM helpful? |
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OCD: cart and bone?
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Bone is dead, cartilage is alive.
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OCD: M/F?
joints affected? %bilateral? |
-M/F is 2:1
-knee, ankle, and elbow -15-30% bilateral |
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Nat Hx juvenile v adult OCD?
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-Juvenile will usually heal with non-operative treatment
-Adult OCD will rarely heal with non-operative treatment. |
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Indications ORIF OCD?
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-reducible OCD
0.5-1.0 cm2 or larter -use minifrag or headless screws -curette soft tissue from base of crater and drill to stimulate bleeding |
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Ideal OATS lesion?
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-focal
-contained -traumatic or OCD -1-3 cm2 (<2cm best) (speaker doesn't harvest more than 2 of these small grafts) |
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Osteochondral Allograft Transplantation indications?
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Best results in single, well-demarcated, full thickness, osteochondral defects of 2-5cm in your patient with an otherwise normal knee
-multiple lesions -AVN of condyles -large OCD |
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15-20 year survivorship osteochondral allografts?
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looks good at this time.
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Autogenous Chondrocyte Implantation (ACI) indications?
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-focal art car lesions of femoral condyles of knee
-large w full-thickness articular cart loss (w or w/o subchondral bone loss - ie OCD) -failed previous art cart treatment such as microfx, OATS |
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technique of periosteal flap sewn to cartilage for ACI?
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periosteal flap sewn w 6-0 Vicryl w cambium later facing subchondral bone
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ACI Indications II?
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-failed OCD repair
-large lesions 2-10cm2 -<6mm subchoncdral bone loss -age 15-55 -Normal alignment -no obesity -no inflammatory disorders -no sensitivity to gentamycin or bovine serum |
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Articular cart aging?
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-size of proteoglycan aggregates decreases
-affrecan molecules become shorter as do their chondroitin sulfate chains -mean # aggrecans in each aggregate decreases -decreased water concentration |
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Concentration Chondroitin-4 sulfate w age?
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decreases w age
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Concentration Chondroitin-6 sulfate concentration w age?
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Increases
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concentration Keratan sulfate w age?
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increases
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Apparent cause of cart breakdown in aging joints?
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action of proteolytic enzymes (proteinases) that are synthesizd by the chondrocytes
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**Articular cartilage changes with DJD?
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-AC fibrillation
-increased water content -decreased proteoglycan -increased permeability -decreased stiffness |
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Viscosupplementation efficacy?
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synvisc v Celestone: no sig diff in pain relief or function at 6 months follow-up
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Indications osteotomy?
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-unicompartmental disease
-young pt (5th-6th) decade -stable knee ROM - full extension, flex to 90 or greater. |
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osteotomy site for:
varus? valgus? |
varus - HTO
valgus - HTO < 12 deg DFO if >12 deg |
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Def Aptosis?
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chondrocyte death
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SONK?
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Spontaneaous OsteoNecrosis of the Knee
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SONK presentation?
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-middle age female following arthroscopy
-usually one compartment, unilateral -ass'd w subchondral deficiency -sudden onset of pain -MFC most commonly affected -Dx by MRI -Rx is NWB, 3-6 months! -do NOT scope again |
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AVN of knee DDx?
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-SONK
-OCD -Bone Bruise -Transient osteopenia |
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AVN of knee presentation?
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-over 45yo, F>M
-multiple compartments -bilateral -gradual onset -ass'd w sickle cell, steroids, EtOH |
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Knee accessory arth portal: posteromedial: where? Structure at risk?
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1 cm above joint line
inj risk to saphenous nerve |
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knee accessory arth portlal: where? structure at risk?
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-knee in flexion stay 1 cm above joint line and stay above biceps.
-inj risk to peroneal nerve |
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Normal synovium:layers?
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1) the intimal layer: synoviocytes, production of synovial flluid content
2) the subintimal supportive layer - fibrous and adipose tissue with a rich capillary network |
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Cell types in normal synovium?:
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Type A(25%): tissue macrophage, phagocytic function
Type B(75%) secretion of hyaluronate - |
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Composition of synovial fluid?
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-dialysate of blood plasma without clotting factors, RBC, HgB
-Hyaluronate (extended GAG) -Lubricin (lubrication glycoprotein) |
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Biomechanices of synovial fluid?
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-viscosity coefficient is not constant but depends on shear rate
-as shear rate increases, viscosity decreases (this is due to the presence of hyaluronate molecues that entangle to form elastic network, or "stringiness") |
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Elastohydrodynamic lubrication?
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under loading of cartilage there is "elastic" deformation which then spreads the going load over a larger surfae area
-decreases shear rate |
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Boundary Lubrication?
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-works when fluid film depleted
-monolayer of glycoprotein (lubricin) is adsorbed on each of the opposing articular surfaces -porvides cushioning and protects against abrasion |
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Synovial chondromatosis presentation?
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-cart tissue converted to ossified loose bodies
-usually middle-aged men -pain, mech Sx, dec motion -knee #1, elbow #2 -Rx complete synovectomy. -recurrence >25% |
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PVNS presentation?
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-slow growing, benign, locally invasive timor of synovium
-usually presents as monoarticular hemarthrosis -most have hemorrhagic, dark brown synovial fluid -**Biopsy is diagnostic -Mechanical symptoms |
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MRI DDx PVNS?
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-hemophilic arthropathy
-fibromatosis -synovial chondromatosis -septic or inflammatory arthritis -hemorrhagic synovitis |
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PVNS histopath?
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lipid-laden foam cells and multinucleated giant cells are interspersed with hemosiderin-laden cells. Sinilar to GCT of tendon sheath.
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Gout ass'd diseases?
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-EtOHism
-obesity -HTN -CAD -hypertriglyceridemia |
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Gout: Rx and recurrence?
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-thiazide diuretics and antimetabolites
-remits and recurs with high rate of recurrence |
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Gout synovial fluid?
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-inc WBC like in infx
-**needle-like intracellular and extracellular monosodium urate crystals seen under polarized light microscopy |
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Pseudogout presentation?
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>50yo,
knee and wrists chondrocalcinosis of menisci CPPD crystals are weak pos birefringence, rhomboib shape |
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Synovial fluid analysis: WBC?
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JRA 15k-80k
septic arthritis >50k gout/pseudogout -high but fluid usually less turbid ` |
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Synovial fluid analysis: crystals?
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Gout: negatively birefringement needles on polarized micro
Pseudo: rod-shapled or rhomboib with weak positive birefringecy |
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Tibial eminence Fx classification, Rx?
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I - minimally displaced - peds, nonop imm ob 6-8 weeks
II - fragment elevated but still attached - same Rx as I III - complete displacement of the fragments - usually ORIF |
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Most common location for osteochondral injury due to acute lateral patellar dislocation?
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medial patellar facet
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14yo w OCD MFC w intact articular cartilage. 4 mo's PT with no improvement. Best option for treatment?
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arthroscopic drilling
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11yo w displaced tibial eminence fx - Rx?
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arthroscopic reduction and fixation
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Open posteromedial approach to avulsion fx post cruciate ligament tibial insertion. How protect posterior NV bundle?
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Retraction of medial heard of the gastrocnemius muscle laterally (P352, look up)
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30 yo jockey failed microfx for 3x4cm bare bone artic cart lesion of MFC. Best treatment?
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Osteochondral allograft
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32yo beach VB w artic crt lesion of bare bone 1cm2. Microfx technique: most important technical step?
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the calcified cartilage layer must be removed.
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What is type collagen resulting from microfx?
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Type I
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14yo Basketball player w knee pain due to OCD femoral condyle. Pain began previous season. No trauma. No response to 6 weeks dec activity. Next step?
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Surgica intervention (p355)
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12yo w OCD w catching and effusions. Most common location of lesion?
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Posterolateral aspect of MFC>
p 356 |
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22 yo basketball player w OCD trochlea. Next step?
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arthroscopic eval and treatment.
p357 |
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33yo w loaclized PVN. Treatment?
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Arthroscopic excision of the focal lesion (total synovectomy not necessary, p 357)
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13yo w patellar dislocation, MRI shows displaced osteochondral fragment from LFC. Treatment?
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ORIF LFC artic cart fragment
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The structure of cartilage proteoglycans can be described as:
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Multiple glycosaminoglycans bound to core portein, which is subsequently bound to hyaluronate vie a link protein
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Fluid within a cartilage layer is pressurized under dynamiic joint motion because of what factor?
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Low hydraulic permeability of the tissue.
p360 |
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Compared with the surface of articular cartilage, the deeper layers have which characteristics (Q23 p 360)?
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An increase in chondrocyte volume and collagen fibers perpendicular to the joint surface
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Factor not associated with the limited capacity of cartilage to heal following injury?
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No initial response by chondrocytes to injury (?)
p 360 |
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Coefficient of frictoin between articulating surfaces in the healthy human hip is in general range of___?
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0.002 to 0.04
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Most likely mechanism of lubrication responsible for very low coefficient of friction in articular surface?
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Elastrohydrodynamic
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