Knee Flashcards
Patella
Largestsesamoid bone,protectstheknee • Fulcrumforquadriceps • Bipartitepatella– usuallyasymptomatic
BipartitePatella
Not a fracture! But often confused as one. a congenital condition (present at birth) that occurs when the patella (kneecap) is made of two bones instead of a single bone. Normally, the two bones would fuse together as the child grows but in bipartite patella, they remain as two separate bones
Tibia
• Jointcapsule:15mmdistaltojointline • Intercondylar tubercles(spines):ACLattachment • Gerdy’s tubercle:ITbandattachment • Medialplateau(ovalandconcave) • Lateralplateau(circularandconvex) • Lateralmoresensitivetomeniscalinsufficiency • Mostcommonlyfractured
Fibula
• Styloid process • LCLandBicepsfemoris insertions • Commonperoneal nerve
ACL– anteriorcruciateligament
• Extrasynovial butintra‐capsular • Providesstabilitytoanteriorandrotationalforce • Twobundles– Anteromedial andPosterolateral
PCL– posteriorcruciateligament
• Providesstabilitytoposteriorforce • Twobundles– AnterolateralandPosteromedial • Remember“PAL”
Posterolateral Corner
• Providesstabilitytorotationalstability • Arcuate ligament,popliteus,posterolateral capsule,LCL,popliteofibular ligament,lateralheadofgastrocnemius
Name the ligaments of the Knee (8)
PCL, ACL, MCL, LCL, Medial/Lateral Menisci, Patellar, Transverse Lig of the knee
ACL
O: Lat wall of intercondylar notch, I: Ant intercondylar notch, F: Anterior/rotational forces
PCL
O: Med wall of intercondylar notch, I: post tibial sulcus, F: posterior force
Deep MCL
O: med epicondyle, I: medial meniscus, F: holds MM to femur
Superficial MCL
O: medial epicondyle, I: medial tibia, F: resist valgus force
LCL
O: lat epicondyle, I: fibular head, F: resist varus force
Intermeniscal
O: anterolateral meniscus, I: anteromedial meniscus, F: stabilize menisci
Coronary
O: meniscus, I: tibial periphery, F: meniscal attachment
Menisci- Key Points
Meniscideepentheconcavityoftibial facets • Outer1/3isvascular(Red‐Redzone) • Inner2/3isavascular(Red‐whiteandwhite‐white) • Medialtears– overallmorecommonbecauseitislessmobile(fixed) • Lateraltears‐ commonwithACLtears
Radiographic Landmarks of the Knee
Femur, Tibia, Fibula, Med/Lat condyles (femur and tiba), Tibiofemoral joint, Prox/dist tibiofibular joint, Patellofemoral joint
Articular Cartilage
• Linesthejointsurfaces • Lowcoefficientoffriction(0.001; Teflon0.04) • Alymphatic,aneural,avascular • Consistsofwater,chondrocytes, andmatrix
Composition of Cartilage
Water– 65‐80%wetweight • IncreasesinOsteoarthritis(OA) • Responsiblefornutrition • Collagen– 10‐20%wetweight • TensileStrength • TypeIIcomprises90% • Othertypes:V,VI,IX,X,andXI • TypeX– hypertrophicchondrocytesduringcartilagegrowth • HighconcentrationinDeerAntlers • Schmidt’sMetaphyseal Chondrodysplasia
Proteoglycans
• Compressivestrength • 10‐15%wetweight • ComprisedofGlycosaminoglycans (GAGs) • ChondroitinSulfate • KeratinSulfate • GAGsboundtoproteincoretoformAggrecan molecule • Aggrecan boundtoHyaluronicAcid(HA)toformaggregate
Chondrocytes
• 5%ofwetweight • Producesthematrixcomponents • “Highlyspecialized” • Respondtomechanicalloads,solublemediators • Metabolismslowswithage
CartilageHealing
• Deepinjuryleadstoinfluxofmesenchymal stem cellsandfibrocartilageproduction • Superficialinjurydoesnotheal
Knee Exam
HIPROT
History
• Onset • Location • Severity • Aggravatingfactors • Nature • Mechanicalsymptoms • Treatments
Inspection
• Generalalignment • Scars • Effusion
Palpation
Tendernesstopalpation • Jointlines • Mostaccurateformeniscaltear • Patellartendon • Quadricepstendon • Pes anserinebursa • Fibularhead • Popliteal space • Gerdy’s tubercle
RangeofMotion
• Usegoniometer • Locateaxesoffemurandtibia • Normalkneehyperextends
StabilityExams
Lachman, Ant/Post Drawer, Pivot Shift, External Rotation‐Recurvatum, Valgus and Varus Stress, TEST THE GAIT