NORMAL ANATOMY Osteology Distal femur anterior/posterior view lateral view Proximal tibia anterior/posterior view Patella anterior/posterior view Attachments Muscle anterior view posterior view lateral view Ligament/tendon anterior/posterior view lateral view AP/PA view Positioning patient supine (AP) vs. prone (PA) knee extended + leg IR 3-5° beam aim 1.5cm distal to apex of patella Indications fracture joint alignment OA PA view preferred over AP view weightbearing view preferred over non-weightbearing view Critique symmetrical femoral + tibial condyles fibular head should be bisected by the tibia visualization of intercondylar eminence in intercondylar fossa Lateral view Positioning patient rolled lateral (mediolateral) = lateral decubitus on ipsilateral side + knee flexed 20-30° horizontal ray (lateromedial) = supine + knee extended beam aim 2.5cm distal to medial epicondyle tilt 5-7° cephalad (if rolled lateral) Indications patella fracture = horizontal ray view to avoid displacement patella alta/baja = requires knee in 30° flexion trochlear dysplasia OA joint effusion Critique visualization of suprapatellar fat pad = via knee flexion < 30° appropriate IR/ER superimposition of posterior aspect of femoral condyles superimposition of fibular head + tibia open patellofemoral joint no visualization of adductor tubercle appropriate cephalad angulation = open tibiofemoral joint Oblique view Positioning patient AP = supine + knee extended + leg IR/ER 45° PA = prone + knee flexed 10° + leg IR/ER 45° beam aim 1.5cm distal to apex of patella Indications fracture = femoral condyle, patella OA intercondylar fossa pathology = loose bodies Critique superimposition of patella + ipsilateral femoral condyle asymmetrical tibiofemoral joint spaces Intercondylar view Positioning METHODPATIENTBEAMBecleresupineknee flexed 40°AP40° cephaladCamp Coventry/Tunnelproneknee flexed 40°PA40° caudadHolmbladerectvs. kneelingknee flexed 70°PA0° Indications OCD = displaced cartilage congenital slipped patella = flattening/underdevelopment of lateral femoral condyle hemophilia = intercondylar widening intercondylar fossa pathology = loose bodies Critique superimposition of patella + ipsilateral femoral condyle asymmetrical tibiofemoral joint spaces Tangential view Positioning METHODPATIENTBEAMSunrise/Settegastsupinevs. proneknee flexed 90°inf-sup10-20° cephaladHughstonproneknee flexed 50-60°inf-sup45° cephaladMerchantsupineknee flexed 40°sup-inf30° caudadLaurinesemi-recumbentknee flexed 30°inf-sup30° cephalad Indications patellar malalignment trochlear groove depth OA vertical patella fracture Critique visualization of femoral condyles + trochlear groove no superimposition of patella + femur open patellofemoral joint NORMAL FINDINGS Normal anatomy Normal variants fabella sesamoid bone in lateral head of gastrocnemius best seen on lateral view cyamella sesamoid bone in popliteus tendon usually present in lateral aspect of distal femur in popliteal groove best seen on AP view cortical desmoid cortical lucency in posteromedial aspect of distal femur represents origin of medial head of gastrocnemius + insertion of adductor magnus seen in adolescents (10-15 yo) bipartite/tripartite patella usually superolateral with smooth margins double-layered patella rare form of bipartite patella multiple fragmented patella with smooth well-corticated borders pathognomonic for multiple epiphyseal dysplasia