NORMAL ANATOMY Osteology & Attachments Anterior view Anterolateral view Posterior view Medial view Lateral view Superior view RADIOGRAPHIC VIEWS AP view Positioning patient supine knee extended + foot dorsiflexed beam aim at mid-tibiotalar joint Critique lateral malleolus closer to plate open medial joint space + tibiotalar joint closed lateral joint space slight superimposition of talus + fibula increased by ER + decreased by IR Mortise view Positioning patient supine knee extended + leg IR 15° + foot dorsiflexed beam aim at mid-tibiotalar joint Critique slight superimposition of fibula + tibia open lateral joint space + tibiotalar joint closed medial joint space no visualization of sinus tarsi too much IR if visible Lateral view Positioning patient supine knee extended + leg/ankle ER 90° + foot dorsiflexed beam aim at medial malleolus Critique superimposition of medial + lateral malleoli superimposition of talar domes superoinferior plane = lateral dome moves more proximal if proximal tibia higher than distal tibia AP plane = lateral dome moves posterior if too much ER superimposition of fibula + tibia fibula on posterior half of tibia but not superimposing posterior malleolus fibula moves anteriorly if too much IR open tibiotalar joint visualization of pre-talar fat pad requires foot dorsiflexion Oblique view Positioning patient supine knee extended + foot IR/ER 45° beam aim at mid-tibiotalar joint Critique medial/IR open lateral mortise + tibiotalar joint mortise closes with too much IR closed medial mortise slight superimposition of fibula + tibia no superimposition of talus + fibula no visualization of sinus tarsi too much IR if visible lateral/ER superimposition of fibula + tibia Stress view Positioning patient manual stress = supine + knee extended + ankle inverted/everted gravity stress = supine + hip ER + knee flexed + ankle placed on bump beam aim at tibiotalar joint Uses joint stability = < 5° difference between ipsilateral + contralateral ankles ER stress = evaluates syndesmotic/deep deltoid ligament injury IR stress = evaluates LCL injury NORMAL FINDINGS VIEW MEASUREMENT TECHNIQUE NORMAL FINDINGS Tib-fib clear space AP/mortise measure 1 cm above joint < 6mm Tib-fib overlap AP/mortise measure at maximum overlap > 6mm or 42% fibular width on AP view; > 1mm on mortise view Talar tilt AP/mortise difference in width of superior clear space < 2mm or < 2° on AP view, < 2mm or 0° on mortise view Talocrural angle mortise angle between intermalleolar line + line perpendicular to tibial articular surface < 83° ± 4° Medial clear space mortise distance between lateral medial malleolus + medial talus ≤ 4mm Shenton's line mortise line along lateral plafond continuous Dime test mortise line along lateral talus + lateral malleolus continuous Hawkin's sign mortise subchondral radiolucent band in talar dome seen 6-8 wks post-injury, results from revascularization of talar body present (absence indicates AVN) Heel-pad thickness lateral shortest distance between plantar calcaneus + skin 23mm in females, 25mm in males (increased in acromegaly) Achilles tendon thickness lateral measure 1-2cm above calcaneus 4-8mm