The Ottawa Ankle Rules (OAR)• The commonly used criteria for predicting which patients require radiographic images.• Radiographs are only required for those patients with • tenderness at the posterior edge or tip of the medial or lateral malleolus. • inability to bear weight (4 steps) either immediately after the injury or in the emergency room. • pain at the base of the fifth metatarsal
Projections• Three main projections:• AP • Identifies fractures of malleoli, distal tibia/fibula, plafond, talar dome, body and lateral process of talus, calcaneus.• Mortise • Ankle 15-35 degrees internal rotation (20-25-degrees commonly used). • Evaluate articular surface between talar dome and mortise.• Lateral: • Identifies fractures of anterior/posterior tibial margins, talar neck, displacement of talus.• Other views like AP ankle plantar flexion view, medial oblique foot view, AP of proximal fibula, etc. may also be required in conjunction with above mentioned views.
Antero-posterior viewThe ankle is slightlydorsiflexed so that theplantar surface of the foot isperpendicular to thefilm, which brings theweight-bearing talar surfaceinto optimum tangentialprojection. Internally rotatethe lower leg so that a linethrough the malleoli isparallel with the film surface.
Measurements in AP view • Tibial shaft line (A). A line is drawn through and parallel to the tibial shaft. • Medial malleolus line (B). A line is drawn tangential to the articular surface of the medial malleolus. • Lateral malleolus line (C). A line is drawn tangential to the articular surface of the lateral malleolus. • Talus line (D). A line is drawn tangential to the articular surface of the talar dome. • Tibial angle (I). The angle is formed medially between the medial malleolus line and talus line. • Fibular angle (II). The angle is formed laterally between the lateral malleolus line and talus line. Angle Average (°) Min (°) Max (°) These angles will be altered in fractures ofTibial (I) 53 45 65 the malleoli, ankle mortise instability, andFibular (II) 52 43 63 tibiotalar slant deformities.
Measurements in AP view• Tibio-fibular clear space: - tibiofibular clear space is the cartilaginous space between lateral border of posterior tibia (incisura fibularis) & medial border of fibula, measured 1 cm above the joint line; - normally the clear space is less than 5-6 mm on both AP and Mortise views. (increase indicates syndesmotic and deltoid disruption).• Tibio-fibular overlap: - should be greater than 6 mm or 42% of fibular width.• Superior clear space: Difference in width of superior clear space between medial & lateral sides of joint should be < 2 mm
Measurements in AP view Talar Tilt:- difference in width of superior clear space between medial & lateral sidesTib-fib Clear Space > 5mm or of joint should be < 2 mmTib-fib Overlap < 10mmmay indicate syndesmotic injury > 2 degrees angulation may indicate medial or lateral disruption
Specialized Projections (AP)• Plantar flexion view (lazy AP view): For subtle fractures of the talar dome, including osteochondritis dissecans, plantar flexion will often demonstrate the fracture site as the posterior articular surface comes into view.• Inversion-eversion stress views: The stress is induced by a third person, who wears lead gloves and lead apron, or by the patient, who holds a strap that is looped around the sole of the foot. The views should be performed and measurements compared bilaterally. • Joint stability is defined by less than 5 deg difference between the injured and uninjured sides.• Weight-bearing AP view: Performed AP and weight bearing with a horizontal beam. This is especially valuable in showing degenerative decreased joint space and chronic instability with lateral talar tilt or lateral shift. Diastasis of the distal tibiofibular syndesmosis may also be more apparent as a widened joint with lack of tibiofibular overlap.
Radiographic Stress Tests of the Ankle• Talar Tilt Stress Test • Contralateral ankle used for comparison • Line is drawn across the talar dome and tibial vault • Degree of lateral opening angle is measured • Normal tilt is less than 5 deg • Considered abnormal if tilt greater than 10 deg (indicator of lateral ligament injury). • Standing Talar Tilt Stress Test: • may be more sensitive • Patient stands on an inversion stress platform with the foot and ankle in 40 deg of plantar flexion and 50 deg of inversion• External Rotation Stress Test Evaluates syndesmoses & deep deltoid ligaments
Lateral View of the Ankle• The lateral surface of the ankle is in contact with the film, with the foot slightly dorsiflexed. Cross the opposite leg over the leg being examined, and support the opposite knee to avoid rotation of the ankle.
Lateral View of the AnklePosterior tibial Dome of the talus:tuberosity fractures centered under& direction of fibular and congruousinjuries can be with tibial plafondidentified Avulsion fractures of the talus by the anterior Any deformity capsule can to the be identified talus, calcaneu s or subtalar joint
Measurements in Lateral view• Heel-Pad measurement: • The shortest distance between the plantar surface of the calcaneus and external skin contour is measured. • Increased skin thickness, especially of the heel pad, is a frequent accompanying feature of acromegaly.• Achilles tendon thickness can be assessed on a lateral view at 1-2 cm above the calcaneus and is normally 4-8 mm in dimension. Edema from inflammatory arthritis can thicken the ligament. Average Maximum Sex (mm) (mm)Male 19 25Female 19 23
Measurements in Lateral viewBoehler’s Angle:• The three highest points on the superior surface of the calcaneus are connected with two tangential lines. The angle formed posteriorly is then assessed.• The angle formed posteriorly averages between 30° and 35° in most normal subjects but may range between 28° and 40°• The most common cause for an angle < 28° is a fracture with displacement through the calcaneus. Dysplastic development of the calcaneus may also disturb the angle.
Specialized Projections (Lateral)• Drawer view: A third person, who wears lead gloves and a lead apron, stabilizes the tibia and pulls the hind foot forward.• Flexion-extension (dancer views): These can be performed with or without weight bearing with the foot on maximal plantar and then dorsiflexion for demonstrating bony impaction anteriorly and posteriorly as a sign of impingement syndromes.• Lunge’s view: Performed weight bearing in plantar flexion, the view demonstrates the degree of impaction of the anterior tibial margin to the neck of the talus, as part of the assessment for anterior impingement syndrome.• Lazy lateral: The posterior tibial margin is a frequent site of fracture and can be best demonstrated in an off-lateral projection, with slight external rotation of the foot. In addition, signs of posterior impingement syndrome can be shown to advantage at the posterior talus and os trigonum.
Radiographic Stress Tests of the Ankle• Anterior Drawer Test • The anterior drawer test evaluates ATFL integrity. • Abnormal anterior translation is between 5 to 10 mm, or 3 mm more than other side
Mortise view• The ankle is slightly dorsiflexed so that the plantar surface of the foot is perpendicular to the film. The lower leg is then internally rotated so that the intermalleolar line forms an angle of 35° with the film.• The amount of medial rotation is open to variation, with some advocating views at 20°, 35°, and 45° to demonstrate the mortise
Mortise X-Ray• This is an important view in the assessment of the post-traumatic ankle for detecting subtle fractures of the distal fibula, posterior tibia, talar dome, and base of the fifth metatarsal
Measurements in Mortise view• Medial clear space • Between lateral border of medial malleous and medial talus • <4mm is normal • >4mm suggests lateral shift of talus• Tibiofibular overlap:should normally be more than1 mm
Measurements in Mortise view• Talo-crural angle is formed by: - line drawn parallel to articular surface of distal tibia - line connecting tips of both malleoli (intermalleollar line). - this angle is normally 8 - 15 degrees. - alternative method: - angle formed by perpendicular to tibial articular surface & intermalleollar line. - this angle is normally between 75 and 87 degrees. - Shortening: - by either method this angle should be within 2 - 5 deg of opposite side. - difference of greater than this indicates fibular shortening.
Measurements in Mortise view• Talar tilt • line drawn parallel to articular surface of distal tibia; - second line drawn parallel to talar surface • Both lines should be parallel to each other and normal tilt angle is 0 deg (range 1.5 to 1.5 deg) • alternative method: - angle between intermalleolar line & each of these two articular surface lines is measured; - difference between these two angles is the talar tilt;
Syndesmotic disruption:• On the AP radiograph syndesmotic disruption is indicated by a • Tibial Clear Space >5mm • Tibio Fibular Overlap <10mm• On the mortise view a • Tibio Fibular Overlap <1mm
25 y/o male tennis player“torqued” his right ankle Grade III ATFL ankle sprain
Ankle Fracture Classification• Danis-Weber Classification • Defined by location of the fracture line • Type A: below the tibiotalar joint • Type B: at the level of the tibiotalar joint • Type C: above the tibiotalar joint • Syndesmotic ligament compromise• Lauge-Hansen Classification • Infrequently used, clinically; mostly academic
AO classification: • Similar to Danis-Weber scheme • Takes into account damage to other structures (usually medial malleolous) • ~2 pages of classifications
Pott’s classification: • First degree • unimalleolar • Second degree • bimalleolar • Third degree • trimalleolar
Weber Type AlateralmalleolarfractureTreatconservatively
28 y/o M who “twisted” his left ankle while playing basketball 1 day agoDanis-Weber Type Bfibular ankle fracture
• MEDIAL MALLEOLUS FRACTURE AND ASSOCIATED DISTAL FIBULA FRACTURE. AP Ankle. Note the medial malleolus fracture (arrowhead) and an oblique fracture of the distal fibula, along with lateral displacement of the talus. The linear subchondral radiolucency in the talar dome (arrows) is a radiographic sign for an intact blood supply to the talus (Hawkin’s sign), which represents the unlikelihood of complicating avascular necrosis.
• LATERAL MALLEOLUS FRACTURE. Medial Oblique Ankle. Note the most common fracture of the lateral malleolus is an oblique fracture extending upward (arrow). This fracture is best seen on the medial oblique projection• These fractures occurs as a result of outward or external rotation of the foot and is best observed on the medial oblique projection as a radiolucent oblique line with adjacent soft tissue swelling (McKenzie’s sign)
BIMALLEOLARFRACTURE.AP Ankle. Note thecharacteristictransversefracture throughthe medialmalleolus(arrow), alongwith a spiralfracture of thelateral malleolus(arrowhead).
Pott’s FracturePott’s fracture, as classicallydescribed, is a partialdislocation of the ankle, withfracture of the fibula within6-7 cm above the lateralmalleolus and rupture of thedistal tibiofibular ligamentsof the ankle.
Pilon (tibial plafond) fractures • Fracture of distal tibial metaphysis • Often comminuted • Often significant other injuries • Mechanism • Axial load • Position of foot determines injury • Treatment • Unstable • X-ray tib/fib & ankle • Orthopedic consultationSource:Rosen
Maisonneuve Fracture• This fracture is caused by forceful inversion and external rotation of the ankle.• This motion forces the talus laterally against the fibula ( d/t either deltoid ligament tear or avulsion fracture of medial malleolus), initially producing rupture of the inferior tibiofibular syndesmosis. As the force is maintained, the fibula, freed from the tibia, continues to be displaced laterally and posteriorly. The superior tibiofibular joint, remaining intact, secures the proximal fibula so that the long lever of the fibula produces a fracture of the fibula in its proximal third.
Dupuytren’sfracture,is a fracture of thedistal fibula (lateralmalleolus) with ruptureof the distal tibiofibularligaments, diastasis ofthe syndesmosis,lateral dislocation ofthe talus, anddisplacement of thefoot upward andoutward.
Tillaux Fracture• Salter Harris III fracture involving avulsion of anterolateral tibial epiphysis. • Occurs in older adolescents, after the middle and medial parts of epiphyseal plate has closed, but before the lateral part closes (usually 12 to 15 yrs of age). • Fracture occurs after medial part of the epiphyseal plate has closed, but before the lateral part closes; resultant fracture through epiphyseal plate runs across epiphysis and distally into the joint, creating SH type 3 or 4 fracture. • External rotation forces stresses on anterior tibiofibular ligament, causing avulsion of distal tibial epiphyseal plate anterolaterally; further lateral rotation causes displacement of fracture.
Toddler’s FractureToddler’s fracture, anundisplaced spiral fracture ofthe tibia, occurs in children from9 months to 3 years of age. It iscaused by a fall or by the childgetting a foot caught betweenthe slats of the crib and thenrolling over. The baby, often tooyoung to verbalize itscomplaints, may evidence only amysterious refusal to bearweight on the extremity.
Ankle effusion: tear drop sign NORMAL WITH EFFUSIONAn ankle effusion suggests a significant injury to the ankle joint. The anteriorand posterior extra-capsular region of a normal ankle joint should appear as afat-like density. In the presence of an ankle effusion, the capsule can becomedistended and may appear to have a more fluid-like density
Soft Tissue Swelling over the Lateral Malleolus NORMAL MILD MODERATE SEVERE• An extreme amount of soft tissue swelling does not necessarily indicate a fracture is present and is frequently seen in severe sprain injuries (tendon/ligament injuries).• In equivocal cases where you are suspecting a lateral malleolus fracture and there is little or no soft tissue swelling laterally, you would lean towards a diagnosis of no fracture.
Achilles Tendon Rupture This patient has aNormal Kagers fat pad with ruptured Achilles tendonclearly delineated normal Achilles (white arrow). Note thetendon changes in Kagers Fat Pad (black arrow)
This patient presented to theEmergency Department followinga fall from a ladder. Note thatKagers fat pad is abnormalshowing increased density andindistinct margins. There alsoappears to be a large ankleeffusion. These soft tissue signsshould lead you to undertake acareful examination of the bonyanatomy. The patient has afractured calcaneum.
This 55 year old lady presentedto the Emergency Departmentwith a boggy infected area ofskin over her Achilles tendon.The patient was referred forankle radiography with a viewto establishing whether therewas an underlyingosteomyelitis. The infectionclearly involves the deeper softtissues with almost completeobscuration of Kagers fatpad.There is no evidence ofosteomyelitis.
This patient presented to the EDfollowing a sports injury to the leftankle. On examination, the patientwas unable to weightbear . Swellingover the lateral malleolus of theankle was visible clinically andradiographically.The lateral view demonstrates* an ankle effusion- (white arrows)* abnormal Kagers fat pad (grey arrow)* suggestion of fracture or accessoryossification centre (os subfibulare)- blackarrowThe combination of patient history, clinicalsigns, soft tissue signs and equivocalevidence of a fracture was sufficient forthe radiographer to perform additionalviews
The orientation of thepossible fibula fracturedemonstrated on thelateral projection imagesuggested that an AP ankleposition with cephalic tubeangulation might align theX-ray beam with the planeof the fracture.