Section: CME Category: Imaging Radiology

Podiatric Emergency Radiology - Ankle Fractures

Marlena Jbara, MD

Marlena Jbara, MD discussed normal ankle anatomy as well as the normal ankle X-ray views. Dr Jbara also discusses the mechanism of injury as well as the classification systems and X-ray evaluation of adult ankle fractures. She also discusses pediatric ankle fractures and its differences from adult ankle pathology.

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Goals and Objectives
  1. Review normal ankle anatomy
  2. Review ankle X-ray anatomy
  3. Describe the mechanism of injury, classification systems, and X-ray evaluations of adult ankle fractures
  4. Review pediatric ankle fractures
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    Release Date: 09/26/2018 Expiration Date: 12/31/2020

  • Author
  • Marlena Jbara, MD

    Assistant Professor Radiology
    SIUH Northwell Health
    Staten Island, NY

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  • Lecture Transcript
  • TAPE STARTS – [00:00]


    Marlena Jbara: Hi, my name is Marlena Jbara and I am going to be taking you through the first lecture on podiatric emergency radiology ankle fractures. I or related party have no financial relationship to disclose. Learning objectives: We will review normal ankle anatomy, ankle x-ray anatomy, mechanism of injury, classification systems, x-ray evaluation and pediatric ankle fractures. The significance of ankle fractures is increasing. It's a bimodal distribution involving me at 15 to 24 and women over 60. It's not necessarily related to osteoporosis and it's related to obesity. The ankle has three primary joints. The medial malleolus with the medial talus, the tibial plafond with a talar dome, the lateral malleolus with lateral talus. There are three articulating bones. The tibia, fibula and talus and three sets of ligaments, the lateral collateral ligaments, the anterior and posterior talofibular ligament and the calcaneal fibular ligament. Then there are these syndesmotic ligaments and the medial ligaments, the deltoid ligaments with spring ligament complex. The anatomy is a complex articulation that involves retaining joint stability over congruous bony articulations and multiple different muscular forces driving across the ankle. The medial and lateral ligamentous complexes served to keep ankle stability as well as the capsule.

    [02:05]

    And this illustration demonstrating the intraosseous membrane joining the tibia and fibula and relative posterior position of the fibula and of course the talar body head and neck. The syndesmosis is the strongest of the tibial fibular ligament joining these body structures and it consists of a posterior and superior and posterior inferior as well as anterior superior and inferior tibial fibula ligaments. And there is the intraosseous membrane that joints the tibia and fibula throughout the diaphysis. And note on ankle biomechanics, the ankle is involved in complex motion that resists four times a bodyweight and stance of phases of gait. The normal range of motion is approximately 20 degrees of extension and 40 degrees of flexion and there is at least 10 degrees of dorsiflexion necessary for normal gait. It's interesting to note that 1-mm of lateral talar shift decreases the tibiotalar surface contact by up to 40%. In terms of patient evaluation, it's important to take a thorough history noting the mechanism, the time since injury, the ankle and foot position at the time of injury, the degree of dysfunction after event, associated injuries, comorbidities including diabetes, neuropathy, obesity, alcoholism and drug abuse. With regards to physical exam, inspection of the ankle deformity, ecchymosis, swelling and perfusion issues will be noted noting the range of motion of 30 to 50 degrees of plantar flexion, 20 degrees of dorsiflexion and any deviations from the normal.

    [04:03]

    In terms of palpation, individually palpating the medial and lateral collateral ligaments, the syndesmosis and tendons and examining the knee for the higher maisonneuve fracture and base of fifth metatarsal for the dancer fractures. In terms of special tests including the anterior drawer or the squeeze test, the anterior drawer test denoting integrity of the anterior talofibular ligament and the squeeze test noting whether or not pain is induced on squeezing the tibia and fibula 6 to 8 inches below the knee to test the syndesmotic ligaments. I am sure your patients would much prefer an x-ray evaluation. In terms of x-rays, approximately 10% to 15% of all traumas occurring at the ankle and 80% of all ankle x-rays get an x-ray. View within 15% have a significant fracture and we have been able to stratify those based on the Ottawa classification, which I will go over. In terms of the x-ray views, you will obtain AP, the lateral and the mortis that's 15 to 20 degrees of internal rotation and we are going to obtain weightbearing if at all possible. In terms of Ottawa ankle and foot rules, these were designed to determine which patients need radiographs that following ankle trauma and this was meant to decrease unnecessary x-rays and improve patient's wait times and diagnostic cost and the sensitivity was nearing a 100% for detecting malleolar midfoot fractures. The limits for this stratification is that it's only recommended for skeletally mature patients and it only applies for recent injuries within 10 days of injury. So an ankle x-ray is essentially only required, if there is pain in the malleolar zone and any one of the following:

    [06:00]

    Bone tenderness along 6 cm of posterior edge of fibula or tip of lateral malleolus, bone tenderness along distal 6 cm of posterior tibia or tip of medial malleolus and inability to bear weight for four steps both medially and in the emergency department. In terms of the AP or anteroposterior view, we are looking for tibial fibula overlap, which is less than 10 mm implying syndesmotic injury. The tibial fibula clear space greater than 5 mm would imply syndesmotic injury and talar tilt with more than 2 mm is considered abnormal. In terms of the measurements, we are going to go 1 cm up from the tibial plafond and measure over the space between the lateral clear space denoted between lines A and B. And we aren't going to want more than 5 mm. In terms of the mortis view, which is a 15-degree internal oblique view, we can get a better look at the syndesmosis noting that there is always meant to be an edge of overlap between the tibial lip and the distal fibula. Sort of like trying to pick up sushi without actually having your chopsticks connected. So you want to have them connected so that the talus is driven forward in every phase of gait. On the lateral view, I think it's important to look at the fibula and see if there is any kind of angulation or coronal oblique fracture by looking through the tibia. In terms of the lateral view, the posterior malleolar fracture, we will be looking for subluxation of the talus, angulation of the distal fibular, talar fractures and calcaneal fractures and on these x-rays, we can see through to the fibula and this transaxial view showing us that the fibular is relatively posterior structure and even more posterior if the patient has pes cavus.

    [08:01]

    The ankle mortis view is an AP view of the ankle with the foot rotated 15 degrees internally and we are going to look for the medial and lateral clear space again and the degree of tibia and fibular overlap. A note on ankle sprain and fractures, the ankle is the most commonly injured joint amongst athletes and 85% of all ankle injuries are sprains. Most 85% are inversion injuries denoted by this illustration. Here, we are seeing on this frontal view of the x-ray, a degree of lateral malleolar swelling with no associated x-ray fracture. In terms of the underlying anatomy, there are three groups of stabilizing ligaments on the lateral side and that's the anterior talofibular ligament, the calcaneal fibula ligament, the posterior talofibular ligaments and these will limit ankle inversion and prevent anterior and lateral subluxation of the talus. And you can see in this illustration on your right, the anterior tibial fibula ligament in syndesmotic region and lower down where the fibula is sort of taped down to its joining talus through the anterior and posterior talofibular ligaments intact onto the calcaneus through the calcaneal fibular ligament. And a note about the calcaneal fibular ligament, that's running deep to the peroneal tendons. In terms of the anatomy, the medial deltoid ligament is a group of four ligaments essentially the deep deltoid for its anterior and posterior tibiotalar ligaments and superficial deltoid comprised of the tibionavicular, tibiocalcaneal and the important tibial spring ligament, which attaches directly to the superior medial band of the spring ligament and this is stabilized in the joint during eversion and preventing talar subluxation.

    [10:01]

    These are 20% to 50% stronger than lateral ligaments. Sprain grading, grade 1, soft tissue swelling and joint effusion. Grade 2 and 3, that may be soft tissue swelling with a joint effusion and may also have a flake avulsion at the dorsal aspect of the talus or the navicula. And the management differs depending on the grade. In terms of lateral ankle sprains and treatment, for grade 1, it's usually recommended to have a limited time off of weightbearing including an ACE wrap and crutches and grade 2 and 3 may require an air or posterior splint crutches and a prolong period off of weightbearing. It's interesting to note that lateral avulsion or any avulsion less than 3 mm of size can be treated as an ankle sprain. Other than lateral ankle sprains, you can have a syndesmotic or high ankle sprain and this is stretching or tearing of the syndesmosis and a common mechanism would be forced external rotation of foot or internal rotation of tibia on the planted foot. An isolated deltoid ligament sprain, which is usually rare, usually accompanied by a lateral malleolar fracture and/or syndesmotic injury. And rehabilitation similar to lateral ankle sprain is required but more likely to require immobilization and have residual symptoms. For non-healing ankle sprain, which are symptoms not improving after six weeks, pain and/or recurrent stability and the top three causes would be inadequate rehabilitation. And other causes would be things that might necessitate further advanced imaging looking for OCD, peroneal tendon injuries, whether or not the ligaments are swollen, sprained and synovitic resulting in impingement syndrome having a joint body or other complex regional pain syndrome

    [12:13]

    In terms of classification systems, there are several Lauge-Hansen, the American Orthopedic classification and Danis-Weber classification. The Lauge-Hansen Classification associates a specific fracture pattern with the mechanism of injury and it's a two-term scheme requiring knowledge of the position of the foot and the direction of the force. The Lauge-Hansen classification in terms of supination adduction injury uses a transverse avulsion type fracture of the fibula below the level of the joint or tear of the lateral collateral ligament complexes associated with a vertical fracture of the medial malleolus. The supination eversion or external rotation, the famous SER injury is noted when there is disruption of the anterior tibial fibula ligament, a spiral oblique fracture of the distal fibula, disruption of the posterior tibial fibula ligament or fracture of the posterior malleolus and fracture of the medial malleolus or rupture of the deltoid ligament. Moving on to a pronation abduction injury, which includes a transverse fracture of the medial malleolus or rupture of the deltoid ligament, rupture of the syndesmosis or avulsion of their insertions and then a short horizontal or oblique fracture of the distal fibula above the level of the joint. For a PER or pronation eversion injury, we will be looking at a transverse fracture of the medial malleolus and disruption of the medial deltoid ligament, disruption of the anterior tibial fibular ligament.

    [14:02]

    A short oblique fracture of the fibula above the level of the joint and rupture of the posterior tibial fibula ligament or avulsion fracture of the posterolateral tibia. As per pronation dorsiflexion, that may require fracture of the medial malleolus, fractures of the anterior margin of the tibia, a supramalleolar fracture of the fibula and a transverse fracture of the posterior tibial surface. Moving on to the American Orthopedic Classification, which is a modification of Weber's classification, they typed out 44 separate injuries, which account for medial and posterior injuries. Then moving onto what's most widely used is the Danis-Weber classification and that's based on the mechanism of injury divided into three fracture types defined by the location of the fibular fracture. And this is fracture below the level of the tibiotalar joint would be type A, at the level of the tibiotalar joint type B and above the tibiotalar joint type C. Weber's classification is based only on the location of the fibular fracture and is irrelevant whether the medial malleolus is fractured. In terms of A, B and C injuries, all are from inversion. Weber A, anterior and posterior tibial fibular and intraosseous ligaments are intact and stable. Weber B, anterior and posterior tibial fibula ligaments are torn and it may be unstable or moderately unstable and that needs to be tested with some stress x-rays and Weber C, interosseous ligaments are torn and it's completely unstable requiring ORIF. The Danis-Weber classification again based on the location and appearance of the distal fibula fracture, type A is below the level of the syndesmosis seen here, type B is in the transyndesmotic region possibly tearing the tibial fibular ligaments, type Cs are above the level of the syndesmosis and there may be associated medial and posterior malleolar fractures and deltoid ligamentous ruptures.

    [16:11]

    The management of Weber injuries, Weber As are generally casted for six weeks, Weber Bs frequently require ORIF depending on the integrity of the syndesmosis and stability of the fracture site and Weber Cs always require ORIF. Moving on to the x-ray evaluation in Weber A note that hairline fracture along the infra-syndesmotic distal fibula and the associated lateral ankle swelling in this nonweightbearing x-ray, the medial clear space is intact. It's important to remember unimalleolar fractures that any lateral avulsion less than 3 mm in size can be treated as an ankle sprain. Unimalleolar fractures type A below the level of the tibiotalar joint usually associated with no medial tenderness. You can use a below the knee walking cast and a follow-up in a week to ensure no displacement. Nonweightbearing more than three weeks can weightbearing for another three to five weeks and then will check the medial ankle mortis to see if there is any persistent tenderness or displacement. Examples of Weber B fractures can be seen here and example to the left noticed a distal fibular displaced fracture at the transsyndesmotic region. In the central image, minimally displaced transsyndesmotic oblique distal fibula fracture with a non-displaced medial malleolar transverse fracture. And in this example on the bottom right, noting the oblique distal fibular fracture with dorsal displacement that you can see through the tibia.

    [18:04]

    In this bimalleolar fracture, we can still use the Weber classification. The presence of the medial malleolar fracture does not change the classification and this is a Weber B fracture pattern. Moving on to examples of Weber C fractures, these are fractures that are occurring above the level of syndesmosis and you can see here on this example on the left, this minimally displaced fracture and example higher up in the distal diaphysis of a more displaced Weber C fracture and another example here along the distal fibula demonstrating a minimally displaced Weber C supra syndesmotic fracture. And the issue here is that the ankle force came in. The ligaments are torn and the exit fracture line is above the level of the syndesmosis denoting that there is a syndesmotic injury even when you don't see widening. Maisonneuve fractures, eversion injuries that are associated with a medial malleolar fracture. They have a high exit fibular shaft fracture, all are unstable and that the syndesmosis and interosseous membranes are torn and they require ORIF. Trimalleolar fractures are [indecipherable] [19:31] fractures. The management is including managing the disruption of three parts of the ring, the medial malleolus, supra syndesmotic distal fibula and in this case the posterior malleolar fracture and all will require ORIF. Pilon fracture, the mechanism is axial compression where the talus is driven into the plafond. They are usually comminuted and displaced with extensive soft tissue swelling.

    [20:02]

    We are going to look for associated injuries involving the calcaneus, the femoral neck, the acetabulum, the lumbar [indecipherable] [20:10]. Here is an example of pilon fracture, notice the comminuted distal diaphyseal, metaphyseal intraarticular epiphyseal tibial fractures with an oblique medial malleolar component and a transverse distal fibular component. There is widening of the lateral tibial fibula clear space and disruption of the ankle mortis. Pediatric ankle injuries, these are not just little adult fractures. The ligaments attached to the bone are stronger than the physis, so we can expect more fractures and less sprains. And overall the management is similar to adults, although with fractures you may be able to accept more angulation though remodeled and you usually will stick with little or no displacement. The common classification will be the Salter classification, which includes transverse fractures through the physis as denoted in this illustration where these little prickly lines here are the physis. Above the level of the physis into the metaphysis is a Salter-Harris 2 fracture, which is a common fracture to note in non-accidental trauma. Salter-Harris 3 includes a fracture through the epiphysis. Salter-Harris 4 fracture in both the epiphysis and the metaphysis and Salter-Harris 5, which is a crush injury to the physis. A particular type of pediatric fracture would be a Tillaux fracture and this is a special type of I mentioned and that it's often missed on x-rays. The Salter-Harris type 3 fracture of the lateral tibial epiphysis occurs with extreme eversion and lateral rotation.

    [22:04]

    Mostly in adolescents where the physis is fusing and it's closing moving from medial to lateral. There is a fracture at the lateral aspect and into the joint and their management is going to require ORIF. And here is an illustration on the left of the distal lateral tibial epiphysis and you can see in this example on the x-ray on the right, there is hairline fracture through the epiphysis and no widening of the clear space to clue you in, so the presence of swelling and this lucency that does not belong are the only clues in this case of a juvenile Tillaux fracture. And it gets worse just like my son growing up to be a teenager now. Ankle dislocations, this is a relatively common injury usually associated with a fracture. The goal of the report is to assess the alignment and describe the position of the foot or talus relative to the tibia. If the fracture is open, it should not delay reduction as neurovascular compromise and skin tenting reduce the likelihood that there will be ongoing vascular supply to the talus. Of course, you want to obtain initial x-rays, administer analgesia, and pain medicine. You want to reduce splint and get post-reduction films right away. And of course, you can see through this guy's smiling face and double thumbs up sign that he is happy camper although his foot that you could see the sole up there must be a significant amount of analgesia on board and these x-rays at the bottom half of the screen showing the distal tibial fibular dislocation posteriorly and associated Weber C type fracture of the distal fibula.

    [24:00]

    And of course, this x-ray on the bottom right showing the partial reduction of the tibiotalar joint still significantly subluxed because even 1 mm will decrease ability for contact, right? Force contact. So in summary, what we have discussed in the last 30 minutes are normal ankle anatomy noting the three articulating surfaces of the tibia, the fibula and talus. The important ligamentous complexes that join them including the anterior and posterior tibial fibular ligaments, the anterior and posterior talofibular ligaments and the calcaneal fibular ligament as well as full discussion of the deltoid ligament complex including the superficial bands and the deep bands of the tibiotalar, tibial spring and tibiocalcaneal ligaments. We looked at ankle x-ray anatomy noting the most important measurement is to be obtained at the lateral tibiofibular clear space where we are going to measure 1 cm up from the talar plafond and measure over noting that anything greater than 5 mm will require stress x-rays to determine if the syndesmosis is intact. We talked over the different mechanisms of the injury including a description of the Lauge-Hansen classification and the important ability for knowledge at the foot and ankle level at the time of injury and the associated predictable mechanism of injury that occur. We noted that the classification system that is most widely used is the Weber classification and that even flake avulsions will be treated as ankle sprains. We went through an example of a Weber A, Weber B and Weber C, went on to describe examples of pilon fracture, ankle dislocations. Further descriptions of pediatric ankle fractures we undertook, we described the Salter-Harris classification and noted the juvenile to low fracture being a Salter-Harris 3 fracture through the epiphysis often seen in adolescents where the fusing growth plate is moving from medial to lateral.

    [26:09]

    And we concluded with complex ankle fracture patterns and dislocation noting the importance for reduction as soon as the patient enters whether the skin is tented and that every second is counting towards skin salvage and the presence of AVM in the bony structures. I thank you for your generous time and attention and look forward to going over foot fractures in this second part of the series.


    TAPE ENDS - [26:34]