Regarding fracture of the talar dome, which ONE of the following statements is TRUE?
Answer: A: Although talar dome fractures are relatively uncommon, they can easily be missed as the clinical findings are non-specific. They can mimic and accompany ankle sprains. The mechanism generally is an inversion injury at the ankle. The talar dome fracture is an osteochondral fracture, meaning a fracture involving both the cartilage and subchondral bone. The fractures can be located medially or laterally on the talar dome with equal frequency.
This fracture should be considered in any ankle sprain with gross oedema and also when a patient represents to the ED after the initial presentation with an ankle sprain. In lateral talar dome fractures, the tenderness is usually located anterior to the lateral malleolus. In medial talar dome fractures, the tenderness is located posterior to the medial malleolus.
Careful review of standard AP, lateral and mortise views of the ankle may identify these fractures. The lateral X-ray may show a joint effusion. Lateral lesions are best seen on a mortise view as thin, wafer-shaped lesions. Medial lesions are best seen on an AP view as deep cup-shaped lesions. In suspected cases with negative radiographs CT and MRI can identify the lesions.
Potential sequelae of inadequately managed talar dome fractures are chronic ankle pain, osteoarthritis and osteochondritis dissecans (with stiffness, crepitance and recurrent swelling with activity). Definitive management involves cast immobilization or surgical excision of the fracture.
References:
Regarding ankle fractures, which ONE of the following statements is TRUE?
Answer: A: Pilon fracture is an often comminuted fracture of the distal tibial metaphysis secondary to a massive primary axial force driving the talus into the tibial plafond in major traumatic mechanism such as falling from a height. Some of these fractures are open. Frequently, these fractures are associated with other injuries such as fractures of the calcaneus, tibial plateau, neck of femur, acetabulum and lumbar spine, caused by axial mechanism. The majority of medial malleolar fractures do not occur in isolation. They are usually associated with fractures at the lateral malleolus or posterior malleolus. These bimalleolar fractures are unstable. A potential proximal fibular fracture should be considered in the presence of an apparent isolated medial malleolar fracture.
A lateral malleolar fracture above the ankle joint line (Danis-Weber type C) is more likely to be associated with distal tibiofibular syndesmosis disruption than a fracture below that level (Danis-Weber types B and A).
Reference:
Which ONE of the following features is LEAST likely to be associated with a significant Lisfranc’s injury?
Answer: C: Lisfranc’s injury occurs in the midfoot with significant mechanisms such as plantar flexion of the foot with an axial load. The injury spectrum consists of sprains to the Lisfranc’s ligament to complete disruption to the midfoot with displacement and fractures. The very high strength Lisfranc’s ligament runs between medial cuneiform and the base of the second metatarsal, and the disruption of this ligament is inevitable in significant injuries. Consequently, bony diastasis between the first and second metatarsal bases occurs and if this diastasis is ≥1 mm it should be considered an unstable injury. Due to the significance of mechanisms causing this injury, associated metatarsal and tarsal fractures and loss of foot arch height are relatively common. The soft tissue swelling could cause compartment syndrome in the foot.
Injuries to the foot due to significant traumatic mechanisms should be assessed for Lisfranc’s injury. If suspected, CT scan is the investigation of choice because it can reveal otherwise occult injuries that cannot be identified with plain films.
Regarding unilateral facet joint dislocation in the cervical spine, which ONE of the following statements is TRUE?
Answer: D: Unilateral and bilateral facet joint dislocations are important cervical spine injuries that cause recognizable signs on cervical spine X-ray. The mechanisms involved are:
In facet joint dislocation, the inferior facet of the vertebra above dislocates anteriorly over the superior facet of the vertebra below. Therefore, on the lateral view, vertebral body above is anteriorly displaced. In unilateral facet dislocation this displacement is <50% of the vertebral body width and in bilateral dislocation it is 50% or more. Unilateral dislocation is usually associated with nerve root injury and bilateral injury causes complete cord injury. When there are no associated fractures the unilateral injury is considered to be mechanically stable but bilateral injury is always unstable. However, as a matter of caution, as with any spinal injury with radiographic abnormality or neurological deficit, this injury may be considered as unstable for practical purposes in the ED.
A lesser degree of distractive flexion can cause bilateral perched facets as compared with complete facet dislocation and the facet may not have a significant neurological deficit. This injury is considered unstable as well.
An adult male who had a cervical spine injury with a significant mechanism presents to the ED complaining of severe pain and limited range of motion. Fracture and dislocation have been excluded with a CT scan.
Regarding isolated ligamentous injury to the cervical spine, which ONE of the following statements is INCORRECT?
Answer: A: Ligaments such as the anterior longitudinal ligament, posterior longitudinal ligament and posterior ligamental complex provide stability to the cervical spine. During significant mechanisms of injury isolated ligamental injuries can occur without associated fracture or dislocations. However, these injuries are rare, even with high-risk mechanisms. Once bony injury has been excluded with plain radiography and CT, these patients generally continue to have excessive pain and limited range of motion. If missed these injuries may cause delayed mechanical and neurological instability.
Three types of isolated ligamentous injuries have been described:
The presence of equivocal or subtle findings on the plain films have been found to increase the chance of having ligamentous injury in patients with excessive pain and limited motion. These findings include:
As CT cannot exclude ligamentous injury, MRI is the investigation of choice in their diagnosis. Flexion and extension views are only rarely used in the ED.
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