Can you describe the radiograph?
This is an AP radiograph of the left ankle showing a fracture dislocation. There is an avulsion type fracture of the medial malleolus. There is an obvious diastasis at the distal tibiofibular syndesmosis and a spiral fracture of the fibula. This therefore represents a pronation–external rotation type injury.
- This is an isolated injury, with no neurovascular deficit. How would you manage this in the emergency department?
There is an obvious fracture dislocation of the ankle. To avoid swelling, which may preclude early surgical intervention in addition to protecting the cartilage and reducing patient discomfort preoperatively, I would advocate an emergent closed reduction under sedation in the emergency department by reversing the deformity. The leg will be placed in a below knee backslab, followed by check radiographs to confirm a satisfactory reduction of the talus. I would admit the patient to the ward for elevation +/– ice and discuss operative intervention with the patient.
- What are the components to the syndesmosis of the ankle?
The syndesmosis of the ankle is the distal tibio–fibular joint. There are three com- ponents. Anteriorly, there is the anterior inferior tibio–fibular ligament (AITFL). Posteriorly, there is the posterior inferior tibio–fibular ligament (PITFL). Between these lies the interosseus ligament.
- What form of treatment would you recommend?
This is a clearly unstable injury with an obvious syndesmosis injury. Assuming the patient has no contraindications to surgery, I would recommend operative interven- tion in order to provide the best chance of a relatively normal ankle in the future. It would be unlikely that a satisfactory position could be achieved in plaster, and even less likely that it would remain in that position. It would be important to counsel the patient in relation to the usual risks of surgery, in particular the risk of ongoing pain and stiffness owing to the severe nature of the injury.
The key to managing this injury is recognition of the syndesmosis injury. The syndesmosis requires particular care given the high rate of malreduction reported in the literature, with rates of over 50% reported (on postoperative CT scans). If the fibula can be reduced anatomically, the length and rotation of the fibula will be such that the syndesmosis is reduced and can be fixed in situ. My preferred method of fixation would be with a single small fragment (3.5 mm) screw, placed through three cortices, with no plan to remove the screw. The patient would be treated in a below knee cast, non-weight bearing for approximately 8 weeks.
In cases where there is dubiety over fibular reduction, for example, due to com- minution, or in a Maisonneuve type injury, I would advocate an open approach to the syndesmosis to confirm the ‘Mercedes Benz’ sign, seen at the confluence of the tibia, fibula and talus. An alternative method would be to compare the image inten- sifier views of the injured side to the contralateral side intraoperatively. A true lateral of the talus on the contralateral side will show the appropriate relationship between the tibia and the fibula, and the AP view can determine the appropriate degree of tibiofibular overlap and fibular length. The latter can be assessed with talocrural angle and the ‘dime sign’.
- What factors determine your surgical outcome?
Outcome depends on anatomical reduction of the ankle mortise: 1 mm shift decreases contact by 42%. However, osteoarthritis – associated with instability or malreduction – is only symptomatic in approximately 10% of patients with radio- graphic changes.
Diabetic patients with poor diabetic control have a much higher rate of wound problems and deep infections.
One must also ensure that the syndesmosis is intact or fixed, otherwise this can lead to a severe and progressive valgus deformity.
