Operative treatment of AO Weber C fibular fractures with additional posterior malleolar fragment: Does anatomical reduction and fixation improve syndesmotic reduction? POSTFIX-C trial.

In AO Weber type C fractures, there is a combination of a proximal fibular
fracture, a medial fracture or ruptured deltoid ligament, and a syndesmotic
injury. Anatomical repair and reduction of the syndesmosis is essential to
prevent diastasis in the ankle-joint. Widening and chronical instability of the
syndesmosis is related to worse functional outcome and development of
posttraumatic osteoarthritis in the ankle. There is limited biomechanical and
clinical evidence that syndesmotic stability in AO Weber type C fractures with
an additional posterior malleolar fracture can also be reached by fixation of
the posterior malleolar fragment. Maybe, this is even superior to the usual
treatment with syndesmotic positioning screws. Some authors concluded that
stability of the syndesmosis in these fractures can be much more achieved by
fixation of the posterior malleolar fragment than by placement of syndesmotic
positioning screws alone. Another additional benefit of open reduction and
fixation of the posterior malleolar fragment is that this will lead to an
anatomical reconstruction of the syndesmosis. Although there is no current
evidence, it is likely that a malreduction of the fibula in the tibial incisura
will lead to a worse functional outcome on the long-term. No clear consensus in
the literature is found as to which fragment size of the posterior malleolus
should be internally fixed. The general opinion is that displaced fragments
that involve more than 25% of the distal articular tibia should be fixed.
Traditionally, reduction of these larger fragments is indirectly, followed by
percutaneous screw fixation in anterior-posterior direction. Disadvantages are
that it is hard to achieve an anatomical reduction, and that percutaneous
fixation of smaller fragments is very difficult. Recently, a direct exposure of
the posterior tibia via a posterolateral approach in prone position, followed
by open reduction and fixation with screws in posterior-anterior direction or
antiglide plate is advocated by several authors. This approach allows perfect
visualization of the fracture, articular anatomical reduction, and strong
fixation. Another advantage is that even small posterior fragments can be
addressed. Several case series are published, which describe minimal major
wound complications, good functional outcomes, and minimal need for
reoperation.

To compare the accuracy of syndesmotic reduction on an axial CT-scan
postoperatively (reflecting syndesmotic malreduction) after anatomical open
reduction and fixation of the posterior malleolar fragment versus no fixation
of the posterior fragment in AO Weber-C ankle fractures with involvement of the
posterior malleolus.

Multicenter Randomized Clinical Trial.

Participating Centers:
1. MC Haaglanden
2. Haga Hospital
3. Bronovo Hospital
4. Leiden University Medical Center

Patients presenting with an ankle fracture at the Emergency Department of the
hospital will receive the usual treatment initially. Patients who met the
inclusion criteria will be informed at the emergency department about the
current study and will get the written patient information. Before visit of the
outpatient clinics a CT-scan of the ankle will be performed. Preoperatively, at
the outpatients clinic or ward, the surgeon will discuss the study again with
the patient and he or she is asked to participate. In case of participation,
Informed Consent will be taken and patients will be included and scheduled for
the operation. After inclusion, randomization will take place between
additional Open Reduction and Fixation of the posterior fragment (group 1) or
no additional fixation of the posterior fragment (group 2).

Patients in the first group will be treated according to the current
directives. If present, medial and distal fibular shaft fractures are fixed
according to AO principles. Treatment of syndesmotic injury will take place by
1 or 2 transsyndesmotic screws. Additional the posterior fragment will be
reduced and fixed by a butress or antiglide plate using the posterolateral
approach. The second group will also be treated according to AO-principles:
medial and distal fibular shaft fractures are fixed and syndesmotic injury will
be treated by 1 or 2 transsyndesmotic screws. The posterior fragment will not
be fixated.

Post-operatively, a CT-scan of both ankles will be performed in order to
evaluate the success of reposition of the fibula in the tibial incisura and the
posterior fragment. The postoperative treatment will be identical and according
to the current local protocols. Patients will be seen at the outpatient clinics
at 2 weeks, 6 weeks, 12 weeks, 26 weeks and 52 weeks postoperatively. In
addition to the regular treatment, the patients will be asked to fill in a
questionnaire during every visit and to perform a short functional test during
the last 2 visits. The results between these two groups will be compared.

Additional to the regular treatment, the burden lies in the fact of several
questionnaires which will be answered during the visits at the outpatient
clinic. Also, postoperative a CT-scan of the ankle will be performed. The
additional radiation is in our eyes negligible respected the normal, daily
background radiation in the Netherlands.
Several case-series showed a comparable rate of woundinfections or reoperations
in the posterolateral approach compared to the original approach.