Medium sized POSTerior fragments in AO Weber-B fractures, does open reduction and FIXation improve outcome? A multicenter randomized controlled trial.

The optimal treatment of ankle fractures with involvement of the posterior
malleolus remains a subject of debate. Despite a large amount of literature on
the role of the posterior malleolus in a so-called trimalleolar fracture, there
are no clear guidelines for its treatment. Its size is the leading indication
whether fixation of the fragment is necessary or not. Most orthopedic surgeons
consider a posterior malleolar fracture fragment larger than 25% to 33% an
indication for fixation. Interestingly, after careful evaluation of the
available literature, there does not seem to be hard evidence for these numbers.

It is generally accepted that restoration of a normal anatomic mortise and
normal tibiotalar contact area are key elements for a good functional outcome.
Inadequate reduction of the posterior fragment may alter the tibiotalar contact
area and the joint biomechanics with altered stresses in parts of the joint,
leading to the development of osteoarthritis and worse functional outcome.

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 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. Since 2 years, in our institution we perform an open, anatomical
reduction and fixation of all medium-sized posterior fragments via this
approach. Although not thoroughly investigated yet, it seems to lead to better
clinical outcomes than described in the literature and our retrospective cohort
study.

Compare open reduction and fixation of the posterior fragment in trimalleolar
AO-Weber B fractures with additional medium-sized posterior fragment (5-25% of
the involved articular surface, AO type 44-B3) with no fixation of the
posterior malleolar fragment on functional outcome assessed by the AAOS-score
after 1 year.

Multicenter Randomized Controlled Trial

Participating Centers:
1. Haaglanden MC
2. Haga Hospital
3. 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. 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. After Informed Consent,
randomization will take place.

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. No additional posterior fragment will be fixed. The second group
will also be treated according to AO-principles, however the posterior fragment
will be reduced and fixed by a butress or antiglide plate using the
posterolateral approach.

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. Pre-operative and
post-operative a CT-scan will be performed. 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.

The first group: Open reposition and fixation of the medial and lateral
malleolus will take place. Additionally, closed reduction of the posterior
malleolus will take place without internal fixation.
The second group: Open reposition and fixation of the medial, lateral and
posterior malleolus will take place. (fixation of the lateral and posterior
malleolus will take place using the posterolateral approach)

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, post-operative an additional 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.

There is no additional risk in the second intervention group compared to the
intervention in the first group. Several case-series showed a comparable rate
of woundinfections or reoperations in the posterolateral approach compared to
the original approach.