Fracture Dislocation of Ankle Joint Clinical Trial
Official title:
A Prospective Randomized Pilot Study to Compare Open Versus Percutaneous Syndesmosis Repair of Unstable Ankle Fractures
This study evaluates fracture healing, anatomic reduction and return to functioning in patients with unstable Weber C type fractures of the ankle. Best outcomes are obtained when a good alignment of the ankle joint is maintained and natural function of the syndesmosis (space between the tibia and fibula bones) is restored. The syndesmosis and ankle joint is stabilized by a series of ligaments which are often damaged in Weber C type fractures. Current syndesmosis repair techniques traverse the tibia and fibula, but do not anatomically reconstruct the ligaments. The investigators will compare reconstruction of the unstable syndesmosis by open reduction and internal fixation using a syndesmosis screw coupled with anterior ligament (AiTFL) anatomic repair technique (ART) to percutaneous repair using a syndemosis screw only (SCREW). Radiographic, pain and functional outcome scores will be compared between the groups using validated outcome measures.
High ankle fractures involve fracture of the fibula above the level of the syndesmosis (space
between the tibia and fibula bones) that result from indirect mechanisms (e.g.
pronation-external rotation (twisting) injuries. The method of injury is assumed to disrupt
one or more of the syndesmotic ligaments, leading to instability of the ankle mortise . High
ankle fractures comprise a significant proportion of ankle injuries (16 to 45 % of all ankle
fractures patterns) . It is generally agreed that operative intervention of ankle injuries is
indicated in cases of instability . However, recent advances in the understanding of the
biomechanics of the ankle have given rise to particular areas of clinical uncertainty,
including the treatment of unstable syndesmotic injuries and reliability of strictly
radiographic assessment of ankle fractures .
The goal of operative treatment is to anatomically reduce the ankle mortise to permit
syndesmosis ligament healing and restoration of the normal tibiofibular joint dynamics. Even
1 mm of displacement or lateral shift of the talus will affect ankle joint loading and lead
to dysfunction and potentially degenerative joint changes. Accurate reduction of the
syndesmosis and maintenance of this reduced position until the ligaments heal is crucial to
ensure good outcome and to avoid long term arthritic changes in the tibiofibular joint .
If the ankle joint is unstable (too much sideways movement), the syndesmosis space between
the two bones in the ankle (tibia and fibula) needs to be stabilized. One method to treat
unstable syndesmosis injuries is making an incision to expose the ankle to provide direct
visualization of fracture for anatomic reduction (alignment) and insertion of one or two
syndesmosis screws to maintain the relationship of the fibula to the tibia. This is referred
to as open reduction and internal fixation (ORIF).
Another method of repair is by closed reduction of the ankle joint and the use of one or two
percutaneous syndesmosis screws only. That is, syndesmosis stabilization can be done
percutaneously using intraoperative fluoroscopy to visualize the repair . Literature and
standard practice support both of these methods.
The syndesmosis joint complex is composed of the anterior inferior tibiofibular ligament
(AiTFL), the posterior inferior tibiofibular ligament (PiTFL) and the interosseous membrane
(IOM). This complex is believed to permit ankle mortise stability and flexibility due to the
elasticity of the ligaments, which allows the intermalleolar distance to change and
facilitates tibial and fibular rotation. It also maintains the axis of balanced loading of
the foot through the fibula. Adequate stability and anatomic restoration of the syndesmosis
joint complex is vital to restoring normal tibiotalar contact forces in order to lessen the
risk of posttraumatic arthritis.
Clinical studies have shown that anatomic reduction of the PiTFL provides a more accurate
reduction of the ankle mortise than percutaneous reduction while ORIF fixation of the PiTFL
has been shown on both biomechanical and clinical studies to provide greater stability than
with syndesmotic screws alone .
However, due to the mechanism if injury, the AiTFL is the initial and may be the only lateral
ligamentous stabilize structure compromised in syndesmotic injury. Kinematically, this
ligament provides roughly half of the strength of the syndesmosis and acts as a vital primary
restraint to excessive fibular displacement. The remainder of the stability is believed to
come from bony restraints such as the posterior malleolus and the PiTFL . As such, direct
reconstruction of the AiTFL component of the syndesmosis joint may accurately restore
syndesmotic stability. Current syndesmosis repair techniques traverse the tibia and fibula
(trans syndesmotic repair), but do not anatomically reconstruct the AiTFL.
Although it is known that an accurate reduction of the syndesmosis is essential to a good
outcome, current treatments may have malreduction rates greater than 40% . In light of the
existing models of syndesmosis injury, and the investigators' understanding of the importance
of syndesmosis reduction, it may be that restoration of the AiTFL may potentially unlock a
higher rate of anatomic reductions and positive outcomes.
Cadaveric and clinical studies have demonstrated that a flexible trans-osseous fixation
technique may be viable and may improve ligamentous healing . However, current flexible
techniques may not provide adequate stability and may not reduce the rate of malreduction
compared to screw fixation.
The investigators recently conducted biomechanical studies in our lab using cadaveric ankles.
The investigators compared whether a technique of syndesmosis repair concentrating on
restoration of the AiTFL ligament (Anatomic repair technique or ART) provides a more anatomic
reconstruction of the syndesmosis joint than rigid screw or posterior malleolus fixation.
The investigators' findings have demonstrated that our anatomic repair technique (ART) offers
a repair which is sufficiently stable compared to screw fixation, with a lower incidence of
malreduction as visualized on CT scan.
The investigator research suggests that ORIF repair of the AiTFL in addition to the stability
provided by syndesmotic screw repair enhances syndesmosis stability substantially, as the
AiTFL is a primary stabilizer to external rotation forces. In other words, fixing the
anterior ligament may provide a better outcome and faster return to functioning.
Further in vivo testing is required to evaluate ART for repair of unstable syndesmosis
injuries.
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