The patient is placed supine on a standard operating-room table, with a
small bump under the ipsilateral hip so the knee is straight up and down. No
tourniquet is utilized. If the ankle fracture is bimalleolar and the medial
malleolar fracture pattern is supracollicular, it is reduced and fixed as the
first step in the procedure. This aids in the reduction because the deep
deltoid ligament, the strongest portion of the ligament, which attaches to the
posterior colliculus and the intercollicular groove, is attached to the
displaced medial malleolar
fragment2. Thus, an
anatomic reduction of a supracollicular medial malleolar fracture restores
medial support, gains talar congruence, and assists with reduction of the
lateral
malleolus2,3
(Fig. 2-A). The incision used
on the medial side is slightly concave anteriorly and is centered over the
medial malleolus, as this allows both visualization of the reduction and
placement of the screws (Fig.
2-B). Bicortical lagscrew fixation, perpendicular to the fracture
line, is preferred to increase the stability of the fixation and to compress
across the fracture site (Fig.
3).
Attention is then turned to the lateral side. The ankle should be
positioned with bolsters under the ankle joint and not under the heel.
Bolsters under the heel can cause anterior subluxation of the talus and a
malreduction. The foot is adducted and medially translated to center the talus
in the mortise, which aids in fibular alignment. Because the lateral ankle
ligaments are intact in this injury pattern, reducing the talus under the
plafond usually aligns the distal fibular fragment and restores fibular
length. Fluoroscopic imaging at this point allows an assessment of fibular
length. The lateral cortex of the fibula is comminuted, but the medial cortex
typically starts as a transverse fracture line, so one can evaluate the
reduction at this location to assess length
(Fig. 4). Finally the
talocrural angle on the affected side is compared with the contralateral,
normal ankle to confirm fibular
length4. As the
talocrural angle is not related to the size of an image, fluoroscopic
evaluation is not affected by magnification, as are other measures of fibular
length. After determining the necessary manipulation of the foot that
recreates fibular length, one can proceed. (For additional techniques to gain
fibular length, see separate section below.)
Once the general reduction of the fibula can be obtained, the incision is
made. The incision is centered over the posterior one-half of the fibula. When
the incision has been made through the skin, care is taken not to incise the
periosteum. It is found immediately subcutaneously and often has small rents
in it as part of the injury, which can make it difficult to recognize. Sharp
Weitlaner retractors can aid by applying tension to the skin, helping to peel
the subcutaneous tissues from the periosteum. The periosteum is left entirely
intact; individual fracture fragments are not identified, stripped, or further
handled. Once the dissection is at the level of the periosteum
(Fig. 5), all retractors are
removed from the wound as they can shorten the fibula because of the tension
placed on the surrounding soft tissues. Reduction is obtained by manipulating
the foot, and then a lateral fluoroscopic image is made to confirm that there
is no angulation or translation of the fibula. This is the last time that an
unobstructed lateral radiograph can be made so it is imperative that any
sagittal plane displacement of the fibula is corrected now. Once this is
completed, the anteroposterior radiograph is made again to confirm the coronal
plane reduction. Residual lateral translation or angulation is often seen;
this is normal and is corrected later with the undercontoured plate.
Next, a precontoured direct lateral fibular plate, or a straight one-third
tubular small-fragment plate that the surgeon contours to the shape of the
distal aspect of the fibula, is placed into the wound. It is vital that the
plate be slightly undercontoured in relation to the lateral surface of the
fibula as this ultimately corrects the lateral translation of the fibula. The
plate is placed onto the fibula, with the surgeon ensuring that it is centered
between the anterior and posterior borders of the bone. This is done initially
by feel as one cannot strip the soft tissue from the fibula to visualize the
bone directly, but a Kirschner wire can be used as a probe to assist in
identifying the anterior and posterior borders of the fibula. Fluoroscopic
lateral imaging is required to confirm that the plate is centered on the bone
before fixation is placed (Fig.
6-A). This is paramount for the reduction as the direction of the
force provided by the plate must be directly medially to reduce the laterally
translated fibula. Additionally, the fibula must be evaluated for angulation.
Any anterior or posterior angulation must be corrected prior to fixation by
moving the bolster to an appropriate position. Once appropriate plate position
is confirmed, the plate is provisionally fixed to the bone with Kirschner
wires or provisional fixation pins (Fig.
6-B). After temporary fixation, the centered location of the plate
on the fibula is again confirmed. Screws can then be placed, from proximal to
distal, which will push the fibula (and therefore the talus) medially, under
the plafond (Figs. 7-A and
7-B). The reduction is confirmed on the anteroposterior
radiograph. If the talus does not reduce, one of two problems exists. Either
the syndesmosis is unreduced or the plate is incorrectly contoured to effect a
reduction and the fibula is not anatomic. If the fibula is not accurately
reduced, then the plate must be removed, recontoured, and replaced, with
attention to fibular length. If the fibula is anatomically aligned, then the
syndesmosis is unstable and needs to be reduced and stabilized as described
below.
With both medial and lateral stability restored, the syndesmosis must be
tested for stability. If the medial injury is ligamentous, the syndesmosis is
tested by applying an abduction stress on the foot and evaluating the medial
clear space, the syndesmotic space, and residual talar subluxation
(Fig. 8-A). If the medial
injury is osseous and fixation is in place, then a clamp is placed on the
fibula and an abduction stress is applied. If >2 mm of lateral translation
occurs at the syndesmotic notch, syndesmotic fixation is indicated. The
reduction of the syndesmosis can be accomplished in several ways. Most
commonly, we use a large ball-tipped reduction clamp, which engages a plate
hole or screw head on the fibula and the anteromedial distal aspect of the
tibia. It does not require much force to accurately reduce the syndesmosis,
but tightening the clamp too hard can translate the fibula posteriorly. A
perfect lateral radiograph to confirm the fibular location and compare it with
the normal ankle prevents malreduction as there is no direct visualization of
this region. Alternately, direct digital pressure by the surgeon can be used
to hold the reduction. In rare cases, the syndesmotic screw can be placed as a
lag screw to obtain the reduction, but it must be placed through the plate
exactly in the plane perpendicular to the tibiofibular axis and care must be
taken not to overtighten it as this will overcontour the plate through the
area of fibular comminution. Once the reduction is achieved and is confirmed
on the anteroposterior and lateral radiographs, the syndesmotic screws are
placed through the plate, which acts as a substitute for the lateral cortex
(Fig. 8-B). Typically,
syndesmotic fixation is achieved with one or two fully threaded 3.5-mm
cortical position screws (non-lag), placed just proximal to the subchondral
bone of the plafond, through the plate, and through three cortices. When there
is substantial comminution in the fibula, screws can be placed through the
plate and into the tibia to gain additional fixation even if the syndesmosis
is stable with a stress examination. This is recommended if more than two
screw holes in the plate are not usable because of fibular comminution.
Fibular Length
Restoring fibular length is one of the most important aspects of this
technique. In general, it is not difficult to restore length because of the
pure bending mechanism of the injury. Occasionally, however, restoring and
confirming fibular length with use of the previously described methods can be
challenging. Close attention to the reduction of the un-comminuted medial
cortex of the fibula and use of the talocrural
angle4 are the best
ways to judge length (Fig. 9).
If length is not restored with the previously described technique, one can try
grasping the distal end of the fibula with a bone tenaculum and applying
straight distal traction. Sometimes, the restored length can be held with a
Kirschner wire driven into the tibia; alternatively, one must maintain the
length manually while inserting the proximal screws into the
plate. If fibular length is restored with this technique, screws must be
placed into the distal fragment or length will be lost once the Kirschner wire
(or manual traction) is removed.
If fibular length cannot be restored with use of this method, then the last
option is to fix the plate to the distal fragment of the fibula and use an
articulated compression-distraction device proximally to push the fibula out
to length. When this is done, a clamp must be used to hold the plate to the
bone proximally or the tensioning device will lift it off the bone. Once
length is restored in this way, the proximal screws can be inserted in the
plate. The downside to this technique is the additional exposure required to
use the articulated compression-distraction device. However, without
restoration of fibular length, proper ankle mechanics will not be
reestablished. Care should be taken to maintain as much soft-tissue integrity
of the fracture fragments as possible to preserve healing potential. This
outrigger method is simple and predictable but is rarely needed.
Postoperatively, patients who have a stable syndesmosis are kept
non-weight-bearing for six weeks, but, in compliant patients, active and
passive motion is permitted as soon as the wounds are healed. If syndesmotic
screws are required, weight-bearing is deferred for twelve weeks. Active and
passive motion is begun at four weeks in compliant patients. After twelve
weeks, patients are offered syndesmotic screw removal. If the patient chooses
to have the hardware removed, it is removed prior to the commencement of any
weight-bearing. If the patient elects not to have the screw removed, he or she
is told that the screw(s) will either loosen or break at some point in the
future and the patient is unlikely to know when that happens.
CRITICAL CONCEPTSINDICATIONS:Ankle fractures caused by a lateral bending force (Lauge-Hansen
pronation-abduction ankle fractures)CONTRAINDICATIONS:Ankle fractures caused by rotational or medial bending forces (Lauge-Hansen
supination-external rotation, pronation-external rotation, or
supination-adduction ankle fractures)Substantial lateral soft-tissue injury causing blisters, unresolved
swelling, or other open woundsPITFALLS:Not correctly evaluating or restoring fibular lengthNot placing the plate directly laterally, thereby creating an inappropriate
vector with the plate, which will not counter the deforming forces on the
anklePlacing the bolster under the heel, which can cause anterior talar
subluxation and ankle malreductionAggressive dissection, thereby stripping the periosteum. This violates the
blood supply, increases the risk for nonunion, and destroys the ability to use
soft-tissue tension to generally align the fragments.Not obtaining a perfect reduction on the lateral radiographAUTHOR UPDATE:No changes have occurred in the surgical technique since the original
article was published.
CRITICAL CONCEPTS
INDICATIONS:
Ankle fractures caused by a lateral bending force (Lauge-Hansen
pronation-abduction ankle fractures)
Ankle fractures caused by a lateral bending force (Lauge-Hansen
pronation-abduction ankle fractures)
CONTRAINDICATIONS:
Ankle fractures caused by rotational or medial bending forces (Lauge-Hansen
supination-external rotation, pronation-external rotation, or
supination-adduction ankle fractures)Substantial lateral soft-tissue injury causing blisters, unresolved
swelling, or other open wounds
Ankle fractures caused by rotational or medial bending forces (Lauge-Hansen
supination-external rotation, pronation-external rotation, or
supination-adduction ankle fractures)
Substantial lateral soft-tissue injury causing blisters, unresolved
swelling, or other open wounds
PITFALLS:
Not correctly evaluating or restoring fibular lengthNot placing the plate directly laterally, thereby creating an inappropriate
vector with the plate, which will not counter the deforming forces on the
anklePlacing the bolster under the heel, which can cause anterior talar
subluxation and ankle malreductionAggressive dissection, thereby stripping the periosteum. This violates the
blood supply, increases the risk for nonunion, and destroys the ability to use
soft-tissue tension to generally align the fragments.Not obtaining a perfect reduction on the lateral radiograph
Not correctly evaluating or restoring fibular length
Not placing the plate directly laterally, thereby creating an inappropriate
vector with the plate, which will not counter the deforming forces on the
ankle
Placing the bolster under the heel, which can cause anterior talar
subluxation and ankle malreduction
Aggressive dissection, thereby stripping the periosteum. This violates the
blood supply, increases the risk for nonunion, and destroys the ability to use
soft-tissue tension to generally align the fragments.
Not obtaining a perfect reduction on the lateral radiograph
AUTHOR UPDATE:
No changes have occurred in the surgical technique since the original
article was published.