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methodology calls for orienting syndesmosis fixation from
posterolateral to anteromedial just proximal to the tibiofibular joint, or about 25 to 30 degrees externally rotated relative to the horizontal with the hip and knee in neutral
rotation.2 This is due to the posterolateral location of the
fibula relative to the tibia. However, with time, the need for
more accurate and precise methodology has become apparent. The reported rates of postsurgical syndesmosis malreduction range from 0% to 54%.7,10,12,15-17 Recent reports in
cadaveric biomechanical studies have demonstrated that
deviation from the optimal axis of syndesmosis fixation
with clamp or screw placement results in iatrogenic malreduction through translation and rotation of the fibula most
often in the sagittal plane.4,6,11-13,16
Two reports have recently proposed ideal axes for syndesmotic fixation that differ from that used by the traditional technique. First, Kennedy and colleagues studied the
syndesmoses of 200 uninjured ankles imaged with computed tomography (CT). They located the geometric centers
(centroid) of the tibia and fibula, respectively, and reasoned
that fixation passing through these points would not result
in sagittal plane displacement of the fibula. They concluded
that the optimal axis of syndesmosis fixation varies by individual but originates close to the lateral fibular apex and
exits through the anterior half of the medial distal tibia
metaphysis.8 Second, and independently of this, Cancienne
and Yarborough proposed a "Center-Center" clinical technique for aligning syndesmosis fixation through the central
axes of the tibia and fibula using an internally rotated lateral
fluoroscopic view of the ankle.3 They reasoned that the center of the fibula and tibia can be aligned on this view and
that fixation through the center of each bone prevents fibula
displacement. Theoretically, this aligns the centroids of the
fibula and tibia, which achieves the same ideal patient-specific alignment proposed by Kennedy et al. However, the
center-center technique was described in technical detail
only and no supportive validation or clinical outcomes data
was included.
These studies raise the question as to the extent to which
the centroid and center-center axes correlate in the general
population. If present, a strong correlation has potentially
high clinical importance. That is, a validated intraoperative
methodology for achieving patient-specific syndesmosis
fixation axis alignment has the potential to improve the
quality of care through the reduction of iatrogenic malreduction. Therefore, the primary aim of this study was to
assess the extent to which the centroid and simulated center-center axes align to one another within the zone of distal
tibia containing the distal tibiofibular joint and just proximal to it that is commonly used for syndesmosis fixation.
The secondary aim was to look for differences in the orientation of these 2 axes when comparing different distances
relative to the tibial plafond.

Foot & Ankle International 41(9)

Materials and Methods
This IRB-approved retrospective descriptive study used
ankle and foot CT scans obtained from a convenience sample of patients 21 years of age or older who were seen at the
senior author's practice between July 1, 2016, and June 30,
2018. Enrollment proceeded in reverse chronological order
of study dates. Inclusion criteria were presence of an ankle
or foot CT scan covering a minimum of 40 mm of tibia
proximal to the distal tibia articular surface and concomitant weight-bearing 3-view ankle radiographs that were
read as normal by the senior author. The weight-bearing
radiographs were used as part of the exclusionary criteria to
rule out existing deformity. Exclusion criteria included a
chief complaint of ankle deformity or traumatic ankle injury
as the indication for the imaging or imaging findings of
ankle deformity, arthritis, prior ankle injury, or surgery.
Demographic data were recorded.
Thirty patients were included in the study and 95 were
excluded (Figure 1). Eighteen patients (67%) were male.
The average age was 44.2 years (range, 20-85). Eighteen
(67%) were right limbs. Twenty-four patients (80%) were
white, 5 (17%) were black, and 1 (3%) was Asian.
All image analyses were performed using the tools provided by the institutional picture archiving and communications system (Visage 7, Visage Imaging, San Diego, CA).
Images for analysis were prepared in a standardized fashion
by a member of the study staff. First, axial-plane images
corresponding to 10, 20, and 30 mm proximal to the distal
tibia articular surface were identified. Note that the axial
plane of the CT images was oriented perpendicular to the
long axis of the tibia. Identified images were then magnified to 300%. Finally, the center-center fluoroscopic alignment technique was simulated by internally rotating each
image until the anterior and posterior borders of the fibula
were equidistant from the anterior and posterior borders of
the tibia, respectively (Figure 2). This was facilitated by a
system tool that allowed measurement of distance between
parallel lines. The parameters needed to locate and reproduce each image were recorded.
Three trained observers, who were blinded to one another's measurements, performed data collection on the study
images. For each image, each observer first acquired the correct image, reproduced the prescribed magnification and
rotational alignment, and confirmed the simulated "centercenter" alignment using the recorded parameters. Referencing
this alignment, a midcoronal plane bisector was plotted making the center-center axis. Next, the centroid axis was plotted
using a system tool for locating the centroid of a traced shape.
The fibula and tibia were manually traced separately and a
line was drawn between their centroids.
The angular deviation between the centroid and centercenter axes was measured. This was completed at the 10-,

Foot & Ankle International - September 2020

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