The additional value of the stress radiograph and gravity stress radiograph in predicting deep deltoid ligament integrity in isolated distal fibula fractures

Supination-external rotation (Lauge-Hansen SER) Weber B-type ankle fractures
are among the most common injuries seen at the Emergency Department. The
decision whether to operate or treat conservatively is principally based on the
stability of the ankle. The deep deltoid ligament (DDL) is, together with the
medial malleolus, the main stabiliser of the ankle joint during axial load.
Fibular fractures without medial injury are considered stable and most surgeons
advocate conservative treatment, because nonoperative treatments have good
clinical outcomes. On the other hand, a bimalleolar or a bimalleolar equivalent
fracture, i.e. a fibular fracture with additional deep deltoid ligament
rupture, will be unstable due to the incompetent lateral and medial restraints
of the ankle and requires operative treatment.

Accurate exclusion of medial injury in a SER ankle injury with an isolated
lateral malleolus fracture is of great clinical importance, because this
information confirms the choice of safe conservative management.
Widening of the medial clear space (MCS) at a mortise X-ray view is generally
used to predict and indicate a DDL rupture. However, the latter might lead to
surgical overtreatment of stable ankle fractures.

According to several authors, magnetic resonance imaging (MRI) is considered
the reference standard for detecting DDL rupture. However, recognized
disadvantages of MRI are its availability and costs. An alternative tool for
MRI is the stress radiograph. In this examination, a radiograph is performed
with the patient standing on his/her broken ankle. A complete deltoid rupture
in the absence of a talar shift on the conventional mortise view may be
detected by manifest widening of the MCS on this additional radiograph.

The purpose of the current study is to examine the additional diagnostic value
of the stress radiograph in determining deltoid ligament disruption in ankle
fractures. The sensitivity and specificity of this test will be compared with
findings on MRI, which is used as the reference standard.
The sensitivity and specificity of this diagnostic tool will be calculated. The
value of the standard X-mortise view, compared with the stress radiograph and
the gravity stress radiograph will be compared.
To be able to distinguish between a stable and instable fracture is of the main
importance in deciding to operate or treat conservatively. We hope to be able
to make a better distinction between these two fractures and thus a better
treatment.
The hypothesis is that nowadays too many (stable) fractures are being operate
(based on the current diagnostics) while MRI shows that there was no
instability of the ankle.

All patients who are seen at the Emergency Room of the Haaglanden Medisch
Centrum with an isolated distal fibula fracture and who meet the inclusion
criteria will be asked to perform in this study. They will receive an
information letter.
If they decide to take part, next tot the common diagnostics (the X-mortise
view) an additional gravity stress view will be made.
Within one week, an extra MRI scan of the ankle will be made, together with an
additional stress radiograph of the ankle. After these additional diagnostics
tests, the doctor will make his decision of treatment.

After having included all patients; the multiple radiographs will be anonymised
and will be scored by a panel of two trauma surgeons and two skeletal
radiologists. They will score the radiographs independently, based on
dislocation, medial clear space widening, syndesmosis aspect and the indication
to operate (yes/no). These results will be compared with the results of the MRI
scan. These scans will be judged by a radiology intern and a musculoskeletal
radiologist. All scores are being blinded before being analysed.
To determine intra-observer variability, the radiographs are being scored after
2 months again by the four doctors who scored them at first.

N.a.

One extra visit to the hospital, where the MRI scan and the stress radiograph
will be made. This is not a very invasive burden for the patient. The stress
radiograph can be painful while the patient has to stand on his broken ankle.
However, this is only for a very short time and extra painkillers can be taken
in advance.The time of this one extra visit will take about an hour of the
patients' time.
An advantage for the patient, when they decide to participate in this study, is
that they receive these extra diagnostic examinations. The decision to treat
conservatively or to operate, will be made with extra focus on these
investigations and they will receive the best treatment possible, with more
knowledge about their fracture than patients with only conventional radiograph.