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Distal tibiofibular radiological overlap: Does it always exist?

Article

Distal tibiofibular radiological overlap: Does it always exist?

Abstract

Overlap between the distal tibia and fibula has always been quoted to be positive. If the value is not positive then an injury to the syndesmosis is thought to exist. Our null hypothesis is that it is a normal variant in the adult population. We looked at axial CT scans of the ankle in 325 patients for the presence of overlap between the distal tibia and fibula. Where we thought this was possible we reconstructed the images to represent a plain film radiograph which we were able to rotate and view in multiple planes to confirm the assessment. The scans were taken for reasons other than pathology of the ankle. We found there was no overlap in four patients. These patients were then questioned about previous injury, trauma, surgery or pain, in order to exclude underlying pathology. We concluded that no overlap between the tibia and fibula may exist in the population, albeit in a very small proportion.
VOL. 1, No. 2, F EBRUARY 2012 20
RESEARCH
Distal tibiofibular radiological overlap
DOES IT ALWAYS EXIST?
B. Sowman,
R. Radic,
M. Kuster,
P. Y a t es ,
B. Breidiel,
S. Karamfilef
From Department of
Orthopaedic Surgery,
Royal Perth Hospital,
Perth, Australia
B. Sowman, BDS, MBB S,
Orthopaedic Registrar
R. Radic, MBBS, Orthopaedic
Regis trar
M. Kuster, MD , PhD, F RACS,
Professor of Orthopaedic Surgery
Royal Perth Hospital, Department
of Orth opaedic Surgery , 197
Well ington Stree t, Per th, We stern
Australia 6000, Australia.
P. Yates, FRCS(Tr & Orth),
FRACS(Ort h), Professor of
Orthopaedic Surgery
Fremant le Uni versit y Hospita l,
Alma Street, Fremantle, Western
Australia 6160, Australia.
B. Breidiel, MBBS, FRANZCR,
Consultant Radiologist
S. Karamfilef, Radiologist
Perth Radiological Clinic, 127
Hamersl ey Road, Subi aco, Per th
6008, Austral ia.
Corresponde nce should be sent
to Dr B. Sowman; e-mail:
braadsowman@hotmail.com
10.1302/2046-3758.12.2000048
$2.00
Bone Joint Res 2012; 1:20 –24.
Received 12 December 2011;
Accepted after revision 20 February
2012
Objectives
Overlap between the distal tibia and fibula has always been quoted to be positive. If the
value is not positive then an injury to the syndesmosis is thought to exist. Our null
hypothesis is that it is a normal variant in the adult population.
Methods
We looked at axial CT scans of the ankle in 325 patients for the presence of overlap between
the distal tibia and fibula. Where we thought this was possible we reconstructed the images
to represent a plain film radiograph which we were able to rotate and view in multiple
planes to confirm the assessment.
Results
The scans were taken for reasons other than pathology of the ankle. We found there was no
overlap in four patients. These patients were then questioned about previous injury, trauma,
surgery or pain, in order to exclude underlying pathology.
Conclusion
We concluded that no overlap between the tibia and fibula may exist in the population,
albeit in a very small proportion.
Article focus
To investigate if the presence of no over-
lap between the distal tibia and fibula is
always pathological or whether it can
exist in asymptomatic ankles
Key messages
No overlap between the tibia and fibula at
the ankle joint can exist in a painless ankle
It is an uncommon finding, with an inci-
dence in the population of 1.25%
If other investigations are negative then
the possibility of this anatomical variant
should be considered
Strengths and limitations
Disproves a long-held belief, by providing
evidence that the absence of overlap
between the tibia and fibula at the ankle is
not always pathological
Is a very uncommon finding, so it should
only be used if other investigations such
as CT, MRI and arthroscopy find no
pathological cause
Introduction
The distal tibiofibular joint is prone to dis-
ruption of the syndesmosis as a result of
bony fracture of the ankle or ligamentous
injury.1,2 Injury to the syndesmosis is diag-
nosed by initial clinical examination and
plain film radiography. There may be subtle
changes on plain films which may lead to
the suspicion of a syndesmotic injury. These
can be further investigated with CT, MRI and
arthroscopy of the ankle.3-10 While clinical
examination and plain film radiography are
the everyday tools of the orthopaedic sur-
geon, the use of other modalities such as CT
and MRI has become more widespread.
However, arthroscopy of the ankle has a
more limited role as a result of its availability,
cost and the expertise required.3-8
Therefore, taking measurements on radio-
graphs is an important decision-making
tool.1,9 Variations from published guidelines
are interpreted as pathological, leading to
surgical treatment.1,2 However, it is impor-
tant to recognise the variations of normal
Freely available online
Keywords: Tibiofibular overlap, Syndesmosis, Fractured ankle, Medial clear space, Diastasis, Ankle
21 B. SOWMAN, R. RADIC, M. KUSTER, P. YATES, B. BREIDIEL, S. KARAMFILEF
BONE & JOINT RESEARCH
anatomy and their prevalence in the population, so that
unnecessary treatment is avoided.
The measurement of overlap between the distal tibia
and fibula on plain film imaging is used clinically, and in
the literature, to predict injur y to the syndesmosis.1-4 The
value is measured 1 cm proximal to the plafond, and is
the horizontal distance between the medial border of the
fibular and the anterior tubercle of the tibia; it should be
greater than 1 mm on the mortise view.1,4 This value has
been reported in previous studies to always be positive
and should exist in all views (Fig. 1).4,11
A case was encountered at our institution where no
overlap existed between the tibia and fibula in a Weber B-
type ankle fracture. The ankle was tested intra-operatively
using the method described by Stoffel et al12 and the syn-
desmosis was found to be stable. Intra-operative screening
and plain film imaging of the contralateral limb showed no
overlap between the tibia and fibula (Fig. 2). The patient
reported no previous trauma, pain or surgery to the
unaffected limb. These findings led us to the null hypo-
thesis that non-pathological overlap between the tibia and
fibula in the population does, indeed, exist.
The aim of this study was to review axial CT scans of
ankles taken for reasons other than ankle pathology and to
investigate if there is a percentage of the population in
which no overlap exists between the distal tibia and fibula.
Patients and Methods
Ethical approval was obtained for this study. Axial CT
scans of patients who underwent CT scans for reasons
other than ankle pain or ankle pathology were used. Axial
scans were used as they impart the ability to observe the
presence of overlap between the tibia and fibula. This
procedure also avoided the need to unnecessarily expose
patients with asymptomatic ankles to radiography.
Ebraheim et al5 demonstrated that axial CT scans were
more accurate at diagnosing diastasis than plain films.
The CT scans were taken from patients who had under-
gone total knee replacement and who were being
assessed for rotational alignment in accordance with the
Perth CT protocol,13 or those undergoing CT angio-
graphy looking at blood flow in the distal extremity. Path-
ology of the ankle was not the reason for the CT scan in
any patient. All imaging was performed with a 64-slice CT
scanner in all cases, albeit with different models and at
different insitutions.
Two observers (BS, RR) for this study reviewed CT scans
from 325 patients. The axial slices were initially reviewed
using Inteleviewer (Intelerad Medical System Inc.,
Montreal, Canada) to measure overlap between the distal
tibia and fibula (Figs 3a and 3b). Where absence of over-
lap was considered to be a possibility, the images were
viewed using the GE Workstation (GE Healthcare,
Chalfont St Giles, United Kingdom) with three-
dimensional (3D) volume rendering using transparent
bone windows (Fig. 3c). This software enabled the ankle
to be rotated in three axes to visually inspect and confirm,
or deny, the presence of overlap.
Exclusion criteria included previous history of injury to
the ankle, current ankle pain or evidence on CT scanning
of prior injury or surgery. One patient was excluded
(evidence of significant trauma to ankle) leaving
324 patients eligible for inclusion. A total of 209 of these
scans in clu ded both a nkl e joints, ena bli ng us to note if t he
anatomy was present bilaterally, resulting in a total of
533 ankles.
Fig. 1
Diagram showing the typical syndesmotic rela-
tionship in patients without overlap between the
tibia and fibula (A, medial fibular border; B, ante-
rior tibial tubercu le; C, lateral border of the poste-
rior tibia; D, plane 1 cm above plafond; E, medial
clear space; AC, tibiofibular clear space). The dis-
tance AB in these patients is positive.
Fig. 2b
Plain radiographs post-operatively of a 32-year-old female patient who sus-
tained a Weber B fracture of the left ankle, with no overlap existing between
the tibia and fibula, showing a) the left ankle, which showed no increase in
the distance between the tibia and fibula or increase of the medial clear space
during intra-operative testing and b) the right ankle, showing that the condi-
tion was present on the right side, which had no history of trauma, pain or
previous surgery.
Fig. 2a
DISTAL TIBIOF IBULAR RADIOLO GICAL OVERLAP 22
VOL. 1, No. 2, F EBRUARY 2012
Any patients in whom no overlap was seen were then
contacted and questioned about: 1) ankle pain; 2) previ-
ous trauma; and 3) surgery to the ankle joint. If there was
a positive response to any of these three questions, the
patients were not recorded in the positive group.
Measurements from scans in patients where no overlap
existed were made. These were: 1) the angle that the over-
lap was present compared with the intermalleolar axis in the
coronal plane; 2) angle compared with the talus, in the
coronal plane; 3) medial clear space1; 4) tibiofibular clear
space (syndesmosis A) (Fig. 4).1,14 We measured the inter-
malleolar axis, as the tips of the malleoli palpated clinically
and it was felt that the angle between the overlap, com-
pared with the talus, was representative of the mortise view.
Results
Of the 324 patients assessed, four displayed no overlap
between tibia and fibula, giving a prevalence of 1.23% in
the sample population. Two of these patients had
bilateral scans of the ankle, and in both patients no over-
lap was demonstrated bilaterally. None of the four
patients reported any previous ankle pain, surgery to the
ankle or previous trauma to the ankle joint.
The mean age of these four patients was 61.8 years
(38 to 75). Of the six ankles with no overlap assessed, the
mean angle of the intermalleoli and diastasis was 91.
(86° to 95°), the mean angle of the diastasis to the talar
axis 18.5° (15° to 23°) and the mean tibiofibular clear
space was 5.6 mm (5.3 to 5.8) (Table I).
Fig. 3b
Figures 3a and 3b – axial CT views a) in a patient with overlap between the distal tibia and fibula, showing that a plain film x-ray beam (represented by the
yellow arrow) cannot be passed between the bones, and b) in a patient without overlap, with the x-ray beam (yellow line) able to pass between the tibia and
fibula. Figure 3c – three-dimensional image of the patient in Figure 3b, reconstructed from CT scans. This image resembles a radiograph and can be rotated
through 360° using GE Workstation software (GE Healthcare).
Fig. 3a Fig. 3c
Fig. 4b
Figure 4a – diagram of a mortise view showing approximate levels of axial slices shown in the diagrams in Figures 4b and 4c. Line 1 is represented by solid lines
and Line 2 represented by dotted lines in Figures 4b and 4c. Line 3 is the line between the tips of the medial and lateral malleoli (intermalleoli line). Figures 4b
and 4c – diagrams of superimposed axial slices for b) measurement of the angle (ABC) between the diastasis (AB) and the intermalleoli axis (BC), and c) mea-
surement of the angle (ABC) between the diastasis (AB) and the talus (BC) (MM, medial malleolus).
Fig. 4a Fig. 4c
23 B. SOWMAN, R. RADIC, M. KUSTER, P. YATES, B. BREIDIEL, S. KARAMFILEF
BONE & JOINT RESEARCH
Discussion
Injury to the syndesmotic ligaments of the ankle can be
diagnosed using many different modalities.1,3,6,7,14,15
These range from clinical examination and plain film inves-
tigation to arthroscopy of the ankle. While arthroscopy has
been reported to be the benchmark procedure,8 it is inva-
sive and not all surgeons have the expertise and equip-
ment to utilise this diagnostic tool. MRI is less
uncomfortable for the patient than arthroscopy and has
been reported to be more accurate than plain radio-
graphs.1,7 However, it remains more costly and of limited
availability when compared with plain radiographs.3,7
As a result of the limited availability of MRI, many sur-
geons rely on clinical examination and measurements
from plain films for diagnosis. The main values used are:
1) the tibiofibular clear space (syndesmosis A), which is
the distance from the medial fibula to the posterior tuber-
cle of the medial border of the tibia. This is measured 1 cm
above the tibial plafond1,4; 2) the tibiofibular overlap
(syndesmosis B), which is the maximum overlap between
the tibia and fibula, measured 1 cm above the tibial
plafond1,4; and 3) the medial clear space.
The overlap between the tibia and fibular (syndes-
mosis B) has always been stated as being positive, i.e.
there should always be overlap between the tibia and
fibula.4 This has propagated into practice, such that
overlap should exist on all views of the ankle.4 If overlap
is not present, a syndesmotic injury is implied and treat-
ment in the form of a syndesmotic fixation is usually
undertaken.1,2 Pneumaticos et al4 found that there was
always overlap between the two bones and implied that
this should always exist. However, their study observed
a total of 14 cadavers, making it unlikely to pick up a vari-
ant with a low prevalence, and only plain films were
used; this would also decrease the likelihood of discov-
ering the condition, as multiple images of the distal tibia
and fibula would be required, in different orientations.
These results were confirmed by Beumer et al,11 in a
study of 20 cadavers. Our study has the advantage of
large numbers and the ability to rotate the reformatted
axial images in multiple planes in order to increase the
accuracy of identification of the condition. Using CT
scans gave us the ability to view large numbers to look
for this uncommon variant. The software enabled the
images to be converted into a movable image, simulat-
ing a plain film. We are not aware of any studies that
show no overlap to be an anatomical variant, or that
assess its prevalence in the population.
In our population of 324 patients, we found the preva-
lence to be 1.23%. Where both ankles were imaged, the
condition was bilateral, suggesting this was normal for
this patient. The angle where no overlap was present, in
relation to the talus and intermalleoli axis, was within 4°
of the contralateral side. Using axial CT scans gives us the
best chance of detecting this variant. Using plain film
imaging would require the x-ray beam to be located
within a very small arc to identify the absence of overlap,
if it exists. The best position for the beam is at approxi-
mately 90° to the tips of the malleoli in the coronal plane.
Multiple plain film images around this angle would give
the best chance of locating its presence, or the use of con-
tinuous fluoroscopy about the arc described.
The tibiofibular clear space (syndesmosis A) has been
re porte d to be le ss tha n 6 mm in ank les in whi ch t he syn-
desmosis is intact.4,16 The medial clear space is reported
to be normal if it is similar to the distance from the talus
to the tibial plafond, as was the case with the measure-
ments in all six ankles investigated (Table I). We found
the mean syndesmosis A to be 5.6 mm, with all six mea-
surements less than the quoted 6 mm. This suggests
that the absence of overlap between the tibia and fibula
in all views, with other normal radiological measure-
ments, does not imply syndesmotic injury and requires
investigation with MRI or arthroscopy in order to con-
firm it. This anatomical variant risks over-treatment if
treatment were based purely on the presence of tibio-
fibular overlap, with the subsequent costs and morbid-
ity. This study shows that it is possible to have no overlap
in an asymptomatic ankle. We therefore suggest that no
overlap may represent anatomical variation, in cases in
which injury is not demonstrated on further testing with
CT, MRI or arthroscopy.
Tabl e I. Results from the four patients (six ankles) with no overlap seen on axial CT scans
Patient (side) Age (yrs)
Talus/diast asis angle
(°)
Intermalleolar angle
(°)
Tibiofibular clear
space (mm)
1 – Left 38 23 95 5.5
1 – Right 22 93 5.6
2 – Left 68 15 86 5.8
2 – Right 16 90 5.7
3 – Left 75 19 9 4 5.4
4 Right6616915.3
Mean 61.8 18.5 91.5 5.6
DISTAL TIBIOF IBULAR RADIOLO GICAL OVERLAP 24
VOL. 1, No. 2, F EBRUARY 2012
We acknowledge that the population is age-biased;
however, obtaining a large number of ankle CT scans for
which the primary reason is not ankle pathology in a
younger population was not possible. We do not believe
that advancing age would increase the prevalence of the
condition. If anything, the variant could become less
prevalent given increasing degenerative changes and for-
mation of osteophytes. However, this study looks at over-
lap in the skeletally mature population only.
Conclusions
We found that the absence of overlap between the distal
tibia and fibula exists in the normal asymptomatic popu-
lation, with an incidence in our study of 1.23%. These
patients had no history of previous ankle trauma, surgery
or pain, suggesting that this is an anatomical variant.
When other diagnostic modalities such as MRI or arthros-
copy are not available to confirm or deny disruption of
the syndesmosis, or intra-operative testing shows a stable
syndesmosis, we recommend plain film imaging or
dynamic fluoroscopy of the contralateral limb to screen
for the presence of this uncommon variant.
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Funding statement:
None declared
Author contributions:
B. Sowman: Author, Study design, Data collection
R. Radic: Data collection
M. Kuster: Study design, Advice
P. Yates: Study des ign, Advice
B. Breidiel: Radiological advice
S. Karamfilef: Data collection, Image manipulation
ICMJE Co nflict of Intere st:
None declared
©2012 British Ed itorial Society of Bo ne and Joint Surge ry. This is an open-access article
distributed under the terms of the Creative Commons Attributions licence, which permits
unrestricted use, distribution, and reproduction in any medium, but not for commercial
gain, provided the original author and source are credited.
... 23 TFO has a sensitivity of 36% and specificity 78% compared to MRI. 23 The absence of TFO typically indicates a diastasis injury. 24,25 Shah et al. reported the minimum TFO to be À1.9 mm on the mortise views and Sowman et al. found that 1.23% of 324 patients without ankle diastasis injury had an absent TFO. 15,25 Tibiofibular clear space Tibiofibular clear space (TCS) is measured between the fibular medial border and lateral border of the tibia perineal incisor. ...
... 24,25 Shah et al. reported the minimum TFO to be À1.9 mm on the mortise views and Sowman et al. found that 1.23% of 324 patients without ankle diastasis injury had an absent TFO. 15,25 Tibiofibular clear space Tibiofibular clear space (TCS) is measured between the fibular medial border and lateral border of the tibia perineal incisor. TCS effectively measures the posterior aspect of the syndesmosis. ...
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Background Minimally invasive plate osteosynthesis (MIPO) has been reported to be superior to open reduction and internal fixation (ORIF) in the treatment of different long bone fractures. Nevertheless, in distal fibula fractures, the evidence of MIPO remains scarce. The aim of this retrospective study was to compare the clinical and radiological outcomes of the minimally invasive techniques applied to the distal fibula with open reduction and internal fixation within a 12 months follow-up. Methods A consecutive series of patients who underwent surgery using either ORIF or MIPO for the treatment of distal fibula fractures between 2010 and 2014 were retrospectively analyzed. All distal fibular fractures requiring an operative treatment (Danis-Weber type B ≙ AO type 44 B1, 2, 3 and Danis-Weber type C ≙ AO type 44 C1, 2) were included (ORIF n = 35, MIPO n = 35). Patients were assessed for postoperative pain using a visual analog scale (VAS) for pain (ranging from 0 to 10) and classified into 4 groups: “no pain” for VAS = 0, “low” for VAS = 1–3, “moderate” for VAS = 3–5, and “severe” for VAS = 5–10. In addition, complications of postoperative fracture-related infection, wound healing disorders, vascular and nerve injury and development of nonunion were evaluated and analyzed. Radiologic outcome measures assessing the talocrural angle, lateral and medial clear space, tibiofibular overlap, and talar tilt angle were evaluated postoperatively. Results The overall complication rate showed to be lower in the MIPO group compared to the ORIF group (14% vs. 37%, p = 0.029). Even though not statistically significant, specific surgery-related complications such as skin necrosis (3% vs. 9%, p = 0.275), nonunion (0% vs. 6%, p = 0.139), infections and wound healing disorders (9% vs. 20%, p = 0.141), as well as postoperative pain (17% vs. 26%, p = 0.5) were found more frequently in the ORIF group. The tibiofibular overlap demonstrated to be significantly lower in the ORIF group (3.3 mm vs. 2.7 mm, p = 0.033). The talocrural angle, talar tilt angle, and lateral and medial clear space showed to be equivalent in both groups. Conclusion In this retrospective single-center consecutive series, MIPO was superior to ORIF in the surgical treatment of distal fibula fractures with respect to the overall complication rate. Trial registration EKNZ Project-ID: 2019-02310 , registered on the 20th of December 2019 with swissethics
... The observed statistically signi cant difference of the tibio bular overlap between MIPO and ORIF might be accidental, with a large variety of this value described in the literature (42). In general the tibio bular overlap should be greater than or equal to 10 mm (43). ...
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Background Minimally invasive plate-osteosynthesis (MIPO) has been reported to be superior to open reduction and internal fixation (ORIF) in the treatment of different long bone fractures. Nevertheless, in distal fibula fractures the evidence of MIPO remains scarce. The aim of this retrospective study was to compare the clinical and radiological outcomes of the minimally invasive techniques applied to the distal fibula with open reduction and internal fixation within a 12 months follow-up. Methods A consecutive series of patients who underwent surgery using either ORIF or MIPO for the treatment of distal fibula fractures between 2010 and 2014 were retrospectively analysed. All distal fibular fractures requiring an operative treatment (Danis-Weber type B ≙ AO type 44 B1, 2, 3 and Danis-Weber type C ≙ AO type 44 C1, 2) were included (ORIF n=35, MIPO n=35). Patients were assessed for postoperative pain using a visual analogue scale (VAS) for pain (ranging from 0 to 10) and classified into 4 groups; “no pain” for VAS=0, “low” for VAS=1-3, “moderate” for VAS=3-5 and “severe” for VAS=5-10. In addition, complications of postoperative fracture-related infection, wound healing disorders, vascular and nerve injury as well as development of nonunion, were evaluated and analyzed. Radiologic outcome measures assessing the talocrural angle, lateral and medial clear space, tibiofibular overlap and talar tilt angle were evaluated postoperatively. Results The overall complication rate showed to be lower in the MIPO group compared to the ORIF group (14% vs. 37%, p=0.029). Even though not statistically significant, specific surgery related complications such as skin necrosis (3% vs. 9%, p= 0.275), nonunion (0% vs. 6%, p=0.139), infections and wound healing disorders (9% vs. 20%, p=0.141) as well as postoperative pain (17% vs. 26%, p=0.5) were found more frequently in the ORIF group. The tibiofibular overlap demonstrated to be significantly lower in the ORIF group (3.3mm vs. 2.7mm, p=0.033). The talocrural angle, talar tilt angle, lateral and medial clear space showed to be equivalent in both groups. Conclusion In this retrospective single-center consecutive series MIPO was superior to ORIF in the surgical treatment of distal fibula fractures with respect to the overall complication rate. Trial registration: EKNZ Project-ID: 2019-02310; registrated 20th of December 2019 with swissethics
... As far as we know, the DTS has wide anatomic variability in the depth of the incisura fibularis, and the shape of the tibial tubercles 28,29 . It was hypothesized that the width of the ankle mortise would vary with the different depth of the incisura fibularis and shape of the tibial tubercles during the changes of gait cycle, and the shape of the DTS could be involved in the risk of recurrent lateral ankle sprains. ...
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The tibiofibular clear space, a commonly used parameter in assessing the reduction of the syndesmosis in the management of ankle injuries, its anatomic boundaries, and resultant diagnostic ramifications were evaluated. This interval is seen to reflect the posterior aspect of the distal tibiofibular relationship and to vary not only with direct lateral displacement of the distal fibula but also potentially with rotational abnormalities of the fibula.
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We analyzed 50 sets of ankle radiographs to determine the interobserver and intraobserver reliability when obtaining common linear and angular measurements. The radiographs were divided into two groups: one group included 25 normal ankles, and the second group included 25 fractured ankles. Each set of radiographs was evaluated independently by four different observers on two separate occasions under controlled conditions. Six radiographic parameters were measured on all 50 sets of films: syndesmosis A, syndesmosis B, syndesmosis C, the medial clear space, and the talocrural and bimalleolar angles. On the 25 sets of fracture films, four additional measurements of fracture displacement were included: displacement of the medial malleolus (mortise), displacement of the lateral malleolus (AP and lateral), and displacement of the posterior malleolus. Reliability was evaluated with an analysis of variance intraclass correlation coefficient. Among the examiners, 9 of the 10 parameters could be measured reliably. Intraobserver reliability was found to increase with the experience of the examiner.
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Twelve cadaver lower limbs were used for radiographic and CT assessment of the tibiofibular syndesmosis. Plastic spacers were placed in the distal tibiofibular intervals of each specimen in successive 1-mm increments until diastasis could be appreciated on the plain radiographs. All 2- and 3-mm diastases could be noted and clearly identified on CT scans, while the 1-, 2-mm, and half of the 3-mm syndesmotic diastases could not be appreciated with routine radiographs. CT scanning is more sensitive than radiography for detecting the minor degrees of syndesmotic injuries. Therefore, a CT scan can be performed in cases of syndesmotic instability after ankle injuries and for preoperative or postoperative evaluation of the integrity of the distal tibiofibular syndesmosis in cases of doubtful condition of the syndesmosis.