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Arch Orthop Trauma Surg (2013) 133:1377–1384
DOI 10.1007/s00402-013-1823-5
ORTHOPAEDIC SURGERY
Evaluation of reduction and fixation of calcaneal fractures:
a Delphi consensus
M. S. H. Beerekamp · J. S. K. Luitse · D. T. Ubbink ·
M. Maas · N. W. L. Schep · J. C. Goslings
Received: 17 November 2012 / Published online: 28 July 2013
© Springer-Verlag Berlin Heidelberg 2013
percentage of respondents with identical answers. Consen-
sus was defined as an agreement of at least 80 %.
Results All experts were invited for the three Delphi
rounds and 16, 18, and 15 specialists responded per round,
respectively. Agreement was reached for 23/38 (60 %)
items regarding imaging techniques, 20/21 (95 %) ana-
tomical landmarks, 13/16 (81 %) items regarding fracture
reduction and 8/9 items (89 %) regarding fracture fixation.
Conclusion This Delphi consensus shows that more
aspects require evaluation than currently used in radiologi-
cal evaluation protocols. With this consensus, we provide
the basis for a universal evaluation protocol to assess the
radiological outcome of calcaneal fracture treatment.
Keywords Calcaneus · Fracture · Reduction · Fixation ·
Imaging · X-ray · Measurement · Delphi · Consensus
Background
Anatomical reduction and subsequent operative fixation
of calcaneal fractures are considered as the best founda-
tion for an optimal functional outcome [27]. Because the
quality of fracture reduction and fixation is considered to
greatly influence functional outcome, radiological evalu-
ation seems essential in determining treatment success.
Although the importance of radiological assessment is
acknowledged, an international consensus on the optimal
assessment of the quality of fracture reduction and fixation
is currently unavailable.
Although, computer tomography is the unquestionable
imaging modality of choice in terms of preoperative frac-
ture assessment, the best technique to visualize and evalu-
ate the result of calcaneal fracture reduction and fixation
remains controversial [1, 2, 15, 25, 29, 31]. There is lack of
Abstract
Background Postoperative radiological assessment of
the quality of reduction and fixation of calcaneal fractures
is essential when evaluating treatment success. However,
a universally accepted radiological evaluation protocol is
currently unavailable. The aim of this study was to obtain
an expert-based consensus on the most important criteria
for the radiological assessment of the quality of reduction
and fixation of calcaneal fractures.
Methods The Delphi method, consisting of three rounds,
was used to obtain consensus. Each round focused on four
main topics of calcaneal fracture evaluation: imaging tech-
nique (38 items), anatomical landmarks (21 items), fracture
reduction (16 items) and position of the fixation material
(9 items). We invited ten radiologists and 44 surgeons from
the USA and Europe (all calcaneus experts) to complete
online questionnaires. They were asked which aspects
require evaluation to determine the quality of fracture
reduction and fixation. Agreement was expressed as the
Electronic supplementary material The online version of this
article (doi:10.1007/s00402-013-1823-5) contains supplementary
material, which is available to authorized users.
M. S. H. Beerekamp (*) · J. S. K. Luitse · N. W. L. Schep ·
J. C. Goslings
Trauma Unit, Department of Surgery, Academic Medical Center,
P. O. Box 22660, 1100 DD Amsterdam, The Netherlands
e-mail: m.s.beerekamp@amc.nl
D. T. Ubbink
Department of Quality and Process Innovation, Academic
Medical Center, Amsterdam, The Netherlands
M. Maas
Department of Radiology, Academic Medical Center,
Amsterdam, The Netherlands
1378 Arch Orthop Trauma Surg (2013) 133:1377–1384
1 3
consensus concerning imaging modality and technique of
choice in the evaluation of radiological outcome. In a study
of Parmer et al. [23], comparing calcaneal fracture treatment,
postoperative CT scans were performed to evaluate treatment
result. They reported that there were no satisfactory methods
to grade the quality of the reduction based on CT scans in the
operated group, since then others have introduced CT-based
measurements [16, 19]. However, most current measure-
ments, like those of the commonly used Böhlers angle and
Gissane’s critical angle, are not one of them and only based
on radiographs [2, 10, 12, 14, 25, 27, 32]. This is probably
due to the difficulty of capturing all anatomical landmarks
needed to measure these angles in one slice. Moreover, indi-
vidual studies use different thresholds of Böhlers angle, step-
off and gaps that are considered acceptable [10, 12, 19, 25,
29, 30]. Intra-articular gaps and step-offs remain better visu-
alized with the use of CT scans [19].
In addition, available literature on the reliability of the
above-mentioned measurements is scarce. Clint et al. [13]
found that inter-observer agreement of the postoperative
measurement of Böhler’s angle in children was excellent,
in contrast to Gissane’s critical angle which was only fair to
poor. To our knowledge, reliability of subjective evaluation
criteria of anatomical landmarks has not been investigated.
However, Basile [4] showed that subjective evaluation of
the anatomic reduction of the PTC-joint can have prognos-
tic value for the clinical outcome.
These apparent differences in radiological evaluation
prevent a good comparison between different study results
and reduce reproducibility. Therefore blinded, independent
radiological assessment should be standard, as was stated
in a systematic review of Richards and Bridgman [25].
However, no recommendations were given about the radio-
logical parameters to be assessed. Well-defined criteria for
evaluation are fundamental to be able to compare treatment
results. The purpose of this study was to obtain an expert-
based consensus on the most important radiological crite-
ria for the assessment of the quality of fracture reduction
and fixation of the calcaneus, which can be used in clinical
practice.
Materials and methods
The Rand Corporation developed the Delphi method to
measure and obtain group consensus [11, 17, 18, 21]. In
this structured, anonymous and repeated process, experts
are being asked to respond to non-leading, unambiguous
statements on items relevant to the topic [17]. We used this
effective method to obtain consensus among specialists in
this study.
To assess the level of agreement on useful criteria in the
radiological evaluation of the calcaneus, a list of possible
criteria was composed based on literature data and on the
authors’ experience [2, 12, 14, 22, 25, 27, 30, 32]. These
items were divided into four main topics: (1) imaging
technique, (2) evaluation of anatomical landmarks of the
operated joint, (3) reduction of fracture fragments and (4)
position of the fixation material.
Medical specialists invited
Experts in treating patients with calcaneal fractures were
selected by approaching research groups from Europe
and the USA that have published papers on calcaneal
fractures. In addition, we approached the president of
the European Ankle and Foot Society as well as the pres-
ident of the AO Foot and Ankle Association and asked
them to recommend experts and spread the invitation
among their committee members. The email addresses
of three experts thus selected could not be acquired.
Finally, a total of 54 international experts, 44 surgeons
and 10 radiologists, were invited to participate by
email.
Study procedure
Online questionnaires were used for all three Delphi
rounds. All experts received an invitation containing a
motivational statement to participate in this study, an expla-
nation of the Delphi procedure, and a link to the URL of
the online questionnaire. Up to three reminders were sent
every 2 weeks in case the invited expert did not respond.
The complete questionnaires can be found on the internet
[6–8].
The questionnaires generally consisted of multiple-choice
questions regarding the imaging technique, evaluation of
anatomical landmarks of the operated joint, reduction of
fracture fragments and position of the fixation material.
Answer options to the requirement of an item were ‘yes’,
‘no’ or ‘selective’. Examples of the imaging technique or
measurements were added to most of the questions for
clarification. The questions regarding imaging technique
focused on requirement of imaging modalities and tech-
niques during the pre-, intra and postoperative evaluation.
On the subject of anatomical landmarks, the experts were
asked if certain features required evaluation for the deter-
mination of the quality of fracture reduction and fixation of
calcaneal fractures. If the answer to the question was ‘yes’,
a follow-up question appeared asking the experts which
method of evaluation they considered most appropriate,
e.g. a distance/angle measurement or visual assessment. A
free text field was always available to specify other evalu-
ation methods when necessary. Each section ended with
open questions, asking if the experts had suggestions for
additional criteria or other remarks.
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Arch Orthop Trauma Surg (2013) 133:1377–1384
1 3
The second and third rounds were constructed by incor-
porating remarks and suggestions of the previous round, as
is required by the Delphi method. We included a histogram
presenting the relevant results from the previous round in
the introduction of each question. If the 80 % threshold
of agreement on an item had been reached in the previous
round, this was reported to the experts and the question was
omitted in the next round.
Statistical analysis
The number of identical answers was divided by the num-
ber of respondents and expressed as a percentage. For every
question, consensus was defined as an agreement of at least
80 %.
Results
Respondents
The invitations of the first Delphi round were sent in
May 2010. Of the 54 invitees, 30 % (16 experts) eventu-
ally completed the questionnaire. An additional 13 %
(7 experts) responded by email; they did not want to par-
ticipate because of lack of time or interest. These experts
were removed from our mailing list and not approached
for further Delphi rounds. The second round started in July
2011 and generated a response rate of 38 % (18 experts)
of the 47 invitees. In this round, two experts replied that
they did not want to participate due to lack of time. The
final round commenced in October 2011 to which 33 %
(15 experts) of the 45 invitees responded (Table 1). Ten
experts completed all Delphi rounds, seven experts partici-
pated in two Delphi rounds, and three experts participated
in one Delphi round.
Approximately, 30 % of the responding experts were
radiologists, 70 % were surgeons (Table 1). The number of
years in practice ranged from less than 5 years to more than
20 years, while the majority (61 %) had more than 15 years
experience (Table 2). Almost all experts were employed by
a university hospital (84 %).
Agreement regarding the imaging of the calcaneus
A consensus on the role of different imaging modalities in
preoperative, intraoperative and postoperative evaluation of
calcaneal fractures was obtained for 23 of the 38 proposed
techniques after three Delphi rounds (Table 3). The per-
centage of agreement for each item can be found in online
Appendix 1. A lateral projection of the ankle and axial
projection of the calcaneus were considered mandatory in
the pre-, intra- and postoperative evaluation of calcaneus
fractures. Consensus on these items was reached in the first
Delphi round. An additional 20° Brodén radiograph was
also found necessary in the intra-operative evaluation.
A CT scan with reconstructions in the anatomical sag-
ittal, coronal and axial planes was considered manda-
tory in the preoperative evaluation of calcaneus fractures.
Although a majority of the experts thought intra-operative
3D-imaging (73 %) or a postoperative CT scan (68 %) is
required, no consensus was reached.
Agreement regarding the evaluation of anatomical
landmarks
Consensus was obtained for all but one of the proposed
anatomical landmarks (Table 4, online Appendix 2). The
congruency of the three articulations (calcanocuboid (CC),
anterior talocalcaneal (ATC) and posterior talocalcaneal
(PTC) joints), Böhlers angle, Gissanes angle and the position
of the tuber were considered the only anatomical landmarks
of the calcaneus that required evaluation (Figs. 1, 2, 3).
Table 1 Response rate of the specialists
Delphi
round
Response rate specialists (n)
Experts
responded
No
participation
No response Total invited
I 30 % (16) 13 % (7) 57 % (31) 100 % (54)
II 38 % (18) 4 % (2) 57 % (27) 100 % (47)
III 33 % (15) 0 % (0) 66 % (30) 100 % (45)
Table 2 Characteristics of the respondents
a
Respondents could indicate that they are working in more than one
type of hospital if applicable
Characteristic Delphi round I
(n = 16)
Delphi round II
(n = 18)
Delphi round
III (n = 15)
Specialty
Surgeon 69 % (11) 72 % (13) 73 % (11)
Radiologist 31 % (5) 28 % (5) 27 % (4)
Years of experience (years)
0–5 25 % (4) 6 % (1) 7 % (1)
5–10 0 % (0) 11 % (2) 20 % (3)
10–15 19 % (3) 17 % (3) 13 % (2)
15–20 25 % (4) 22 % (4) 7 % (1)
>20 31 % (5) 44 % (8) 53 % (8)
Type of hospital
a
University
hospital
88 % (14) 83 % (15) 80 % (12)
Urban hospital 19 % (3) 17 % (3) 20 % (3)
Suburban hospital 0 % (0) 0 % (0) 7 % (1)
Rural hospital 0 % (0) 0 % (0) 0 % (0)
Private clinic 6 % (1) 17 % (3) 7 % (1)
1380 Arch Orthop Trauma Surg (2013) 133:1377–1384
1 3
Böhlers angle can only be evaluated by angle measurement
on a lateral X-ray. However, no consensus could be obtained
on the method of evaluation of Gissanes angle, as 50 % of
the experts preferred angle measurement and 50 % preferred
visual evaluation. Visual evaluation was considered sufficient
for the remaining anatomical landmarks.
Agreement regarding reduction of fracture fragments
Consensus was reached for 13 of the 16 proposed aspects
of evaluation of the reduction of fracture fragments of the
calcaneus (Table 4, online Appendix 2). Postoperative
assessment of the presence of intra-articular step-offs and
gaps in the CC- and PTC-joint was considered necessary.
The same holds for steps and gaps in the processus ante-
rius. A step-off or gap of no more than 2 mm was deemed
acceptable. Although a majority (60 %) of the experts also
considered assessment of the presence of a step-off or gap
in the ATC-joint essential, no agreement was reached.
Assessment of extra-articular step-offs and gaps was not
considered necessary. According to the experts, the pres-
ence of intra-articular bone fragments should be evaluated.
No agreement could be reached on the assessment of extra-
articular bone fragments.
Agreement regarding fracture fixation
Consensus was reached for all but one of the proposed
items regarding the evaluation of fracture fixation (Table 4,
online Appendix 2). Although a majority (73 %) of the
experts agreed that the grip of screws, i.e. protrusion of
screws in the opposite cortex, in the processus anterius
requires evaluation, no consensus was reached. The experts
agreed that correct positioning of the fixation plate on the
lateral wall, the adequate length of the screws (i.e. not too
short), the grip of the screws in the sustentaculum tali, the
presence of protruding screws in the CC-, ATC- and PTC-
joint as well as protrusion of screws in the medial wall and
the tuber calcanei need to be assessed.
Discussion
By means of this Delphi study, consensus among experts
was reached which imaging techniques, anatomical land-
marks, fracture reduction and position of the fixation mate-
rial should and should NOT be used in the postoperative
evaluation of calcaneus fractures. This international con-
sensus could form the basis for a universal evaluation pro-
tocol to assess the radiological outcome of treatment of cal-
caneal fractures.
For almost all proposed items of the evaluation of ana-
tomical landmarks, fracture reduction and fixation, consen-
sus was reached. For more than half of the proposed items
concerning imaging technique consensus was reached. Lat-
eral and axial radiographs of the calcaneus were considered
required in the pre-, intra- and postoperative evaluation. In
addition to radiographs, the experts also deemed a CT scan
necessary in the pre-operative evaluation of the fracture.
For the intra-operative evaluation, an additional radiograph
Table 3 Results of the Delphi consensus regarding the imaging of calcaneus fractures
Consensus regarding the imaging of calcaneus fractures
Imaging technique is required (≥80 % agreement) Imaging technique is NOT required (≥80 % agreement)
Preoperative X-ray
Lateral projection of the ankle
Axial projection of the calcaneus
X-ray
Mortise projection of the ankle
Medial oblique projection of the foot
Projection of the contra lateral joint
CT scan
Sagittal reconstructions
Coronal reconstructions
Axial reconstructions
MRI scan
Intra-operative 2D-fluoroscopy
Lateral projection of the ankle
Axial projection of the calcaneus
20° Brodén projection of the calcaneus
2D-fluoroscopy
Anteroposterior projection of the ankle
Mortise projection of the ankle
Valgus stress projection of the ankle
Lateral oblique projection of the foot
Projection of the contra lateral joint
Postoperative X-ray
Lateral projection of the ankle
Axial projection of the calcaneus
X-ray
Anteroposterior projection of the ankle
Medial oblique projection of the foot
Lateral oblique projection of the foot
Projection of the contra lateral joint
MRI scan
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with a 20° Brodén projection of the calcaneus is required.
Surprisingly, for the postoperative evaluation, only two
radiographic projections (lateral and axial) were considered
mandatory by our experts, even though postoperative intra-
articular irregularities, particularly in the ATC- and PTC-
joint, can be difficult to detect on plain radiographs.
The large majority of proposed anatomical landmarks
were not considered essential to evaluate in clinical prac-
tice, although some of the items, like the tibiotalar angle,
have shown to be correlated with the clinical outcome [30].
For wrist and ankle fractures, such landmarks appeared
more relevant [5]. Anatomical landmarks of the calca-
neus that require evaluation according to our experts, like
Böhlers and Gissanes angle, are the ones most frequently
mentioned in the literature [10, 12, 25, 29, 30]. There is a
difference in the method of evaluation of these anatomical
landmarks: In contrast to the other items which can be
assessed visually, Böhlers angle requires to be measured.
Surprisingly, no agreement could be reached on the evalu-
ation method of Gissanes critical angle, even though this
angle is frequently measured in the literature.
As expected, extra-articular step-offs and gaps do not
require evaluation when assessing the quality of calcaneus
fracture reduction and fixation. The generally accepted cut off
point for acceptability of a step-off or gap that requires treat-
ment lies at 2 mm [27]. However, since CT scanning is used
for the postoperative evaluation also some evaluation proto-
cols use lower thresholds [12, 19, 27]. In this consensus, only
one expert found a lower threshold acceptable (<1 mm).
Although some studies reporting on intra-operative
imaging specifically score the accuracy of screw placement
[24, 26], to our knowledge fixation has not been part of an
Table 4 Results of the Delphi consensus regarding the evaluation of the quality of fracture reduction and fixation of the calcaneus
a
This item requires evaluation by visual assessment
b
This item requires evaluation by angle measurement
Consensus regarding the evaluation of the quality of fracture reduction and fixation of the calcaneus
Item is required in the evaluation (≥80 % agreement) Item is NOT required in the evaluation (≥80 % agreement)
Anatomical landmarks Congruency of the CC-joint
a
Congruency of the PTC-joint
a
Congruency of the ATC-joint
a
Böhlers angle
b
Gissanes angle
Varus/Valgus position of the tuber calcanei
a
Heel height
Fat pad height
Achilles tendon fulcrum
Talocalcaneal angle
Calcaneal inclination angle
Tibiotalar angle
Talar horizontal angle
Talar declination angle
Calcaneal facet height
Calcaneal facet inclination angle
Arch angle
Length of the calcaneus
Fibulocalcaneal distance
Reduction Presence of step-offs
Presence of step-offs in the CC-joint
a
Presence of step-offs in the PTC-joint
Presence of Step-offs in the Processus Anterius
a
Threshold of acceptability of step-off ≤2 mm
Presence of gaps
Presence of Gaps in the CC-joint
a
Presence of Gaps in the PTC-joint
Presence of Gaps in the Processus Anterius
a
Threshold of acceptability of gaps ≤2 mm
Presence of bone fragments
Presence of Bone fragments in the CC-joint
a
Presence of Bone fragments in the ATC-joint
a
Presence of Bone fragments in the PTC-joint
a
Presence of extra-articular step-offs
Presence of extra-articular gaps
Fixation Position of the fixating plate
a
The presence of too short screws
a
Grip of screws in the sustentaculum tali
a
Presence of protruding screws in the CC-joint
a
Presence of protruding screws in the ATC-joint
Presence of protruding screws in the PTC-joint
a
Presence of protruding screws in the Medial wall
a
Presence of protruding screws in the Tuber Calcanei
a
1382 Arch Orthop Trauma Surg (2013) 133:1377–1384
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evaluation protocol of treatment result. However, in this
Delphi consensus, our experts considered the position of
the fixating plate and adequate length of the screws impor-
tant in the evaluation of the quality of the position of the
fixation material.
The limited number of experts participating might be
considered a limitation even though this number is compa-
rable to other Delphi consensus studies [3, 17]. No prior
invitation had been sent to the experts to preselect experts
willing to participate. Retrieving personal email addresses,
particularly from some internationally renowned senior
specialists of calcaneal fractures, was more difficult than
we had anticipated. In addition, experts tend to get over-
whelmed by questionnaires and, therefore, lack time or
willingness to participate. Although the characteristics of
the non-responding experts in this study are not known, it
has been shown that characteristics of non-responders do
not differ in terms of qualifications, experience and spe-
cialty [20]. Therefore, similar results for this Delphi study
are to be expected with more experts participating.
Second, the reliability of this evaluation protocol has
yet to be determined as well as the prognostic value for the
patients’ clinical outcome of the (combination of) items
found in this consensus. Currently, we are performing a
prospective multicenter study to determine the effective-
ness of intra-operative 3D-fluoroscopy [9]. In this study,
patients with calcaneal fractures are included and followed
until 5 years after open reduction and internal fixation of
Fig. 1 Brodén projection of the calcaneus. PTC posterior talocalca-
neal joint, ATC anterior talocalcaneal joint
Fig. 2 Lateral projection of the calcaneus. CC calcaneocuboïdal
joint, G Gissane’s critical angle—the angle between the line tangent
to the articular surface of the medial posterior facet fragment and the
line tangent to the dorsal surface of the calcaneal neck, B Böhler’s
angle—angle between the line from the highest point on the anterior
process to the highest point on the posterior edge of the posterior
facet, and the tangent to the superior surface of the tuberosity
Fig. 3 Axial projection of the calcaneus. Displacement of the tuber
calcanei in the direction of one of the arrows indicates a varus or val-
gus position of the tuber calcanei
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Arch Orthop Trauma Surg (2013) 133:1377–1384
1 3
their calcaneal fracture. The postoperative radiological
parameters of the evaluation protocol will be determined
on both radiographs and a CT scan by three experts. Both
intra- and interobserver agreement will be determined for
the evaluation of these experts. In addition, the evaluation
of the subjective radiological parameters can be correlated
to the clinical parameters like range of motion and self-
reported questionnaires.
In conclusion, this Delphi consensus shows that cur-
rent evaluation protocols are not comprehensive; adding
items that require evaluation, namely, the position of the
tuber calcanei and the position of the fixation material,
i.e. fixating plate and presence of protruding screws intra-
articularly need to be considered [16, 19, 26]. In addition,
most aspects could be assessed visually, although angle or
distance measurements have frequently been advocated in
the literature [10, 19, 25, 28, 30]. Similar conclusions were
drawn when studying criteria for wrist and ankle fractures
[5]. With this Delphi consensus, we have provided the basis
for a universal evaluation protocol to assess the radiological
outcome in association with clinically relevant outcomes of
the treatment of calcaneal fractures.
Acknowledgments We would like to thank the following experts
for their participation in this Delphi Study: A. Witteveen, MD, Ortho-
paedic Surgeon, Prof. Dr. B. Hintermann, MD Ph.D, Orthopaedic Sur-
geon, D. Den Hartog, MD Ph.D Trauma Surgeon, Prof. Thodarson,
MD Ph.D, Orthopaedic Surgeon, Dr. H. Goost, MD Ph.D, Trauma
Surgeon, Dr. M. Poeze, MD Ph.D, Trauma Surgeon, Prof. dr. P. Brink,
MD Ph.D, Trauma Surgeon, Dr. S. Rammelt, MD Ph.D,Trauma Sur-
geon, Dr. I.G. Winson, MD Ph.D, Orthopaedic Surgeon, Dr. W.J. Har-
ries, MD Ph.D, Orthopaedic Surgeon, Dr. J.B. Gerstner, MD Ph.D,
Orthopaedic Surgeon, M. Andoljsek, MD, Trauma Surgeon, Dr. A.
Karantanas, MD Ph.D, Radiologist, Dr. D.J. Wilson, MD Ph.D, Radi-
ologist, Dr. F. Vanhoenacker, MD Ph.D, Radiologist, M. Obradov,
MD, Radiologist, S.A. Schreinemachers, MD, Radiologist, Dr. O.
Schoierer, MD Ph.D, Trauma Surgeon.
Conflict of interest All authors declare to have no conflict of
interest.
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