Keywords
medical education - bone fractures - radiology - traumatology
Introduction
Plain radiographic assessment of the pelvis remains the initial diagnostic pillar
for pelvic ring fractures, and it is recommended by the Advanced Trauma Life Support
(ATLS), which was developed by the American College of Surgeons (ACS) Committee on
Trauma (COT). However, injuries to the structures of the posterior pelvic ring (posterior
portion of the iliac bone, sacroiliac joint and sacrum) are difficult to diagnose,
and may cause delay and failure in the treatment of these lesions.[1]
Professionals with longer experience are considered to have a greater ability to diagnose
posterior pelvic ring lesions by plain radiography.[2] However, studies show a high frequency of misdiagnosis with the use of plain radiography,
especially in lesions involving the posterior pelvic ring structures, and they deem
an imperative the performance of computed tomography (CT) scans, which are considered
the gold standard in the diagnosis of these lesions.[3] To this end, the aim of the present study was to evaluate the interobserver agreement
of a radiologist, hip specialist orthopedists, general orthopedists, orthopedics residents
and radiology residents regarding the diagnosis of posterior pelvic ring injuries
using plain radiography.
Materials and Method
A cross-sectional study conducted in September 2017 at the Orthopedics and Traumatology
Service of Hospital Cristo Redentor (HCR) – Grupo Hospitalar Conceição (GHC), in the
city of Porto Alegre, Southern Brazil. The research was approved by our institution's
Ethics in Research Committee (under CAAE: 72595617.7.0000.5530). Retrospective examinations
of 20 patients with traumatic injuries of the posterior pelvic ring previously treated
in the emergency unit were randomly selected by lot. Only cases with simultaneous
plain radiographic evaluation of the anteroposterior (AP) view of the pelvis and with
CT scans were included in the study; the CT scans were used as confirmatory diagnostic
criteria.
Examiners and image evaluation
The nine examiners were physicians, among them a radiologist with at least ten years
of experience in trauma emergency, two orthopedic specialists in hip surgery with
at least ten years of professional experience and with experience in pelvic and acetabulum
fracture surgery, two general orthopedists, two orthopedics residents, and two radiology
residents, all with experience in emergency care.
The images were evaluated as follows: a) a room reserved for slide projections was
allocated to the nine examiners; b) a chart with the pelvis design was presented,
enabling the examiner to mark the lesion sites in the posterior pelvic ring regions:
posterior iliac, sacroiliac joint and sacrum ([Figure 1]) for each case presented, as well as for the absence of injury, if they so deemed
it. In the present study, 120 anatomical sites were evaluated by each examiner; c)
the radiographs of the selected cases were presented to the examiners through slide
projections, with 30 seconds to consider each case. All of the selected cases presented
an identifiable anterior pelvic ring lesion on the radiographs.
Fig. 1 Pelvic drawing sheet for the evaluation of injury sites in the regions of the posterior
pelvic ring.
Data analysis
The data regarding the categorical variables were presented by frequency (%). Interobserver
agreement was assessed by the Kappa test (κ) and 95% confidence intervals (95%CIs), and the values assumed for agreement were
considered as follows: 0.20: poor; 0.21–0.40: fair; 0.41–0.60: moderate; 0.61–0.80:
good; 0.81–1.00: very good.[4]
[5]
[6] The CT diagnosis was assumed as a reference evaluation. All analyses were performed
using the Statistical Package for the Social Sciences (SPSS, IBM Corp., Armonk, NY,
US), version 22.0 for Windows.
Results
A total of 28 lesions in the posterior pelvic ring were determined by CT from a total
of 120 possible injuries (23%; 95%CI: 16%–32%), since our schematic chart enabled
the identification of 6 lesion sites for each of the 20 cases. [Table 1] shows the interobserver agreement between the CT and the plain radiographic evaluation.
Among the most experienced examiners, the agreement was moderate: radiologist (κ = 0.461; 95%CI: 0.270–0.652), hip specialists 1 and 2 (κ = 0.534; 95%CI: 0.348–0.721 and κ = 0.431; 95%CI: 0.235–0.627 respectively), and general orthopedists 1 and 2 (κ = 0.497; 95%CI: 0.307–0.686 and κ = 0.449; 95%CI: 0.254–0.645 respectively).When comparing the CT results with the diagnoses
made by the orthopedics and radiology residents, the interobserver agreement was considered
poor ([Table 1]).
Table 1
|
Parameters
|
Lesion diagnosis
|
CT agreement
|
|
Negative
|
Positive
|
%
|
Kappa (95%CI)
|
|
CT (reference)
|
092 (77)
|
028 (23)
|
|
|
|
Radiologist
|
196 (80)
|
024 (20)
|
82
|
0.461 (0.270–0.652)
|
|
Hip specialist 1
|
100 (83)
|
020 (17)
|
85
|
0.534 (0.348–0.721)
|
|
Hip specialist 2
|
100 (83)
|
020 (17)
|
82
|
0.431 (0.235–0.627)
|
|
General orthopedist 1
|
198 (82)
|
022 (18)
|
83
|
0.497 (0.307–0.686)
|
|
General orthopedist 2
|
101 (84)
|
019 (16)
|
82
|
0.449 (0.254–0.645)
|
|
Orthopedics resident 1
|
101 (84)
|
019 (16)
|
81
|
0.397 (0.198–0.596)
|
|
Orthopedics resident 2
|
101 (84)
|
019 (16)
|
79
|
0.344 (0.143–0.545)
|
|
Radiology resident 1
|
198 (82)
|
022 (18)
|
78
|
0.346 (0.146–0.545)
|
|
Radiology resident 2
|
198 (81)
|
022 (19)
|
77
|
0.329 (0.130–0.529)
|
High false negative values were found in the diagnoses of all of the examiners: radiologist
(46%), hip specialists 1 and 2 (46% and 54% respectively), general orthopedists 1
and 2 (46% and 54% respectively), orthopedics residents 1 and 2 (57% and 61% respectively)
and radiology residents 1 and 2 (57% and 57% respectively).
[Figure 2] shows the 28 lesions according to their respective anatomical sites: 3 posterior
iliac fractures, 10 sacroiliac joint injuries and 15 sacral fractures were found on
the CT. [Figure 3] shows the lesions found at each anatomical site in relation to the respective examiners.
Fig. 2 Sites evaluated on computed tomography (CT) of the regions of the posterior pelvic
ring (posterior iliac, sacroiliac joint and sacrum) with or without lesions.
Fig. 3 Number of posterior pelvic ring lesions by site and examiner.
Discussion
In the present study, we identified that experienced professionals have a greater
ability to diagnose posterior pelvic ring lesions by plain radiography. However, plain
radiography was susceptible to a high percentage of false negative evaluations among
all of the examiners when compared to the CT scans, that is, there was great difficulty
in identifying posterior iliac and sacrum fractures.
Posterior pelvic ring injuries are severe and difficult to diagnose,[7]
[8]
[9]
[10] often requiring urgent stabilization to reestablish the polytraumatized patient
from the hemodynamic point of view,[11]
[12]
[13]
[14] and/or subsequent surgical procedures to fix fractures or dislocations, enabling
the patient to return to his or her best functional condition.
Pelvic radiography is indicated as one of the routine exams in high-energy trauma
care, but in some situations this exam is insufficient for the diagnosis, classification
and procedure definition.[15]
[16]
[17]
[18]
[19] The factors that make pelvic assessment difficult through isolated plain radiography
are the lack of patient preparation, with the presence of artifacts such as gas, fecal
content, bladder distension, and the complex three-dimensional conformation of the
pelvis.[20]
[21] Due to the angle of inclination of the sacrum, visualization is limited in the pelvis
AP.[1]
The CT is often not available in non-specialized centers,[8]
[22]
[23]
[24] and with it the patient is subjected to a higher radiation dose. Publications have
shown a high frequency of failure to diagnose pelvic lesions on radiographs, especially
lesions involving the sacroiliac joint and the sacrum.[25]
[26] The identification of up to 30% of sacrum fractures is late, which has a negative
effect on long-term outcomes.[3]
[27]
[28] Montana et al[29] found diagnosis failure in 28% of sacroiliac joint dislocations, and in 57% of iliac
and sacral fractures adjacent to the sacroiliac joint, with the isolated use of plain
radiography.
The present study has some limitations: a) the inferior quality of some of the selected
radiographs, a usual occurrence in the emergency care context; and b) the definition
of the number of selected cases, as well as of the examiners, was performed through
a convenience sample.
Conclusion
Professionals with greater experience in the field have a better ability to identify
posterior pelvic ring lesions by plain radiography; however, we emphasize that simple
pelvic radiography was susceptible to false negative diagnoses among all of the professionals
assessed, especially regarding fractures of the posterior region of the iliac and
sacrum.
