Introduction
Transtrochanteric fractures are those between the base of the femoral neck up to 2.5
cm distal to the minor trochanter.[1 ] Although they may occur in young people after high-energy trauma, elderly people
falling to the ground are the most affected.[2 ] Populational aging resulted in a significant increase in the prevalence of osteoporosis
and of hip fractures, leading to higher mortality rates, sequelae, and associated
costs[3 ]
[4 ]
[5 ]
[6 ]
[7 ] when compared with the prevalence and the indexes of other fractures.[3 ]
[8 ]
[9 ]
[10 ]
The diagnosis of transtrochanteric fractures is based on anamnesis and clinical evaluation;
in an elderly individual, a low-energy trauma causes functional incapacity, shortening,
and external rotation of the lower limb.[11 ] Radiographic evaluation in anteroposterior (AP) (with lower limbs in internal rotation
and traction) and lateral (L) views of the hip confirms the diagnosis, as well as
the characteristics of the fracture.[11 ]
A good understanding of the fracture type and its correct classification are critical
to define the most appropriate osteosynthesis procedure.[12 ] Thus, to be adequate for the daily clinical practice, the classification system
must be simple, easy to apply, and present good intra- and interobserver reproducibility.[13 ] In order to achieve this objective, several radiographic classifications have been
developed, such as those by Boyd et al,[14 ] by Tronzo,[8 ] by Jensen,[15 ] by Evans,[16 ] and the AO classification.[1 ] However, in some cases, classificatory divergences impair intra- and interobserver
reproducibility.[17 ]
[18 ]
[19 ] These cases may require diagnostic methods for better identification and agreement
to allow a good choice of treatment.[2 ]
[17 ]
[18 ]
[20 ]
[21 ]
Computed tomography (CT) is a more advanced radiological technique that generates
more detailed and complete images, which are useful for the evaluation of complex
and articular fractures, such as those of the tibial pilon,[22 ]
[24 ] of the tibial plateau,[24 ]
[25 ] of the distal humeral,[26 ] and of the calcaneus.[27 ] Following this principle, the use of a tomographic classification was proposed for
transtrochanteric fractures, as suggested by Nakano.[28 ]
The availability of CT and its use led to the possibility of better intra- and interobserver
reproducibility, as well as of a greater diagnostic precision for routine practice.[19 ]
[29 ]
[30 ]
[31 ] However, the literature is still controversial. In some studies, this technique
is deemed dispensable, whereas others considered it superior when compared with radiography.[28 ]
[32 ]
[33 ]
Therefore, we have performed a systematic review to determine if the addition of CT
presents superior intra- and/or interobserver reproducibility compared with fracture
classifications based on plain radiographies alone.
Materials and Methods
A query was performed at the Pubmed, Lilacs, Scielo and Cochrane databases between
July 2016 and June 2017, limited to the last 15 years. The following descriptors were
used: (intertrochanteric OR hip ) AND fracture AND (classification OR Tronzo OR AO OR Evans Jensen OR Boyd Griffin ) AND (reproducibility OR validation studies OR reliability ) AND (tomography OR CT ) AND (x-ray OR radiography ). At the initial query, all papers presenting two or more terms in the title and
an abstract were included for review.
After the review of the papers, references were crossed to ensure the inclusion of
all potential studies. All retrospective, prospective, and systematic English-language
review articles with male and/or female patients comparing the reproducibility of
radiographic and tomographic analysis of transtrochanteric fracture classifications
were considered for evaluation. We excluded case reports, studies assessing CT or
radiography in isolation, duplicate studies, and diagnostic studies of occult or stress
fractures.
The following data were extracted from the included studies: name of the first author,
year of publication, country, study design, study objective, sample size, number of
evaluators, as well as their specialties, classification used, method of analysis,
and results. These data were tabulated in Microsoft Excel version 2016 (Microsoft
Corporation, Redmond, WA, USA) and analyzed descriptively. The Preferred Reporting
Items for Systematic Reviews and Meta-Analyzes (PRISMA) recommendation for systematic
reviews was followed.[34 ]
The reproducibility of the studies was interpreted according to the kappa coefficient,
based on the guidelines proposed by Landis et al: values from 0.00 to 0.20 indicate
bad reproducibility; from 0.21 to 0.40, reasonable; from 0.41 to 0.60, moderate; from
0.61 to 0.80, strong; and from 0.81 to 1.00, excellent reproducibility.[35 ]
Results
Initially, the query resulted in 112 papers; after applying the inclusion and exclusion
criteria, 5 papers were obtained. Published between 2003 and 2017, these papers present
a minimum of 30 and a maximum of 110 patients, with a mean age ranging from 59 to
85 years old. Due to the restricted number of papers, conflicts of interests were
not considered as exclusion criteria ([Fig. 1 ]).
Fig. 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyzes protocol for literature
review.
All of the papers used the AO classification system, while two of them employed the
Evans-Jensen classification, and only one used the Boyd Griffin system (as evidenced
in table 1).
Three papers concluded that the use of CT has benefits for the correct classification
of transtrochanteric fractures with good reproducibility, especially in the identification
of comminution and of unstable traits.[29 ]
[30 ]
[33 ] In contrast, two papers indicated that CT does not present better classification
reproducibility when compared with plain radiography[1 ]
[33 ] ([Table 1 ]).
Table 1
Articles
Sample
Evaluators
Classification
Index
Result
Chapman CB et al, 2003.[32 ]
61 patients
3 orthopedists and 2 radiologists
AO1 e Evans-Jensen
kappa
No reproducibility improvement
Cavaignac E et al, 2013.[20 ]
53 patients
1 radiology resident and 1 radiologist
AO1 e Evans-Jensen
kappa
No reproducibility improvement
Mihir Thanvi et al, 2013.[29 ]
31 patients
2 orthopedists and 2 radiologists
AO1 e Boyd Griffing
kappa
Reproducibility improvement
Isida R et al, 2015.[30 ]
110 patients
1 orthopedist and 1 radiologist
AO1
kappa
Reproducibility improvement
Van Embden D et al, 2016.[33 ]
30 patients
4 orthopedists, 5 radiologists and 2 orthopedics residents
AO2
kappa
Reproducibility improvement
Discussion
The reproducibility of the classification of transtrochanteric fractures had variable
results and was influenced by several factors, such as classification system, sample
size, use of the AO classification in its simplified or complete form, the specialty
of the evaluators (radiologist versus orthopedist), the experience of the evaluators
(staff professionals versus residents), and the methodology proposed by each work.
Thus, the discussion was based on questions about the various factors that could influence
these results.
Which classification has better reproducibility?
The simplified AO classification had better reproducibility compared with other classifications,
such as the complete AO classification and its subgroups, the Evans-Jensen and Boyd
Griffin classifications,[20 ]
[29 ]
[33 ] both for tomography and radiography. These results are probably due to the lower
number of information in the simplified AO classification, which would make both their
comprehension and memorization easier when compared with the complete classification.
When analyzing CT scans, Ito et al[36 ] obtained a 75% concordance with the complete AO classification, and a 65.9% concordance
with the Evans-Jensen classification. Van Embden D. et al.[33 ] did not observe a higher reproducibility for the simplified AO classification when
adding CT to the radiographic study, obtaining kappa values of 0.70 (strong) not using
CT, and of 0.68 (strong) using CT images. Cavaignac E. et al.[20 ] observed a reasonable reproducibility with the addition of CT to the complete AO
classification (0.28 to 0.33), whereas the reproducibility of the Evans-Jensen classification
was moderate (0.50) with only radiography, and reasonable (0.35) using radiography
associated with CT.
Isida R. et al.[30 ] found a strong reproducibility using CT and the complete AO classification (kappa
value of 0.78), with a 100% positive predictive value, a 79% negative predictive value,
and 95% specificity for comminution presence. When analyzed only by radiographs, the
sensitivity was 48%, and the negative predictive value was 29%.
Does radiographic and tomographic standardization influence reproducibility?
Although CT has a well-documented importance in complex and intra-articular fracture
detection,[22 ]
[23 ]
[24 ]
[25 ]
[26 ]
[27 ] the results of transtrochanteric fractures may have been influenced by the divergences
in the radiological techniques used.
Cavaignac E. et al.[20 ] and Shen et al[31 ] analyzed AP and L hip radiographs in only 56% and 68% of the cases, respectively.
This is an inadequate method, since Koval et al[11 ] previously demonstrated that the radiographic evaluation of transtrochanteric fractures
should follow a pattern, obtaining two radiographic views (AP and L) in all cases.
It is undeniable that radiographic examinations are limited in trauma rooms and in
patients with pain and difficulty in positioning, but the creation of protocols for
test standardization is of paramount importance.[12 ]
The same occurs with CT, despite some standardization in its performance. A technique-related
bias was observed by Cavaignac E et al.,[20 ] who used only axial CT sections, whereas Van Embden D. et al.[33 ] used three tomographic views (coronal, sagittal and axial), but no 3D reconstruction.
An additional factor is the lack of specification of the technique employed in the
other studies, such as the number of radiographs, radiographic and CT scan views,
patient positioning, and the use of 3D reconstruction models.
It can be inferred that the limitations of the tests and inadequate execution may
have impaired the evaluation and generated a bias in the reproducibility results found.
Which classification subgroup is subject to greater variation? Does the use of computed
tomography influence the choice of the treatment?
With the simplified AO classification, unstable fractures (A3) examined by CT presented
higher reproducibility than those analyzed by plain radiographies.[30 ]
The study by Van Embden D. et al.[33 ] corroborates these results when CT is added to the analysis. In this study, type
A3 fractures presented lower concordance and a greater number of surgical implant
modifications when compared with implants chosen based only on plain radiographic
evaluations[33 ] ([Figs. 2 ]
[3 ] to [4 ]). It is worth mentioning that type A3 fractures present the highest complication
rates, such as pseudoarthrosis and fixation failure in up to 32% of the cases.[33 ]
Fig. 2 Anteroposterior and lateral views of the hip, AO classification 31 A1.
Fig. 3 Anteroposterior and lateral views of the hip, AO classification 31 A2.
Fig. 4 Anteroposterior and lateral views of the hip, AO classification 31 A3.
Although type A3 fractures are subject to the largest changes in their classification,
Van Embden D. et al.[33 ] showed that types A1 and A2 fractures also had a change in the choice of implants
after performing CT scans in 11 of their 30 cases.[33 ] In addition, Shen et al[31 ] showed that CT use resulted in a better understanding of the fracture, which promoted
a statistically significant reduction in surgical time for intramedullary nailing
placement, regardless of the classification.
Therefore, adding CT scans to unstable fractures workup is plausible because it leads
to a better understanding of the fracture trait, facilitates the proper choice of
the implant, and is economically less costly compared with the expenses associated
with increased surgical time and/or complications. However, the question is whether
this examination would also not be beneficial for simple, stable fractures, due to
the possibility of diagnostic inaccuracies and, consequently, to wrong choices of
implants and to the occurrence of complications.
Does the specialty and/or experience of the evaluators influence reproducibility values?
One of the difficulties in evaluating these papers is the divergence in the type and
level of the specialty of the evaluators. Two studies allowed the comparison between
radiologists and orthopedists. Chapman CB. et al.[32 ] demonstrated a strong reproducibility for radiologists (0.67) and a moderate reproducibility
for orthopedists (0.57) in the complete AO and in the Evans-Jensen classifications.
Mihir Thanvi et al[29 ] presented a lower reproducibility among radiologists compared with orthopedists,
both for the simplified and complete OA classifications using radiographic, tomographic,
and tomographic analysis with 3D reconstruction.
Furthermore, as exemplified by Isida R. et al.,[30 ] there is a bias in reproducibility evaluation that is related to the specialty of
the evaluators. Orthopedists achieved moderate reproducibility (0.45), whereas radiologists
presented excellent reproducibility (0.94), but the former evaluated exclusively radiographies,
and the latter only analyzed CT scans. So it does not allow us to conclude that the
specialty influences reproducibility.
Another variable that could influence reproducibility is the experience of the evaluators.
In this sense, there are studies with resident physicians presenting classification
errors and lower reproducibility, especially in unstable fractures,[20 ]
[33 ] as well as studies in which evaluation by less experienced professionals did not
compromise the quality of the classification compared with more experienced personnel.[29 ]
Van Embden D. et al.[33 ] supported this latter claim by demonstrating that residents achieved similar reproducibility
rates as both trauma surgeons and radiologists. However, Cavaignac E. et al.,[20 ] while agreeing that less experienced evaluators do not compromise the study, demonstrate
excellent interobserver reproducibility (0.85) for senior evaluators and strong reproducibility
(0.79) for junior evaluators when CT was added.
Limitations
There is a large variation in the number of evaluators in the review papers (between
2 and 11 individuals), and in their specialties (radiologists, orthopedists, and residents
from both specialties), setting different degrees of experience and of technical knowledge.
Discrepancies in sample size were also an important factor (30 to 110 patients). This
isolated factor could justify variations in kappa values, since the confidence interval
for interobserver agreement depends directly on the sample size and on the number
of evaluators, which are inversely proportional.[37 ] Finally, the use of different methods and of difficult standardizations compromised
the data analysis and the interpretation of the results.
Final Considerations
There is evidence that CT use is beneficial, especially for fractures considered unstable.
Routine CT addition as a tool to ensure better reproducibility (both intra- and interobserver),
as well as for decision-making in transtrochanteric fracture treatment, remains controversial.
We believe that it is necessary to develop studies with a better level of evidence
and equivalent methodologies to elucidate the benefits of CT as a tool for the classification
of transtrochanteric fractures.
