362

OTHERS
A novel three-dimensional classification system forintertrochanteric fractures based on computed
tomography findings
Keizo Wadaa, Hiroshi Mikamib, Rui Amaria, Shunichi Tokia, Michihiro Takaib, and Koichi Sairyoa
Department of Orthopedics, Institute of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
Department of Orthopaedic Surgery, Yoshinogawa Medical Center, Tokushima, Japanab

Abstract : A novel three-dimensional fragment-based classification system based on computed tomography findings was established to characterize femoral intertrochanteric fractures. The intertrochanteric bone fragments
were defined as follows : neck, posterior portion of the greater trochanter, anterior portion of the greater trochanter, lesser trochanter, and shaft. Each type of fracture was classified as 2-, 3-, 4-, or 5-fragment according
to the number of floating bone fragments. Following the description of the fracture type, each floating bone
fragment was appended, with the exception of a fragment involving the shaft. Ninety-five intertrochanteric fractures were classified by the same surgeon. The fractures occurred in 14 men and 81 women with a mean age of
84.7 years. The frequency of each type of fracture was investigated. Thirty-one fractures (32.6%) were 2-fragment
and 64 (67.4%) were ≥ 3-fragment. A fragment of the anterior portion of the greater trochanter, which cannot beclassified using conventional systems, was included in 29 cases (30.5%). A 5-fragment fracture was detected in
two cases (2.1%). Using this fragment-based classification system, intertrochanteric fractures can be evaluatedin more detail than is possible using conventional classification systems. J. Med. Invest. 66 : 362-366, August, 2019
Keywords : intertrochanteric fracture, computed tomography, classification

INTRODUCTION
The number of intertrochanteric fractures in the elderly population has been increasing worldwide because of increasing life
expectancy (1). Osteosynthesis has been widely used for intertrochanteric fractures (2). However, it is not always possible for
elderly patients with unstable fractures to have good outcomes
after osteosynthesis (3, 4). To address this problem, both improvement of surgical technique and advances in implant technology have been promoted (5-9). Therefore, intertrochantericfractures need to be classified accurately to determine the mostappropriate treatment method.
The Evans (10), Jensen (11), and AO/OTA (12) systems forclassifying femoral intertrochanteric fractures are based on
findings on two-dimensional plain radiographic images andare commonly used. There are some recent reports of computed
tomography (CT) being used by surgeons to evaluate the fragments in comminuted intertrochanteric fractures in more detail.
However, even with CT, the reliability was not satisfactory
based on the two-dimensional classification in a previous report(13). Their results indicated that two-dimensional classification
systems were not appropriate for evaluating intertrochantericfractures on CT scans. In other words, a three-dimensionalclassification system would be needed to define the fragmentsthat could not be classified by two-dimensional classifications.
Therefore, our group has established a novel three-dimensional
CT classification system for intertrochanteric fractures, called
the fragment-based classification system.
Received for publication February 14, 2019 ; accepted May 5, 2019.
Address correspondence and reprint requests to Keizo Wada, Department of Orthopedics, Institute of Biomedical Sciences, Tokushima
University Graduate School, 3-18-15 Kuramoto, Tokushima 7708503, Japan and Fax : +81-088-633-0178.

The aim of this research was to determine the frequency ofintertrochanteric fractures in the elderly population using thefragment-based classification system based on CT findings.

MATERIAL AND METHODS

The fragment-based classification system
In our experience, the fracture line of the greater trochanter
often runs from the anterosuperior edge of the greater trochanter toward the lesser trochanter. The posterior portion of
the greater trochanter is frequently seen as a triangular bone
fragment because of the attachment of the gluteus medius andthe rotator muscles, including the piriformis. On the other hand,the anterior portion of the greater trochanter is less frequently
seen, but is found in double fractures or reverse oblique fractures of the greater trochanter. Therefore, we defined 5 majorbone fragments in an intertrochanteric fracture as the neck(N), posterior portion of the greater trochanter (GP), anterior
portion of the greater trochanter (GA), lesser trochanter (L), andshaft (S) (Figure 1). Each type of fracture was then classified
as 2-, 3-, 4-, or 5-fragment according to the number of floatingbone fragments. Following the description of the fracture type,each floating bone fragment was appended, with the exceptionof a fragment involving the shaft, with the symbol “/” between
the fragments. The fracture fragment complex was marked byincluding the fragments that comprised it with the symbol “+”
between the fragments. In cases involving 3 or more fragments,
the description of the simple N fragment was omitted. A fracturewith only one N fragment was described as 2-fragment (N) (Figure 2). A fracture that had an N fragment and a complex of GP
and L fragments was classified as 3-fragment (GP+L) (Figure 3).
If a floating N, GA, and a complex of GP and L fragments were
present, the fracture was classified as 4-fragment (GP+L/GA)(Figure 4). If there were 5 floating fragments, the fracture was

The Journal of Medical Investigation Vol. 66 2019

The Journal of Medical Investigation Vol. 66 August 2019363

then classified as 5-fragment (Figure 5).

Figure 1 Schematic diagram showing the fragment-based classifi-

cation.
GA, anterior portion of the greater trochanter ; GP, posterior portionof the greater trochanter ; L, lesser trochanter ; N, neck ; S, shaft

Figure 4 Appearance of the 4-fragment (GP+L/GA) fracture on
three-dimensional reconstruction computed tomography and a schematic image of this fracture. (a) Anterior view. (b) Posterior view.

Figure 5 Appearance of the 5-fragment fracture on three-dimen-

sional reconstruction computed tomography and a schematic image ofthis fracture. (a) Anterior view. (b) Posterior view.

Figure 2 Appearance of the 2-fragment (N) fracture on three-di-mensional reconstruction computed tomography and a schematic
image of this fracture. (a) Anterior view. (b) Posterior view.

Figure 3 Appearance of the 3-fragment (GP+L) fracture on three-di-mensional reconstruction computed tomography and a schematic
image of this fracture. (a) Anterior view. (b) Posterior view.

The study was approved by our institutional review board.
Ninety-five patients (14 male, 81 female ; mean age 84.7 [range,
54–99] years) admitted to our hospital with an intertrochantericfracture were reviewed retrospectively. CT was performed in allcases for diagnostic purposes. The CT procedure was performedin the supine position using a high-speed scanner (multi-director
CT ; Aquilion CX edition, Toshiba Medical Systems Co., Ltd.,Tokyo, Japan). Three-dimensional reconstruction was performed using images with 1-mm slice thickness on an Aquarius
Net Viewer workstation (TeraRecon Inc., San Mateo, CA). The
fragment-based classification system was used to evaluate theintertrochanteric fractures. All evaluations were performed by
the same surgeon (RA). The frequency of each type of fracture
was determined.
The Mann-Whitney U test was used to evaluate differencesin age between patients with 2-fragment fractures and thosewith ≥ 3-fragment fractures. A P-value < 0.05 was considered
statistically significant. All statistical analyses were performed
using SPSS software (version 25 for Mac OS X ; IBM Corp.,
Armonk, NY).

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K. Wada, et al. Intertrochanteric fracture classification

RESULTS
Various combinations of the 5 fragments are possible but only
9 types of fracture were observed in the present series (Table 1).

Table 1 Frequency of each type of fracture detected by thefragment-based classification system
Classification

Cases, n

(%)

(N)

10

10.5

(N+GA)

21

22.1

2-fragment

3-fragment(N+GP/L)

9

9.5

(GP)

24

25.3

(GP+GA)

5

5.3(GP+L)

5

5.3(GP/L)

18

18.9(GP+L/GA)1

1.1

5-fragment2

2.1

4-fragment

N, neck ; GP, posterior portion of the greater trochanter ; GA, anterior portion of the greater trochanter ; L,lesser trochanter

Thirty-one patients (32.6% ; 3 male, 28 female ; mean age
82.8 [range, 54–98] years) had 2-fragment fractures and 64(67.4% ; 11 male, 53 female ; mean age 82.8 [range, 68–99]
years) had ≥ 3-fragment fractures. There was no statistically significant difference in age between the patients with 2-fragment
fractures and those with ≥ 3-fragment fractures (p = 0.509).
The most common type of fracture was 3-fragment (GP)followed by 2-fragment (N+GA). Two patients (2.1%) had a
5-fragment fracture. Sixty-four (67.4%) of the 95 patients hadintertrochanteric fractures that included a GP or GA fragment.
A GA fragment fracture was included in 29 cases (30.5%).

DISCUSSION
The most important finding in this study is that the GA
fragment, which cannot be classified by conventional intertrochanteric fracture classification systems, was detected in 30.5%
of cases in the present series using the fragment-based classification system based on CT. Using this novel system, the greater
trochanter fragments could be evaluated in detail. To our knowledge, this is the first study to investigate the fragment-basedclassification system. A 5-fragment fracture was diagnosed in
two cases using this system.
Intertrochanteric fragility fractures are common in the elderly population and are becoming increasingly frequent with
continued aging of populations worldwide (14). Intertrochantericfractures are usually treated by osteosynthesis, which includes
intramedullary and extramedullary fixation (2, 15). However,elderly individuals have poor bone quality, so intertrochantericfractures in the elderly are likely to be unstable. Helin et al. reported that intramedullary nailing provides poorer stabilizationof unstable fractures compared to stable fractures (16). In someprevious reports, relatively high complication rates were notedin patients with unstable intertrochanteric fractures (3, 17).
From the viewpoint of treatment methods, Chun et al. introduced

a unique reduction technique using a 4.2-mm Steinmann pin
for unstable intertrochanteric fractures (18). Regarding implants, Sanders et al. compared outcomes in elderly patientswith intertrochanteric hip fractures treated with either thesliding hip screw or the intramedullary device, and concluded
that the intramedullary device better improved outcome inactive, functioning patients with unstable intertrochantericfracture than the sliding hip screw (6). Irgit et al. reported thatlong intramedullary nails remain the preferred option for thetreatment of reverse oblique and transverse fractures, demonstrating acceptable complication rates, low reoperation rates,
and high rates of healing (19). Furthermore, a recent report by
Wada et al. suggested that hemiarthroplasty is a good surgicaloption for very elderly patients with unstable intertrochantericfractures (9). Therefore, the importance of identifying the typeof intertrochanteric fracture is necessary to decide the optimaltreatment method.
To evaluate fracture type, CT can provide detailed information about the fracture pattern. According to Cho et al., there
is a high incidence of coronal fragments in intertrochantericfractures when analyzed with three-dimensional CT reconstructions (20). Ishida et al. compared plain radiography andCT findings of intertrochanteric fractures to intraoperative
findings, and reported that plain radiograph assessment underestimates posterior comminution and the complexity of thefracture line (21). They also stated that coronal fragments arevery difficult to recognize on plain radiographs. The present
series also included a high frequency of intertrochanteric fractures with ≥ 3 fragments. The lack of a statistically significant
difference in age between patients with 2-fragment fractures
and those with ≥ 3-fragment fractures could reflect the fact thatthe mean age of our patients was relatively high. Therefore,
detailed evaluation of greater trochanter fragments could be
important, particularly in elderly patients. However, Chapman
et al. used a combination of CT scans and plain radiographs toevaluate intertrochanteric fractures using the two-dimensional
Evans-Jensen and AO/OTA classification systems and concluded
that there was no marked change in interobserver agreement
when information from CT scans was added (13). Their results
suggested that two-dimensional classification systems were notappropriate when evaluating intertrochanteric fractures on CT
scans. Based on their results, a three-dimensional classification
system using CT images would be needed for the fragments that
could not be classified by two-dimensional classifications.
Some previous studies introduced the concept of three-dimensional classification of intertrochanteric fractures. Nakano
et al. (22) and Shoda et al. (23) proposed a three-dimensional
CT classification that defined an intertrochanteric fracture asthat containing 4 major fragments and evaluated each greater
trochanter fragment by its size. However, in the present study,
30.5% of fractures (n = 29) included the GA fragment, suggestingthat intertrochanteric fractures can be classified more accurately by dividing the fracture into 5 fragments. This is the basisof the fragment-based classification system, which seems to besuperior to conventional classification systems. On the other
hand, Futamura et al. introduced a new three-dimensional classification focusing on AO/OTA classification 31-A3 fractures (24).
In a subgroup of their classification, the shape of the posteriorfragment was used to characterize the fractures. In the present
fragment-based classification, as in their study, the shape of bothanterior and posterior fragments can be characterized by a combination of the 5 fragments. Therefore, all types of intertrochanteric fractures can be simply classified using the fragment-basedclassification system and can be easily shared.
This study has several limitations. First, the type of fracture
was evaluated by only one surgeon. Although CT scans enabled

The Journal of Medical Investigation Vol. 66 August 2019
accurate evaluation of intertrochanteric fractures, considerationof both interobserver and intraobserver reliability is important
for a robust fracture classification system. Moreover, previous
reports suggest that reliability tends to decrease as a classification system becomes more detailed (25, 26). Further studyof the reliability of the fragment-based classification system isneeded to address this limitation. Second, we did not performa biomechanical evaluation. Therefore, it is difficult to discuss
the fragment-based classification in terms of stable and unstablefractures because this structure-based classification system
explains fractures in terms of only each bone fragment combination. Do et al. performed a biomechanical study to evaluate
the effect of fracture geometry on the stability of 3-part intertrochanteric fractures by assessing the fragment size (27). Basedon their results, fractures which comprise both GP and GA fragments under the fragment-based classification might be moreunstable due to loss of both anterior and posterior structure of
the greater trochanter. Thus, further biomechanical studies
are needed to determine the stability of the fracture. The final
limitation is that the study did not include a clinical evaluationof the fragment-based classification system. Tsukada et al. investigated comminution at the intertrochanteric fracture site andfound that comminution at the anterior cortex may predict cutout after osteosynthesis (28). Similar clinical studies including
the present classification system are necessary. Despite theselimitations, we believe that the fragment-based classification
system allows surgeons to evaluate intertrochanteric fracturesin detail.
In conclusion, we have introduced a novel three-dimensional CT system for classification of intertrochanteric fractures,
called the fragment-based classification. Using this classification system, surgeons can evaluate intertrochanteric fracturesin more detail than using the conventional two-dimensionalclassifications.

CONFLICT OF INTERESTS
All authors declare that they have no conflicts of interest.

ACKNOWLEDGEMENTS
This research received no specific grant from any funding
agency in the public, commercial, or not-for-profit sectors.

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