Three-dimensional Mapping of Intertrochanteric Fracture Lines

Three-dimensional Mapping of Intertrochanteric Fracture Lines

Intertrochanteric fractures are a common type of hip fracture, particularly among the elderly population. The incidence of these fractures has been increasing due to the aging population and the rise in traumatic injuries. Surgical intervention is the primary treatment for intertrochanteric fractures, with the goal of achieving stable fixation, allowing early mobilization, and restoring the patient’s functional mobility and independence. However, the complexity of these fractures poses significant challenges for accurate diagnosis and effective surgical management.

Traditional classification systems for intertrochanteric fractures, such as the Evans classification, Jensen classification, Boyd-Griffin classification, Kyle classification, and the AO/OTA classification, have been widely used in clinical practice. These systems are based on radiographic evaluations and aim to describe fracture types, stability, and patterns to predict postoperative prognosis. However, with advancements in radiography, particularly the widespread use of computed tomography (CT) and three-dimensional (3D) CT imaging, these classic X-ray-based classifications are now considered insufficient. They often fail to provide accurate and consistent information about the actual fracture morphology, especially in cases involving large oblique fragments that include the lesser trochanter.

To address these limitations, this study aimed to map intertrochanteric fracture lines using CT data from a series of surgically treated patients. The study included 504 consecutive intertrochanteric fractures treated at the Department of Orthopaedics, Chinese PLA General Hospital, between September 2009 and May 2017. The inclusion criteria were CT data of the proximal femur obtained before surgical intervention, CT images with a thickness of less than 3.0 mm, a minimum of one year of radiographic follow-up, age of 18 years or older, and a low-energy mechanism of injury. Patients with pathological fractures, mental disorders, pre-existing assistive device use, associated neurovascular injuries, or previous surgery or osteoarthritis on the affected hip joints were excluded.

The study utilized a method for describing fracture lines in 3D intertrochanteric fracture patterns. The original Digital Imaging and Communications in Medicine (DICOM) files of the CT data were collected and imported into Mimics 15.0 software to reconstruct all 3D fragments of each patient. The fracture fragments were virtually reduced in the 3D view, and the fracture lines were clearly observed. These reductive fracture models were then modified to develop 2D images presented in the same anatomic plane as the templates. The fracture lines were transcribed freehand onto the template layer and graphically superimposed to create a fracture mapping compilation. The fracture maps were subsequently divided into anterior, posterior, lateral, and medial views to create a 3D pattern by reducing fragments in the 3D models. The fracture maps were then converted into frequency spectra to illustrate the fracture line majorities and trajectories.

The results of the study revealed distinct fracture patterns in each of the four planes. In the anterior plane, the majority of fracture lines (85.9%, 433/504) were concentrated at the intertrochanteric line where the iliofemoral ligament was attached, with a trajectory running from superolateral to inferomedial. The anterior fracture map was divided into typical and non-typical fracture lines, with typical fracture lines being those in which a single fracture line ran from superolateral to inferomedial. Non-typical fracture patterns included reversed V fracture lines, transverse oblique fracture lines, a combination of pertrochanteric and lateral wall fractures, and multiple intertrochanteric lines.

In the medial plane, a cross was constructed to form four quadrants, and the position of the turning points of the fracture lines was assessed. The majority of fracture lines (49.0%, 247/504) had a turning point in the third quadrant, indicating lesser trochanter detachment from the medial cortex. Simple fracture lines traversed the first and second quadrants in 14.7% of cases and the third and fourth quadrants in 21.0% of cases.

In the posterior plane, the majority of fracture lines (52.0%, 262/504) involved the intertrochanteric crest from the greater to the lesser trochanter. The posterior fracture map was divided into six types based on the fracture fragments and the integrity of the intertrochanteric crest. Type I fractures involved only the posterior basal part of the femoral neck with an intact trochanteric crest, while Type VI fractures were reverse trochanteric fractures.

In the lateral plane, the majority of fracture lines (62.7%, 316/504) involved the greater trochanter at the gluteus medius attachment, with a trajectory running from anterosuperior to posteroinferior. The lateral fracture map was divided into four groups based on the involvement of different zones, with Group II fractures traversing the first and second zones being the most common.

The study concluded that the fracture patterns observed could be used to describe the morphologic characteristics of intertrochanteric fractures and aid in management strategies. The 3D mapping technique provided a comprehensive understanding of the fracture lines and their trajectories, which could facilitate surgical planning and implant strategy design. The findings suggested that future classifications or modifications incorporating the identified fracture patterns may be useful in improving the diagnosis and treatment of intertrochanteric fractures.

The study also highlighted the limitations of traditional classification systems, which are based on radiographic evaluations and often fail to capture the complexity of intertrochanteric fractures. The use of CT and 3D CT imaging allowed for a more accurate and detailed assessment of fracture morphology, particularly in cases involving large oblique fragments and comminution zones of the intertrochanteric crest. The study emphasized the importance of considering the size of the intertrochanteric crest detachment, medial cortical support, and lateral femoral wall integrity in the treatment of intertrochanteric fractures, as these factors were not adequately addressed in existing classifications.

In conclusion, this study provided valuable insights into the morphologic characteristics of intertrochanteric fractures using a 3D mapping technique. The findings could enhance the understanding of fracture mechanisms, improve surgical planning, and contribute to the development of more effective classification systems for intertrochanteric fractures. The study demonstrated the potential of CT and 3D CT imaging in providing precise and accurate information about fracture patterns, which could ultimately lead to better patient outcomes.

doi.org/10.1097/CM9.0000000000000446

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