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Letters |
Duke University Medical Center
Durham, NC 27710
I read the articles titled "Acetabular Fractures Revisited: Part 1, Redefinition of the Letournel Anterior Column" [1] and "Acetabular Fractures Revisited: Part 2, A New CT-Based Classification" [2] by Drs. Harris, Lee, Coupe, and Trotscher with great interest. As an orthopedic surgeon who has pursued the study and treatment of patients with acetabular fractures for more than 15 years, I have several comments for the authors.
There is a multiplicity of needs from the imaging of acetabular fractures. The most basic level is the determination of whether an injury to the hip or acetabulum has occurred. In my experience, most radiologists accurately identify the presence of the bone fracture—that is, they achieve diagnostic imaging.
However, for the treatment of these injuries the surgeon needs a more in-depth understanding of the anatomy of the fracture. The works of Judet and Letournel provide a common vocabulary to describe and communicate the anatomic details of acetabular fractures [3]. This terminology is now widely accepted by most surgeons who treat these injuries. The use of the Letournel classification system has been shown to be reproducible by trained observers. Furthermore, the results of treatment in the largest clinical series available all use the Letournel classification system to describe their injuries and, hence, are necessary for future comparisons with these series.
In reading these articles [1, 2], I am struck by the statement that conventional radiographic findings that are used by orthopedic surgeons daily are typically unfamiliar to radiologists. Common examples of this are the center edge angle in the diagnosis of acetabular dysplasia, as described by Wiberg in 1939 [4], or the more recent description of the retroversion of the superior acetabulum as described by Siebenrock and colleagues [5]. In my experience, when I have tried to explain the value of the terminology of Letournel for acetabular fractures to my radiology colleagues, it has been received as interesting—but nonessential—information. Because the radiologist does not have to determine which operative approach and methods of reduction and fixation are needed for treatment of the fracture, this detailed description of fracture anatomy is seen as somewhat abstract.
The primary obstacle for any physician to learn the system of Letournel for interpreting the radiographic imaging and to transfer this knowledge into classification is experience. For this problem, the clinician needs to gain experience for a time directly with an experienced surgeon who, through operative experience and radiographic interpretation, can directly relate radiographic anatomy to bone anatomy.
Of great concern to me is the abandonment of the basic imaging of the pelvis with anteroposterior and oblique views by the authors. These images, commonly known as Judet views, form the basis of the understanding of Letournel's system. Modern techniques with 3D CT reformations using transparent or translucent imaging are said to be able to provide views that are comparable with Judet views. Have the authors used this technique in their investigations? Why must we attempt to define a new system of classification for these already complex injuries when we currently have a vocabulary that clearly works well, has been shown to be clinically useful, and has been used successfully with reproducible and good outcomes for patients?
The artist's rendering of the acetabulum in the anterior column article [1] was used to characterize Letournel's description of the anterior column as nonanatomic. However, in the normal physiologic position of the pelvis, the anterosuperior iliac spines and the pubic symphysis are coplanar in the frontal plane. With the pelvis held in this orientation, Letournel's description of the anterior column is anatomically correct.
The authors state the definition of the associated both column fracture is ambiguous as given by Letournel. However, Letournel was exacting in his definition of a both column acetabular fracture. He stated the definition consists of two parts. First, that the associated both column fracture is one in which the fracture line separates the anterior column from the posterior column (the columns are mutually disassociated from one another), and second, all segments of the articular surface are detached from the residual intact ileum. In fact, Letournel described the radiographic finding of the "spur" sign, the residual portion of the intact ileum that is often seen distinctly from the medialized acetabulum on the obturator oblique radiographic view. His finding is in fact pathognomonic of the diagnosis of associated both column fracture.
In conclusion, it appears the authors have made recommendations to abandon the Letournel classification and its terminology as a result of unfamiliarity with them rather than for a true benefit to the patient or surgeon. It is laudable that the authors have such interest in this subject. However, it would benefit them to better understand the current terminology and classification before attempting to recommend major revisions in an already universally accepted classification scheme.
References
The University of Texas
Medical School at Houston
Houston,
TX
My coauthors and I are flattered that Dr. Olson has studied our articles redefining the Letournel anterior column [1] and our proffered CT-based classification of acetabular fractures [2], and we are most appreciative of his comments regarding our work.
Olson questioned our familiarity with the Letournel system and our qualifications to prepare these articles. Our qualifications to undertake this work and reach the conclusions presented in the articles cited are based on significant emergency radiologic and trauma orthopedic experience. The senior author has more than 40 years experience in emergency (including trauma) imaging, the past 21 years of which as Chief of Emergency Radiology at the Hermann Hospital, Houston, Texas, a level I trauma center in which 150-160 patients with acetabular fractures are admitted annually. The senior investigator was involved in the initial clinical and imaging management of most of these patients. The trauma orthopedic surgeon coinvestigator has 10 years' experience with the same institution and has a primary interest in acetabular fractures. The third coinvestigator has had 2 years of emergency radiology at Hermann Hospital.
My coauthors and I were all motivated to conduct this investigation by the frustration of attempting to apply the Letournel classification of only 10 types of acetabular fractures to the infinite variety of acetabular fracture patterns seen in our practice, many of which did not fit any of the Letournel types. The Hermann Hospital is the primary teaching hospital of the University of Texas-Houston Medical School; consequently, all of our experience with acetabular fractures was conducted with strict academic rigor. Based on that experience and contrary to Olson's gratuitous comment regarding our understanding of "the current terminology and classification before attempting to recommend major revisions," we have the experience and knowledge to that very thing.
Olson claims that "the use of the Letournel classification system has been shown to be reproducible by trained observers" (emphasis added), which means that orthopedic surgeons who have been taught by Letournel or those who treat acetabular fractures on a regular basis. Unfortunately, that does not include most trained orthopedic surgeons throughout the world who are called on to treat these injuries. Matta et al. [3] suggested "a certain degree of centralization of acetabular fracture treatment—especially of associated types—can lead to an improved standard of care overall." This suggestion is theoretically ideal but realistically impractical.
A search of recent and current literature related to the reproducibility of the Letournel classification by trained observers is considerably less than stated by Olson. Ohashi et al. (presented at the Radiological Society of North America annual meeting, 2004) found "Kappa values between two readers were 0.38 (fair reliability) by radiology and 0.59 (moderate reliability) by MDCT." They concluded that "The standard Judet pelvic radiographs add little to improve the MDCT classification." Potok et al. [4] found "...the Judet and Letournel system is complicated and easily misunderstood reflecting the nature of the anatomy itself." Visutipol et al. [5] reported conventional radiographic intraobserver reproducibility to be 0.42 (moderate) and interobserver reliability to be 0.24 (low). They state further:
We think the reason why both the intraobserver reproducibility and the interobserver reliability were low in the L-J classification is because the classification is too complicated (there are ten types) and too difficult to differentiate one type from the other especially in complex fracture groups.
These authors concluded, "Intraobserver reproducibility and interobserver reliability were found to be low in L-J classification...."
In one article [6], the authors assessed interobserver and intraobserver reliability, and they reached the following conclusions:
Letournel's acetabular classification with use of plain radiographs with or without supplemental computed tomography scans has substantiated reliability (kappa > 0.7) when used by surgeons who have been taught how to interpret the images (by Letournel) or by those who treat acetabular fractures on a regular basis.
Olson's criticisms of radiologists being unfamiliar with the "central edge angle in the diagnosis of acetabular dysplasia" and the "description of the retroversion of the superior acetabulum" are interesting but irrelevant with regard to our articles in particular and to acetabular fractures in general.
My coauthors and I stated in Part 2 [2], we freely acknowledge the seminal work of Letournel and Judet in developing their classification of acetabular fractures based only on conventional radiographs. Before CT became readily available and clinically useful, the anteroposterior radiograph of the pelvis and the oblique views of the involved acetabulum were integral to revealing the acetabular fracture pattern. However, with the availability of CT in most major trauma centers, perpetuating the practice of obtaining the Judet oblique projections is no longer necessary and is, clearly, in violation of a basic tenet of initial fracture management—namely, immobilization of the suspected fractured part. Emergency medical technicians, in compliance with the American College of Surgeon's standards, strap patients with multiple injuries to a board for transport from the scene to the emergency department.
I have, for 40 years, been personally and hands-on involved in assisting radiologic technologists in positioning patients with acetabular fractures so that Judet oblique views can be obtained. In conscious polytraumatized patients, the movement needed to achieve the positions for the Judet views, particularly the iliac oblique view in which the patient is required to roll and lay on the fractured acetabulum, is not only extremely painful, but could change the position of fracture fragments. Before the time of CT, such patient positioning was acceptable because the Judet oblique projections were necessary to show the fracture pattern. Today, such patient movement, particularly and primarily for historic purposes, is not only unacceptable, but also unconscionable.
Today, the accepted imaging technique for patients with suspected pelvic or acetabular fractures is anteroposterior radiography of the pelvis to include each hip. In the best interest of patient care, subsequent imaging of an acetabular fracture should be 2D or 3D CT. If the orthopedic surgeon has difficulty in mentally integrating the axial CT images, 3D reformatted images, which can be viewed in any plane, will unequivocally show the fracture pattern.
My coauthors and I believe the Letournel anterior column is not anatomically correct in that it extends to the iliac crest. Anatomically, the acetabulum is a structure of the true pelvis. In addition, as we pointed out in Figure 1 of Part 1 [1], the Letournel anterior column is not similar to the Letournel posterior column. Our schematic drawings of the anterior column are anatomically correct as supported by figures from Gray's Anatomy [7]. Furthermore, our schematics and narrative regarding the anatomy of the anterior column were stringently reviewed by Dr. William H. Harris, Emeritus Chief, Adult Implant Service, Massachusetts General Hospital. Our contention that the Letournel "both column" description and definition are ambiguous is supported by the following quotation from Vrahas and Tile [8]:
The both column fractures should not be confused with other fractures in which both columns are fractured. Both columns are disrupted with transverse, T-type, and anterior with posterior hemi-transverse fractures, but none of these is to be considered a both-column fracture.
We believe that is ambiguity personified. To eliminate that ambiguity, Tile advocates, as we do, the use of the term "floating acetabulum" to indicate those uncommon acetabular fractures in which the acetabulum is separated both anteriorly and posteriorly from the axial skeleton (our category III) from those fractures that involve both columns (our category II and its four subcategories).
In conclusion, my coauthors and I believe our classification, which is based on CT visualization of acetabular fracture patterns, is easily understandable by all radiologists and orthopedic surgeons called on to diagnose and treat acetabular fractures—not only those orthopedic surgeons who have studied under Letournel or who specialize in acetabular fracture surgery. Furthermore, our CT-based system provides a mechanism for unambiguously classifying the infinite number of acetabular fracture patterns.
My coauthors and I thank Dr. Olson for his comments that prompted us to look critically again at our work. Our reconsideration, prompted by his comments, has reconfirmed our original work.
References
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