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Mandibular Deformity in Hemifacial Microsomia

A Reassessment of the Pruzansky and Kaban Classification

Bartlett, Scott P. M.D.; Taylor, Jesse A. M.D.; Goldstein, Jesse A. M.D.; Wink, Jason D. B.A.; Paliga, James T. B.A.

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Plastic and Reconstructive Surgery: October 2014 - Volume 134 - Issue 4 - p 658e-659e
doi: 10.1097/PRS.0000000000000705
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Sir:

We thank Dr. Kaban et al. for their interest in our recent publication in Plastic and Reconstructive Surgery entitled “The Mandibular Deformity in Hemifacial Microsomia: A Reassessment of the Pruzansky and Kaban Classification.”1 We appreciate their criticisms of our work. It is essential for all of us to continue to be critical of ourselves and open to the well-formulated opinions of others in order to improve as surgeons and researchers.

The concept of this study came about after experienced craniofacial surgeons at our institution began to realize the frequency with which there was disagreement in classification of many of their hemifacial microsomia patients. There is no doubt that the Pruzansky modification of the Kaban classification system has been the “gold standard” for classifying these patients since the late 1980s.2 However, the diagnosis of these patients has changed drastically since its inception, with the adoption of three-dimensional computed tomography enabling surgeons to clearly visualize the heterogeneity of hemifacial microsomia. The Pruzansky modification, on the other hand, was developed with the use of plain radiography and clinical examination. While it remains the standard in stratifying these patients, we aimed to study the clinical value of this classification schema by evaluating its reproducibility among a number of experienced craniofacial surgeons in light of the modern availability of three-dimensional computed tomography.

We acknowledged the implicit limitations of this study, but we believe that our results demonstrate that there are inconsistencies in the way the Pruzansky modification is being applied for clinical use. In order to test the efficacy of a classification system, it is essential that reviewers be compared with an accepted standard; in the case of our study, this was the clinical evaluation performed by the senior author (S.P.B.) at the time of initial presentation. We acknowledge that this was not perfect, but our study required a baseline to which we could compare the results of each reviewer. In order to attempt to remedy the disagreements that we appreciated, we created the mild (0 to I), moderate (IIA), severe (IIB to III) classification. This result improved rater agreement, but by less than we would have expected. In a second attempt to remedy the lack of a quality accepted standard, we utilized the Fleiss kappa statistic3 to assess for interrater variability among all study participants. Again, we appreciated a lack of interrater agreement among reviewers (κ = 0.238, 0.438). While Kaban et al.’s criticism that this study tests the application of the reviewers’ understanding of the Pruzansky modification of the Kaban classification is well received, this is indeed the way the Pruzansky modification is currently being applied in clinical practice. A classification schema derives its efficacy and, thus, clinical import by being readily understood and ultimately reproducible. Our results indicate that neither may be true of the Pruzansky modification of the Kaban classification system when paired with modern imaging modalities.

There is no debate that the Pruzansky modification remains the classification system of choice; each of our study participants—trained craniofacial surgeons—acknowledged using it in their practice. Each participant was shown the correct original definition of the Pruzansky modification prior to undertaking the study survey, with a type IIA mandible being defined as “abnormal in shape.” We apologize for the error in the legend of Figure 1; however, the mislabeling of the images as Kaban et al. define it is an example of a possible disagreement among physicians that we appreciated in our study. I believe, though, that we are in agreement that the treatment of choice would not differ in either of these cases.

Again, we appreciate their thoughtful criticisms of our study and agree, “A classification system should aid in diagnosis of a condition, improve communication among clinicians, help predict progression of disease/deformity, and guide research.” We hope that with the resources available to us, we were able to conduct a study that demonstrated the immense difficulty of classifying patients with a diagnosis of hemifacial microsomia in a reliable and reproducible manner. The use of three-dimensional computed tomography has allowed physicians to clearly visualize the complexity of each case of hemifacial microsomia. We believe that the information available in each three-dimensional computed tomography scan may hold the key to classifying this extremely amorphous disorder in a more objective manner.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.

Scott P. Bartlett, M.D.

Jesse A. Taylor, M.D.

Jesse A. Goldstein, M.D.

Jason D. Wink, B.A.

James T. Paliga, B.A.

Children’s Hospital of Philadelphia

University of Pennsylvania

Philadelphia, Pa.

REFERENCES

1. Wink JD, Goldstein JA, Paliga JT, Taylor JA, Bartlett SP. The mandibular deformity in hemifacial microsomia: A reassessment of the Pruzansky and Kaban classification. Plast Reconstr Surg. 2014;133:174e–181e
2. Kaban LB, Moses MH, Mulliken JB. Surgical correction of hemifacial microsomia in the growing child. Plast Reconstr Surg. 1988;82:9–19
3. Fleiss JL. Measuring nominal scale agreement among many raters. 1971;76:378–382

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