Commentary & Perspective

Commentary & Perspective on
"Glenoid Rim Morphology in Recurrent Anterior Glenohumeral Instability"
by Hiroyuki Sugaya, MD, et al.

Commentary & Perspective by
Jon J.P. Warner, MD*,
Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA

This article deals with an aspect of shoulder instability that has not been considered adequately in the literature—the importance of glenoid rim morphology in recurrent anterior glenohumeral instability. While authors of prior biomechanical and anatomical studies^1-5 have considered the importance of glenoid concavity in shoulder stability, there have been few clinical studies that address the relationship between glenoid morphology and glenohumeral instability^6-11. Sugaya et al. studied a large series (100 shoulders) with recurrent unilateral anterior glenohumeral instability and developed a quantification method for grading osseous defects. They evaluated glenoid morphology using three-dimensionally reconstructed computer tomography images, with the humeral head eliminated during the image-creation process. They found a 90% prevalence of abnormal morphology of the glenoid rim—either glenoid rim fracture or erosion—in the setting of recurrent anterior glenohumeral instability. When the authors compared the three-dimensionally reconstructed computerized tomographic images of affected glenoids with those of seventy-five normal glenoids, they found a clear difference in glenoid morphology between the two groups.

The strength of this study was the large number of shoulders that were evaluated and the clear visual documentation of osseous glenoid abnormalities that accompany recurrent anterior instability. This observation has great importance for surgical decision-making. However, the study has a number of shortcomings that indicate a need for further validation of the techniques and results reported before they can be applied to the clinical treatment of recurrent anterior glenohumeral instability.

First, in the introduction the authors suggested that prior studies have not approached consensus on the prevalence of glenoid rim abnormality in patients with recurrent anterior glenohumeral instability, because accurate and practical quantitative imaging techniques are not routinely employed prior to surgical treatment. While this may be true, the authors stated that the purpose of their report was to present a simple, practical method of quantitative assessment of "the morphology of the anteroinferior portion of the glenoid rim… and to determine the prevalence of lesions of the glenoid rim" in these patients. While Sugaya et al. have presented interesting data in this report, they did not accomplish both of these goals in their paper.

They presented a method of analyzing glenoid rim morphology and measuring the osseous defects without any validation of the technique, such as reliability and repeatability studies. Thus, one may assume that observer bias influenced the results. Furthermore, the number of shoulders analyzed in the study seems to have been chosen arbitrarily as there is no mention of a power analysis. Finally, the authors have not provided any real insight into the importance of their observations as they have not stated how these findings actually influenced treatment of the patients in the study. In the Discussion section, Sugaya et al. mentioned that bone-grafting should be considered in shoulders with severe glenoid erosion; however, the reader does not know how many of the patients were so treated or the effect of this treatment on the overall outcome.

Burkhart and De Beer⁷ evaluated arthroscopic determination of glenoid erosion and pointed out that failure to recognize this erosion and to treat glenoid bone loss with a bony reconstruction was associated with a very high failure rate. Sugaya et al. included an arthroscopic evaluation of the one hundred shoulders with recurrent anterior glenohumeral instability but did not present any methodology for this evaluation or a quantitative comparison between the arthroscopic and the computed tomographic evaluations.

In addition, no justification was provided for the added cost of preoperative computed tomography and three-dimensional reconstruction of the images. For this method of analysis to be cost-effective, it should provide valuable additional information that aids in the determination of surgical treatment and thus reduces the overall failure rate and, ultimately, the cost of treatment. A cost-benefit analysis was not performed in this study.

In my view, the most valuable conclusion that the reader can draw is that glenoid bone loss is common in shoulders with recurrent anterior glenohumeral instability, and preoperative detection can help the surgeon to decide the best method of treatment for his or her patients. Unfortunately, this decision cannot be made on the basis of the method of evaluation presented in this paper. Nevertheless, the authors are to be congratulated on their important study which should be used as the basis for a more detailed analysis of the value of three-dimensional computed tomography in terms of clinical decision-making and cost-effectiveness.

*The author did not receive grants or outside funding in support of the research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

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