Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.
Dr. Frank is Assistant Professor, Department of Orthopaedic Surgery, University of Colorado School of Medicine, Aurora, Colorado. Mr. Golijanin is a Medical Student, Geisel School of Medicine, Dartmouth Medical School, Hanover, New Hampshire. Dr. Vopat is Assistant Professor, Department of Orthopaedic Surgery, University of Kansas, Kansas City, Kansas. Dr. Gross is a Resident, DGMD Medical, Omaha, Nebraska. Dr. Chauhan is a Resident, Ninewells Hospital, Dundee, United Kingdom. Dr. Romeo is Chief of Orthopaedics, Rothman Institute New York, New York. Dr. Provencher is an Orthopaedic Surgeon, The Steadman Clinic, Vail, Colorado.
Address correspondence to: Rachel M. Frank MD, Department of Orthopaedic Surgery, University of Colorado School of Medicine, Aurora, CO 80045 (email, Rachel.Frank@ucdenver.edu).
Am J Orthop. 2018;47(6). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
Rachel M. Frank, MD Petar Golijanin, BS Bryan G. Vopat, MD Daniel J. Gross, MD Vidhya Chauhan, BS Anthony A. Romeo, MD CAPT Matthew T. Provencher, MD, MC, USNR . Impact of Sagittal Rotation on Axial Glenoid Width Measurement in the Setting of Glenoid Bone Loss. Am J Orthop.
June 5, 2018
References
ABSTRACT
Standard 2-dimensional (2-D) computed tomography (CT) scans of the shoulder are often aligned to the plane of the body as opposed to the plane of the scapula, which may challenge the ability to accurately measure glenoid width and glenoid bone loss (GBL). The purpose of this study is to determine the effect of sagittal rotation of the glenoid on axial anterior-posterior (AP) glenoid width measurements in the setting of anterior GBL.
Forty-three CT scans from consecutive patients with anterior GBL (minimum 10%) were reformatted utilizing open-source DICOM software (OsiriX MD). Patients were grouped according to extent of GBL: I, 10% to 14.9% (N = 12); II, 15% to 19.9% (N = 16); and III, >20% (N = 15). The uncorrected (UNCORR) and corrected (CORR) images were assessed in the axial plane at 5 standardized cuts and measured for AP glenoid width.
For groups I and III, UNCORR scans underestimated axial AP width (and thus overestimated anterior GBL) in cuts 1 and 2, while in cuts 3 to 5, the axial AP width was overestimated (GBL was underestimated). In Group II, axial AP width was underestimated (GBL was overestimated), while in cuts 2 to 5, the axial AP width was overestimated (GBL was underestimated). Overall, AP glenoid width was consistently underestimated in cut 1, the most caudal cut; while AP glenoid width was consistently overestimated in cuts 3 to 5, the more cephalad cuts.
UNCORR 2-D CT scans inaccurately estimated glenoid width and the degree of anterior GBL. This data suggests that corrected 2D CT scans or a 3-dimensional (3-D) reconstruction can help in accurately defining the anterior GBL in patients with shoulder instability.
The treatment of glenohumeral instability has substantially evolved over the past several decades. The understanding of glenoid bone loss (GBL), in particular, has advanced to such a level that we utilize the quantification of GBL for surgical decision-making. Unrecognized and/or untreated GBL is associated with recurrent instability, pain, and disability. Controversy exists, however, regarding the precise amount of anterior GBL that is significant enough to warrant surgical treatment. While historically, 25%1,2 of anterior GBL was thought to be the critical number required to warrant osseous augmentation, studies that are more recent have highlighted the need to perform osseous glenoid reconstruction with lesser degrees of GBL, particularly in the contact athlete.3-9 As small differences in the amount of GBL can change surgical decision-making from an all-soft tissue repair to an osseous reconstruction, it is paramount that we have accurate, valid, and reproducible methods for calculating GBL.