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Rationale for Small Glenoid Baseplate: Position of Central Cage within Glenoid Vault (Exactech® Equinoxe® Reverse System)
Clin Should Elbow 2019;22:24-28
Published online March 1, 2019;  https://doi.org/10.5397/cise.2019.22.1.24
© 2019 Korean Shoulder and Elbow Society.

Joo Han Oh, Sanghyeon Lee1, Sung-Min Rhee, Hyeon Jang Jeong2, Jae Chul Yoo1

Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 1Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 2Department of Orthopedic Surgery, Bundang Jesaeng Hospital, Seongnam, Korea
Correspondence to: Jae Chul Yoo
Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
Tel: +82-2-3410-3501, Fax: +82-2-3410-0061, E-mail: shoulderyoo@gmail.com, ORCID: https://orcid.org/0000-0001-8378-1583
IRB approval: Samsung Medical Center (SMC 2019-02-055), Seoul National University Bundang Hospital (B-1902-522-108).
Received November 6, 2018; Revised January 1, 2019; Accepted January 21, 2019.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Background: Glenoid baseplate location is important to good clinical outcomes of reverse total shoulder arthroplasty (RTSA). The glenoid vault is the determining factor for glenoid baseplate location, but, to date, there are no reports on the effect of central cage location within the glenoid vault on RTSA outcomes when using the Exactech® Equinoxe® Reverse System. The purpose of this study was to determine the appropriate cage location in relation to the glenoid vault and monitor for vault and/or cortex penetration by the cage.
Methods: Data were retrospectively collected from the Samsung Medical Center (SMC) and Seoul National University Bundang Hospital (SNUBH). Patients who underwent RTSA between November 2016 and February 2018 were enrolled. Glenoid vault depth, central cage location within the vault were examined. Inferior glenoid rim–center distance, inferior glenoid rim–cage distance, and center–cage center distances were collected.
Results: Twenty-two patients were enrolled. Three SNUBH patients had inappropriate central cage fixation (33.3%) versus 4 SMC
patients (30.8%). All cage exposures were superior and posterior to the glenoid vault. Mean center–cage distance was 5.0 mm in the
SNUBH group and 5.21 mm in the SMC group. Center–prosthesis distance was significantly longer in the inappropriate fixation group
than in the appropriate fixation group (p<0.024).
Conclusions: To ensure appropriate glenoid baseplate fixation within the glenoid vault, especially in a small glenoid, the surgeon should place the cage lower than usually targeted, and it should overhang the inferior glenoid rim.
Keywords : Rotator cuff injuries; Arthropathies; Arthroplasty; Anatomy