Lateralization in reverse shoulder arthroplasty: a descriptive analysis of different implants in current practice
Since its first description, the concept of reverse shoulder arthroplasty (RSA) has evolved. The term lateralization remains unclear and is used to describe implants that lateralize on the glenoid side, the humeral side, or both. The objective of this study was to provide a clear definition of lateralization and to measure the lateralization achieved by the most commonly used implants.
Materials and methods
Twenty-eight different configurations with 22 different implants were analyzed. Glenoid, humeral, and global lateralization was measured on digitized templates. Implant lateralization was normalized to the lateral offset of the Delta III. Each implant was defined as a combination of one of two glenoid categories (medialized glenoid (MG), lateralized glenoid (LG), and one of four humeral categories (medialized humerus (MH), minimally lateralized humerus (LH), lateralized humerus (LH+). In addition, implants were separated in categories of 5-mm increments for global offset (medialized RSA (M-RSA), minimally lateralized RSA (ML-RSA), lateralized RSA (L-RSA), highly lateralized RSA (HL-RSA), and very highly lateralized RSA (VHL-RSA).
The global lateral offset of the Delta III was 13.1 mm; global lateral offset of all designs in this study varied between 13.1 and 35.8 mm. Regarding their global lateral offset, five implants are M-RSA (lateral offset < 18.1 mm), five ML-RSA (18.1–23.1 mm), seven L-RSA (23.1–28.1 mm), six HL-RSA (28.1–33.1 mm), and one VHL-RSA (33.1–38.1 mm).
There is high variability in the amount of lateralization provided by the majority of RSAs currently available. This descriptive analysis can help surgeons understand the features of implants in the market based on their lateralization in order to adapt the surgical technique depending on the expected lateral offset of the design being implanted.
KeywordsShoulder arthroplasty Lateralization Templates Humeral lateralization Glenoid lateralization
Compliance with ethical standards
Each author certifies that his or her institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
Conflict of interest
Philippe Valenti and Jean-David Werthel receive royalties for shoulder prosthesis design from FH Orthopedics. Gilles Walch receives royalties for shoulder prosthesis design from Wright Medical. Joaquin Sanchez-Sotelo receives royalties for shoulder prosthesis design from Stryker.
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