• R. Ortmaier, Guido Wierer, M. S. Gruber
• Published 22 January 2022
• Medicine
• Journal of Clinical Medicine

Glenoid implant position and fixation are challenging in severe glenoid defects in reverse total shoulder arthroplasty (rTSA). Custom-made glenoid implants are metal augmented implants that are specially produced for a certain defect. They provide the restoration of the joint line and proper fixation. This retrospective data analysis investigated the clinical and radiological outcomes after revision using custom-made glenoid implants. Between 2018 and 2020, nine patients (10 shoulders) with severe glenoid defects underwent revision rTSA using a custom-made glenoid implant (Materialise Glenius or Lima ProMade). The pre- and postoperative Constant Murley Score (CMS), UCLA Score and Subjective Shoulder Value (SSV) were assessed. Postoperative CT scans and X-rays in two planes were available. The minimum follow-up was 12 months, with a mean follow-up of 23.1 months. The mean preoperative CMS, UCLA Score and SSV were 10.9, 4.1 and 11.0, respectively. The mean postoperative CMS, UCLA Score and SSV showed significant increases of 51.7 (<0.001), 22.9 (<0.001) and 52.0 (<0.001), respectively. There were no signs of loosening implants or scapular notching, and no revision was necessary. This trial showed promising clinical and radiological short-term outcomes for custom-made glenoid components in revision rTSA. ​

tapping the central glenoid hole for a screw without a guide may enlarge the hole. Using a guide makes the tap inline with the drill hole; this may be better when using a wedge augment 

.A PSI guide helps execute the preoperative plan. 
​If the surgeon choses to check the position of the guide using the floor as a reference to check inclination, an error may occur because of the positioning of the scapula.
​This may happen if an assist arm is used

Which is the best option for glenoid baseplate fixation in the elderly?
Here are some variables to consider:
​

1. A 6.5 mm screw is often used. Will this gain sufficient purchase in the elderly?
2. A central post has the potential of ingrowth but has a larger diameter of a 6.5 mm screw. 
3. A revision of a post will need at least a 9.5 mm screw or a completely different hole position
​4. The dimensions of the glenoid vault will determine post perforation which may not be desirable

The inlay stem offers specific advantages
1. bone conservation
2, easier revision
3. less calcar resorption
4. helpful in small patients
5. less tendency to stuff the joint

IMO, importing the post operative xray image into the software program  may be helpful.  assessment of lateralization, distalization, DSA and positioning of the implant 

using an inlay system, the DSA is reduced to 62 degrees and distatlization is 17 mm

Maybe distalization greater than 20-25 mm may result in a difficult reduction. A lower neck cut, smaller sphere ,  or using an inlay stem are options. I think (opinion) the preop planning software to include DSA to anticipate tightness of shoulder reduction

The COR was medially displaced by 28 4 mm with the Delta prosthesis and by 19 3 mm with the Encore prosthesis 
​Matthew D. Saltzman, MDa , Deana M. Mercer, MDc , Winston J. Warme, MDb , Alexander L. Bertelsen, PA-Cb , Frederick A. Matsen III, MDb, * 

​: Frederick A. Matsen III, MD, Department of Orthopedics and Sports Medicine, University of Washington Medical Center, Box 356500, 1959 NE Pacific St, Seattle, WA 98195. E-mail address: matsen@u.washington.edu (F.A. Matsen III).

Causes of a tight shoulder with a reverse shoulder arthroplasty:
SUPERIOR HUMERAL MIGRATION
MEDIALIZED HUMERUS
TIGHT CAPSULE 
HIGH NECK CUT
EXCESSIVE LATERALIZATION OF BASE PLATE
EXCESSIVE LATERALIZATION OF SPHERE
LARGE MUSCULAR MALE
LOW  GLENOSPHERE 
OVERSIZED GLENOSPHERE
ONLAY SYSTEM
INTACT ROTATOR CUFF
PRIOR SURGERY
PREOPERATIVE STIFFNESS
LARGE DELTOID
INCOMPLETE PARALYSIS
FAILED INTERSCALENE BLOCK ​