Reverse total shoulder - does geometry affect the outcome ? Part 2

In a prior post, What determines the outcome of reverse total shoulder arthroplasty - does geometry matter?, a substantial amount of evidence was presented showing a lack of correlation between clinical outcomes and radiographic measurements after reverse total shoulder arthroplasty (RSA). In a recent study, the authors of Radiographic and anatomic variations on postoperative acromion fractures after inlay and lateralized reverse shoulder arthroplasty attempted to identify associations between the occurrence of acromial fractures after RSA and the relative humeral and glenoid positioning as well as the geometry of the acromioclavicular (AC) joint .

Of a total of 920 RSAs performed, 47 (5.1%) patients suffered a postoperative acromion fracture. Patients with a postoperative acromion fracture were matched in a 3:1 ratio based on sex, indication, and age to those without a fracture and with a 2-year minimum follow-up.

Preoperative and the immediate postoperative radiographs were reviewed to measure critical shoulder angle (A), delta angle (B), global lateralization (C), acromion-humeral interval (D), the level of inlay or onlay of the humeral stem (E) and the preoperative glenoid height.

The morphology, width, and stigmata of osteoarthritis in the AC joint were assessed using computed tomography scans taken preoperatively.

The authors found no significant differences between the fracture and nonfracture groups with respect to the critical shoulder angle, acromion-humeral interval, global lateralization, delta angle both preoperatively and postoperatively, preoperative glenoid height, postoperative degree of inset or offset of humeral implant relative to the anatomic neck, and AC joint morphology, joint space, and stigma of osteoarthritis.

Comment: In the absence of associations among preoperative and postoperative radiographic findings and postoperative acromion fractures, other risk factors such as osteoporosis, inflammatory arthropathy, chronic dislocations, and rotator cuff tear arthropathy may be more important in the pathogenesis of acromion fractures.

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).