Prospective FDA IDE study of 96 shoulders treated with a modified reverse shoulder prosthesis (Encore Medical) using 5.0-mm peripheral locking screws and a lateralized center of rotation. The central question: could these design changes eliminate the mechanical failures and scapular notching that plagued earlier implant generations? Minimum two-year follow-up across four diagnostic subgroups: primary cuff deficiency, failed cuff repair, failed arthroplasty, and proximal humeral nonunion.
The Grammont Delta III prosthesis — the dominant reverse shoulder design through the early 2000s. Carried notching rates approaching 96% and significant complication burdens. The prior generation of this lateralized implant solved notching but introduced a new problem: 12% baseplate failure from excessive moment forces on undersized screws.
This paper closed that loop. When you see a patient with cuff tear arthropathy, pseudoparesis, or a failed prior shoulder arthroplasty, the design principles validated here. 5.0-mm locking screws, inferior glenosphere tilt, lateralized center of rotation. Are why modern reverse shoulder systems perform as reliably as they do.
For revision cases specifically, counsel patients preoperatively that their functional ceiling is lower: expect ASES in the high 60s rather than mid-80s, and do not promise external rotation recovery. It was the one motion that failed to improve significantly in that subgroup.
The external rotation finding also matters for latissimus transfer planning: patients treated with a lateralized design gained nearly 15° of external rotation without transfer, suggesting the lateral offset itself provides mechanical advantage to residual posterior cuff. A consideration when deciding whether to add a transfer at the time of index RSA.
Prospective FDA IDE study of 96 shoulders treated with a modified reverse shoulder prosthesis (Encore Medical) using 5.0-mm peripheral locking screws and a lateralized center of rotation. The central question: could these design changes eliminate the mechanical failures and scapular notching that plagued earlier implant generations? Minimum two-year follow-up across four diagnostic subgroups: primary cuff deficiency, failed cuff repair, failed arthroplasty, and proximal humeral nonunion.
The Grammont Delta III prosthesis — the dominant reverse shoulder design through the early 2000s. Carried notching rates approaching 96% and significant complication burdens. The prior generation of this lateralized implant solved notching but introduced a new problem: 12% baseplate failure from excessive moment forces on undersized screws.
This paper closed that loop. When you see a patient with cuff tear arthropathy, pseudoparesis, or a failed prior shoulder arthroplasty, the design principles validated here. 5.0-mm locking screws, inferior glenosphere tilt, lateralized center of rotation. Are why modern reverse shoulder systems perform as reliably as they do.
For revision cases specifically, counsel patients preoperatively that their functional ceiling is lower: expect ASES in the high 60s rather than mid-80s, and do not promise external rotation recovery. It was the one motion that failed to improve significantly in that subgroup.
The external rotation finding also matters for latissimus transfer planning: patients treated with a lateralized design gained nearly 15° of external rotation without transfer, suggesting the lateral offset itself provides mechanical advantage to residual posterior cuff. A consideration when deciding whether to add a transfer at the time of index RSA.