This biographical sketch profiles Paul Grammont, designer of the reverse shoulder prosthesis. It explains the biomechanical rationale behind his 1985 design for arthritic, cuff-deficient shoulders. The piece traces the evolution from earlier failed constrained implants to the modern reverse total shoulder arthroplasty.
The core teaching point is why the reverse prosthesis works when a standard anatomic implant cannot: in a cuff-deficient shoulder, you need a different motor for elevation. Grammont's two moves solve this. Medializing the center of rotation onto the glenoid eliminates the destructive torque that loosened every prior lateralized reverse design.
Distalizing the humerus tensions the deltoid and improves its lever arm, converting the anterior and posterior deltoid into functional abductors. For boards, anchor this cause-and-effect chain: lateral center of rotation causes glenoid loosening, medialization prevents it, and deltoid retensioning substitutes for the missing cuff.
Know the classic indications: pseudoparalysis from an irreparable cuff tear, fracture sequelae, failed arthroplasty, and tumor reconstruction. The 155° humeral inclination and neckless glenosphere are the two implant features most likely to appear in a question stem.
This biographical sketch profiles Paul Grammont, designer of the reverse shoulder prosthesis. It explains the biomechanical rationale behind his 1985 design for arthritic, cuff-deficient shoulders. The piece traces the evolution from earlier failed constrained implants to the modern reverse total shoulder arthroplasty.
The core teaching point is why the reverse prosthesis works when a standard anatomic implant cannot: in a cuff-deficient shoulder, you need a different motor for elevation. Grammont's two moves solve this. Medializing the center of rotation onto the glenoid eliminates the destructive torque that loosened every prior lateralized reverse design.
Distalizing the humerus tensions the deltoid and improves its lever arm, converting the anterior and posterior deltoid into functional abductors. For boards, anchor this cause-and-effect chain: lateral center of rotation causes glenoid loosening, medialization prevents it, and deltoid retensioning substitutes for the missing cuff.
Know the classic indications: pseudoparalysis from an irreparable cuff tear, fracture sequelae, failed arthroplasty, and tumor reconstruction. The 155° humeral inclination and neckless glenosphere are the two implant features most likely to appear in a question stem.