This landmark paper explains the design rationale and biomechanics of Grammont's reverse shoulder prosthesis (Delta III). It asks: why did this design succeed where all prior constrained prostheses failed, and do the biomechanical advantages translate to clinical results? Boileau reports outcomes in 45 cuff-deficient shoulders with mean 40-month follow-up.
Every prior constrained shoulder prosthesis failed by keeping the center of rotation lateral to the scapula, generating torque that destroyed glenoid fixation. Grammont solved this by eliminating the glenoid neck entirely — a single geometric change that defines all modern reverse shoulder arthroplasty.
When evaluating a patient with cuff tear arthropathy and pseudo-paralysis, check teres minor on MRI before consenting for reverse shoulder arthroplasty. Fatty infiltration or tearing predicts zero active external rotation postoperatively, which changes the conversation. And may indicate a simultaneous latissimus dorsi transfer.
When operating in revision cases, counsel patients that reoperation risk is 42%, versus 5% in primary cuff tear arthropathy. Treat revision RSA as a salvage procedure with correspondingly guarded expectations.
The scapular notching rate of 74% identified here directly drove subsequent technical refinements. Inferior glenoid tilt (15–20°) and lateralized glenosphere designs. That define contemporary RSA practice.
This landmark paper explains the design rationale and biomechanics of Grammont's reverse shoulder prosthesis (Delta III). It asks: why did this design succeed where all prior constrained prostheses failed, and do the biomechanical advantages translate to clinical results? Boileau reports outcomes in 45 cuff-deficient shoulders with mean 40-month follow-up.
Every prior constrained shoulder prosthesis failed by keeping the center of rotation lateral to the scapula, generating torque that destroyed glenoid fixation. Grammont solved this by eliminating the glenoid neck entirely — a single geometric change that defines all modern reverse shoulder arthroplasty.
When evaluating a patient with cuff tear arthropathy and pseudo-paralysis, check teres minor on MRI before consenting for reverse shoulder arthroplasty. Fatty infiltration or tearing predicts zero active external rotation postoperatively, which changes the conversation. And may indicate a simultaneous latissimus dorsi transfer.
When operating in revision cases, counsel patients that reoperation risk is 42%, versus 5% in primary cuff tear arthropathy. Treat revision RSA as a salvage procedure with correspondingly guarded expectations.
The scapular notching rate of 74% identified here directly drove subsequent technical refinements. Inferior glenoid tilt (15–20°) and lateralized glenosphere designs. That define contemporary RSA practice.