Grammont and Baulot's 1993 paper introduced the Delta Shoulder Prosthesis — a reverse ball-and-socket design placing the convex component on the glenoid and the cup on the humerus. The central question: can the deltoid alone restore shoulder function when the rotator cuff is irreparably absent? This paper established the biomechanical logic underlying every modern reverse total shoulder arthroplasty implant.
Every reverse total shoulder arthroplasty implant used today traces its geometry back to Grammont's four conditions. Before this framework, reverse designs failed because they lacked a fixed fulcrum and placed excessive torque on glenoid fixation.
When you see a patient with rotator cuff arthropathy and pseudoparalysis (active forward elevation below 90 degrees), Grammont's logic is why reverse TSA is the reconstruction of choice rather than hemiarthroplasty or anatomic TSA.
The medialized, distalized center of rotation is not arbitrary; it is the specific geometric change that recruits the anterior and posterior deltoid as elevators from zero degrees of abduction onward.
Recognize that this paper's sample was only 14 patients at 2 years. The durability data that validated the design came from subsequent larger series, but Grammont's four biomechanical conditions remain the testable foundation on the OITE and in clinical practice.
Grammont and Baulot's 1993 paper introduced the Delta Shoulder Prosthesis — a reverse ball-and-socket design placing the convex component on the glenoid and the cup on the humerus. The central question: can the deltoid alone restore shoulder function when the rotator cuff is irreparably absent? This paper established the biomechanical logic underlying every modern reverse total shoulder arthroplasty implant.
Every reverse total shoulder arthroplasty implant used today traces its geometry back to Grammont's four conditions. Before this framework, reverse designs failed because they lacked a fixed fulcrum and placed excessive torque on glenoid fixation.
When you see a patient with rotator cuff arthropathy and pseudoparalysis (active forward elevation below 90 degrees), Grammont's logic is why reverse TSA is the reconstruction of choice rather than hemiarthroplasty or anatomic TSA.
The medialized, distalized center of rotation is not arbitrary; it is the specific geometric change that recruits the anterior and posterior deltoid as elevators from zero degrees of abduction onward.
Recognize that this paper's sample was only 14 patients at 2 years. The durability data that validated the design came from subsequent larger series, but Grammont's four biomechanical conditions remain the testable foundation on the OITE and in clinical practice.