Grammont's idea: The story of Paul Grammont's functional surgery concept and the development of the reverse principle

Abstract

Background: The increased use of the reverse prosthesis over the last 10 years is due to a large series of publications using the reverse prosthesis developed by Paul Grammont. However, there is no article reporting the story of the concepts developed by Grammont.

Questions/purposes: The purposes of this review are to describe the principles developed by Grammont, the chronology of development, and the biomechanical concepts and studies that led to the current design of the reverse prosthesis.

Methods: We selectively reviewed literature and provide personal observations.

Results: From phylogenetic observations, Grammont developed the principle of functional surgery applied to the rotator cuff tears. To increase the deltoid lever arm, he imagined two possibilities: the lateralization of the acromion, which facilitates the action of the rotator cuff, and the medialization of the center of rotation, which has been developed to respond to situations of rotator cuff deficiency. Grammont proposed the use of an acromiohumeral prosthesis, which was quickly abandoned due to problems of acromial loosening. Finally, Grammont used the principle of reverse prosthesis developed in the 1970s, but made a major change by medializing the center of rotation in a nonanatomic location. In 1985, Grammont validated the concept by an experimental study and the first model using a cemented sphere was implanted.

Conclusions: The development of the modern reverse prosthesis is the result of the intellectual and experimental work conducted by Grammont and his team for 20 years. Knowledge of this history is essential to envision future developments.

Fig. 1

An original diagram from Paul Grammont shows the “medializing” prosthesis design. His first idea was to propose a varus position of the humeral head to medialize the COR and to increase the deltoid lever arm. A rotating system has been imagined at the junction between the stem and the neck of the prosthesis. Image from the personal archives of Emmanuel Baulot. COR = center of rotation.

Fig. 2

A photograph shows the first prototype of the “medializing” prosthesis. This prototype was based on the drawing of Grammont but does not include the metaphyseal rotation system. The stem was screwed. This prototype was never implanted. Image from the personal archives of Emmanuel Baulot.

Fig. 3

A diagram from Paul Grammont illustrates the “Acropole” prosthesis. This prosthesis used the principle of an acromiohumeral resurfacing. About 20 such prostheses were implanted by Grammont. Most of them had acromial component loosening. Image from the personal archives of Emmanuel Baulot.

Fig. 4

The “Ovoide” prosthesis is shown. This prosthesis has theoretically two CORs. It obtained medialization by early elevation. Approximately 10 such prostheses were implanted, but it was abandoned because of problems of instability. Image from the personal archives of Emmanuel Baulot. COR = center of rotation.

Fig. 5

The “Trompette” reverse prosthesis is shown. This is the modern version of the “medializing” reverse prosthesis as Grammont had imagined. The prototype dates from 1985 and the first implantation was in 1986. This prosthesis included a polyethylene humeral component and an alumina ceramic glenoid component with a volume equivalent to 2/3 of a sphere of 44 mm. Image from the personal archives of Emmanuel Baulot.