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We provide a link to the original description of the ''delta'' reverse shoulder arthroplasty published in 1993 by Paul Grammont and Emmanuel Baulot. While many surgeons view ''anatomic reconstruction'' as essential for virtually all operations, Grammont recognized that not all reconstructions needed to be anatomic and in fact some problems with so-called anatomic reconstructions could be solved by developing nonanatomic approaches. Through careful reasoning and intuition, Grammont and Baulot suggested placing the ball of the shoulder on the glenoid and the concave matching surface on the humerus in patients with an absent rotator cuff (essentially rendering any anatomic reconstruction ''nonanatomic'' when the cuff function could not be normally restored). They argued the deltoid muscle could compensate for an absent rotator cuff if four conditions were present: (1) a lever arm effective from the start of movement; (2) a fixed center of rotation; (3) inherent stability; (4) maintenance of adequate external rotation.

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.

Osteonecrosis of the femoral head affects mainly young patients with high functional needs this increases the risk of dislocation. Dual mobility cups known for low rate of dislocation and high mobility range seems indicated. We evaluate functional efficiency, survival and dislocation rate of dual mobility cup for total hip arthroplasty for osteonecrosis in young patients. Monocentric retrospective clinical study, from 2000 to 2008. With a clinical analysis in pre-operative and over ten years of follow-up of one cohort of patients under 55 years old with an indication of THA for ONFH. The judgement criteria was: clinical scores at the maximal follow-up, the dislocation rate, and the cumulate survival rate over ten years follow-up. Forty THA in 31 patients, nine bilateral cases, 23 males and eight females with average age of 44 (±4) years old. In pre-operative: PMA 11 (±3.3), HHS 50,8 (±15.5). At the final follow-up of 129.8 (±33.8) months: PMA (17.4 ± 1.12), HHS (95.7 ± 6.9), no dislocation. We had 11 deaths on average at 95.2 ± 47.3 months. The cumulate survival rate over ten years follow-up is 100% without revisions or long-term dislocation. Analysis concludes to very significant functional improvement without any dislocation despite the young population with high level of activity. Thus, dual mobility cups is a reliable choice preventing dislocation with a very good survival rate without premature wear, preserving mobility and activity.