Short-Term Outcomes of the Grammont Reverse Shoulder Arthroplasty: Comparison between First and Second Generation Delta Prosthesis.

 This article compares short-term outcomes of two series of patients, who underwent reverse total shoulder arthroplasty (RTSA) with two different implants, both based on Grammont's principles: the Delta III (D-3) and the Delta Xtend (D-XT) prostheses.  The D-3 group included a consecutive series of 26 patients (mean age 75 years), that were treated between 2000 and 2006; the D-XT group included a consecutive series of 31 patients (mean age 72.5 years), for a total of 33 implants performed between 2011 and 2015. In both groups the most common diagnoses were cuff tear arthropathy (18 and 22 shoulders, respectively) and malunion of proximal humerus fractures (3 and 5). All procedures were performed by the same surgeon. Constant-Murley score (CMS) was used to assess clinical and functional outcomes. Radiographic evaluation included the true anteroposterior and axillary views.  Twenty-three patients of the D-3 group and 22 patients (24 shoulders) of the D-XT group were evaluated at a mean follow-up of 42 months (range 26-84) and 44 months (range 26-66), respectively. Four complications occurred in the D-3 group (1 partial deltoid detachment, 1 dislocation, and 2 glenoid component loosening), while one early postoperative infection occurred in the D-XT group. Increases in elevation and CMS between preoperative and postoperative period were observed in both groups; only the D-XT group showed a slight improvement in rotations. The incidence of scapular notching was significantly different between the two groups: 100% for D-3 and 22.2% for D-XT in patients with a minimum follow-up of 5 years.  Prosthetic design evolution and greater acquaintance with this surgery have undoubtedly led to an improvement in short-term outcomes with second generation implants of RTSA. Future studies will have to ascertain whether newer implants, relying on biomechanical solutions alternative to Grammont's original concept, might provide additional advantages and minimize drawbacks.