Reverse shoulder arthroplasty: does reduced medialisation improve radiological and clinical results?

The purpose of this retrospective study was to assess the effect of the reduced medialisation of the Arrow reverse shoulder prosthesis on short-term clinical and radiological results. The clinical and radiological results of 47 Delta III reverse prostheses and 49 Arrow reverse prostheses were retrospectively compared at a minimum of twelve months follow-up. There was a significant increase (p < 1.10(-4)) in range of motion from the preoperative range in the two groups except for internal rotation in the Delta III group (p = 0.1). Radiological analysis on anteroposterior view in neutral position showed greater lateralisation (p < 0.001) with the Arrow prosthesis. Scapular notching was noted in 32 patients with a Delta III prosthesis, and in no instance with an Arrow prosthesis. Complication rates were 14.9% for the Delta group and 10.2% for the Arrow group. The design features of the Arrow prosthesis--reduced medialisation of the center of rotation with lateralisation of the humerus--were found to be associated with slight improvement in range of motion and absence of scapular notching.