Background: Reverse total shoulder arthroplasty is currently being used to treat selected patients with disabling shoulder arthropathy. The purposes of this study were to investigate the medium-term results of reverse total shoulder arthroplasty and to analyze the influence of etiology on the result.
Methods: We carried out a multicenter study with a minimum follow-up of five years and determined the survival rate of the prosthesis according to the initial etiology of the shoulder arthropathy. Eighty prostheses were implanted in seventy-seven patients between 1992 and 1998. Sixty-six shoulders had an arthropathy with a massive rotator cuff tear, and fourteen shoulders had a disorder with another etiology (rheumatoid arthritis, trauma, or revision arthropathy). At the time of review, eighteen patients had died and two were lost to follow-up. The remaining fifty-seven patients (sixty shoulders) were examined or interviewed by telephone at a mean follow-up of 69.6 months. Cumulative survival curves were generated with replacement of the prosthesis, glenoid loosening, and a functional Constant score of <30 as the end points.
Results: The survival rate with replacement of the prosthesis and glenoid loosening as the end points were 91% and 84%, respectively, at 120 months, with shoulders that had arthropathy with a massive rotator cuff tear demonstrating a significantly better result than those that had a disorder with another etiology (p < 0.05). On the other hand, the survival rate with an absolute Constant score of <30 as an end point was 58% at 120 months, with no significant difference with respect to etiology. Two breaks were observed in the survival curves. The first concerned survival until replacement of the prosthesis and occurred at around three years, reflecting early loosening of the prosthesis. The curve then became stable. A second break started at around six years and reflected progressive deterioration of the functional result.
Conclusions: Our findings indicate that the reverse total prosthesis should be reserved for the treatment of very disabling shoulder arthropathy with a massive rotator cuff rupture, and it should be used exclusively in patients over seventy years old with low functional demands.
Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.