Survival and long-term (minimum 10-year) outcomes of bony increased-offset-reverse shoulder arthroplasty

Bony increased-offset-reverse shoulder arthroplasty (BIO-RSA) has shown promising short- to medium-term results; however, long-term outcomes are lacking. The goal of the present study was to report on survival and long-term (minimum 10-year follow-up) outcomes of BIO-RSA.

Retrospective single-center study with prospectively collected data, including 192 patients (196 shoulders) who underwent primary BIO-RSA for the treatment of osteoarthritis with cuff deficiency between 2006 and 2014. Mean age at surgery was 73 ± 7 years, and 70% were female. A structural bone graft, harvested from the humeral head, was fixed on the glenoid with a long-post baseplate, and a Grammont-type (Aequalis Reversed II [Tornier], 155° of neck-shaft angle) prosthesis was used. At a minimum of 10 years, 55 patients died, 31 were lost to follow-up, and 6 patients had dementia, leaving 100 patients (104 shoulders) to assess long-term clinical and subjective results. Graft incorporation, scapular notching, and glenoid inclination correction were assessed on 41 shoulders who accepted to come back for radiographic and computed tomographic (CT) scan analysis. The mean follow-up was 12.7 years (10-18 years).

The 10-year prosthesis survival, using Kaplan-Meier method with revision as end point, was 98% (95% confidence interval 94%-99%). Among the 196 BIO-RSAs performed, 4 (2%) were revised: 1 for traumatic postoperative humeral fracture and 3 for glenoid loosening. Glenoid loosening occurred in 5 cases (2.5%): 3 cases of aseptic loosening (all with superior tilt of the glenoid), 1 case of septic loosening, and 1 case of traumatic glenoid mobilization; there was no glenoid failure after 5 years. On the last follow-up CT scan images, we observed full integration of the bone graft without resorption in 95% (39/41). Severe (grade 3 or 4) scapular notching occurred in 32% and was associated with superior glenoid tilt (P = .002). At last follow-up, no prosthesis dislocation was reported, and acromial/scapular spine fractures occurred in 2%. The mean Constant score was 72 ± 14 points and mean Subjective Shoulder Value 80% ± 18%. Overall, 93% (98/104) were satisfied and stated that they would undergo the procedure again, if needed.

The BIO-RSA is a safe and durable surgical procedure, with 98% of prosthesis survival rate at a mean follow-up of 12.7 years (10-18 years) and 95% of complete bone graft incorporation. Bony lateralization does not increase the risk of glenoid loosening or acromial/scapular spine fractures, although it protects from prosthetic instability. Superior glenoid tilt is a risk factor for scapular notching and baseplate loosening and should be corrected.