BONY INCREASED OFFSET REVERSE SHOULDER ARTHROPLASTY (BIO-RSA) VERSUS METAL AUGMENTS: A SYSTEMATIC REVIEW

Reverse shoulder arthroplasty (RSA) is often employed to manage acute or chronic traumatic sequelae and rotator cuff arthroplasty, with lateralised designs increasing in popularity. Glenoid side lateralisation was initially popularised through the use of bony increased offset reverse shoulder arthroplasty (BIO-RSA). Novel implants use augmented metal glenoid baseplates to lateralise the implant, however little is known about how these patients compare to those with BIO-RSA.This systematic review and meta-analysis aimed to compare outcomes between bone increased offset (BIO-RSA) or metal increased offset (MIO-RSA) in patients with RSA.A detailed search of Pubmed, Cochrane, Medline and EMBASE was carried out, including all studies focusing on primary reverse total shoulder replacements with lateralised glenoid components using either bone graft (BIO-RSA) or metal augments (MIO-RSA). Collected data for included studies included demographics, method of lateralisation and complications.Two-thousand-one hunded-sixty (2160) patients were included in 28 studies, with a mean age of 72.6 (23- 93), with 57.7% being female. 964 patients underwent BIO-RSA and 1196 underwent MIO-RSA. After a mean follow-up of 32.7 months (3–126), there was no significant difference in range of movement post-operatively. There was a significantly lower pain score (p<0.01) and higher Constant (p=0.02), ASES (p=0.02) and UCLA (<0.01) scores in patients post MIO-RSA. Moreover, there was lower rates of revisions (1.3% v 3.0%, p<0.01), loosening (0.8% v 2.6%, p<0.01) and scapular notching (4.0% v 17.9%, p<0.01) in the MIO-RSA group.This systematic review and meta-analysis has shown favourable outcomes with MIO-RSA when compared with BIO-RSA. BIO-RSA and MIO-RSA outcomes are summarised, but contemporary literature is too heterogenous to allow direct comparison. Long term studies are required to ascertain if this effect is maintained.