Can convertible metal-backed glenoid components replace cemented polyethylene glenoid components in anatomical total shoulder arthroplasty?

Abstract

Background Anatomical total shoulder arthroplasty (aTSA) has been used to manage degenerative diseases such as primary osteoarthritis. An increase in the use of this procedure has led to several developments in humeral and glenoid components to improve patient outcomes. This study aimed to compare clinical and radiological outcomes of the newly-introduced convertible metal-backed glenoid components with cemented polyethylene glenoid components in aTSA, and to determine whether the new component would be comparable to a conventional one for reducing the burden of future revision or conversion surgeries. Methods Medical records of fifty patients who underwent aTSA with at least two years of follow-up were retrospectively reviewed. Eighteen patients received convertible metal-backed glenoid components with vitamin E1-coated liner (MB group), while thirty-two patients received conventional cemented polyethylene glenoid components (PE group). Pre- and postoperative clinical and radiological outcomes (acromion-greater tuberosity angle [AGA] and humeral lateral offset [LO]) at final follow-up were assessed. Radiolucent lines (RLLs) and loosening around the humeral and glenoid components were also evaluated. Results Clinical outcomes improved after surgery in both groups (all p < 0.001). The arc of rotation measured by AGA improved postoperatively in both groups (all p < 0.001), and AGA and LO were not different according to the type of glenoid components (all p > 0.05). Overall complication rates including RLLs of PE and MB groups were 43.8% (14/32) and 16.7% (3/18), respectively (p = 0.031). Although the PE group had more RLLs than did the MB group (p < 0.05), related symptoms and/or glenoid implant loosening were not observed in both groups. Subscapularis failure occurred in two patients in the PE group and in one in the MB group. Conclusion The convertible metal-backed glenoid implant with vitamin E1-coated liner may be a good alternative for considering the potential for an easier conversion to reverse total shoulder arthroplasty.