S57 ARE NON-CEMENTED, MODULAR PROSTHESES SUITABLE FOR TOTAL SHOULDER REPLACEMENT IN RHEUMATOID ARTHRITIS?

Abstract

Introduction: The restoration of the anatomical centre of rotation can be achieved in total shouder arthroplasty (TSA) using newly developed modular shoulder prosthesis (Promos), anchored with rectangled, non-cemented shaft. Especially patients with complex pathological destructions due to rheumatoid arthritis (RA) should benefit from this feature. So far it was not clear, whether the concept works in their poor bone stock too. The aim of this prospective study was to assess outcome and complication rate of patients with RA and Omarthrosis (OA) after TSA with Promos prosthesis.

Materials and Methods: All patients that received a TSA either due to OA or due to RA were prospectively recorded and evaluated 6 and 12 month after surgery. Functional outcome and quality of life was charged with a standardized scores set (DASH, Constant-Murley score, SPADI, ASES and SF-36, all normalized from 0=worst to 100=best) and compared with normative data as well as with data from a retrospective control, operated with an Aequalis prosthesis. Number and types of complications were recorded and the radiological findings evaluated from an independent observer.

Results: Although RA patients (n=8) did not reach the same functional results than OA patients (n=53) operated with Promos“ prostheses (DASH 78 in OA vs. 67.4 in RA, CS 74.3 in OA vs. 67.6 in RA) the difference between both indication groups was significantly smaller than for the Aequalis prosthesis (p< 0.001). Whereas RA patients after Promos“ prosthesis revealed functional deficits ranging from −6.7 in the Constant score, −10.6 in the DASH to −11.1 in the SPADI, this difference was larger in the Aequalis group with −16.4 in the Constant score, −25.2 in the DASH and −19.6 in the SPADI. Radiological findings and complication rate did not differ significantly.

Discussion: The newly developed modular design of the Promos prosthesis seems to offer better features to restore the complex anatomy, especially in RA patients. The required cementless shaft anchorage is not associated with a higher complication risk. Methodological issues limit the comparison of the two studies and the differences have to be proven in a prospective, comparative study therefore.