A Short and Convertible Humeral Stem for Shoulder Arthroplasty

Abstract

Introduction As the revision number of shoulder arthroplasties increases, we focused on the difficulties of extracting or converting the humeral stem. The purpose of this multicentric study was to assess the outcomes and the radiographic results of a new, short, and convertible humeral stem (Aequalis Ascend™ Flex, Tornier SAS–Wright Medical Inc®, Bloomington, MN, USA), which could settle these complex revision problems. Methods Sixty-six primary shoulder replacements were enrolled with an average follow-up of 25.6 months (24–30.8 months). There were 24 reversed shoulder arthroplasty (RSA) and 42 anatomical shoulder arthroplasty. The functional outcomes were evaluated with the Constant-Murley score (CS) and the active range of motion. Humeral stems were radiologically analyzed at the last follow-up with special care to mechanical complications and bone resorption. Results The average CS improved from 30 preoperatively to 74 postoperatively ( P < .0001) for anatomical shoulder replacements and from 21 to 63 ( P < .0001) for RSA. The active anterior elevation and external rotation improved from 97° and 6° to 163° and 46°, respectively, for anatomical prosthesis ( P < .0001) and from 79° and 10° to 139° and 28°, respectively, for RSA ( P < .0001). No mechanical complication or loosening was reported. The comparison between postoperative and last follow-up X-rays showed a tendency to medial cortical bone thinning in some cases without any clinical relevance. Conclusion Two years follow-up of this short stem showed promising clinical and radiographic results without implant-related complication. Further X-rays study would be necessary. Level of evidence: IV