Revision of shoulder replacements using modular components: a systematic review.

Abstract

The advent of modular implants aims to minimize morbidity associated with revision of hemiarthroplasty or anatomic total shoulder arthroplasty (aTSA) to reverse shoulder arthroplasty (rTSA) by allowing retention of the humeral stem. This systematic review aimed to summarize outcomes following the use of modular implants and reasons why modular humeral stems may be revised. A systematic review of PubMed, MEDLINE, and Embase was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines of all patients undergoing revision of a modular hemiarthroplasty or aTSA to rTSA. Primary implants, glenoid revisions, surgical technique, and opinion-based reports were excluded. Collected data included demographics, outcomes, and incidence of complications. Three hundred eighty-one shoulders in 374 patients with a mean age of 68.6 years (range: 44-91 years) were studied, with 95 (24.9%) being male. A total of 123 hemiarthroplasties and 183 aTSA were revised to rTSA at an average of 48.9 months (range: 3-432 months) following the primary operation. The most common reason for revision was cuff failure (28 patients). Two hundred sixty-three patients underwent modular conversion and 118 underwent stem revision. Of those who underwent humeral stem revision, 23 were exchanged because stem position was deemed too proximal, 5 stems were exchanged due to loosening, and 1 was exchanged due to significant retroversion of the index implant compromising stability. Three stem revisions required osteotomy and cerclage wiring of the humerus. After a mean follow-up of 41.3 months (range: 12-91), the Constant score improved from a mean of 24.4 to 49.9 in the retention group, but worsened from 38.5 to 35.5 after stem exchange. Stem exchange of modular implants was associated with a significantly higher risk of infection and periprosthetic fracture. The increased use of modular stems has reduced stem revision; however, more than 30% of these implants still require revision due to intraoperative findings. Further large-volume comparative studies between revised and maintained humeral stems post revision of modular implants can adequately inform implant innovation to further improve the stem revision rate.