Reverse shoulder arthroplasty for proximal humerus fractures: Is the glenoid implant problematic?

Abstract

Introduction: Reverse shoulder arthroplasty (RSA) is a key tool in the orthopedic trauma surgeon's arsenal, especially when faced with a proximal humerus fracture in older patients. However, few studies have focused on the glenoid side of RSA in this indication as the implant is placed in a generally healthy scapula.

Hypothesis: Glenoid implants for RSA after trauma are well positioned and do not often cause complications.

Material and methods: Retrospective multicenter study of 513 patients who underwent RSA because of a proximal humerus fracture. The mean follow-up was 55 months. Radiographs were used to assess the height and tilt of the glenoid implant, along with the development of scapular notching or loosening. The clinical outcomes were determined based on the Constant score.

Results: At the last follow-up, 44% of shoulders had scapular notching, 7% of which were severe (stages 3-4). This notching was progressive, with two resulting in loosening. The rate of severe notching was higher in patients with a high glenoid implant (62.5% vs. 42.3%, p=0.03) or glenosphere with superior tilt (58.3% vs. 37.8%, p=0.02). Nine patients had confirmed loosening and 63 had potential loosening. This was more common in cases with superior tilt (9.3% vs. 0.4%, p<0.001). Patients with a high glenoid implant had a lower Constant score (57 vs. 45, p<0.001). There fewer cases of severe notching when a lateralized glenoid implant was used (0% vs. 7%, p<0.05) and/or the humeral implant had a smaller neck-shaft angle (implants<155°: 3% vs. implants at 155°: 8.5%, p=0.03).

Discussion and conclusion: Glenoid loosening and severe scapular notching are related to poor positioning and/or incorrect orientation of the glenosphere. Implant selection is important, as there is little to no notching when less-angled humeral implants and lateralized glenoid implants are used.

Level of evidence: IV.

Keywords: Joint Prosthesis; Orthopedic Surgical Procedure; Shoulder joint; Traumatology.