Radiographic changes around the glenoid component in primary reverse shoulder arthroplasty at mid-term follow-up

Some local events after reverse shoulder arthroplasty (RSA) occur without the patient experiencing symptoms and yet may be detected on diagnostic imaging, thereby serving as indicators of future complications that may require revision. Most of these events involve the glenoid component, but radiographic studies evaluating this component are scarce, especially medium- and long-term studies. This study aimed to analyze the radiographic changes around the glenoid component and determine the risk factors associated with the presence of these radiographic changes.

A retrospective review of 105 primary Grammont-style RSAs implanted between 2003 and 2014 was conducted. Radiographic outcomes were evaluated in patients with ≥5 years of radiographic follow-up. Standardized digital radiographs obtained immediately postoperatively and at a minimum follow-up time of 5 years were analyzed to determine (1) glenoid component position (inclination and height) and (2) minor radiographic changes (Sirveaux grade 1 or 2 scapular notching; nondisplaced acromial fracture; radiolucent lines around 1 or 2 screws; Brooker grade 1a, 1b, or 2 heterotopic calcifications; or single screw rupture), as well as major radiographic changes (Sirveaux grade 3 or 4 scapular notching; radiolucent lines around ≥3 screws or central peg; Brooker grade 1c or 3 heterotopic calcifications; prosthetic dislocation; loosening or migration; or disassembly).

Major radiologic changes were identified in 14.3% of the cases. Bivariate analysis showed that more changes were associated with the arthroplasties implanted in the first years of the study (odds ratio [OR] = 0.81, P = .012). This time-related variable was also associated with inclination (OR = 0.88, P = .045) and height (OR = 0.75, P = .001), improving in arthroplasties implanted in the last years of the study. Multivariate analysis revealed an increased risk of severe scapular notching mainly associated with superior tilt (OR = 2.52, P = .036) and a high (OR = 2.68, P = .019) or excessively high (OR = 7.55, P = .013) position and an increased risk of loosening signs associated with superior tilt (OR = 8.92, P = 9.1 × 10^-6).

The percentage of radiologic changes of the glenoid component in RSA is considerable, despite the detection of a decrease in their presence among the arthroplasties implanted outside the initial period. Superior tilt and an excessively high position appear to be associated with a severe degree of scapular notching development and increased risk of radiographic loosening signs. Knowledge of the factors associated with major radiologic changes in the medium-term follow-up will help to optimize the primary surgical technique for each patient and indication, improving implant survival in primary RSA surgery.