Abstract Objectives To describe typical MRI findings 1 year after reverse total shoulder arthroplasty (rTSA) implantation. Materials and methods Metal artifact reduction (MARS) MRI including CSSEMAC techniques was prospectively acquired in N = 25 consecutive patients (18/25 female; 61–80 years) 1 year after rTSA. MRI findings of bone and soft tissue and artifact reduction were assessed semi-quantitatively. Clinical Constant-Murley scores (CMS) were obtained, including its subscores pain, activities-of-daily-living (ADL), range-of-motion (ROM), and strength. Preoperative MRI was available in 13/25 subjects. Statistical analyses included descriptive statistics, Spearman correlations, nonparametric tests, and multivariable regression models. Results MARS MRI of rTSA showed overall good image quality. Subacromial edema (88%), mild effusion (52%), and synovitis (44%) were frequent postoperative findings. Synovitis was associated with more pain ( B = −2.044, 95% CI −3.617, −0.470, p = 0.039) and lower strength ( B = −4.497, 95% CI −7.101, −1.893, p = 0.008). Minor bone marrow edema (BME) at the shaft was found in all subjects (100%). BME in Gruen zone 4 (88%) and 6 (80%) was most frequent. A higher number of Gruen zones with BME correlated significantly with lower ADL ( R = −0.532, p = 0.024). There was a significant increase in fatty infiltration between pre- and postoperative images for the midacromial deltoid muscle (1 (IQR, 1–1) versus 2 (IQR, 1–2), p = 0.008; postoperatively present 100%). It was associated with an increase in deltoid length (chi-square 4.35, p = 0.037), but not with inferior clinical scores. However, fatty infiltration of the more anterior deltoid muscle was associated with lower ADL ( B = −3.064, p = 0.008). Conclusion Subacromial edema, minor shaft BME, and fatty infiltration of the midacromial deltoid muscle were typical, asymptomatic MRI findings 1 year after rTSA.
Jungmann et al. (Wed,) studied this question.