Eiji Itoi

Purpose Radiographic measurements have gained wide acceptance in anticipating the risk of inappropriate glenoid component positioning in reverse shoulder arthroplasty (RSA). This study aims to investigate whether the RSA angle overcorrects the base plate inclination, tilting it inferiorly, compared to the base plate correction angle (BCA), which provides neutral inclination and lateralization. Methods One hundred normal anteroposterior shoulder radiographs were evaluated to determine the average values of the RSA angle, BCA, base plate orientation angle (BOA), and the base plate shoulder angle (BSA), which represents the amount of overcorrection accomplished via the RSA angle beyond the BCA’s scope. The interobserver reliability among two independent testers was assessed by the intraclass correlation coefficient. A t-test was applied to compare the mean values of the BCA and RSA angle. Results The mean BOA and BCA values were 118° ± 5.7° and 17° ± 4.6°, respectively. The RSA angle value was 23° ± 6°. Compared to the BCA, the RSA angle overcorrected the base plate inclination by 15° ± 5° (BSA). The Student’s t-test showed a statistically significant difference between the values of the BCA and RSA angle (p-value = 0.000). The interobserver reliability was excellent for all angle measurements among two independent testers. Conclusion The RSA angle and the BOA/BCA are reliable radiographic measurements to determine the inclination of the inferior glenoid segment prior to RSA. However, surgeons need to consider the inherent inferior inclination associated with positioning the base plate according to the RSA angle (15° ± 5°).

Aizawa K, et al. Clin Orthop Surg. 2024 Dec;17:e3. https://doi.org/10.4055/cios24079

Objectives: The purpose of this study was to prospectively investigate the progression of cartilage thinning in patients with symptomatic rotator cuff tears using MRI. Methods: Two hundred twenty-five consecutive patients with symptomatic rotator cuff tears visited our institute between 2009 and 2019. Of these, 28 shoulders of 27 patients (mean age, 65 years) who underwent at least two magnetic resonance imaging (MRI) examinations were prospectively enrolled. They all received conservative treatment. The mean follow-up was 67 months. Changes in cartilage thickness and the combined cartilage and subchondral bone thickness at the initial and final MRI were measured using a RadiAnt DICOM-viewer (Medixant, Poznan, Poland). The cartilage thickness of the humeral head was measured in the oblique coronal and sagittal images. The glenoid cartilage was measured in the axial and oblique coronal images. Results: At an average period of 5 years, 12 of 28 shoulders (42%) showed more than a 30% decrease in cartilage thickness in the humeral head. The glenoid showed cartilage thinning in only one shoulder (4%). In the humeral head, progressive cartilage thinning was seen mainly in the anterior and posterior parts of the humeral head in the sagittal plane. In the glenoid, progressive cartilage thinning was seen on the entire surface except the posterior area. There was no significant difference in cartilage thickness between the first and final follow-ups for both the humeral head and the glenoid. Conclusions: A total of 12 of 28 shoulders (42%) showed more than a 30% decrease in cartilage thickness in the humeral head, which was mainly observed in the anterior and posterior areas of the humeral head.