The aim of this study was to compare the clinical and radiological outcomes of reverse shoulder arthroplasty (RSA) using small and standard baseplates in Asian patients, and to investigate the impact of a mismatch in the sizes of the glenoid and the baseplate on the outcomes. This was retrospective analysis of 50 and 33 RSAs using a standard (33.8 mm, ST group) and a small (29.5 mm, SM group) baseplate of the Equinoxe reverse shoulder system, which were undertaken between January 2017 and March 2021. Radiological evaluations included the size of the glenoid, the Aims
Methods
We evaluated clinical and radiographic outcomes of total shoulder
arthroplasty (TSA) using the second-generation Trabecular Metal
(TM) Glenoid component. The first generation component was withdrawn
in 2005 after a series of failures were reported. Between 2009 and
2012, 40 consecutive patients with unilateral TSA using the second-generation
component were enrolled in this clinical study. The mean age of
the patients was 63.8 years (40 to 75) and the mean follow-up was
38 months (24 to 42). Patients were evaluated using the Constant score (CS), the American
Shoulder and Elbow Surgeons (ASES) score and routine radiographs.Aims
Methods
The glenopolar angle assesses the rotational
alignment of the glenoid and may provide prognostic information
and aid the management of scapula fractures. We have analysed the
effect of the anteroposterior (AP) shoulder radiograph rotational
offset on the glenopolar angle in a laboratory setting and used
this to assess the accuracy of shoulder imaging employed in routine
clinical practice. Fluoroscopic imaging was performed on 25 non-paired scapulae
tagged with 2 mm steel spheres to determine the orientation of true
AP views. The glenopolar angle was measured on all the bony specimens
rotated at 10° increments. The mean glenopolar angle measured on
the bone specimens in rotations between 0° and 20° and thereafter
was found to be significantly different (p <
0.001). We also obtained
the AP radiographs of the uninjured shoulder of 30 patients treated
for fractures at our centre and found that none fitted the criteria
of a true AP shoulder radiograph. The mean angular offset from the
true AP view was 38° (10° to 65°) for this cohort. Radiological
AP shoulder views may not fully project the normal anatomy of the scapular
body and the measured glenopolar angle. The absence of a true AP
view may compromise the clinical management of a scapular fracture. Cite this article:
In 100 patients the fulcrum axis which is the line connecting the anterior tip of the coracoid and the posterolateral angle of the acromion, was used to position true anteroposterior radiographs of the shoulder. This method was then compared with the conventional radiological technique in a further 100 patients. Three orthopaedic surgeons counted the number of images without overlap between the humeral head and glenoid and calculated the amount of the glenoid surface visible in each radiograph. The analysis was repeated for intraobserver reliability. The learning curves of both techniques were studied. The amount of free visible glenoid space was significantly higher using the fulcrum-axis method (64 vs 31) and the comparable glenoid size increased significantly (8.56 vs 6.47). Thus the accuracy of the anteroposterior radiographs of the shoulder is impaired by using this technique. The intra and interobserver reliability showed a high consistency. No learning curve was observed for either technique.
