Post-operative Baseplate Radiographic Evaluation Using Routine pre-Operative CT

• Published in: Journal of shoulder and elbow arthroplasty Vol. 7; p. 24715492231211122
• Main Authors: Song, Daniel J, Lanham, Nathan S, Ahmed, Rifat, Knudsen, Michael L, Levine, William N, Jobin, Charles M
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-01-2023; Sage Publications Ltd; SAGE Publishing
• Subjects: Joint surgery; Radiography; Shoulder; Tomography; mimcs; baseplate; reverse shoulder arthroplasty; retroversion; radiolucent lines; 3D CT
• ISSN: 2471-5492; 2471-5492
• DOI: 10.1177/24715492231211122

Background
There is limited data evaluating post-operative component position and fixation in reverse shoulder arthroplasty (RSA). Therefore, the purpose of this study was to evaluate baseplate position and fixation using routine pre-operative CT and post-operative radiographs.
Methods
A retrospective analysis of a series consecutive patient who underwent primary RSA was performed. Pre-operative and post-operative glenoid retroversion and inclination were measured using radiographs aligned with projection silhouettes of 3D scapula models in Mimics software. Baseplate retroversion and inclination were measured followed by evaluating for the presence of radiolucent lines (RLLs).
Results
Twenty-four patients met inclusion criteria. The average age was 73.4 ± 10.7 years (range, 45-89 years). Radiographic follow-up was 3.4 ± 1.3 years. Post-operative glenoid baseplate retroversion was 2 ± 10 degrees (range, 30 to −9). Post-operative glenoid baseplate inclination was 3.8 ± 9.1 (range, −13 to 19). Five (21%) RSAs had baseplate retroversion >10 degrees. Follow-up radiographs revealed no RLLs around the baseplate, central post, or peripheral screws in any patient.
Conclusions
Pre-operative CT imaging enabled evaluation of baseplate component placement and fixation on post-operative radiographs. Baseplate version was within 10 degrees of neutral in 79% (19/24) of patients. No RLLs or loss of fixation were found in any cases.
Level of Evidence
Level IV: Diagnostic Study.