A smaller preoperative-to-prosthetic center of rotation shift is associated with better range of motion after bony increased-offset reverse shoulder arthroplasty: A retrospective cohort study of 97 patients by the FP-UCBM Shoulder Group
Mauro Ciuffreda, Piergianni Luigi Di Santo, Antonino De Rosa, Edoardo Franceschetti, Michele Paciotti, Giovanni Perricone, Chiara Capperucci, Mauro La Bruna, Pietro Gregori, Rocco PapaliaBackground
Reverse shoulder arthroplasty (RSA) alters the glenohumeral center of rotation (CoR), but the relevance of preoperative-to-prosthetic CoR shift remains unclear. This study evaluated its association with postoperative outcomes after bony increased-offset RSA (BIO-RSA).
Methods
We retrospectively reviewed 120 patients undergoing BIO-RSA with a 145° onlay humeral stem and a minimum 24-month follow-up; 97 met inclusion criteria. CoR positions were quantified using angular measurements based on reproducible scapular landmarks. Preoperative measurements were obtained from scapular-plane computed tomography reconstructions and postoperative measurements from 2-year true anteroposterior radiographs. ΔCoR was defined as Pre-CoR angle minus Post-CoR angle. Outcomes included visual analog scale pain, Constant–Murley score, Simple Shoulder Test, and active range of motion; associations were assessed using linear-regression and Spearman correlation analyses.
Results
Each 1° increase in ΔCoR was associated with lower postoperative abduction (−1.13°,
Conclusion
A smaller preoperative-to-prosthetic CoR shift may be associated with greater elevation after BIO-RSA. Given the weak associations, ΔCoR should be interpreted cautiously as a radiographic parameter rather than an independent predictor.