Dissociation of the Glenosphere: A rare Post-operative Complication of Reverse shoulder Replacement

Introduction: Reverse shoulder replacement (RSR) has been accepted as the treatment of choice for glenohumeral arthritis with irreparable rotator cuff tear. Dislocation has been a potential complication of RSR but glenosphere disengagement is a rare complication itself. There have been only few published reports of this complication in the literature. Case Report: In this case report, we have presented a case of repeated disengagement of glenoid sphere post-RSR in a 72-year-old male retired army personnel operated with Zimmer Biomet comprehensive RSR design. Conclusion: In our case scenario, we postulate that soft-tissue interposition was the reason for disengagement during first episode and was successfully relocated after removal. However, the subsequent disengagement was due to improper seating of sphere due to large central screw. Revision to a smaller central screw size appears to be the definitive solution in such case. Keywords: Reverse shoulder replacement, glenosphere disengagement, glenohumeral arthritis, irreparable rotator cuff tear.

Prospective multicentre mid-term clinical and radiological outcomes of 159 reverse total shoulder replacements and assessment of the influence of post-operative complications

Background The aim of our prospective multicentre study is to evaluate the five-year follow-up outcomes of primary reverse shoulder replacement utilizing two different designs of glenoid baseplates. Methods There were 159 reverse shoulder replacements (91 cemented and 68 uncemented stems, 67 Trabecular Metal baseplates and 92 Anatomical Shoulder baseplates in 152 patients (99 women) with a mean age of 74.5 (58–90) years. The principal diagnosis was rotator cuff arthropathy in 108 shoulders. Results Clinical and functional results improved significantly overall; the adjusted Constant Murley score improved from 28.2 ± 13.3 pre-operatively to 75.5 ± 22.8 ( p < 0.0001) and the mean Subjective Shoulder Value improved from 27.5 ± 20 to 73.8 ± 21.3 points ( p < 0.0001). Radiologically, there was good bony stability in 88% and 86% of cemented and uncemented stems without significant impact on the Constant Murley score and Subjective Shoulder Value at one, two and five years post-surgery. There were no significant clinical differences between Trabecular Metal and Anatomical Shoulder baseplates at five years. There were four cases of intraoperative shaft fractures that were managed with cables. Although the Trabecular Metal baseplates showed better integration radiologically, there was no significant difference in the mean of Constant Murley, Subjective Shoulder Value and the range of motion depending on the grade of inferior scapular notching at one-, two- and five-year intervals. Conclusions Reverse total shoulder arthroplasty restores the function in shoulder with significant improvements in function and moderate complications with minor differences between both designs of baseplates that were not reflected clinically.

Numerical Study of the Biomechanical Behaviour of the Different Implantation Methods of the Reverse Shoulder Replacement

Despite the widespread use of reverse total shoulder arthroplasty, there is still a problem of conflict between the polyethylene cup of the prosthesis and the scapula, which over time causes the phenomenon of notching. In order to circumvent this problem correctly, several innovations have been proposed regard to the implementation method. In this context, the aim of this work is to study the biomechanical behavior of new implantation methods using different glenoid configurations in order to avoid the notching phenomenon between the cup and the scapula. The study was performed using virtual prototypes of the shoulder prosthesis assembly. Using CT scan images, three-dimensional models of shoulder bones were reconstructed. The implantation of the prosthesis in the three-dimensional model was performed in collaboration with an experienced surgeon from the Caduceus Clinic (Oran, Algeria). The numerical models were imported to finite element calculation software. After the validation of the numerical model using the literature results, we assessed the biomechanical behavior of four implantation methods under the same boundary conditions and abduction movements. From the obtained results, it was found that among the proposed methods, the BIO-SR lateralization method offers significant biomechanical advantages in terms of the forces applied to the glenoid during the abduction movement.

Failed shoulder stabilization procedure in the elderly: reverse shoulder replacement is the treatment ultimum

<p class="abstract">Shoulder instability, though often seen in younger individuals it can also occur in the elderly. Shoulder instability in the elderly is often missed and definitive management gets delayed. Treatment delay has a significant influence on the choice of surgical procedure and its functional outcome. We report a 77 year old female who presented with a missed anterior dislocation of the glenohumeral joint. She had undergone an open Latarjet procedure for shoulder instability eight months before her presentation. Considering her age, humeral head bone defects, rotator cuff tear and degenerative changes in the joint we opted for a Reverse Shoulder Replacement in her. The patient now has a pain free, stable and mobile shoulder joint. Her pre-operative Constant score was 11 which improved to 67 at 6 months follow up. Now after 12 months follow up, she has active flexion up to 150°, abduction- 90°, external rotation- 10°, internal rotation- 30⁰ and extension- 50°. Reverse shoulder replacement is a viable treatment option for chronic locked shoulder dislocations with concomitant rotator cuff lesions. Though there is a concern about failure of the glenoid component due to bone defects, RSA is still preferable in elderly patients with low functional demand.</p>