[Translated article] Clinical and radiological outcomes when using standard versus retentive polyethylene humeral...

The most common postoperative complication relating to reverse total shoulder arthroplasty (RTSA) is instability. The risk factors for luxation include a lack of the subscapularis tendon or inadequate soft tissue tension, the prosthetic design, the bone deficiency, the obesity, and mechanical factors such as bone impingement and implant position.. To prevent this luxation, we can insert a retentive polyethylene humeral cup, The purpose of this study was to evaluate the clinical outcomes, the incidence of luxation and scapular notching between standard versus retentive polyethylene humeral cups in Delta III RTSA.

51 patients with rotator cuff insufficiency and osteoarthritis who underwent primary Delta III PIH using a standard and retentive polyethylene humeral cup were retrospectively reviewed between September 2018 and December 2023. The main indication for placing the retentive polyethylene was the complete and irreparable chronic rupture of the subscapularis tendon with impossibility of reinsertion and with muscle atrophy. The average follow-up was 42,4 months (41,6 and 44,3 months respectively) Results. 51 patients were reviewed: 35 with standard humeral cups and 16 with retentive polyethylene humeral cups. We found no prosthesis luxation in either of the two study groups and there were no differences in forward flexion, abduction or internal rotation between the two groups at the end of the follow-up. There was a lower mean for external rotation in the retentive polyethylene humeral cup group (average,36.3 ± 11,6 vs 28,7 ±10,9) but it was not statistically significant. There was no statistical difference in the postoperative Constant score at the end of the follow-up. The incidence of scapular notching was 62.8 % and 62.5 % for the standard and retentive polyethylene humeral cups, respectively.

The Delta III rTSA using either a standard or retentive polyethylene humeral cups provide functional improvement and pain relief. There were no differences between the two groups in clinical mobility, forward flexion, abduction, internal rotation, external rotation, incidence of luxation and scapular notching Level of evidence: Level III; Retrospective Cohort Comparison; Treatment Study.