Clinical and radiological outcomes when using standard versus retentive polyethylene humeral cups in Delta III reverse shoulder arthroplasty

Clinical and radiological outcomes when using standard versus retentive polyethylene humeral cups in Delta III reverse shoulder arthroplasty | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Clinical and radiological outcomes when using standard versus retentive polyethylene humeral cups in Delta III reverse shoulder arthroplasty Manuel Zafra, Pilar Uceda, Luis E Gracia, Sergio Gonzalez, Pilar Font This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7199453/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background. The most common postoperative complication relating to reverse total shoulder arthroplasty (rTSA) is instability. To prevent 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. Materials and methods. Consecutive patients undergoing primary Delta III sTSA between September 2018 and December 2023 using standard versus retentive polyethylene humeral cups were retrospectively reviewed. The minimum clinical follow-up was of 12 months. Results. Fifty-one patients underwent rTSA during the study period: 35 with standard humeral cups and 16 with retentive polyethylene humeral cups. We found no prosthesis luxation in either of the two study groups. At the end of the follow-up, there were no differences in forward flexion, abduction or internal rotation between the two groups. There was a lower mean for external rotation in the retentive polyethylene humeral cup group 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. Conclusion. The Delta III rTSA using standard vs 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 Reverse shoulder arthroplasty polyethylene humeral cup range of motion outcomes notching Figures Figure 1 Introduction Reverse total shoulder arthroplasty (rTSA) is an effective surgical treatment for several pathologies affecting the shoulder [ 1 , 2 ]. Paul Grammont introduced the principle of medialization of the centre of rotation and decreasing the force required by the deltoid for abduction owing to the longer moment arm [ 3 – 5 ]. Despite the improved results of this procedure, there were a number of problems including instability caused by subscapularis muscle deficit or by inadequate soft tissue tensioning [ 6 , 7 ]. To lessen the risk of luxation, meticulous re-attachment of the scapularis to the bone, whenever possible, cementing the humeral component into a 10º retroversion position, and attempting to increase the deltoid offset and tension by increasing the size and thickness of polyethylene insert, were all undertaken [ 8 ]. Another option for preventing luxation is to use a retentive humeral polyethylene cup; this component, with its deeper concavity (Fig. 1) and therefore greater contact with the lower part of the glenoid, can lead to less mobility or a greater appearance of radiological abnormalities, especially scapular notching. The purpose of this study was to compare the clinical and radiological outcomes of rTSA using a standard versus a retentive polyethylene humeral polyethylene cup. The primary indication for the retentive polyethylene humeral cup was a lack of subscapularis tendon or soft tissue tension. Our primary hypothesis was that both patient groups would have an equal number of luxations; secondarily, that patients would have similar clinical outcomes. Materials and methods Consecutive patients undergoing rTSA between September 2018 and December 2023 were retrospectively reviewed. Patients were included if they had a minimum clinical follow-up of 12 months and underwent primary rTSA with a standard or retentive polyethylene humeral cup. The indications for rTSA were rotator cuff tear arthropathy, a massive irreparable rotator cuff tear with chronic loss of elevation, post-traumatic glenohumeral arthritis, primary osteoarthritis and rheumatoid arthritis. Patients were excluded if they were undergoing revision surgery, or had infection, an acute fracture, Parkinson's disease or a tumour. Patients were divided into 2 groups based on whether they had a standard or retentive polyethylene humeral cup. The authors used intraoperative criteria for assignment to each group. To avoid selection bias, the authors took into account the variables of age, sex and pathology causing the surgery so that the assignment to each group was as evenly matched as possible. The clinical and radiological outcomes of both groups were analysed. Demographic data were collected prospectively and analysed retrospectively. All surgical procedures were performed by the senior author and were conducted with the patient in a beach chair position under general anaesthesia and with an interscalene block. A Delta III (Depuy, Warsaw, Indiana) rTSA was used in all patients, and a 10° humeral retroversion was cemented into the humerus. A polyethylene insert of appropriate size and length was used to extend the metaphysis. The main indication for placing a retentive polyethylene humeral cup was the inability to reinsert the subscapularis tendon due to chronic rupture with muscle atrophy or difficulty achieving soft tissue tension that would provide stability to the prosthesis intraoperatively. A long head biceps tenodesis procedure was performed, except for one patient who had a prior spontaneous tear of the bicep tendon. The subscapularis tendon was repaired in all possible cases using transosseous sutures. Postoperatively the arm was immobilized with a sling for four weeks. Passive movement was encouraged and gradually increased. Over the following six weeks, isometric and resistance movements were gradually added to the rehabilitation program. The clinical outcomes were assessed using the Constant-Murley Score pre and postoperatively [ 9 ]. The pain level was evaluated using the visual analogue scale (VAS) preoperatively and at the end of the follow-up. A score of zero indicated no pain and ten indicated the worst possible pain. All patients were asked to assess the subjective outcome of the intervention in terms of being excellent, good, fair or poor. All patients underwent radiological examination at the final follow-up, which was undertaken by a consulting radiologist. Radiolucent notchings were scored using the classification of Boileau et al. 0, no notch; 1, small notch stopping short of the lower screw; 2, medium notch reaching the bottom screw; 3, large notch extending beyond the lower screw [ 8 ]. The nature of study was explained to the patients in detail and both verbally and by written informed consent were obtained from the patients for their anonymised information to be published in this article. The study protocol and informed consent document were approved by the Local Ethical Committee (CN-125-4 / 2018) Statistical analysis The power analysis was performed by an independent statistician. The effect measure used was the mean difference in forward flexion. A mean difference of 15º and a standard deviation of 20 were used to calculate the sample size [ 10 ]. A descriptive study was carried out, calculating the mean and standard deviation for the quantitative variables and the absolute and percentage frequencies for the qualitative variables. For the bivariate analysis, the Wilcoxon T test was used to compare the pre and post-intervention data with each of the surgical techniques, and the Mann-Whitney U test and Chi-square test were used to compare the post-intervention results between the two techniques. All contrasts were bilateral and were considered significant when p < 0.05. The data were collected, processed and analyzed using the IBM SPSS V28 program. Results Fifty-one patients underwent rTSA during the study period: 35 with standard and 16 with retentive polyethylene humeral cups. The mean age and mean follow-up were 69.9 years and 36.4 months, respectively. The findings regarding the demographic data are summarized in Table 1. There were no statistically significant differences between the groups in terms of gender, age or side of surgery. Irreparable rotator cuff tear was the most frequent diagnosis (26 patients) followed by osteoarthritis and posttraumatic (10 patients), cuff tear arthropathy (3 patients) and rheumatoid arthritis (2 patients). The average preoperative pain level decreased from 7.5 to 0.55 in standard and from 7.9 to 0.68 in retentive cup. There were no significant differences between the groups in the pain results at the end of follow-up (P = 000). Forward flexion was the primary outcome measure for which the study was powered. At the end of the follow-up, both groups showed significant improvement in forward flexion, abduction, and external rotation pre to postoperatively. There was a worsening in internal rotation in both groups. At the end of the follow-up, there were no differences between the 2 groups in forward flexion (mean, 164º in standard cup vs 163º in retentive cup; P = 0.90), abduction (mean, 134.3 +/- 20 vs 140.6 +/- 22; P = 0.16) and internal rotation (mean, 5.7 +/- 3 vs 5.6 +/- 2.3; P = 0.96). There was a lower mean in external rotation with the arm placed at the side (mean, 36.3 +/- 11.6 vs. 28.7 +/- 10.9) in the retentive polyethylene humeral cup patients but it was not statistically significant (P = 0.05). Table 2. The overall mean Constant-Murley Score increased significantly from pre to postoperative (from 42.7 +/- 10.6 points to 87.9 +/-5.8 points (P < 0.001) in standard cup patients and 34.6 +/- 9.4 points to 84 +/- 9.1 points (P < 0.001) in retentive cup patients). There was no statistical difference between the standard and retentive polyethylene humeral cup at the end of the follow-up (P = 0.27). In the standard cup group, three (8.6%) patients were satisfied and 32 (91.4%) were very satisfied. In the retentive cup group, three (18.8%) patients were satisfied and 13 (81.2%) very satisfied. We did not find any loosening of the stem or metaglene. The overall incidence of scapular notching was 62.7% (Table 3). The incidence of scapular notching in the standard and retentive polyethylene humeral cups was 62.8% and 62.5%, respectively (P = 0.68). We did not find prosthesis luxation in either of the two study groups. There was one acromial fracture found incidentally in the 2-month postoperative radiographs and there did not appear to be any detrimental effect on function (a Constant scores of 88, an active elevation of 170º and abduction of 140º). There were hematoma in 2 cases: this necessitated surgical intervention in 1 case and aspiration in the other. No subsequent infections occurred. Discussion Over recent years, rTSA has been used increasingly, especially in patients over 65 years old, to treat a number of shoulder disorders [ 11 ]. Most of the complications observed are common to any shoulder prosthesis. However, rTSA had specific problems related to its design, namely luxation and scapular notching. Instability is the most frequent complication - in the systematic review by Zumstein, it was found to be 4.7%, more frequent in revision of a previous hemi or total shoulder arthroplasty than in the primary arthroplasty [ 12 ]. To compensate for the deficient cuff, adequate deltoid muscle tension must be restored [ 5 ]. Insufficient tension in the deltoid muscle can result in prosthesis instability, as occurs more frequently in prosthesis cases due to fracture sequelae [ 13 , 14 ]. Re-attachment of the scapularis tendon to bone seems to be very important [ 2 , 6 , 15 ]. Cementing the humeral component at a 10º to 20º retroversion, to increase the size and thickness of the polyethylene insert or to increase the glenosphere size can lessen or decrease the risk of luxation [ 8 , 15 ]. A retentive polyethylene humeral cup can also be inserted to provide greater stability and prevent luxation. This component, with its deeper concavity, and thus greater contact with the glenoid, can lead to mobility impairment and produce or trigger notching due to contact with the lower part of the glenoid. In the group of patients for which we were unable to reinsert the subscapularis tendon due to chronic tear and atrophy of the muscle, or in cases where we could not provide adequate tension to the soft tissue intraoperatively, we placed a retentive polyethylene humeral cup to provide stability to the prosthesis. In our retrospective work, we found no luxation in any patient in either group. The mean Constant shoulder scores increased from 42.7 to 87.9 in the standard humeral cup group and from 34.6 to 84 in the retentive cup group. There were no significant differences in the clinical outcomes between the two groups. We found no significant differences in flexion, abduction, or internal rotation. There was a lower mean score in external rotation with the arm placed at the side in the retentive polyethylene humeral cup group, but this was not statistically significant. Scapular notching is present in almost half of the cases using the Grammont reverse system [ 12 ]. The use of an inferior eccentric sphere [ 16 – 19 ] and reducing the neck-shaft angle from 155º to 135º [ 20 – 22 ] has been suggested to prevent such notching. A biomechanical study showed that the most important factor in preventing notching is inferior placement of the glenosphere [ 23 ]. The relationship between glenoid lateralization and the notching rate remains unclear [ 16 , 19 , 22 , 24 ]. The clinical significance of scapular notching has not been elucidated [ 25 ]. Some authors refer to an absence of correlation between scapular notching and functional outcomes [22,24,26,] whereas others found lower postoperative clinical outcomes [ 27 , 28 ]. The overall incidence of scapular notching was 62.8% in the standard cup group and 62.5% in the retentive polyethylene humeral cup group (Table 3). There were no significant differences between the two groups. The limitation of this study includes its retrospective design, the small patient sample size, and the short follow-up duration. The midterm follow-up period was sensitive to assessing, scapular notching that first appears in the early postoperative period, between 6 week and 14 months postoperatively [ 29 ]. Another limitation of this study is that this data applies to the Delta III implant and may not be generalizable to other implants. Conclusions The Delta III rTSA using a standard vs a retentive polyethylene cup provided functional improvement and pain relief. There were no differences in luxation, clinical mobility, flexion, abduction, internal and external rotation, or radiological outcomes between the two groups. We can therefore confirm our primary hypothesis, namely that patients with risk factors for luxation who received a retentive polyethylene cup had an equal number of luxations as those receiving a standard polyethylene cup. Our second working hypothesis was likewise confirmed, that both groups had similar clinical outcomes. Declarations Funding: The authors and their immediate family have not received none financial payment or other benefits from any commercial entity related to the subject of this article. Author Contribution Author A : Data collection, wrote the main manuscript and reviewed the manuscript Author B: Data collection, analysis, prepared figure and reviewed the manuscript Author C: : Data collection, prepared tables and reviewed the manuscript Author D: Analysis and reviewed the manuscript Author E: Analysis and reviewed the manuscript References Cuff D, Pupello D, Virani N, Levy J, Frankle M (2008) Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency. J Bone Joint Surg Am 90: 1244-51. https://doi.org/10,2016/JBJS.G.00775 Wall B, Nove-Josserand L, O´Connor DP, Edwards TB, Walch G (2007) Reverse total shoulder arthroplasty: a review of results according to etiology. J Bone Joint Surg Am 89:1476–85. https://doi.org/10.2106/jbjs.f.00666 Berliner JL, Regalado-Magdos A, Ma CB, Feely BT (2015) Biomechanics of reverse total shoulder arthroplasty. 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Clin Orthop Relat Res 469: 2521–30. https://doi.org/10.1007/s11999-010-1720-y Tables Tables 1 to 3 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Table1.docx Table2.docx Table3.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7199453","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":494002376,"identity":"8281d5e5-ead8-4faf-8428-639160ba0a35","order_by":0,"name":"Manuel Zafra","email":"","orcid":"","institution":"Hospital Privado Quiron","correspondingAuthor":false,"prefix":"","firstName":"Manuel","middleName":"","lastName":"Zafra","suffix":""},{"id":494002378,"identity":"6a37c547-add1-46da-a0ec-7090a830e193","order_by":1,"name":"Pilar Uceda","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyUlEQVRIiWNgGAWjYJACCRDBDyISCkjRItkA0mJAihaDA2CSCOUGxw8fvPHjj12e8fnViR8eGDDI84sdIKDlTFqyZW9bcrHZjbebJYAOM5w5O4GAlhs8ZhK8DcyJ226c3QDSkmBwm6AW/m+Sf/7UJ26ecXbzDyK18LBJ87AdTtzA37uNOFskz6QZW8u2HU+ccYN3m0WCgQRhv/AdP/zw5ps/1Yn9/Wc33/xRYSPPL01ACwJIgFVKEKscBPgPkKJ6FIyCUTAKRhIAALSFRuJka5J6AAAAAElFTkSuQmCC","orcid":"","institution":"Hospital Privado Quiron","correspondingAuthor":true,"prefix":"","firstName":"Pilar","middleName":"","lastName":"Uceda","suffix":""},{"id":494002380,"identity":"da8e899c-32e6-4e0c-b067-e1e5014f7c7b","order_by":2,"name":"Luis E Gracia","email":"","orcid":"","institution":"Hospital Privado Quiron","correspondingAuthor":false,"prefix":"","firstName":"Luis","middleName":"E","lastName":"Gracia","suffix":""},{"id":494002383,"identity":"452b70f4-3275-4b88-ab69-6a616c7b2912","order_by":3,"name":"Sergio Gonzalez","email":"","orcid":"","institution":"Hospital Privado Quiron","correspondingAuthor":false,"prefix":"","firstName":"Sergio","middleName":"","lastName":"Gonzalez","suffix":""},{"id":494002386,"identity":"33774c9f-278f-4d11-af2e-2a4322bfd309","order_by":4,"name":"Pilar Font","email":"","orcid":"","institution":"Instituto Maimónides de Investigación Biomédica de Córdoba","correspondingAuthor":false,"prefix":"","firstName":"Pilar","middleName":"","lastName":"Font","suffix":""}],"badges":[],"createdAt":"2025-07-23 19:53:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7199453/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7199453/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":88240686,"identity":"7ed25203-295f-4bcd-b43c-c5a5daff63d3","added_by":"auto","created_at":"2025-08-04 11:11:16","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":511907,"visible":true,"origin":"","legend":"\u003cp\u003eStandard (A) and retentive (B) polyethylene humeral cups; the latter is designed with greater depth to provide more stability in the reversed prosthesis.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7199453/v1/ac7f8735c748918e0efe1b0f.jpeg"},{"id":89433593,"identity":"de1043e6-4acf-4651-81d3-8777f7860d6d","added_by":"auto","created_at":"2025-08-20 01:16:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":891315,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7199453/v1/a1e8f283-b710-4dcf-9110-635f2db3c4ca.pdf"},{"id":88240693,"identity":"4c0e0f01-bcc0-41a4-bf76-4c86f6f4a345","added_by":"auto","created_at":"2025-08-04 11:11:16","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":14966,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-7199453/v1/0bfff60e5ba7fe8811b847ad.docx"},{"id":88240704,"identity":"526a9dbb-c899-452f-b18e-ba97dbc6569f","added_by":"auto","created_at":"2025-08-04 11:11:17","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":17216,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-7199453/v1/e9c1067cc923832e14b39c86.docx"},{"id":88241146,"identity":"2077d420-6570-4954-8a2f-bc4217eeb596","added_by":"auto","created_at":"2025-08-04 11:19:16","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":14547,"visible":true,"origin":"","legend":"","description":"","filename":"Table3.docx","url":"https://assets-eu.researchsquare.com/files/rs-7199453/v1/38668dbbce61fa43b3681bb6.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical and radiological outcomes when using standard versus retentive polyethylene humeral cups in Delta III reverse shoulder arthroplasty","fulltext":[{"header":"Introduction","content":"\u003cp\u003eReverse total shoulder arthroplasty (rTSA) is an effective surgical treatment for several pathologies affecting the shoulder [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Paul Grammont introduced the principle of medialization of the centre of rotation and decreasing the force required by the deltoid for abduction owing to the longer moment arm [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Despite the improved results of this procedure, there were a number of problems including instability caused by subscapularis muscle deficit or by inadequate soft tissue tensioning [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTo lessen the risk of luxation, meticulous re-attachment of the scapularis to the bone, whenever possible, cementing the humeral component into a 10\u0026ordm; retroversion position, and attempting to increase the deltoid offset and tension by increasing the size and thickness of polyethylene insert, were all undertaken [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAnother option for preventing luxation is to use a retentive humeral polyethylene cup; this component, with its deeper concavity (Fig.\u0026nbsp;1) and therefore greater contact with the lower part of the glenoid, can lead to less mobility or a greater appearance of radiological abnormalities, especially scapular notching.\u003c/p\u003e\u003cp\u003eThe purpose of this study was to compare the clinical and radiological outcomes of rTSA using a standard versus a retentive polyethylene humeral polyethylene cup. The primary indication for the retentive polyethylene humeral cup was a lack of subscapularis tendon or soft tissue tension. Our primary hypothesis was that both patient groups would have an equal number of luxations; secondarily, that patients would have similar clinical outcomes.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eConsecutive patients undergoing rTSA between September 2018 and December 2023 were retrospectively reviewed. Patients were included if they had a minimum clinical follow-up of 12 months and underwent primary rTSA with a standard or retentive polyethylene humeral cup. The indications for rTSA were rotator cuff tear arthropathy, a massive irreparable rotator cuff tear with chronic loss of elevation, post-traumatic glenohumeral arthritis, primary osteoarthritis and rheumatoid arthritis. Patients were excluded if they were undergoing revision surgery, or had infection, an acute fracture, Parkinson's disease or a tumour. Patients were divided into 2 groups based on whether they had a standard or retentive polyethylene humeral cup. The authors used intraoperative criteria for assignment to each group. To avoid selection bias, the authors took into account the variables of age, sex and pathology causing the surgery so that the assignment to each group was as evenly matched as possible. The clinical and radiological outcomes of both groups were analysed. Demographic data were collected prospectively and analysed retrospectively.\u003c/p\u003e\u003cp\u003eAll surgical procedures were performed by the senior author and were conducted with the patient in a beach chair position under general anaesthesia and with an interscalene block. A Delta III (Depuy, Warsaw, Indiana) rTSA was used in all patients, and a 10\u0026deg; humeral retroversion was cemented into the humerus. A polyethylene insert of appropriate size and length was used to extend the metaphysis. The main indication for placing a retentive polyethylene humeral cup was the inability to reinsert the subscapularis tendon due to chronic rupture with muscle atrophy or difficulty achieving soft tissue tension that would provide stability to the prosthesis intraoperatively. A long head biceps tenodesis procedure was performed, except for one patient who had a prior spontaneous tear of the bicep tendon. The subscapularis tendon was repaired in all possible cases using transosseous sutures. Postoperatively the arm was immobilized with a sling for four weeks. Passive movement was encouraged and gradually increased. Over the following six weeks, isometric and resistance movements were gradually added to the rehabilitation program.\u003c/p\u003e\u003cp\u003eThe clinical outcomes were assessed using the Constant-Murley Score pre and postoperatively [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The pain level was evaluated using the visual analogue scale (VAS) preoperatively and at the end of the follow-up. A score of zero indicated no pain and ten indicated the worst possible pain. All patients were asked to assess the subjective outcome of the intervention in terms of being excellent, good, fair or poor.\u003c/p\u003e\u003cp\u003eAll patients underwent radiological examination at the final follow-up, which was undertaken by a consulting radiologist. Radiolucent notchings were scored using the classification of Boileau et al. 0, no notch; 1, small notch stopping short of the lower screw; 2, medium notch reaching the bottom screw; 3, large notch extending beyond the lower screw [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe nature of study was explained to the patients in detail and both verbally and by written informed consent were obtained from the patients for their anonymised information to be published in this article. The study protocol and informed consent document were approved by the Local Ethical Committee (CN-125-4 / 2018)\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eThe power analysis was performed by an independent statistician.\u003c/p\u003e\u003cp\u003eThe effect measure used was the mean difference in forward flexion. A mean difference of 15\u0026ordm; and a standard deviation of 20 were used to calculate the sample size [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eA descriptive study was carried out, calculating the mean and standard deviation for the quantitative variables and the absolute and percentage frequencies for the qualitative variables.\u003c/p\u003e\u003cp\u003eFor the bivariate analysis, the Wilcoxon T test was used to compare the pre and post-intervention data with each of the surgical techniques, and the Mann-Whitney U test and Chi-square test were used to compare the post-intervention results between the two techniques.\u003c/p\u003e\u003cp\u003eAll contrasts were bilateral and were considered significant when p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003cp\u003eThe data were collected, processed and analyzed using the IBM SPSS V28 program.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eFifty-one patients underwent rTSA during the study period: 35 with standard and 16 with retentive polyethylene humeral cups. The mean age and mean follow-up were 69.9 years and 36.4 months, respectively. The findings regarding the demographic data are summarized in Table\u0026nbsp;1. There were no statistically significant differences between the groups in terms of gender, age or side of surgery. Irreparable rotator cuff tear was the most frequent diagnosis (26 patients) followed by osteoarthritis and posttraumatic (10 patients), cuff tear arthropathy (3 patients) and rheumatoid arthritis (2 patients).\u003c/p\u003e\u003cp\u003eThe average preoperative pain level decreased from 7.5 to 0.55 in standard and from 7.9 to 0.68 in retentive cup. There were no significant differences between the groups in the pain results at the end of follow-up (P\u0026thinsp;=\u0026thinsp;000).\u003c/p\u003e\u003cp\u003eForward flexion was the primary outcome measure for which the study was powered. At the end of the follow-up, both groups showed significant improvement in forward flexion, abduction, and external rotation pre to postoperatively. There was a worsening in internal rotation in both groups. At the end of the follow-up, there were no differences between the 2 groups in forward flexion (mean, 164\u0026ordm; in standard cup vs 163\u0026ordm; in retentive cup; P\u0026thinsp;=\u0026thinsp;0.90), abduction (mean, 134.3 +/- 20 vs 140.6 +/- 22; P\u0026thinsp;=\u0026thinsp;0.16) and internal rotation (mean, 5.7 +/- 3 vs 5.6 +/- 2.3; P\u0026thinsp;=\u0026thinsp;0.96). There was a lower mean in external rotation with the arm placed at the side (mean, 36.3 +/- 11.6 vs. 28.7 +/- 10.9) in the retentive polyethylene humeral cup patients but it was not statistically significant (P\u0026thinsp;=\u0026thinsp;0.05). Table\u0026nbsp;2.\u003c/p\u003e\u003cp\u003eThe overall mean Constant-Murley Score increased significantly from pre to postoperative (from 42.7 +/- 10.6 points to 87.9 +/-5.8 points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in standard cup patients and 34.6 +/- 9.4 points to 84 +/- 9.1 points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in retentive cup patients). There was no statistical difference between the standard and retentive polyethylene humeral cup at the end of the follow-up (P\u0026thinsp;=\u0026thinsp;0.27). In the standard cup group, three (8.6%) patients were satisfied and 32 (91.4%) were very satisfied. In the retentive cup group, three (18.8%) patients were satisfied and 13 (81.2%) very satisfied.\u003c/p\u003e\u003cp\u003eWe did not find any loosening of the stem or metaglene.\u003c/p\u003e\u003cp\u003eThe overall incidence of scapular notching was 62.7% (Table\u0026nbsp;3). The incidence of scapular notching in the standard and retentive polyethylene humeral cups was 62.8% and 62.5%, respectively (P\u0026thinsp;=\u0026thinsp;0.68).\u003c/p\u003e\u003cp\u003eWe did not find prosthesis luxation in either of the two study groups. There was one acromial fracture found incidentally in the 2-month postoperative radiographs and there did not appear to be any detrimental effect on function (a Constant scores of 88, an active elevation of 170\u0026ordm; and abduction of 140\u0026ordm;). There were hematoma in 2 cases: this necessitated surgical intervention in 1 case and aspiration in the other. No subsequent infections occurred.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOver recent years, rTSA has been used increasingly, especially in patients over 65 years old, to treat a number of shoulder disorders [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMost of the complications observed are common to any shoulder prosthesis. However, rTSA had specific problems related to its design, namely luxation and scapular notching. Instability is the most frequent complication - in the systematic review by Zumstein, it was found to be 4.7%, more frequent in revision of a previous hemi or total shoulder arthroplasty than in the primary arthroplasty [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. To compensate for the deficient cuff, adequate deltoid muscle tension must be restored [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Insufficient tension in the deltoid muscle can result in prosthesis instability, as occurs more frequently in prosthesis cases due to fracture sequelae [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Re-attachment of the scapularis tendon to bone seems to be very important [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Cementing the humeral component at a 10\u0026ordm; to 20\u0026ordm; retroversion, to increase the size and thickness of the polyethylene insert or to increase the glenosphere size can lessen or decrease the risk of luxation [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. A retentive polyethylene humeral cup can also be inserted to provide greater stability and prevent luxation. This component, with its deeper concavity, and thus greater contact with the glenoid, can lead to mobility impairment and produce or trigger notching due to contact with the lower part of the glenoid.\u003c/p\u003e\u003cp\u003eIn the group of patients for which we were unable to reinsert the subscapularis tendon due to chronic tear and atrophy of the muscle, or in cases where we could not provide adequate tension to the soft tissue intraoperatively, we placed a retentive polyethylene humeral cup to provide stability to the prosthesis.\u003c/p\u003e\u003cp\u003eIn our retrospective work, we found no luxation in any patient in either group.\u003c/p\u003e\u003cp\u003eThe mean Constant shoulder scores increased from 42.7 to 87.9 in the standard humeral cup group and from 34.6 to 84 in the retentive cup group. There were no significant differences in the clinical outcomes between the two groups. We found no significant differences in flexion, abduction, or internal rotation. There was a lower mean score in external rotation with the arm placed at the side in the retentive polyethylene humeral cup group, but this was not statistically significant.\u003c/p\u003e\u003cp\u003eScapular notching is present in almost half of the cases using the Grammont reverse system [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The use of an inferior eccentric sphere [\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] and reducing the neck-shaft angle from 155\u0026ordm; to 135\u0026ordm; [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] has been suggested to prevent such notching. A biomechanical study showed that the most important factor in preventing notching is inferior placement of the glenosphere [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The relationship between glenoid lateralization and the notching rate remains unclear [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe clinical significance of scapular notching has not been elucidated [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Some authors refer to an absence of correlation between scapular notching and functional outcomes [22,24,26,] whereas others found lower postoperative clinical outcomes [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe overall incidence of scapular notching was 62.8% in the standard cup group and 62.5% in the retentive polyethylene humeral cup group (Table\u0026nbsp;3). There were no significant differences between the two groups.\u003c/p\u003e\u003cp\u003eThe limitation of this study includes its retrospective design, the small patient sample size, and the short follow-up duration. The midterm follow-up period was sensitive to assessing, scapular notching that first appears in the early postoperative period, between 6 week and 14 months postoperatively [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Another limitation of this study is that this data applies to the Delta III implant and may not be generalizable to other implants.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe Delta III rTSA using a standard vs a retentive polyethylene cup provided functional improvement and pain relief. There were no differences in luxation, clinical mobility, flexion, abduction, internal and external rotation, or radiological outcomes between the two groups. We can therefore confirm our primary hypothesis, namely that patients with risk factors for luxation who received a retentive polyethylene cup had an equal number of luxations as those receiving a standard polyethylene cup. Our second working hypothesis was likewise confirmed, that both groups had similar clinical outcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eThe authors and their immediate family have not received none financial payment or other benefits from any commercial entity related to the subject of this article.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor A : Data collection, wrote the main manuscript and reviewed the manuscript Author B: Data collection, analysis, prepared figure and reviewed the manuscript Author C: : Data collection, prepared tables and reviewed the manuscript Author D: Analysis and reviewed the manuscript Author E: Analysis and reviewed the manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCuff D, Pupello D, Virani N, Levy J, Frankle M (2008) Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency. 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J Shoulder Elbow Surg 15:527\u0026ndash;540. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jse.2006.01.003\u003c/span\u003e\u003cspan address=\"10.1016/j.jse.2006.01.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eErickson BJ, Frank RM, Harris JD, Mall N, Romeo AA (2015) The influence of humeral head inclination in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg 24:988\u0026ndash;93. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jse.2015.01.001\u003c/span\u003e\u003cspan address=\"10.1016/j.jse.2015.01.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLevigne C, Garrret P, Boileau P. Alami G, Favard L, Walch G (2011) Scapular notching in reverse shoulder arthroplasty: is it important to avoid it and how? Clin Orthop Relat Res 469:2512\u0026ndash;20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11999-010-1695-8\u003c/span\u003e\u003cspan address=\"10.1007/s11999-010-1695-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSimovitch RW, Zumstein MA, Lohri E, Helmy N, Gerber C (2007). Predictors of scapular notching in patients managed with the Delta III reverse total shoulder replacement. 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J Bone Joint Surg Br 86:388\u0026ndash;95. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1302/0301-620x.86b3.14024\u003c/span\u003e\u003cspan address=\"10.1302/0301-620x.86b3.14024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNicholson GP, Strauss EJ, Sherman SL (2001) Scapular notching: recognition and strategies to minimize clinical impact. Clin Orthop Relat Res 469: 2521\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11999-010-1720-y\u003c/span\u003e\u003cspan address=\"10.1007/s11999-010-1720-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 3 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Reverse shoulder arthroplasty, polyethylene humeral cup, range of motion, outcomes, notching","lastPublishedDoi":"10.21203/rs.3.rs-7199453/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7199453/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground.\u003c/h2\u003e\u003cp\u003eThe most common postoperative complication relating to reverse total shoulder arthroplasty (rTSA) is instability. To prevent 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.\u003c/p\u003e\u003ch2\u003eMaterials and methods.\u003c/h2\u003e\u003cp\u003eConsecutive patients undergoing primary Delta III sTSA between September 2018 and December 2023 using standard versus retentive polyethylene humeral cups were retrospectively reviewed. The minimum clinical follow-up was of 12 months.\u003c/p\u003e\u003ch2\u003eResults.\u003c/h2\u003e\u003cp\u003eFifty-one patients underwent rTSA during the study period: 35 with standard humeral cups and 16 with retentive polyethylene humeral cups. We found no prosthesis luxation in either of the two study groups. At the end of the follow-up, there were no differences in forward flexion, abduction or internal rotation between the two groups. There was a lower mean for external rotation in the retentive polyethylene humeral cup group 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.\u003c/p\u003e\u003ch2\u003eConclusion.\u003c/h2\u003e\u003cp\u003eThe Delta III rTSA using standard vs 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\u003c/p\u003e\u003ch2\u003eLevel of evidence:\u003c/h2\u003e\u003cp\u003eLevel III; Retrospective Cohort Comparison; Treatment Study\u003c/p\u003e","manuscriptTitle":"Clinical and radiological outcomes when using standard versus retentive polyethylene humeral cups in Delta III reverse shoulder arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-04 11:11:12","doi":"10.21203/rs.3.rs-7199453/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"15562f07-c305-4058-b5a1-056c662a15c7","owner":[],"postedDate":"August 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-08-20T01:08:06+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-04 11:11:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7199453","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7199453","identity":"rs-7199453","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}