Association Between Acromion Morphology and Non-Traumatic Rotator Cuff Injury Among Young Adult Filipinos in a Tertiary Hospital: Cross-sectional Study

Association Between Acromion Morphology and Non-Traumatic Rotator Cuff Injury Among Young Adult Filipinos in a Tertiary Hospital: Cross-sectional Study | 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 Association Between Acromion Morphology and Non-Traumatic Rotator Cuff Injury Among Young Adult Filipinos in a Tertiary Hospital: Cross-sectional Study Terence Aaron Lim Burgo, Brian Andrich L. Pollo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7204992/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 Introduction Rotator cuff injury (RCI) is among the most common shoulder pathologies, significantly affecting quality of life. Acromial morphology has been implicated as a predisposing factor, but limited local data exist. The Bigliani-Kitay classification defines four acromion types: flat (I), curved (II), hooked (III), and convex (IV). MRI is the preferred modality for assessing both acromial morphology and RCI. Objective To assess the association between acromion morphology and RCI among patients undergoing shoulder MRI at Makati Medical Center, a tertiary hospital in the Philippines. Methods A retrospective review of shoulder MRI scans performed from January to December 2019 was conducted. Patients with shoulder pain were included as cases. Acromion morphology and presence of RCI (tendinosis, partial, or full-thickness tears) were documented. Images were interpreted by radiologists accredited by the Philippine College of Radiology. Results Of 132 patients (mean age: 31.2 ± 5.4 years), 65.9% were male. The period prevalence of RCI was 58.3% (n = 77). There was no significant sex-based difference in RCI prevalence ( p = 0.4036). RCI was significantly associated with Type II (70.5%, p < 0.00001) and Type III (100%, p = 0.00158) acromion morphologies. No significant association was found for Types I and IV. Conclusion Type II and Type III acromial morphologies are significantly associated with higher prevalence of RCI. Recognition of these morphologies on MRI may help identify patients at increased risk and allow for early intervention. Acromion Rotator Cuff Rotator Cuff Injuries Cross-Sectional Studies Philippines Advances in knowledge Confirms a statistically significant association between Type III (hook-shaped) acromion and rotator cuff injury (RCI) in a Filipino young adult population. While associated with RCI as well, type II acromion is most prevalent in the study population. This is among the first studies in the Philippines to characterize acromial types in relation to documented RCI. Application to patient care Early identification of type III acromion may support clinical suspicion for rotator cuff pathology, improving diagnostic accuracy. Patients with type III acromion may benefit from earlier referral to physical therapy or orthopedic evaluation. Incorporating acromial morphology in radiology reports may enhance multidisciplinary communication between radiologists, primary care providers, and orthopedic surgeons. Introduction Rotator cuff injuries (RCI) are among the most common shoulder pathologies, yet their precise etiology remains incompletely understood. 1 While both intrinsic factors ( e.g. , age-related degeneration, reduced vascularity, and collagen abnormalities) and extrinsic factors ( e.g. , subacromial impingement and repetitive overhead activity) have been implicated, relatively few studies have focused on the role of specific acromion morphologies in predisposing individuals to RCI. Of these, the hook-shaped type III acromion has been most consistently associated with rotator cuff pathology. 2 Mechanical impingement is a leading extrinsic cause of rotator cuff injury, implicated in up to 95% of tears. 3 It results from repetitive compression of the tendons under the acromion, contributing to tendon degeneration. Acromioplasty, which addresses this impingement, has become increasingly common. Early diagnosis and management of mechanical factors are associated with better outcomes, emphasizing the need to identify structural contributors, such as acromial morphology. Acromial morphology is a key anatomical determinant of subacromial impingement. 4,5 The most widely used system for classifying acromion types is the Bigliani classification, later refined by Kitay et al., which describes four morphological types based on the shape of the inferior acromial surface: flat (Type I), curved (Type II), hooked (Type III), and convex (Type IV). 6 Magnetic Resonance Imaging (MRI) has since emerged as the most accurate modality for assessing both acromion shape and rotator cuff integrity. Several studies have examined the relationship between acromion type and impingement or RCI. While many report an association between Type III (hooked) acromion and non-traumatic RCI, 2,7–11 others have found no significant relationship. 12,13 Such conflicting results demonstrate the ongoing uncertainty in the role of acromial morphology in RCI pathogenesis. Notably, nearly all of these studies were conducted among middle-aged and older adults, leaving a gap in understanding of how acromial morphology relates to RCI in younger populations. Moreover, there is a lack of local data from the Philippines on this issue. Hence, the primary objective of this study was to assess the association between acromial morphology and non-traumatic rotator cuff injury among young adult Filipinos (< 40 years old) using MRI-based classification. RCIs are known to reduce quality of life to levels comparable with chronic conditions such as heart failure, diabetes, and depression. Treatment costs can accumulate rapidly, and delays in appropriate management can result in poorer outcomes. Early identification of anatomical risk factors, particularly in younger adults, may aid in preventive strategies and more tailored treatment approaches. 11 Methods This cross-sectional study retrospectively reviewed the MRI results of all patients (ages 25 to 50 years) of Makati Medical Center who underwent shoulder MRI from January 1, 2019 to December 31, 2019 as interpreted by radiologists accredited by the Philippine College of Radiology and fellows of the CT-MRI society of the Philippines. This study included as cases all patients with RCI, either tendinosis, partial or full thickness. We excluded individuals with (1) previous shoulder surgery, (2) fractures and/or dislocation, (3) infections or tumors of the shoulder, and (4) presence of acromial spurs. Asymptomatic patients with intact rotator cuff were also included to serve as control. All scans were performed using a 1.5-Tesla MRI scanner (Siemens). A shoulder array coil was used. The patients were positioned supine with their arms on the sides of their body in partial external rotation. Coronal oblique, sagittal oblique and axial images were obtained. The coronal oblique plane were selected parallel to the course of the supraspinatus tendon for ideal image acquisition of the tendon. The sagittal oblique image was used to identify acromion morphology. The main outcome was the presence of rotator cuff injury was determined by radiologic report. Complete rotator cuff tears were identified as a hyperintense signal area within the tendon on T2W and fat-suppressed images, seen in two planes. Complete tears are described as T2/PD signals extending from the articular or bursal surface, which most commonly affect the supraspinatus tendon. Fluid signal within the tendon defect is highly suggestive of rotator cuff injury. 14 Partial tears were defined as T2/PD signals that extend in either, not both, the bursal or articular surface. Partial tears are also seen within the tendon substance, hence the term, intrasubstance partial tear. Radiologists use tendinosis as an all-encompassing term to indicate all tendon pathology. Also, they may use it to suggest a chronic tendon disease that does not resolve. 15 The primary exposure was acromion morphology, classified using the Bigliani system by a single radiologist (T.B.). Information on age and sex were collected as well. MRI reports and images of all patients who underwent shoulder MRI were retrieved from the Novarad radiology information system (NovaRIS) and picture archiving and communication system (NovaPACS) of the Department of Radiology. The data were tabulated using Microsoft Excel-based data abstraction tool. The sample size was computed with 95% confidence level, an acceptable margin of error at 5%, an estimated prevalence of rotator cuff injury in certain acromion morphology of 56%. 12 The computation for sample size suggested a need for at least 132 patients. MRI reports and images of all patients who underwent shoulder MRI were retrieved from the NOVARAD RIS and PACS system of the Department of Radiology. The data were tabulated using Microsoft Excel-based data abstraction tool. Descriptive statistics were used to describe the demographic characteristics (age and sex) of the participants. Qualitative and quantitative data were numerically expressed as frequencies, proportions and means ± standard deviations (SD). The prevalence of rotator cuff injury according to sex and acromion morphology were determined. For each acromion type, a 2×2 contingency table was constructed comparing the number of patients with the given type versus all others, stratified by RCI status. Fisher’s Exact Test was used for all comparisons due to the small sample sizes, particularly for Types III and IV. A p -value less than 0.05 was considered statistically significant. All statistical tests were conducted in R (v.4.5.0). Results A total of 155 Shoulder MRI studies of young adult patients were reviewed and 132 of them were included in the study due to presence of one of the following: injury of the rotator cuff, either tendinosis, partial or complete tear with no history of previous shoulder surgery, no associated fractures nor dislocation, infections or tumors of the shoulder nor presence of degenerative changes. Of the 155 studies, 20 were not included due to a history of trauma with fracture and/or dislocation; 5 were also not included due to the presence of degenerative changes as stated in the exclusion criteria above. The mean (± SD) age of the participants is 31.22 ± 5.42. Of the 132 participants included in the study, there was a higher proportion of males compared to females (Table 1 ). The overall period prevalence of rotator cuff injury was 58.33% (n = 77). There was higher prevalence of RCI among males, as opposed to females. There was no significant difference between the prevalence of rotator cuff injury among male subjects when compared to that of female subjects (p = 0.4036). Table 1 Association between sex and presence of rotator cuff injury. (+) Rotator Cuff Injury (n = 77) (-) Rotator Cuff Injury (n = 55) Total (n = 132) Male 60.92% (n = 53) 39.08% (n = 34) 100% (n = 87) Female 53.33% (n = 24) 46.67% (n = 21) 100% (n = 45) To determine which acromial shape was most associated with injury, we compared RCI incidence across types. Among all acromion types, Type II acromion, the most common variant, showed the strongest association with RCI ( p < 0.00001). Type III was also linked to higher RCI rates ( p = 00158). Although Type III acromion was present in only 5 patients, it was associated with a 100% rate of rotator cuff injury. Type II acromion, the most common variant, was also linked to higher RCI rates ( p < 0.00001), possibly due to its curved morphology. Fisher’s exact test did not demonstrate a significant relationship between rotator cuff injury and the presence of type I acromion ( p = 0.2041) or type IV acromion ( p = 0.5287). Detailed frequencies are shown in Table 2 . Table 2 Association between acromion morphology and presence of rotator cuff injury. Acromion Type (+) Rotator Cuff Injury (n = 77) (-) Rotator Cuff Injury (n = 55) p-value Type I 44.26% (n = 27) 55.74% (n = 34) 0.2041 Type II 70.49% (n = 43) 29.51% (n = 18) p < 0.00001 Type III 100% (n = 5) 0% (n = 0) 0.00158 Type IV 40% (n = 2) 60% (n = 3) 0.5287 Discussion The most significant finding in this study is the significant association between acromial morphology and non-traumatic RCI. Only ~ 3% of the subjects had Type III acromion and although rare, all of them were associated with RCI ( p = 0.00158) compared to other acromion types. This results align with systematic review findings that Type III morphology nearly triples the odds of rotator cuff tear compared to Types I–II (OR = 2.82, p = 3e − 6 ). 11 This association is probably due to shape of Type III acromion described as being hooked. A hooked acromion differs from the Type I and II due to its increased anterior and inferior extension of the acromial bony process, which is thought to decrease the subacromial space, thereby increasing the likelihood of extrinsic degeneration of the rotator cuff tendons. 11 Type II acromion was also found to be associated with increased occurrence of RCI ( p < 0.00001) which may be due to its curved shape which can also narrow the subacromial space to some extent. However, being the most common type, Type II acromion can therefore significantly instigate a high incidence rate of RCI among all of the acromion types and can notably influence the causal relationship between this certain type and incidence of injury. 16 Majority of the subjects were male but there is no significant difference in the incidence of RCI between sexes. Studies in different populations similarly report no consistent sex-based differences in acromial morphology among rotator cuff tear cases. 17,18 Also, this study also shows similar results to studies conducted with different age cohorts, suggesting that Type III acromion is a risk marker regardless of age. For instance, in a multivariable analysis of surgical cases, acromial morphology (especially type III) remained significantly associated with RCI even after stratification by age. 19 But it is unknown whether these relationships are causal, or simply predictive in nature. Cross-sectional design limits causal inferences. Some investigators have found no significant correlation between acromion type and cuff tear, reinforcing uncertainty in the impingement hypothesis. 12,17,20 These findings support using MRI-based acromial classification to identify individuals at elevated risk for non-traumatic RCI. Early recognition through imaging may guide targeted intervention, such as referral to physical therapists, physiatrists or orthopedic surgeons. This study had some limitations. The analysis was not adjusted for many other extrinsic and intrinsic factors affecting the rotator cuff tendons’ risk of injury. Also, the relationship of the severity/grade of rotator cuff injury and the acromion types was not taken into consideration. Future prospective studies incorporating multivariate modeling and grading of tendon pathology may be needed to clarify causality. Conclusion This study corroborates previous findings that type III acromion, although rare, is associated with a high incidence of non-traumatic rotator cuff injury. Type II acromion was also associated with RCI but it also has the highest prevalence. No significant association was found between sex and rotator cuff injury. Identifying those patients at risk may potentially benefit from corrective or preventive measures to help prevent future injury. Future studies may benefit by examining a greater number of factors and including a better distribution of acromion types. Declarations Statement of Ethics Approval Ethical approval was provided by the Makati Medical Center Institutional Review Board (MMCIRB 2020-105). Statement of Participant Consent The need for consent to participate and publish was waived by the Makati Medical Center Institutional Review Board. References Teunis T, Lubberts B, Reilly BT, Ring D. A systematic review and pooled analysis of the prevalence of rotator cuff disease with increasing age. J Shoulder Elbow Surg . 2014;23(12):1913-1921. doi:10.1016/j.jse.2014.08.001 Tangtrakulwanich B, Kapkird A. Analyses of possible risk factors for subacromial impingement syndrome. World J Orthop . 2012;3(1):5. doi:10.5312/WJO.V3.I1.5 Papatheodorou A, Ellinas P, Takis F, Tsanis A, Maris I, Batakis N. US of the shoulder: Rotator cuff and non-rotator cuff disorders. Radiographics . 2006;26(1). doi:10.1148/rg.e23 Heuberer PR, Plachel F, Willinger L, et al. Critical shoulder angle combined with age predict five shoulder pathologies: A retrospective analysis of 1000 cases. BMC Musculoskelet Disord . 2017;18(1). doi:10.1186/S12891-017-1559-4, Alfaro-Gomez U, Fuentes-Ramirez LD, Chavez-Blanco KI, et al. Anatomical variations of the acromial and coracoid process: clinical relevance. Surgical and Radiologic Anatomy . 2020;42(8):877-885. doi:10.1007/S00276-020-02497-5, Kitay GS, Iannotti JP, Williams GR, Haygood T, Kneeland BJ, Berlin J. Roentgenographic assessment of acromial morphologic condition in rotator cuff impingement syndrome. J Shoulder Elbow Surg . 1995;4(6):441-448. doi:10.1016/S1058-2746(05)80036-9, Kim JM, Kim YW, Kim HS, et al. The relationship between rotator cuff tear and four acromion types: cross-sectional study based on shoulder magnetic resonance imaging in 227 patients. Acta radiol . 2019;60(5):608-614. doi:10.1177/0284185118791211, Inklebarger J, Gyer G, Parkunan A, Galanis N, Michael J. Rotator cuff impingement associated with Type III acromial morphology in a young athlete-a case for early imaging. J Surg Case Rep . 2017;2017(1):rjw234. doi:10.1093/JSCR/RJW234 Andrade R, Correia AL, Nunes J, et al. Is Bony Morphology and Morphometry Associated With Degenerative Full-Thickness Rotator Cuff Tears? A Systematic Review and Meta-analysis. Arthroscopy - Journal of Arthroscopic and Related Surgery . 2019;35(12):3304-3315.e2. doi:10.1016/j.arthro.2019.07.005 Nyffeler RW, Meyer DC. Acromion and glenoid shape: Why are they important predictive factors for the future of our shoulders? EFORT Open Rev . 2017;2(5):141. doi:10.1302/2058-5241.2.160076 Morelli KM, Martin BR, Charakla FH, Durmisevic A, Warren GL. Acromion morphology and prevalence of rotator cuff tear: A systematic review and meta-analysis. Clinical Anatomy . 2019;32(1):122-130. doi:10.1002/CA.23309, Balke M, Schmidt C, Dedy N, Banerjee M, Bouillon B, Liem D. Correlation of acromial morphology with impingement syndrome and rotator cuff tears. Acta Orthop . 2013;84(2):178-183. doi:10.3109/17453674.2013.773413, Azalia X, Singjie LC, Anastasia M, Kholinne E. Characteristics of acromial morphology in patients with painful shoulders from Indonesia. Int Orthop . 2025;49(8). doi:10.1007/S00264-025-06585-2, Tuite MJ. Magnetic Resonance Imaging of Rotator Cuff Disease and External Impingement. Magn Reson Imaging Clin N Am . 2012;20(2):187-200. doi:10.1016/j.mric.2012.01.011 Hodgson R, O’Connor PJ, Grainger AJ. Tendon and ligament imaging. British Journal of Radiology . 2012;85(1016):1157-1172. doi:10.1259/BJR/34786470, Gumina S, Passaretti D, Candela V. Epidemiology and demographics of the rotator cuff tear. Rotator Cuff Tear: Pathogenesis, Evaluation and Treatment . Published online January 1, 2016:53-59. doi:10.1007/978-3-319-33355-7_4 Almokhtar AA, Qanat AS, Mulla A, Alqurashi Z, Aljeraisi A, Hegaze AH. Relationship Between Acromial Anatomy and Rotator Cuff Tears in Saudi Arabian Population. Cureus . 2020;12(5):e8304. doi:10.7759/CUREUS.8304 Venkataraman S, Ethiraj P, Shanthappa A, Vellingiri K. A study of association between acromion types and shoulder pathology. Journal of Orthopaedics and Spine . 2022;10(2):92. doi:10.4103/JOASP.JOASP_53_20 Gill TJ, McIrvin E, Kocher MS, Homa K, Mair SD, Hawkins RJ. The relative importance of acromial morphology and age with respect to rotator cuff pathology. J Shoulder Elbow Surg . 2002;11(4):327-330. doi:10.1067/mse.2002.124425 Liu CT, Miao JQ, Wang H, an Ge H, Wang XH, Cheng B. The association between acromial anatomy and articular-sided partial thickness of rotator cuff tears. BMC Musculoskelet Disord . 2021;22(1):760. doi:10.1186/S12891-021-04639-1 Additional Declarations The authors declare no competing interests. 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. 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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-7204992","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":490284824,"identity":"a27ee9fb-e247-44c9-8704-e5869d8ed010","order_by":0,"name":"Terence Aaron Lim Burgo","email":"","orcid":"https://orcid.org/0009-0002-9987-253X","institution":"Makati Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Terence","middleName":"Aaron Lim","lastName":"Burgo","suffix":""},{"id":490284825,"identity":"41866570-4ed0-4dfc-a759-78e07419cdfc","order_by":1,"name":"Brian Andrich L. Pollo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuElEQVRIiWNgGAWjYBACAxDxgMEGSDI2HiBeSwJDGkhLA0laDoM5xGkxl25++CFxx3m7te2HgbbU2EQT1GI555ixROKZ28nbziQCtRxLy20g6LAbCWYMiW23k80OALUwNhwmRkv6N6CWc8lm5x8SrSUHZMsBO7MbxNpiOSOnGOiX5ASzG0BbEojxi7lE+sYPH3fY2ZudT3/44EONDWEtYMDYwJAIVplAlHKoFnuiFY+CUTAKRsHIAwCiQkprjGeGxwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-6528-1550","institution":"University of the Philippines Manila","correspondingAuthor":true,"prefix":"","firstName":"Brian","middleName":"Andrich L.","lastName":"Pollo","suffix":""}],"badges":[],"createdAt":"2025-07-24 11:21:52","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-7204992/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7204992/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87940455,"identity":"691bbd0e-596d-400a-b127-6c639cf162e0","added_by":"auto","created_at":"2025-07-30 15:09:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":410052,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7204992/v1/c4db6d71-098e-4706-807b-76dbe599ff33.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eAssociation Between Acromion Morphology and Non-Traumatic Rotator Cuff Injury Among Young Adult Filipinos in a Tertiary Hospital: Cross-sectional Study\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Advances in knowledge","content":"\u003cul\u003e\n \u003cli\u003eConfirms a statistically significant association between Type III (hook-shaped) acromion and rotator cuff injury (RCI) in a Filipino young adult population.\u003c/li\u003e\n \u003cli\u003eWhile associated with RCI as well, type II acromion is most prevalent in the study population.\u003c/li\u003e\n \u003cli\u003eThis is among the first studies in the Philippines to characterize acromial types in relation to documented RCI.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eApplication to patient care\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eEarly identification of type III acromion may support clinical suspicion for rotator cuff pathology, improving diagnostic accuracy.\u003c/li\u003e\n \u003cli\u003ePatients with type III acromion may benefit from earlier referral to physical therapy or orthopedic evaluation.\u003c/li\u003e\n \u003cli\u003eIncorporating acromial morphology in radiology reports may enhance multidisciplinary communication between radiologists, primary care providers, and orthopedic surgeons.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Introduction","content":"\u003cp\u003eRotator cuff injuries (RCI) are among the most common shoulder pathologies, yet their precise etiology remains incompletely understood.\u003csup\u003e1\u003c/sup\u003e While both intrinsic factors (\u003cem\u003ee.g.\u003c/em\u003e, age-related degeneration, reduced vascularity, and collagen abnormalities) and extrinsic factors (\u003cem\u003ee.g.\u003c/em\u003e, subacromial impingement and repetitive overhead activity) have been implicated, relatively few studies have focused on the role of specific acromion morphologies in predisposing individuals to RCI. Of these, the hook-shaped type III acromion has been most consistently associated with rotator cuff pathology.\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eMechanical impingement is a leading extrinsic cause of rotator cuff injury, implicated in up to 95% of tears.\u003csup\u003e3\u003c/sup\u003e It results from repetitive compression of the tendons under the acromion, contributing to tendon degeneration. Acromioplasty, which addresses this impingement, has become increasingly common. Early diagnosis and management of mechanical factors are associated with better outcomes, emphasizing the need to identify structural contributors, such as acromial morphology.\u003c/p\u003e\u003cp\u003eAcromial morphology is a key anatomical determinant of subacromial impingement.\u003csup\u003e4,5\u003c/sup\u003e The most widely used system for classifying acromion types is the Bigliani classification, later refined by Kitay et al., which describes four morphological types based on the shape of the inferior acromial surface: flat (Type I), curved (Type II), hooked (Type III), and convex (Type IV).\u003csup\u003e6\u003c/sup\u003e Magnetic Resonance Imaging (MRI) has since emerged as the most accurate modality for assessing both acromion shape and rotator cuff integrity.\u003c/p\u003e\u003cp\u003eSeveral studies have examined the relationship between acromion type and impingement or RCI. While many report an association between Type III (hooked) acromion and non-traumatic RCI,\u003csup\u003e2,7–11\u003c/sup\u003e others have found no significant relationship.\u003csup\u003e12,13\u003c/sup\u003e Such conflicting results demonstrate the ongoing uncertainty in the role of acromial morphology in RCI pathogenesis. Notably, nearly all of these studies were conducted among middle-aged and older adults, leaving a gap in understanding of how acromial morphology relates to RCI in younger populations. Moreover, there is a lack of local data from the Philippines on this issue. Hence, the primary objective of this study was to assess the association between acromial morphology and non-traumatic rotator cuff injury among young adult Filipinos (\u0026lt; 40 years old) using MRI-based classification.\u003c/p\u003e\u003cp\u003eRCIs are known to reduce quality of life to levels comparable with chronic conditions such as heart failure, diabetes, and depression. Treatment costs can accumulate rapidly, and delays in appropriate management can result in poorer outcomes. Early identification of anatomical risk factors, particularly in younger adults, may aid in preventive strategies and more tailored treatment approaches.\u003csup\u003e11\u003c/sup\u003e\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e This cross-sectional study retrospectively reviewed the MRI results of all patients (ages 25 to 50 years) of Makati Medical Center who underwent shoulder MRI from January 1, 2019 to December 31, 2019 as interpreted by radiologists accredited by the Philippine College of Radiology and fellows of the CT-MRI society of the Philippines. This study included as cases all patients with RCI, either tendinosis, partial or full thickness. We excluded individuals with (1) previous shoulder surgery, (2) fractures and/or dislocation, (3) infections or tumors of the shoulder, and (4) presence of acromial spurs. Asymptomatic patients with intact rotator cuff were also included to serve as control.\u003c/p\u003e\u003cp\u003eAll scans were performed using a 1.5-Tesla MRI scanner (Siemens). A shoulder array coil was used. The patients were positioned supine with their arms on the sides of their body in partial external rotation. Coronal oblique, sagittal oblique and axial images were obtained. The coronal oblique plane were selected parallel to the course of the supraspinatus tendon for ideal image acquisition of the tendon. The sagittal oblique image was used to identify acromion morphology.\u003c/p\u003e\u003cp\u003eThe main outcome was the presence of rotator cuff injury was determined by radiologic report. Complete rotator cuff tears were identified as a hyperintense signal area within the tendon on T2W and fat-suppressed images, seen in two planes. Complete tears are described as T2/PD signals extending from the articular or bursal surface, which most commonly affect the supraspinatus tendon. Fluid signal within the tendon defect is highly suggestive of rotator cuff injury.\u003csup\u003e14\u003c/sup\u003e\u003c/p\u003e\u003cp\u003ePartial tears were defined as T2/PD signals that extend in either, not both, the bursal or articular surface. Partial tears are also seen within the tendon substance, hence the term, intrasubstance partial tear. Radiologists use tendinosis as an all-encompassing term to indicate all tendon pathology. Also, they may use it to suggest a chronic tendon disease that does not resolve.\u003csup\u003e15\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eThe primary exposure was acromion morphology, classified using the Bigliani system by a single radiologist (T.B.). Information on age and sex were collected as well. MRI reports and images of all patients who underwent shoulder MRI were retrieved from the Novarad radiology information system (NovaRIS) and picture archiving and communication system (NovaPACS) of the Department of Radiology. The data were tabulated using Microsoft Excel-based data abstraction tool.\u003c/p\u003e\u003cp\u003eThe sample size was computed with 95% confidence level, an acceptable margin of error at 5%, an estimated prevalence of rotator cuff injury in certain acromion morphology of 56%.\u003csup\u003e12\u003c/sup\u003e The computation for sample size suggested a need for at least 132 patients.\u003c/p\u003e\u003cp\u003eMRI reports and images of all patients who underwent shoulder MRI were retrieved from the NOVARAD RIS and PACS system of the Department of Radiology. The data were tabulated using Microsoft Excel-based data abstraction tool.\u003c/p\u003e\u003cp\u003eDescriptive statistics were used to describe the demographic characteristics (age and sex) of the participants. Qualitative and quantitative data were numerically expressed as frequencies, proportions and means ± standard deviations (SD).\u003c/p\u003e\u003cp\u003eThe prevalence of rotator cuff injury according to sex and acromion morphology were determined. For each acromion type, a 2×2 contingency table was constructed comparing the number of patients with the given type versus all others, stratified by RCI status. Fisher’s Exact Test was used for all comparisons due to the small sample sizes, particularly for Types III and IV. A \u003cem\u003ep\u003c/em\u003e-value less than 0.05 was considered statistically significant. All statistical tests were conducted in R (v.4.5.0).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 155 Shoulder MRI studies of young adult patients were reviewed and 132 of them were included in the study due to presence of one of the following: injury of the rotator cuff, either tendinosis, partial or complete tear with no history of previous shoulder surgery, no associated fractures nor dislocation, infections or tumors of the shoulder nor presence of degenerative changes. Of the 155 studies, 20 were not included due to a history of trauma with fracture and/or dislocation; 5 were also not included due to the presence of degenerative changes as stated in the exclusion criteria above.\u003c/p\u003e\u003cp\u003eThe mean (\u0026plusmn;\u0026thinsp;SD) age of the participants is 31.22\u0026thinsp;\u0026plusmn;\u0026thinsp;5.42. Of the 132 participants included in the study, there was a higher proportion of males compared to females (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The overall period prevalence of rotator cuff injury was 58.33% (n\u0026thinsp;=\u0026thinsp;77). There was higher prevalence of RCI among males, as opposed to females. There was no significant difference between the prevalence of rotator cuff injury among male subjects when compared to that of female subjects (p\u0026thinsp;=\u0026thinsp;0.4036).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAssociation between sex and presence of rotator cuff injury.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(+) Rotator Cuff Injury\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;77)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(-) Rotator Cuff Injury\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;55)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;132)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e60.92% (n\u0026thinsp;=\u0026thinsp;53)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39.08% (n\u0026thinsp;=\u0026thinsp;34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e100% (n\u0026thinsp;=\u0026thinsp;87)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e53.33% (n\u0026thinsp;=\u0026thinsp;24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e46.67% (n\u0026thinsp;=\u0026thinsp;21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e100% (n\u0026thinsp;=\u0026thinsp;45)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eTo determine which acromial shape was most associated with injury, we compared RCI incidence across types. Among all acromion types, Type II acromion, the most common variant, showed the strongest association with RCI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.00001). Type III was also linked to higher RCI rates (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;00158). Although Type III acromion was present in only 5 patients, it was associated with a 100% rate of rotator cuff injury. Type II acromion, the most common variant, was also linked to higher RCI rates (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.00001), possibly due to its curved morphology. Fisher\u0026rsquo;s exact test did not demonstrate a significant relationship between rotator cuff injury and the presence of type I acromion (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.2041) or type IV acromion (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.5287). Detailed frequencies are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAssociation between acromion morphology and presence of rotator cuff injury.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcromion Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(+) Rotator Cuff Injury\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;77)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(-) Rotator Cuff Injury\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;55)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eType I\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44.26% (n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55.74% (n\u0026thinsp;=\u0026thinsp;34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.2041\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eType II\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e70.49% (n\u0026thinsp;=\u0026thinsp;43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e29.51% (n\u0026thinsp;=\u0026thinsp;18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.00001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eType III\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e100% (n\u0026thinsp;=\u0026thinsp;5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0% (n\u0026thinsp;=\u0026thinsp;0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.00158\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eType IV\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40% (n\u0026thinsp;=\u0026thinsp;2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60% (n\u0026thinsp;=\u0026thinsp;3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.5287\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe most significant finding in this study is the significant association between acromial morphology and non-traumatic RCI. Only\u0026thinsp;~\u0026thinsp;3% of the subjects had Type III acromion and although rare, all of them were associated with RCI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00158) compared to other acromion types. This results align with systematic review findings that Type III morphology nearly triples the odds of rotator cuff tear compared to Types I\u0026ndash;II (OR\u0026thinsp;=\u0026thinsp;2.82, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3e\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e).\u003csup\u003e11\u003c/sup\u003e This association is probably due to shape of Type III acromion described as being hooked. A hooked acromion differs from the Type I and II due to its increased anterior and inferior extension of the acromial bony process, which is thought to decrease the subacromial space, thereby increasing the likelihood of extrinsic degeneration of the rotator cuff tendons.\u003csup\u003e11\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eType II acromion was also found to be associated with increased occurrence of RCI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.00001) which may be due to its curved shape which can also narrow the subacromial space to some extent. However, being the most common type, Type II acromion can therefore significantly instigate a high incidence rate of RCI among all of the acromion types and can notably influence the causal relationship between this certain type and incidence of injury.\u003csup\u003e16\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eMajority of the subjects were male but there is no significant difference in the incidence of RCI between sexes. Studies in different populations similarly report no consistent sex-based differences in acromial morphology among rotator cuff tear cases.\u003csup\u003e17,18\u003c/sup\u003e Also, this study also shows similar results to studies conducted with different age cohorts, suggesting that Type III acromion is a risk marker regardless of age. For instance, in a multivariable analysis of surgical cases, acromial morphology (especially type III) remained significantly associated with RCI even after stratification by age.\u003csup\u003e19\u003c/sup\u003e But it is unknown whether these relationships are causal, or simply predictive in nature. Cross-sectional design limits causal inferences. Some investigators have found no significant correlation between acromion type and cuff tear, reinforcing uncertainty in the impingement hypothesis.\u003csup\u003e12,17,20\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eThese findings support using MRI-based acromial classification to identify individuals at elevated risk for non-traumatic RCI. Early recognition through imaging may guide targeted intervention, such as referral to physical therapists, physiatrists or orthopedic surgeons.\u003c/p\u003e\u003cp\u003eThis study had some limitations. The analysis was not adjusted for many other extrinsic and intrinsic factors affecting the rotator cuff tendons\u0026rsquo; risk of injury. Also, the relationship of the severity/grade of rotator cuff injury and the acromion types was not taken into consideration. Future prospective studies incorporating multivariate modeling and grading of tendon pathology may be needed to clarify causality.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study corroborates previous findings that type III acromion, although rare, is associated with a high incidence of non-traumatic rotator cuff injury. Type II acromion was also associated with RCI but it also has the highest prevalence. No significant association was found between sex and rotator cuff injury. Identifying those patients at risk may potentially benefit from corrective or preventive measures to help prevent future injury. Future studies may benefit by examining a greater number of factors and including a better distribution of acromion types.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eStatement of Ethics Approval Ethical approval was provided by the Makati Medical Center Institutional Review Board (MMCIRB 2020-105).\u003c/p\u003e\n\u003cp\u003eStatement of Participant Consent The need for consent to participate and publish was waived by the Makati Medical Center Institutional Review Board.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eTeunis T, Lubberts B, Reilly BT, Ring D. A systematic review and pooled analysis of the prevalence of rotator cuff disease with increasing age. \u003cem\u003eJ Shoulder Elbow Surg\u003c/em\u003e. 2014;23(12):1913-1921. doi:10.1016/j.jse.2014.08.001\u003c/li\u003e\n \u003cli\u003eTangtrakulwanich B, Kapkird A. Analyses of possible risk factors for subacromial impingement syndrome. \u003cem\u003eWorld J Orthop\u003c/em\u003e. 2012;3(1):5. doi:10.5312/WJO.V3.I1.5\u003c/li\u003e\n \u003cli\u003ePapatheodorou A, Ellinas P, Takis F, Tsanis A, Maris I, Batakis N. US of the shoulder: Rotator cuff and non-rotator cuff disorders. \u003cem\u003eRadiographics\u003c/em\u003e. 2006;26(1). doi:10.1148/rg.e23\u003c/li\u003e\n \u003cli\u003eHeuberer PR, Plachel F, Willinger L, et al. Critical shoulder angle combined with age predict five shoulder pathologies: A retrospective analysis of 1000 cases. \u003cem\u003eBMC Musculoskelet Disord\u003c/em\u003e. 2017;18(1). doi:10.1186/S12891-017-1559-4,\u003c/li\u003e\n \u003cli\u003eAlfaro-Gomez U, Fuentes-Ramirez LD, Chavez-Blanco KI, et al. Anatomical variations of the acromial and coracoid process: clinical relevance. \u003cem\u003eSurgical and Radiologic Anatomy\u003c/em\u003e. 2020;42(8):877-885. doi:10.1007/S00276-020-02497-5,\u003c/li\u003e\n \u003cli\u003eKitay GS, Iannotti JP, Williams GR, Haygood T, Kneeland BJ, Berlin J. Roentgenographic assessment of acromial morphologic condition in rotator cuff impingement syndrome. \u003cem\u003eJ Shoulder Elbow Surg\u003c/em\u003e. 1995;4(6):441-448. doi:10.1016/S1058-2746(05)80036-9,\u003c/li\u003e\n \u003cli\u003eKim JM, Kim YW, Kim HS, et al. The relationship between rotator cuff tear and four acromion types: cross-sectional study based on shoulder magnetic resonance imaging in 227 patients. \u003cem\u003eActa radiol\u003c/em\u003e. 2019;60(5):608-614. doi:10.1177/0284185118791211,\u003c/li\u003e\n \u003cli\u003eInklebarger J, Gyer G, Parkunan A, Galanis N, Michael J. Rotator cuff impingement associated with Type III acromial morphology in a young athlete-a case for early imaging. \u003cem\u003eJ Surg Case Rep\u003c/em\u003e. 2017;2017(1):rjw234. doi:10.1093/JSCR/RJW234\u003c/li\u003e\n \u003cli\u003eAndrade R, Correia AL, Nunes J, et al. Is Bony Morphology and Morphometry Associated With Degenerative Full-Thickness Rotator Cuff Tears? A Systematic Review and Meta-analysis. \u003cem\u003eArthroscopy - Journal of Arthroscopic and Related Surgery\u003c/em\u003e. 2019;35(12):3304-3315.e2. doi:10.1016/j.arthro.2019.07.005\u003c/li\u003e\n \u003cli\u003eNyffeler RW, Meyer DC. Acromion and glenoid shape: Why are they important predictive factors for the future of our shoulders? \u003cem\u003eEFORT Open Rev\u003c/em\u003e. 2017;2(5):141. doi:10.1302/2058-5241.2.160076\u003c/li\u003e\n \u003cli\u003eMorelli KM, Martin BR, Charakla FH, Durmisevic A, Warren GL. Acromion morphology and prevalence of rotator cuff tear: A systematic review and meta-analysis. \u003cem\u003eClinical Anatomy\u003c/em\u003e. 2019;32(1):122-130. doi:10.1002/CA.23309,\u003c/li\u003e\n \u003cli\u003eBalke M, Schmidt C, Dedy N, Banerjee M, Bouillon B, Liem D. Correlation of acromial morphology with impingement syndrome and rotator cuff tears. \u003cem\u003eActa Orthop\u003c/em\u003e. 2013;84(2):178-183. doi:10.3109/17453674.2013.773413,\u003c/li\u003e\n \u003cli\u003eAzalia X, Singjie LC, Anastasia M, Kholinne E. Characteristics of acromial morphology in patients with painful shoulders from Indonesia. \u003cem\u003eInt Orthop\u003c/em\u003e. 2025;49(8). doi:10.1007/S00264-025-06585-2,\u003c/li\u003e\n \u003cli\u003eTuite MJ. Magnetic Resonance Imaging of Rotator Cuff Disease and External Impingement. \u003cem\u003eMagn Reson Imaging Clin N Am\u003c/em\u003e. 2012;20(2):187-200. doi:10.1016/j.mric.2012.01.011\u003c/li\u003e\n \u003cli\u003eHodgson R, O\u0026rsquo;Connor PJ, Grainger AJ. Tendon and ligament imaging. \u003cem\u003eBritish Journal of Radiology\u003c/em\u003e. 2012;85(1016):1157-1172. doi:10.1259/BJR/34786470,\u003c/li\u003e\n \u003cli\u003eGumina S, Passaretti D, Candela V. Epidemiology and demographics of the rotator cuff tear. \u003cem\u003eRotator Cuff Tear: Pathogenesis, Evaluation and Treatment\u003c/em\u003e. Published online January 1, 2016:53-59. doi:10.1007/978-3-319-33355-7_4\u003c/li\u003e\n \u003cli\u003eAlmokhtar AA, Qanat AS, Mulla A, Alqurashi Z, Aljeraisi A, Hegaze AH. Relationship Between Acromial Anatomy and Rotator Cuff Tears in Saudi Arabian Population. \u003cem\u003eCureus\u003c/em\u003e. 2020;12(5):e8304. doi:10.7759/CUREUS.8304\u003c/li\u003e\n \u003cli\u003eVenkataraman S, Ethiraj P, Shanthappa A, Vellingiri K. A study of association between acromion types and shoulder pathology. \u003cem\u003eJournal of Orthopaedics and Spine\u003c/em\u003e. 2022;10(2):92. doi:10.4103/JOASP.JOASP_53_20\u003c/li\u003e\n \u003cli\u003eGill TJ, McIrvin E, Kocher MS, Homa K, Mair SD, Hawkins RJ. The relative importance of acromial morphology and age with respect to rotator cuff pathology. \u003cem\u003eJ Shoulder Elbow Surg\u003c/em\u003e. 2002;11(4):327-330. doi:10.1067/mse.2002.124425\u003c/li\u003e\n \u003cli\u003eLiu CT, Miao JQ, Wang H, an Ge H, Wang XH, Cheng B. The association between acromial anatomy and articular-sided partial thickness of rotator cuff tears. \u003cem\u003eBMC Musculoskelet Disord\u003c/em\u003e. 2021;22(1):760. doi:10.1186/S12891-021-04639-1\u003cstrong\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Makati Medical Center","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":"Acromion, Rotator Cuff, Rotator Cuff Injuries, Cross-Sectional Studies, Philippines","lastPublishedDoi":"10.21203/rs.3.rs-7204992/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7204992/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction\u003cbr\u003e\n \u003c/strong\u003eRotator cuff injury (RCI) is among the most common shoulder pathologies, significantly affecting quality of life. Acromial morphology has been implicated as a predisposing factor, but limited local data exist. The Bigliani-Kitay classification defines four acromion types: flat (I), curved (II), hooked (III), and convex (IV). MRI is the preferred modality for assessing both acromial morphology and RCI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjective\u003cbr\u003e\n \u003c/strong\u003eTo assess the association between acromion morphology and RCI among patients undergoing shoulder MRI at Makati Medical Center, a tertiary hospital in the Philippines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003cbr\u003e\nA retrospective review of shoulder MRI scans performed from January to December 2019 was conducted. Patients with shoulder pain were included as cases. Acromion morphology and presence of RCI (tendinosis, partial, or full-thickness tears) were documented. Images were interpreted by radiologists accredited by the Philippine College of Radiology.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003cbr\u003e\n \u003c/strong\u003eOf 132 patients (mean age: 31.2 ± 5.4 years), 65.9% were male. The period prevalence of RCI was 58.3% (n = 77). There was no significant sex-based difference in RCI prevalence (\u003cem\u003ep\u003c/em\u003e = 0.4036). RCI was significantly associated with Type II (70.5%, \u003cem\u003ep\u003c/em\u003e\u0026lt; 0.00001) and Type III (100%, \u003cem\u003ep\u003c/em\u003e = 0.00158) acromion morphologies. No significant association was found for Types I and IV.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003cbr\u003e\n \u003c/strong\u003eType II and Type III acromial morphologies are significantly associated with higher prevalence of RCI. Recognition of these morphologies on MRI may help identify patients at increased risk and allow for early intervention.\u003c/p\u003e","manuscriptTitle":"Association Between Acromion Morphology and Non-Traumatic Rotator Cuff Injury Among Young Adult Filipinos in a Tertiary Hospital: Cross-sectional Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-30 15:08:58","doi":"10.21203/rs.3.rs-7204992/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":"104cbd43-2606-4b51-8a3e-60e962f45ef8","owner":[],"postedDate":"July 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-30T15:08:58+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-30 15:08:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7204992","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7204992","identity":"rs-7204992","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}