Reliability and Validity of a Mobile Three-Dimensional Application for Humeral Retroversion Measurement

Reliability and Validity of a Mobile Three-Dimensional Application for Humeral Retroversion Measurement | 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 Reliability and Validity of a Mobile Three-Dimensional Application for Humeral Retroversion Measurement Woo Sub Kim, Soo Ji Park, Seung Yeol Lee This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5714513/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 Humeral fractures and conditions such as Little League Shoulder are common across different age groups, necessitating accurate evaluation of humeral retroversion, especially in preoperative, intraoperative, and postoperative settings. At present, the gold-standard methods for evaluation, such as computed tomography (CT) and magnetic resonance imaging (MRI), although effective, expose patients to radiation and incur high costs, particularly in pediatric patients. Methods This retrospective study reviewed 74 patients who underwent conventional humeral AP radiography, lateral radiography, and CT between May 2020 and July 2022. Using mobile application, conventional radiography-based three-dimensional (3D) humeral reconstruction was performed. Humeral retroversion measurements obtained via the application were compared with those obtained from CT. Reliability was evaluated using intraobserver and interobserver intraclass correlation coefficients (ICCs). In addition, the correlation coefficients between the two methods were calculated. Results Mobile application showed excellent intraobserver reliability (ICC = 0.937) and high interobserver reliability (ICC = 0.901) in humeral retroversion measurements, compared to CT scans, which showed lower ICCs. In addition, no significant difference was found between the retroversion measurements using CT and the mobile application (mean difference: -0.3, p = 0.816). The correlation coefficient between the two methods was strong (0.886, p < 0.001), indicating that the application provides results comparable to those of CT. Conclusion Mobile application offers a reliable, cost-effective, and accessible alternative to CT for evaluating humeral retroversion. It demonstrates comparable accuracy while minimizing radiation exposure and costs, making it an attractive option for clinical practice and research, particularly for pediatric patients and athletes. Future prospective studies are warranted to further validate the application of the mobile application across broader clinical scenarios and establish a standardized approach for measuring retroversion. Level of evidence Level III retrospective cohort study humeral retroversion mobile application computed tomography shoulder arthroplasty pediatric orthopedics orthopedic imaging Figures Figure 1 Figure 2 Figure 3 Background Humeral fractures occur in all age groups and can result from both high- and low-energy injuries. Proximal humerus fractures, in particular, account for 10% of such injuries in older patients, especially those over 65 years of age, with a higher incidence observed in older women. 1 ; 2 Supracondylar distal humerus fractures are common in children, comprising 50–70% of pediatric elbow fractures, with peak incidence at 5–8 years of age. 3 – 5 It is important to assess rotational alignment before and after surgery in these fractures. 6 In addition to fractures, proximal humerus epiphysiolysis, commonly known as Little League Shoulder, is a prevalent overuse injury in young baseball players, particularly pitchers. 7 This condition results from repetitive stress and strain on the growth plate (physis) of the proximal humerus due to frequent overhead throwing activities. 8 Little League Shoulder is most commonly seen in male athletes aged 11–16 years, with peak incidence around 13 years of age, accounting for approximately 10% of shoulder pain related to throwing activities in pediatric patients. 9 The condition is exacerbated by increased humeral retroversion in the dominant arm due to repetitive throwing motions, leading to proximal humeral epiphysiolysis. 10 At present, computed tomography (CT) or magnetic resonance imaging (MRI) are the gold-standard methods for measuring and verifying humeral torsion. However, these methods have several disadvantages, including radiation exposure and high costs, making it challenging to perform these tests repeatedly. Therefore, the proposed mobile application, which is compatible with conventional radiography and does not require additional equipment, is warranted. Therefore, studies have utilized biplane radiographs to create three-dimensional (3D) reconstruction images of long bones, such as the femur and tibia, successfully calculating their rotational profiles with excellent validity and reliability. 11 Consequently, processed biplanar radiography serve as an effective alternative to CT, providing significant advantages for studying torsional issues in bones and rotational problems in joints with minimal radiation exposure. Given the promising results of femoral anteversion assessment, we believe that a similar approach could provide a reliable and efficient method for evaluating humeral retroversion using conventional radiographs, thereby expanding the potential applications of this technology. 11 Therefore, we aimed to evaluate the validity and reliability of measuring humeral retroversion using 3D reconstructed images from biplanar radiographs. Materials and Methods Ethical consideration and study participants This retrospective study (level of evidence, diagnostic level III) was approved by the Institutional Review Board of our hospital (IRB no. MJH-2023-12-011) and conducted in accordance with the Declaration of Helsinki. The medical records of patients who underwent humeral anteroposterior (AP) and lateral (LAT) radiography and humeral CT between May 2020 and July 2022 were reviewed. The following data were reviewed: age, sex, diagnosis, medical history (including surgeries), affected side, trauma findings, and comorbidities. Radiological measurements Conventional humeral AP and LAT radiographs were obtained using a DK radiography machine (Samsung, Seoul, South Korea), with a source-to-image distance of approximately 100 cm. The machine settings were as follows: 75 kVp and 16 mA. CT was conducted using LightSpeed VCT Brilliance 64 (GE Healthcare, Milwaukee, WI, USA) at 120 kVp, with a slice thickness of 5.0 mm for axial views and 2.0 mm for coronal and sagittal views of the humerus. We used a picture archiving and communication system (PACS; Infinitt, Seoul, South Korea) to manipulate and measure the CT images. Subsequently, we employed the Humerus Mobile Application (Didim, Seongnam, Gyeonggi, South Korea) to reconstruct a 3D model from the conventional humeral AP and LAT radiographs. The inclusion criteria were as follows: (1) patients who underwent radiography between 2020 and 2022 and CT within 3 months and (2) radiographs were taken at our hospital. The exclusion criteria were as follows: (1) comorbidities affecting skeletal appearance, such as trauma and tumors; (2) inadequate radiographs, such as those with significant humeral deformities; and (3) radiographs or CT images not taken at our hospital. The mobile application was used on a fourth-generation iPad Air (Apple, Cupertino, CA). Conventional AP and LAT radiographs of the humerus were captured using an integrated camera, and the touch interface of the device was used to outline the humerus. At the completion of the reconstruction using the mobile application, humeral retroversion was analyzed using an embedded evaluation tool (Additional File 1). To assess humeral retroversion on the 3D images generated by the mobile application and CT, the distal reference was set as the elbow transepicondylar axis. The proximal reference markers included the central axis of the humeral head (the standard technique) and the axis extending from the humeral center to a point 9-mm posterior to the posterior boundary of the bicipital groove. In addition, a line was drawn along the posterior margins of the humeral intercondyles, and another reference line was created from the midpoint of the bicipital groove to the center of the humeral head, ensuring a consistent method for defining the proximal axis (Fig. 1 ). 12 Three investigators evaluated the reliability of the mobile applications. They independently reconstructed the humerus from standard AP and LAT radiographs using this application. To determine interobserver reliability, the three examiners measured humeral anteversion on 3D images reconstructed using the mobile application and CT. For intraobserver reliability, a single examiner (SJP) performed a second measurement of humeral anteversion after 4 weeks. The intraclass correlation coefficient (ICC) was calculated to determine the interobserver and intraobserver reliabilities. Statistical analysis To evaluate reliability, we used ICCs and a two-way random effects model based on a single measurement and absolute agreement. Bonett’s approximation was applied to set the 95% confidence interval width at 0.2, with an ICC of 0.8. The minimum sample size required for the reliability testing was 36. ICC values exceeding 0.8 were interpreted as indicating excellent reliability. The Kolmogorov–Smirnov test was used to assess the normality of continuous variable distributions. Pearson’s correlation analysis was used to evaluate the correlations between variables; the Lin’s concordance correlation coefficient was used for agreement analysis. All statistical analyses were conducted using IBM SPSS Statistics for Windows version 20.0 (IBM Co., Chicago, IL, USA), with statistical significance set at p < 0.05. Results Patient demographics A total of 97 patients met the inclusion criteria. After applying the exclusion criteria, 74 patients were included in this study (Fig. 2 ). The mean age of the patients at the time of examination was 73.4 ± 8.5 years (range, 49–92) [Table 1 ]. Retroversion measured using CT was 26.0° (26.0 ± 8.4°; range, 5.0–48.0°), whereas the value obtained using the mobile application was 25.7° (25.7 ± 7.8°; range, 6.0–41.0°). No statistically significant differences were observed between the two measurement methods (P = 0.677). Table 1 Patients’ demographics. Parameter Value Age (years ± SD) 73.4 ± 8.5 (range 49–92) Sex (M/F) 15 / 59 Laterality (right / left) 47 / 27 Diagnosis of the patient Rotator cuff tear 41 Cuff tear arthropathy 14 Osteoarthritis of the shoulder 17 Acute Septic shoulder 2 SD = standard deviation; M = male; F = female Reliability and validity of the mobile application for measuring humeral retroversion The intraobserver reliability of humeral retroversion measurements for the mobile application was excellent, with an ICC of 0.937 (95% CI: 0.936–0.983), whereas CT showed an ICC of 0.778 (95% CI: 0.592–0.883). In addition, interobserver reliability was higher for the mobile application (ICC: 0.901, 95% CI: 0.835–0.944) than for CT (ICC: 0.722, 95% CI: 0.576–0.835), demonstrating better consistency among different observers using the mobile application (Table 2 ). The correlation coefficient between CT and the mobile application was excellent, with a value of 0.886 (p < 0.001), indicating that the mobile application provides measurements comparable to those of CT (Fig. 3 ). Table 2 Intra- and interobserver reliability of humeral retroversion. Measurements Intraobserver reliability Interobserver reliability ICC 95% CI ICC 95% CI CT 0.778 0.592–0.883 0.722 0.576–0.835 Mobile application 0.937 0.936–0.983 0.901 0.835–0.944 ICC = intraclass correlation coefficient; CI = confidence interval Table 3 Comparison of humeral retroversion measurement between three-dimensional computed tomography (3D-CT) and the mobile application. Humeral retroversion Mean difference 95% CI p value CT Femora Total (n = 74) 26.0 ± 8.4 25.7 ± 7.8 -0.3 -2.9 to 2.3 0.816 CT computed tomography, CI confidence interval Discussion This study aimed to validate the use of a mobile application to measure humeral retroversion, extending its application from the femur to the humerus. The findings demonstrated that the mobile application provides reliable and valid measurements and offers several advantages over conventional methods. By enabling the assessment of humeral retroversion, this application may prove invaluable in various clinical settings and across different age groups, from childhood to adulthood. We focused on previous study that indicated that femoral anteversion could be precisely measured using a mobile application based on radiographs, demonstrating high validity and reliability, especially in individuals with cerebral palsy (CP). 11 ; 13 This mobile application eliminates the need for extra equipment and utilizes standard radiographs as a cost-effective alternative to CT with much lower radiation exposure. Although this technique was first validated in young patients with CP, its applicability to a broader adult population or individuals with implants has not been reported. Similar to the femoral retroversion, retroversion of the humerus has traditionally been measured using CT; however, CT has the disadvantages of high costs and radiation exposure. 12 For patients requiring regular follow-ups, it is challenging to perform CT scans at each visit; moreover, because the measurement process is not automated, considerations regarding the time required and accuracy of retroversion measurements during outpatient visits are necessary. Measuring retroversion based on plain radiography using a mobile application has proven to be comparable or even superior to CT; it allows for repeated measurements and potentially replaces the need for CT, offering significant benefits to patients. Measurement techniques and referencing landmarks can significantly impact the accuracy of version assessments. For example, West et al. (2018) found that different referencing axes, such as the forearm and transepicondylar axes, could result in considerable variations in the measured retroversion angles. 14 The conventional measurement methods involves drawing two lines on a CT scan and measuring the angle between them. However, this process is susceptible to various errors, both in drawing of the lines and measurement of the angles. The results of this study highlighted multiple methods for assessing humeral retroversion, each with its distinct advantages and challenges. Previous studies, such as Saka et al. (2015), have indicated that conventional humeral retroversion measurements using two-dimensional (2D) CT slices or ultrasound are often not correlated with 3D CT values owing to inherent biases and limitations in defining the reference. 15 Similarly, Oh et al. (2017) demonstrated variability among different 2D CT-based methods, showing that each method had its own set of reference landmarks, leading to a lack of consistency between measurements. The study showed that the standard method using the central axis of the humeral head did not always agree with alternative methods such as the posterior bicipital groove or the metaphyseal axis. 16 Given these challenges, it is evident that there is no universally accepted gold standard for determining humeral retroversion. Notably, in the present study, there were no statistically significant differences between the measurements obtained using CT and those obtained using the mobile application. This suggests that the mobile application can be reliably used to assess humeral retroversion, making it a valuable alternative to traditional CT-based measurements. With the use of the application, which minimizes errors by allowing users to point to landmarks instead of manually drawing lines, reference lines are automatically generated, angles calculated, and measurement errors significantly reduced. The excellent interobserver and intraobserver reliabilities demonstrated in our study highlight the advantages of this automated approach. The strong correlation between these methods reinforces their clinical applicability. The advent of various smartphone applications has revolutionized orthopedic measurements preoperatively and intraoperatively. This study builds on a previous study that utilized applications to improve the accuracy of corrective osteotomies and rotational assessments of long bones. As demonstrated by Oh et al. (2023), smartphone applications have shown promising results in accurately measuring rotational corrections during minimally invasive derotational osteotomies; similar benefits in assessing humeral retroversion were observed in the present study. 17 Furthermore, various previous studies have utilized the Femora® mobile application, demonstrating its excellent utility. For example, Sung et al. (2020) demonstrated that smartphone applications show promising results in accurately measuring femoral anteversion in patients with cerebral palsy, with high concurrent validity compared to 3D CT (correlation coefficient of 0.968). 13 Lee et al. (2023) showed that the mobile application demonstrated excellent reliability and correlation with CT measurements in femoral anteversion measurements, emphasizing its suitability for routine clinical use, accessibility, cost effectiveness​. 11 The mobile application demonstrates broad applicability in clinical settings by providing a reliable method for periodic monitoring of humeral torsion in pediatric and adolescent athletes or trauma patients. For example, young athletes, such as baseball players, who are at risk of developing shoulder adaptations owing to repetitive stress, can benefit from regular assessments to track changes in retroversion over time. In addition, this application can be highly valuable for preoperative evaluation and postoperative follow up, offering precise measurements of humeral retroversion without radiation exposure or high costs. This allows clinicians to assess retroversion at every follow-up visit, thereby improving the quality of care for surgical and non-surgical patients. Moreover, the automated measurement system not only enhances accuracy but also reduces the time required for assessments, making it an efficient and practical tool for routine clinical use. This study had several limitations. First, as a retrospective study, it relied on a review of medical records, which may have introduced biases related to patient selection. Although we excluded patients with known factors that could significantly affect anatomical deformity, we did not control for other patient-specific variables such as sex, medical history, and positioning. For a more comprehensive validation of the utility of mobile device applications, future research should focus on well-designed prospective studies. Second, the sample size was relatively small. Despite being above the threshold necessary for reliability testing, a larger sample size would help to better validate the findings, particularly when considering a diverse range of potential deformities and fracture patterns. Third, patients with implants, such as those undergoing reverse total shoulder arthroplasty, were not evaluated. Presently, there is no clear gold standard for measuring retroversion after reverse total shoulder arthroplasty, making direct comparisons challenging. However, if a standardized method is developed in the future, further studies comparing the measurements obtained using this application will be necessary. Expanding the cohort size would enhance the adaptability of the application across various clinical scenarios and reinforce its validity. Finally, although the application database covers pediatric and adult skeletons, this study analyzed only adult patients, necessitating further research to validate its utility in younger populations. Conclusion The mobile application demonstrated excellent validity and reliability in measuring humeral retroversion, comparable to CT. Due to its high reproducibility, ease of use, and cost effectiveness, it shows potential as a valuable screening and diagnostic tool. Further studies involving postoperative patients and broader age groups could improve its utility and validate its role in reducing the application of or replacing traditional imaging methods. Declarations Clinical trial number not applicable Ethics approval and consent to participate This retrospective study was approved by Myongji Hospital Institutional Review Board in Goyang. (IRB No: MJH-2023-12-011). The requirement for informed consent was waived because of the retrospective nature of the study. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (No. RS2023–00249202). This funding source had no role in the design of this study and will not have any role during its execution, analyses, interpretation of the data, or decision to submit results. Author Contribution All authors (WSK, SJP, and SYL) in this manuscript made significant contributions to the study design. WSK, SJP, and SYL analyzed and interpreted the data, and wrote the article, and approved the final version of the manuscript. WSK and SYL acquired and analyzed the data. WSK helped to draft the manuscript and critically revised the manuscript. All authors have read and approved the final version of the manuscript. Acknowledgements Not applicable. Data Availability The data are not publicly available due to privacy concerns but can be obtained from the corresponding author upon reasonable request. References Walter N, Szymski D, Riedl M et al. 2023. Proximal Humerus Fractures in the Elderly U.S. Population: A Cross-Sectional Study of Treatment Trends and Comparison of Complication Rates after Joint Replacement, Open Reduction and Internal Fixation, and Non-Surgical Management. J Clin Med 12. Jo Y-H, Lee K-H, Lee B-G. Surgical trends in elderly patients with proximal humeral fractures in South Korea: a population-based study. BMC Musculoskelet Disord. 2019;20:136. Tarabishi MM, Almigdad AK, Ganger R, et al. Distal humeral corrective osteotomy for treatment of supracondylar fracture malunions in children. J Child Orthop. 2023;17:232–8. Brubacher JW, Dodds SD. Pediatric supracondylar fractures of the distal humerus. Curr Rev Musculoskelet Med. 2008;1:190–6. Vaquero-Picado A, González-Morán G, Moraleda L. Management of supracondylar fractures of the humerus in children. EFORT Open Rev. 2018;3:526–40. Kaganur R, Jaisankar P, Sarkar B, et al. Dual Joystick Technique for Reduction of Torsional Profile in Pediatric Supracondylar Humerus Fracture With Delayed Presentation. J Pediatr Orthop. 2024;44:414–20. Saltzman BM, Chalmers PN, Mascarenhas R, et al. Upper extremity physeal injury in young baseball pitchers. Phys Sportsmed. 2014;42:100–11. Kinsella SB, Carl RL. Upper Extremity Overuse Injuries. Clin Pediatr Emerg Med. 2013;14:318–26. Bednar ED, Kay J, Memon M, et al. Diagnosis and Management of Little League Shoulder: A Systematic Review. Orthop J Sports Med. 2021;9:23259671211017563. Ito A, Mihata T, Hosokawa Y, et al. Humeral Retroversion and Injury Risk After Proximal Humeral Epiphysiolysis (Little Leaguer's Shoulder). Am J Sports Med. 2019;47:3100–6. Lee JW, Oh M, Choi MN, et al. Reliability and validity of a mobile application for femoral anteversion measurement in adult patients. J Orthop Surg Res. 2023;18:372. Boileau P, Bicknell RT, Mazzoleni N, et al. CT scan method accurately assesses humeral head retroversion. Clin Orthop Relat Res. 2008;466:661–9. Sung KH, Youn K, Chung CY, et al. Development and Validation of a Mobile Application for Measuring Femoral Anteversion in Patients With Cerebral Palsy. J Pediatr Orthop. 2020;40:e516–21. West EA, Knowles NK, Athwal GS, et al. A 3D comparison of humeral head retroversion by sex and measurement technique. Shoulder Elb. 2018;10:192–200. Saka M, Yamauchi H, Yoshioka T, et al. Conventional Humeral Retroversion Measurements Using Computed Tomography Slices or Ultrasound Images Are Not Correlated With the 3-Dimensional Humeral Retroversion Angle. Orthop J Sports Med. 2015;3:2325967115573701. Oh JH, Kim W, Cayetano AA Jr. Measurement Methods for Humeral Retroversion Using Two-Dimensional Computed Tomography Scans: Which Is Most Concordant with the Standard Method? Clin Orthop Surg. 2017;9:223–31. Oh CW, Park KH, Kim JW et al. 2023. Minimally Invasive Derotational Osteotomy of Long Bones: Smartphone Application Used to Improve the Accuracy of Correction. J Clin Med 12. Additional Declarations No competing interests reported. Supplementary Files AdditionalFile1.mp4 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-5714513","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":396449803,"identity":"356a2f0c-fbf3-4114-8ba4-db3fbba8c2c4","order_by":0,"name":"Woo Sub Kim","email":"","orcid":"","institution":"Hanyang University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Woo","middleName":"Sub","lastName":"Kim","suffix":""},{"id":396449804,"identity":"67e503d9-d922-4f8d-a0ef-8023602793ad","order_by":1,"name":"Soo Ji Park","email":"","orcid":"","institution":"Hanyang University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Soo","middleName":"Ji","lastName":"Park","suffix":""},{"id":396449805,"identity":"7e2197f4-fd9c-467f-893b-ca71f2754315","order_by":2,"name":"Seung Yeol Lee","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzUlEQVRIiWNgGAWjYBACCTBZwMDDxt5AkhYDBjl+ngMkajGWnJFApBbJ9t5nDz4Y1CVuuPn24GeeinsM/O3d+DVL8xw3N5xhcDhxw+28ZGmeM8UMEmfObsCrRU4ijU2ax+AAUEuOgeTMtgQGA4lcAlrkn7FJ/wE77Izxz5n/iNAiLcHGJs1gwAz0Po+ZxMcGIrRI9qSxSfYYHAYGco6ZxYdjCTwE/SJx/BibxI+KOmBUnjG+kVCTIMff3otfCwbgIU35KBgFo2AUjAKsAADT1kDXJFOZZQAAAABJRU5ErkJggg==","orcid":"","institution":"Hanyang University College of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Seung","middleName":"Yeol","lastName":"Lee","suffix":""}],"badges":[],"createdAt":"2024-12-26 07:53:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5714513/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5714513/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":72801236,"identity":"b13a7ee4-82c0-4c92-8229-f6c0ed15d6a5","added_by":"auto","created_at":"2025-01-02 09:36:49","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":280767,"visible":true,"origin":"","legend":"\u003cp\u003eHumeral retroversion measurement using computed tomography (A) and the mobile application with standard radiographs (B). The line 9 mm posterior to the bicipital groove is measured using CT (a). Axis from the humeral center to a point 9 mm posterior to the bicipital groove (b). Elbow transepicondylar axis served as the distal reference (c). The proximal humeral axis is measured through the mobile application (d). Elbow transepicondylar axis served as the distal reference through the mobile application (e).\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5714513/v1/796d1c84f4f6d08b2a418111.jpg"},{"id":72802626,"identity":"99fab119-6e83-4688-9472-90a2a77bfe55","added_by":"auto","created_at":"2025-01-02 09:44:49","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":286670,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of the inclusion criteria.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5714513/v1/0d0e5ee0871b584c792640c3.jpg"},{"id":72800919,"identity":"9ef37b41-2003-4204-85ea-de1604d9dfd7","added_by":"auto","created_at":"2025-01-02 09:28:49","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":218657,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between humeral retroversion measurements using a mobile application and three-dimensional computed tomography (3D-CT).\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5714513/v1/b1c7a417ac78115097d7444c.jpg"},{"id":109761045,"identity":"ff53b329-572a-4e06-a24b-9ec09e1bc378","added_by":"auto","created_at":"2026-05-22 07:29:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":962334,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5714513/v1/23422239-ff93-405a-802c-123fabfa9b3b.pdf"},{"id":72800928,"identity":"499f4b12-a13d-4fcd-8e4b-81c7c94d9d9d","added_by":"auto","created_at":"2025-01-02 09:28:56","extension":"mp4","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":124233441,"visible":true,"origin":"","legend":"","description":"","filename":"AdditionalFile1.mp4","url":"https://assets-eu.researchsquare.com/files/rs-5714513/v1/b4a241ae75b1d42046a9afc4.mp4"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reliability and Validity of a Mobile Three-Dimensional Application for Humeral Retroversion Measurement","fulltext":[{"header":"Background","content":"\u003cp\u003eHumeral fractures occur in all age groups and can result from both high- and low-energy injuries. Proximal humerus fractures, in particular, account for 10% of such injuries in older patients, especially those over 65 years of age, with a higher incidence observed in older women. \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e; \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e Supracondylar distal humerus fractures are common in children, comprising 50\u0026ndash;70% of pediatric elbow fractures, with peak incidence at 5\u0026ndash;8 years of age. \u003csup\u003e\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e It is important to assess rotational alignment before and after surgery in these fractures. \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn addition to fractures, proximal humerus epiphysiolysis, commonly known as Little League Shoulder, is a prevalent overuse injury in young baseball players, particularly pitchers. \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e This condition results from repetitive stress and strain on the growth plate (physis) of the proximal humerus due to frequent overhead throwing activities. \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e Little League Shoulder is most commonly seen in male athletes aged 11\u0026ndash;16 years, with peak incidence around 13 years of age, accounting for approximately 10% of shoulder pain related to throwing activities in pediatric patients. \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e The condition is exacerbated by increased humeral retroversion in the dominant arm due to repetitive throwing motions, leading to proximal humeral epiphysiolysis. \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eAt present, computed tomography (CT) or magnetic resonance imaging (MRI) are the gold-standard methods for measuring and verifying humeral torsion. However, these methods have several disadvantages, including radiation exposure and high costs, making it challenging to perform these tests repeatedly. Therefore, the proposed mobile application, which is compatible with conventional radiography and does not require additional equipment, is warranted. Therefore, studies have utilized biplane radiographs to create three-dimensional (3D) reconstruction images of long bones, such as the femur and tibia, successfully calculating their rotational profiles with excellent validity and reliability. \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e Consequently, processed biplanar radiography serve as an effective alternative to CT, providing significant advantages for studying torsional issues in bones and rotational problems in joints with minimal radiation exposure.\u003c/p\u003e \u003cp\u003eGiven the promising results of femoral anteversion assessment, we believe that a similar approach could provide a reliable and efficient method for evaluating humeral retroversion using conventional radiographs, thereby expanding the potential applications of this technology. \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e Therefore, we aimed to evaluate the validity and reliability of measuring humeral retroversion using 3D reconstructed images from biplanar radiographs.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eEthical consideration and study participants\u003c/h2\u003e \u003cp\u003eThis retrospective study (level of evidence, diagnostic level III) was approved by the Institutional Review Board of our hospital (IRB no. MJH-2023-12-011) and conducted in accordance with the Declaration of Helsinki. The medical records of patients who underwent humeral anteroposterior (AP) and lateral (LAT) radiography and humeral CT between May 2020 and July 2022 were reviewed. The following data were reviewed: age, sex, diagnosis, medical history (including surgeries), affected side, trauma findings, and comorbidities.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRadiological measurements\u003c/h3\u003e\n\u003cp\u003eConventional humeral AP and LAT radiographs were obtained using a DK radiography machine (Samsung, Seoul, South Korea), with a source-to-image distance of approximately 100 cm. The machine settings were as follows: 75 kVp and 16 mA. CT was conducted using LightSpeed VCT Brilliance 64 (GE Healthcare, Milwaukee, WI, USA) at 120 kVp, with a slice thickness of 5.0 mm for axial views and 2.0 mm for coronal and sagittal views of the humerus.\u003c/p\u003e \u003cp\u003eWe used a picture archiving and communication system (PACS; Infinitt, Seoul, South Korea) to manipulate and measure the CT images. Subsequently, we employed the Humerus Mobile Application (Didim, Seongnam, Gyeonggi, South Korea) to reconstruct a 3D model from the conventional humeral AP and LAT radiographs.\u003c/p\u003e \u003cp\u003eThe inclusion criteria were as follows: (1) patients who underwent radiography between 2020 and 2022 and CT within 3 months and (2) radiographs were taken at our hospital. The exclusion criteria were as follows: (1) comorbidities affecting skeletal appearance, such as trauma and tumors; (2) inadequate radiographs, such as those with significant humeral deformities; and (3) radiographs or CT images not taken at our hospital.\u003c/p\u003e \u003cp\u003eThe mobile application was used on a fourth-generation iPad Air (Apple, Cupertino, CA). Conventional AP and LAT radiographs of the humerus were captured using an integrated camera, and the touch interface of the device was used to outline the humerus. At the completion of the reconstruction using the mobile application, humeral retroversion was analyzed using an embedded evaluation tool (Additional File 1). To assess humeral retroversion on the 3D images generated by the mobile application and CT, the distal reference was set as the elbow transepicondylar axis. The proximal reference markers included the central axis of the humeral head (the standard technique) and the axis extending from the humeral center to a point 9-mm posterior to the posterior boundary of the bicipital groove. In addition, a line was drawn along the posterior margins of the humeral intercondyles, and another reference line was created from the midpoint of the bicipital groove to the center of the humeral head, ensuring a consistent method for defining the proximal axis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThree investigators evaluated the reliability of the mobile applications. They independently reconstructed the humerus from standard AP and LAT radiographs using this application. To determine interobserver reliability, the three examiners measured humeral anteversion on 3D images reconstructed using the mobile application and CT. For intraobserver reliability, a single examiner (SJP) performed a second measurement of humeral anteversion after 4 weeks. The intraclass correlation coefficient (ICC) was calculated to determine the interobserver and intraobserver reliabilities.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eTo evaluate reliability, we used ICCs and a two-way random effects model based on a single measurement and absolute agreement. Bonett\u0026rsquo;s approximation was applied to set the 95% confidence interval width at 0.2, with an ICC of 0.8. The minimum sample size required for the reliability testing was 36. ICC values exceeding 0.8 were interpreted as indicating excellent reliability. The Kolmogorov\u0026ndash;Smirnov test was used to assess the normality of continuous variable distributions. Pearson\u0026rsquo;s correlation analysis was used to evaluate the correlations between variables; the Lin\u0026rsquo;s concordance correlation coefficient was used for agreement analysis. All statistical analyses were conducted using IBM SPSS Statistics for Windows version 20.0 (IBM Co., Chicago, IL, USA), with statistical significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003ePatient demographics\u003c/h2\u003e\n \u003cp\u003eA total of 97 patients met the inclusion criteria. After applying the exclusion criteria, 74 patients were included in this study (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). The mean age of the patients at the time of examination was 73.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5 years (range, 49\u0026ndash;92) [Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e]. Retroversion measured using CT was 26.0\u0026deg; (26.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u0026deg;; range, 5.0\u0026ndash;48.0\u0026deg;), whereas the value obtained using the mobile application was 25.7\u0026deg; (25.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u0026deg;; range, 6.0\u0026ndash;41.0\u0026deg;). No statistically significant differences were observed between the two measurement methods (P\u0026thinsp;=\u0026thinsp;0.677).\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePatients\u0026rsquo; demographics.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eValue\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAge (years\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e73.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5 (range 49\u0026ndash;92)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex (M/F)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15 / 59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLaterality (right / left)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47 / 27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDiagnosis of the patient\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRotator cuff tear\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCuff tear arthropathy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOsteoarthritis of the shoulder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAcute Septic shoulder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; M\u0026thinsp;=\u0026thinsp;male; F\u0026thinsp;=\u0026thinsp;female\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eReliability and validity of the mobile application for measuring humeral retroversion\u003c/h2\u003e\n \u003cp\u003eThe intraobserver reliability of humeral retroversion measurements for the mobile application was excellent, with an ICC of 0.937 (95% CI: 0.936\u0026ndash;0.983), whereas CT showed an ICC of 0.778 (95% CI: 0.592\u0026ndash;0.883). In addition, interobserver reliability was higher for the mobile application (ICC: 0.901, 95% CI: 0.835\u0026ndash;0.944) than for CT (ICC: 0.722, 95% CI: 0.576\u0026ndash;0.835), demonstrating better consistency among different observers using the mobile application (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). The correlation coefficient between CT and the mobile application was excellent, with a value of 0.886 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), indicating that the mobile application provides measurements comparable to those of CT (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" style=\"width: 422px;\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eIntra- and interobserver reliability of humeral retroversion.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth style=\"width: 98px;\" rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eMeasurements\u003c/p\u003e\n \u003c/th\u003e\n \u003cth style=\"width: 143.752px;\" colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eIntraobserver reliability\u003c/p\u003e\n \u003c/th\u003e\n \u003cth style=\"width: 143px;\" colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eInterobserver reliability\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003eICC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth style=\"width: 98.7523px;\" align=\"left\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/th\u003e\n \u003cth style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003eICC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth style=\"width: 98px;\" align=\"left\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\" align=\"left\"\u003e\n \u003cp\u003eCT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003e0.778\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98.7523px;\" align=\"left\"\u003e\n \u003cp\u003e0.592\u0026ndash;0.883\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003e0.722\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\" align=\"left\"\u003e\n \u003cp\u003e0.576\u0026ndash;0.835\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\" align=\"left\"\u003e\n \u003cp\u003eMobile application\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003e0.937\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98.7523px;\" align=\"left\"\u003e\n \u003cp\u003e0.936\u0026ndash;0.983\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 45px;\" align=\"left\"\u003e\n \u003cp\u003e0.901\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\" align=\"left\"\u003e\n \u003cp\u003e0.835\u0026ndash;0.944\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 394.752px;\" colspan=\"5\" align=\"left\"\u003e\n \u003cp\u003eICC\u0026thinsp;=\u0026thinsp;intraclass correlation coefficient; CI\u0026thinsp;=\u0026thinsp;confidence interval\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of humeral retroversion measurement between three-dimensional computed tomography (3D-CT) and the mobile application.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth colspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eHumeral retroversion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003eMean difference\u003c/p\u003e\n \u003c/th\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/th\u003e\n \u003cth rowspan=\"2\" align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCT\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFemora\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal (n\u0026thinsp;=\u0026thinsp;74)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-2.9 to 2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.816\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eCT\u003c/em\u003e computed tomography, \u003cem\u003eCI\u003c/em\u003e confidence interval\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study aimed to validate the use of a mobile application to measure humeral retroversion, extending its application from the femur to the humerus. The findings demonstrated that the mobile application provides reliable and valid measurements and offers several advantages over conventional methods. By enabling the assessment of humeral retroversion, this application may prove invaluable in various clinical settings and across different age groups, from childhood to adulthood.\u003c/p\u003e \u003cp\u003eWe focused on previous study that indicated that femoral anteversion could be precisely measured using a mobile application based on radiographs, demonstrating high validity and reliability, especially in individuals with cerebral palsy (CP). \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e; \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e This mobile application eliminates the need for extra equipment and utilizes standard radiographs as a cost-effective alternative to CT with much lower radiation exposure. Although this technique was first validated in young patients with CP, its applicability to a broader adult population or individuals with implants has not been reported. Similar to the femoral retroversion, retroversion of the humerus has traditionally been measured using CT; however, CT has the disadvantages of high costs and radiation exposure. \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e For patients requiring regular follow-ups, it is challenging to perform CT scans at each visit; moreover, because the measurement process is not automated, considerations regarding the time required and accuracy of retroversion measurements during outpatient visits are necessary. Measuring retroversion based on plain radiography using a mobile application has proven to be comparable or even superior to CT; it allows for repeated measurements and potentially replaces the need for CT, offering significant benefits to patients. Measurement techniques and referencing landmarks can significantly impact the accuracy of version assessments. For example, West et al. (2018) found that different referencing axes, such as the forearm and transepicondylar axes, could result in considerable variations in the measured retroversion angles. \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e The conventional measurement methods involves drawing two lines on a CT scan and measuring the angle between them. However, this process is susceptible to various errors, both in drawing of the lines and measurement of the angles. The results of this study highlighted multiple methods for assessing humeral retroversion, each with its distinct advantages and challenges. Previous studies, such as Saka et al. (2015), have indicated that conventional humeral retroversion measurements using two-dimensional (2D) CT slices or ultrasound are often not correlated with 3D CT values owing to inherent biases and limitations in defining the reference. \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e Similarly, Oh et al. (2017) demonstrated variability among different 2D CT-based methods, showing that each method had its own set of reference landmarks, leading to a lack of consistency between measurements. The study showed that the standard method using the central axis of the humeral head did not always agree with alternative methods such as the posterior bicipital groove or the metaphyseal axis. \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e Given these challenges, it is evident that there is no universally accepted gold standard for determining humeral retroversion. Notably, in the present study, there were no statistically significant differences between the measurements obtained using CT and those obtained using the mobile application. This suggests that the mobile application can be reliably used to assess humeral retroversion, making it a valuable alternative to traditional CT-based measurements. With the use of the application, which minimizes errors by allowing users to point to landmarks instead of manually drawing lines, reference lines are automatically generated, angles calculated, and measurement errors significantly reduced. The excellent interobserver and intraobserver reliabilities demonstrated in our study highlight the advantages of this automated approach. The strong correlation between these methods reinforces their clinical applicability.\u003c/p\u003e \u003cp\u003eThe advent of various smartphone applications has revolutionized orthopedic measurements preoperatively and intraoperatively. This study builds on a previous study that utilized applications to improve the accuracy of corrective osteotomies and rotational assessments of long bones. As demonstrated by Oh et al. (2023), smartphone applications have shown promising results in accurately measuring rotational corrections during minimally invasive derotational osteotomies; similar benefits in assessing humeral retroversion were observed in the present study. \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eFurthermore, various previous studies have utilized the Femora\u0026reg; mobile application, demonstrating its excellent utility. For example, Sung et al. (2020) demonstrated that smartphone applications show promising results in accurately measuring femoral anteversion in patients with cerebral palsy, with high concurrent validity compared to 3D CT (correlation coefficient of 0.968). \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e Lee et al. (2023) showed that the mobile application demonstrated excellent reliability and correlation with CT measurements in femoral anteversion measurements, emphasizing its suitability for routine clinical use, accessibility, cost effectiveness​.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe mobile application demonstrates broad applicability in clinical settings by providing a reliable method for periodic monitoring of humeral torsion in pediatric and adolescent athletes or trauma patients. For example, young athletes, such as baseball players, who are at risk of developing shoulder adaptations owing to repetitive stress, can benefit from regular assessments to track changes in retroversion over time. In addition, this application can be highly valuable for preoperative evaluation and postoperative follow up, offering precise measurements of humeral retroversion without radiation exposure or high costs. This allows clinicians to assess retroversion at every follow-up visit, thereby improving the quality of care for surgical and non-surgical patients. Moreover, the automated measurement system not only enhances accuracy but also reduces the time required for assessments, making it an efficient and practical tool for routine clinical use.\u003c/p\u003e \u003cp\u003eThis study had several limitations. First, as a retrospective study, it relied on a review of medical records, which may have introduced biases related to patient selection. Although we excluded patients with known factors that could significantly affect anatomical deformity, we did not control for other patient-specific variables such as sex, medical history, and positioning. For a more comprehensive validation of the utility of mobile device applications, future research should focus on well-designed prospective studies. Second, the sample size was relatively small. Despite being above the threshold necessary for reliability testing, a larger sample size would help to better validate the findings, particularly when considering a diverse range of potential deformities and fracture patterns. Third, patients with implants, such as those undergoing reverse total shoulder arthroplasty, were not evaluated. Presently, there is no clear gold standard for measuring retroversion after reverse total shoulder arthroplasty, making direct comparisons challenging. However, if a standardized method is developed in the future, further studies comparing the measurements obtained using this application will be necessary. Expanding the cohort size would enhance the adaptability of the application across various clinical scenarios and reinforce its validity. Finally, although the application database covers pediatric and adult skeletons, this study analyzed only adult patients, necessitating further research to validate its utility in younger populations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe mobile application demonstrated excellent validity and reliability in measuring humeral retroversion, comparable to CT. Due to its high reproducibility, ease of use, and cost effectiveness, it shows potential as a valuable screening and diagnostic tool. Further studies involving postoperative patients and broader age groups could improve its utility and validate its role in reducing the application of or replacing traditional imaging methods.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eClinical trial number\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003enot applicable\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This retrospective study was approved by Myongji Hospital Institutional Review Board in Goyang. (IRB No: MJH-2023-12-011). The requirement for informed consent was waived because of the retrospective nature of the study.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eConsent for publication\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (No. RS2023\u0026ndash;00249202). This funding source had no role in the design of this study and will not have any role during its execution, analyses, interpretation of the data, or decision to submit results.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors (WSK, SJP, and SYL) in this manuscript made significant contributions to the study design. WSK, SJP, and SYL analyzed and interpreted the data, and wrote the article, and approved the final version of the manuscript. WSK and SYL acquired and analyzed the data. WSK helped to draft the manuscript and critically revised the manuscript. All authors have read and approved the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data are not publicly available due to privacy concerns but can be obtained from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWalter N, Szymski D, Riedl M et al. 2023. Proximal Humerus Fractures in the Elderly U.S. Population: A Cross-Sectional Study of Treatment Trends and Comparison of Complication Rates after Joint Replacement, Open Reduction and Internal Fixation, and Non-Surgical Management. J Clin Med 12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJo Y-H, Lee K-H, Lee B-G. Surgical trends in elderly patients with proximal humeral fractures in South Korea: a population-based study. BMC Musculoskelet Disord. 2019;20:136.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTarabishi MM, Almigdad AK, Ganger R, et al. Distal humeral corrective osteotomy for treatment of supracondylar fracture malunions in children. J Child Orthop. 2023;17:232\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrubacher JW, Dodds SD. Pediatric supracondylar fractures of the distal humerus. Curr Rev Musculoskelet Med. 2008;1:190\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVaquero-Picado A, Gonz\u0026aacute;lez-Mor\u0026aacute;n G, Moraleda L. Management of supracondylar fractures of the humerus in children. EFORT Open Rev. 2018;3:526\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaganur R, Jaisankar P, Sarkar B, et al. Dual Joystick Technique for Reduction of Torsional Profile in Pediatric Supracondylar Humerus Fracture With Delayed Presentation. J Pediatr Orthop. 2024;44:414\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaltzman BM, Chalmers PN, Mascarenhas R, et al. Upper extremity physeal injury in young baseball pitchers. Phys Sportsmed. 2014;42:100\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKinsella SB, Carl RL. Upper Extremity Overuse Injuries. Clin Pediatr Emerg Med. 2013;14:318\u0026ndash;26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBednar ED, Kay J, Memon M, et al. Diagnosis and Management of Little League Shoulder: A Systematic Review. Orthop J Sports Med. 2021;9:23259671211017563.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIto A, Mihata T, Hosokawa Y, et al. Humeral Retroversion and Injury Risk After Proximal Humeral Epiphysiolysis (Little Leaguer's Shoulder). Am J Sports Med. 2019;47:3100\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee JW, Oh M, Choi MN, et al. Reliability and validity of a mobile application for femoral anteversion measurement in adult patients. J Orthop Surg Res. 2023;18:372.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoileau P, Bicknell RT, Mazzoleni N, et al. CT scan method accurately assesses humeral head retroversion. Clin Orthop Relat Res. 2008;466:661\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSung KH, Youn K, Chung CY, et al. Development and Validation of a Mobile Application for Measuring Femoral Anteversion in Patients With Cerebral Palsy. J Pediatr Orthop. 2020;40:e516\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWest EA, Knowles NK, Athwal GS, et al. A 3D comparison of humeral head retroversion by sex and measurement technique. Shoulder Elb. 2018;10:192\u0026ndash;200.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaka M, Yamauchi H, Yoshioka T, et al. Conventional Humeral Retroversion Measurements Using Computed Tomography Slices or Ultrasound Images Are Not Correlated With the 3-Dimensional Humeral Retroversion Angle. Orthop J Sports Med. 2015;3:2325967115573701.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOh JH, Kim W, Cayetano AA Jr. Measurement Methods for Humeral Retroversion Using Two-Dimensional Computed Tomography Scans: Which Is Most Concordant with the Standard Method? Clin Orthop Surg. 2017;9:223\u0026ndash;31.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOh CW, Park KH, Kim JW et al. 2023. Minimally Invasive Derotational Osteotomy of Long Bones: Smartphone Application Used to Improve the Accuracy of Correction. J Clin Med 12.\u003c/span\u003e\u003c/li\u003e\u003c/ol\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":"humeral retroversion, mobile application, computed tomography, shoulder arthroplasty, pediatric orthopedics, orthopedic imaging","lastPublishedDoi":"10.21203/rs.3.rs-5714513/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5714513/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eHumeral fractures and conditions such as Little League Shoulder are common across different age groups, necessitating accurate evaluation of humeral retroversion, especially in preoperative, intraoperative, and postoperative settings. At present, the gold-standard methods for evaluation, such as computed tomography (CT) and magnetic resonance imaging (MRI), although effective, expose patients to radiation and incur high costs, particularly in pediatric patients.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003e This retrospective study reviewed 74 patients who underwent conventional humeral AP radiography, lateral radiography, and CT between May 2020 and July 2022. Using mobile application, conventional radiography-based three-dimensional (3D) humeral reconstruction was performed. Humeral retroversion measurements obtained via the application were compared with those obtained from CT. Reliability was evaluated using intraobserver and interobserver intraclass correlation coefficients (ICCs). In addition, the correlation coefficients between the two methods were calculated.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eMobile application showed excellent intraobserver reliability (ICC\u0026thinsp;=\u0026thinsp;0.937) and high interobserver reliability (ICC\u0026thinsp;=\u0026thinsp;0.901) in humeral retroversion measurements, compared to CT scans, which showed lower ICCs. In addition, no significant difference was found between the retroversion measurements using CT and the mobile application (mean difference: -0.3, p\u0026thinsp;=\u0026thinsp;0.816). The correlation coefficient between the two methods was strong (0.886, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), indicating that the application provides results comparable to those of CT.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eMobile application offers a reliable, cost-effective, and accessible alternative to CT for evaluating humeral retroversion. It demonstrates comparable accuracy while minimizing radiation exposure and costs, making it an attractive option for clinical practice and research, particularly for pediatric patients and athletes. Future prospective studies are warranted to further validate the application of the mobile application across broader clinical scenarios and establish a standardized approach for measuring retroversion.\u003c/p\u003e\u003cp\u003e\u003cb\u003eLevel of evidence\u003c/b\u003e\u003c/p\u003e \u003cp\u003eLevel III retrospective cohort study\u003c/p\u003e","manuscriptTitle":"Reliability and Validity of a Mobile Three-Dimensional Application for Humeral Retroversion Measurement","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-02 09:28:44","doi":"10.21203/rs.3.rs-5714513/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":"dcc89f88-8254-4109-900b-07c0fa395bce","owner":[],"postedDate":"January 2nd, 2025","published":true,"recentEditorialEvents":[{"type":"decision","content":"Withdrawn","date":"2026-05-20T08:26:50+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-20T08:41:31+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-02 09:28:44","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5714513","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5714513","identity":"rs-5714513","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}