RUP Ultrasonic Ossification Rate: A Novel Parameter for Pediatric Bone Age Assessment

RUP Ultrasonic Ossification Rate: A Novel Parameter for Pediatric Bone Age Assessment | 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 RUP Ultrasonic Ossification Rate: A Novel Parameter for Pediatric Bone Age Assessment Fanlun Zeng, Xiantao Shen, Xia Xiao, Xing Wu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9497803/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Background The Greulich-Pyle atlas is generally used in clinical practice; however, it involves radiation exposure. Our aim was to clarify the correlation between ultrasonic ossification rate and radiographic bone age, and to develop a repeatable ultrasonic parameter for assessing bone age. Objective To determine the correlation between ultrasonic ossification rates and radiographic bone age, and to test the hypothesis that a summed ultrasonic ossification parameter provides a highly correlated, reproducible, radiation‑free method for pediatric bone age assessment. Materials and methods Ultrasonic imaging was performed on seven ossification centres and epiphyses in 144 consecutive patients aged 0.1–18.0 years. The ossification rates were measured and compared with the radiological bone age. The correlation between ultrasonic ossification rate and GP bone age was analyzed by the Pearson correlation coefficient. The intra-observer and inter-observer reliability were evaluated using the intraclass correlation coefficient (ICC). Results The sum of the ossification rates (ORs) of the distal radius, distal ulna, and proximal radius (RUP) was highly correlated with the GP atlas (boys: r = 0.98; girls: r = 0.97). Appending the ORs of other bones did not increase the value of Pearson's r, while summing the ORs of all assessed bones slightly reduced it (boys: r = 0.97; girls: r = 0.96). The reliability of RUF and RUP was identical (intra-observer ICC = 0.99 [95% CI: 0.98, 0.99], p < 0.001; inter-observer: RUF: ICC = 0.99 [95% CI: 0.97, 0.99], RUP: ICC = 0.99 [95% CI: 0.98, 0.99], both p < 0.001), which was significantly higher than that of single sonographic parameters. Conclusion The ultrasonic RUP ossification rate is an easy-to-operate, efficient, radiation-free, operator-friendly indicator of bone age with high correlation to skeletal age and excellent reproducibility. It serves as a practical alternative for paediatric screening and developmental staging. Ossification rate Bone age assessment Ultrasound Greulich-Pyle (GP) atlas Figures Figure 1 Figure 2 Introduction Bone age assessment is critical for evaluating biological development and treating growth-related diseases. It is commonly used to predict limb length in children with leg length discrepancy and to assess idiopathic scoliosis progression [ 1 , 2 ]. Furthermore, it can determine growth potential, guide treatment, and predict outcomes in paediatric limb deformities. Bone age assessment relies on radiography, with the Tanner-Whitehouse (TW) method[ 3 ] and the Greulich-Pyle (GP) atlas[ 4 ] being the gold standards. However, there are risks from ionising radiation[ 5 ], and MRI is limited by cost, time-consuming, and accessibility[ 6 ]. Recently, ultrasound (US) has emerged as a cost-effective, non-ionizing alternative for bone age estimation[ 7 – 9 ]. It is well-tolerated in paediatric medicine and suitable for unossified epiphyses. Pilot studies have utilized US bone age (USBA) assessment by examining various anatomical sites, including the iliac crest[ 10 ], wrist[ 7 ], elbow[ 11 ], hand[ 8 ], clavicle[ 12 ], knee[ 13 ], shoulder[ 14 ], ankle[ 15 ], and femoral[ 16 ]. However, the USBA is limited by issues of accessibility and overlay effects that can compromise reliability. Additionally, the age range covered by these assessments varies across studies[ 17 ], with many studies focusing on defining growth stages rather than precise bone ages. Further validation is needed for USBA to be a "gold standard." The USBA has not been applied to estimate the ossification centre rates of the proximal radius and proximal/distal humerus. The presence of bony structures is discernible in US images[ 18 , 19 ]. Consequently, the necessity for further research into bone age based on US imaging is paramount. The objective of this study is to analyse the correlation between ultrasonic ossification rate of the wrist, elbow, shoulder, and knee and radiographic findings, with a view to identifying new USBA parameters. It is hypothesised that these parameters will provide an accurate and practical clinical tool. Materials and methods Study design and participants This prospective, cross-sectional study was approved by the institutional review board. Written informed consent was obtained from the guardians of all participants. Between September 2023 and September 2024, we prospectively recruited 144 consecutive outpatients (72 girls, 72 boys) aged <18 years. Inclusion required an unremarkable history—no tumour, trauma, infection, or prior surgery—at the wrist, elbow, shoulder, or knee. Children with systemic disorders known to alter skeletal maturation were excluded. All participants underwent left-wrist radiography and ultrasound of the wrist, elbow, shoulder, and knee; demographic data were obtained from electronic medical records. Imaging protocols Ultrasound Examinations All ultrasound examinations were performed using a GE LOGIQ e ultrasound system (GE Healthcare, Milwaukee, WI, USA) equipped with a 7.0–12.5 MHz high-frequency linear-array transducer (model L8-12i, GE Healthcare, Tokyo, Japan). A single musculoskeletal sonographer with eight years of paediatric experience acquired every scan while remaining blinded to participants’ chronological age and radiographic bone age. Radiography Examinations Left-wrist radiographs were obtained according to Tanner et al[20]. Two paediatric radiologists, blinded to all clinical data, independently assessed bone age using the GP atlas; discrepancies were resolved by averaging the two readings. In cases of discrepancies between the two readings (difference >6 months), a consensus was reached by averaging the two bone age values. Ultrasound measurements Seven ossification centres/epiphyses were evaluated in this study: the first metacarpal(proximal), distal radius, distal ulna, capitellum of the humerus, proximal radius, proximal humerus, and medial epicondyle of the femur. Participants were positioned supine during all ultrasound examinations, with the elbow fully extended, shoulder abducted, and knees extended with slight abduction to optimise visualisation. Probe positioning and image acquisition followed standardized protocols adapted from prior studies: (1) first metacarpal, distal radius, distal ulna, and medial epicondyle of the femur: as described by Wan et al. [21]; (2) humeral capitellum and proximal radius: as described by Shen et al. [19]; (3) proximal humerus: as described by Sanchez et al.[14]. On ultrasound images, each ossification center appeared as a discrete, variably sized echogenic focus surrounded by a circumferential hypoechoic cartilaginous halo (Fig. 1). The maximum epiphyseal diameter (D) and the corresponding ossification-centre diameter (d) were measured along the longitudinal axis; the ultrasonic ossification ratio (OR = d/D) was calculated immediately after image acquisition. All measurements were performed twice; if the discrepancy between the two measurements exceeded 0.1 mm for either d or D, a third measurement was acquired. Reliability analysis Inter- and intra-rater reliability of the ultrasound assessments was evaluated using intraclass correlation coefficients (ICC), which were calculated with ICC interpretations based on standard criteria: ICC ＞ 0.75 indicating good agreement, and ICC＞ 0.85 indicating excellent agreement. Inter-rater reliability reflected the consistency between two independently orthopaedic surgeons with 1 and 8 years of experience in musculoskeletal ultrasound and independent, blinded investigators. Intra-rater reliability was determined by blinded reevaluation of 40 randomly selected images by the same investigator. Each surgeon repeated the measurements two months later. Statistical analysis The sample size was estimated a priori for the diagnostic test, with two-sided α = 0.05 and β = 0.10. Guided by the findings of previous studies (Ultrasound in Med. & Biol. 2020;46(7):1761-1768), it was hypothesised that there would be a strong correlation between the ultrasonic ossification rate and the radiographic bone age scores (expected Pearson r = 0.96). The power analysis of PASS 22.0 indicated that the minimum theoretical sample size required was four. In order to provide a comprehensive overview of the annual age ranges from 0 to 18 years (18 age strata), while ensuring a 1:1 sex ratio, a total of 144 subjects were enrolled in the study (72 males and 72 females). The data used in this study were analyzed using SPSS 27.0 (IBM Corp., Armonk, NY, USA) and Excel 2013 (Microsoft Corp., Seattle, WA, USA). Pearson correlation was used to examine the relationship between ultrasonic ossification rate and radiographic bone age. A two-tailed p < 0.05 was considered statistically significant. Results A total of 144 consecutive patients (72 boys and 72 girls) were ultimately enrolled. The boys’ chronological age ranged from 0.2 to 17.8 years, and the girls’ from 0.4 to 17.8 years. Correlation analyses between ultrasonic ossification rate and bone age of each bone revealed in Table 1 the first metacarpal had the weakest correlation with radiographic bone age (boys: r=0.80; girls: r=0.77), while the proximal radius had the strongest (boys: r=0.95; girls: r=0.94). Ultrasonic ossification rate at the distal radius, distal ulna, and medial epicondyle of the femur were all highly correlated with bone age (r = 0.91–0.95). Notably, the sum of the ossification rates of the distal radius, distal ulna, and proximal radius (RUP) exhibited excellent correlation with the GP atlas (boys: r=0.98; girls: r=0.97). No obvious increase in Pearson’s r was observed when the OR of the other bone was appended. Summing the ossification rates of all assessed bones slightly decreased this correlation (boys: r = 0.97; girls: r = 0.96) (Table 1, Fig. 2). Table 2 presents the percentage ultrasonic ossification rate for the distal radius and ulna, and the proximal radius across different bone-age groups. In adolescence (bone age 14–16 years), boys exhibited ossification rates of 82.3 %, 61.7 %, and 79.1 % for the distal radius, distal ulna, and proximal radius, respectively, with an RUP of 232 %; corresponding values for girls were 90.1 %, 81.6 %, 76.1 %, and 247.5 %. In 16–18 years group, rates approached 80–90% (three bones) and 250–260% (RUP), indicating near-complete ossification. RUF and RUP showed identical excellent reliability. Intra-observer reproducibility for both parameters was excellent (ICC=0.99 [95% confidence interval: 0.98, 0.99], p<0.001). Inter-observer reproducibility was also high (RUF: ICC=0.99 [95% confidence interval: 0.97, 0.99], p<0.001; RUP: ICC=0.99 [95% confidence interval: 0.98, 0.99], p<0.001). Importantly, the reliability of RUF and RUP was significantly higher than that of single sonographic parameters, among which the first metacarpal had the lowest inter-observer reliability (ICC=0.84) (Table 3). Discussion The ultrasonic ossification rate of the distal radius, distal ulna, and proximal radius was highly correlated with bone age, and the summation of ossification ratios of the RUP exhibited a strongly significant correlation with GP atlas (r = 0.98 for boys, 0.97 for girls), suggesting that RUP can serve as a reliable predictor of bone age in pediatric populations. Ultrasound offers the advantages of no ionizing radiation, bedside feasibility, and cost-efficiency, and has become a routine diagnostic modality in pediatric clinical practice. It clearly depicts epiphyseal structures, providing an anatomic basis for quantitative analysis. Compared with radiography, it eliminates radiation exposure(critical for pediatric repeated assessments); in contrast to MRI, it is more convenient and economical, especially for pediatric follow-ups and field assessments in resource-limited settings[13, 22]. Currently, USBA estimation strategies are categorized into four classes: (i) the left-wrist ultrasound atlas method [8]; (ii) measurement of epiphyseal distance or ratio [23]; (iii) ossification staging [14, 24]; and (iv) skeletal maturity scoring [7, 21]. The first two enable direct bone age estimation, while the latter two derive values via standardized staging or scoring. However, 76.7 % of ultrasound studies report only maturity stages rather than specific bone-age values [17] . Recently, Wan et al. [7, 21, 25] constructed a maturity scoring system based on the ossification ratio (OR) of long-bone ossification centres, which correlates numerically with wrist chronological age, providing a novel quantitative USBA approach. To date, no gold standard USBA method for bone age evaluation has been consensus-based, but its clinical translation potential has attracted considerable academic attention. The key finding of this study is demonstrated an extremely high correlation between the sum of ultrasonic ossification rate of the RUP and the GP atlas. is that the composite RUP parameter exhibited an excellent correlation with the GP atlas (boys: r = 0.983; girls: r = 0.969), which is comparable to or even superior to previously reported ultrasonic bone age parameters[17]. The ultrasound-based bone age scoring system, established by visually comparing the presence, size, and morphology of ossification centres with reference to the GP atlas, exhibits a strong linear association with RBA in pediatric populations. Bilgili et al[26] demonstrated an extremely significant correlation between USBA adaptation of the GP atlas and GP in normal children aged ≤6 years (boys: r = 0.994; girls: r = 0.986). Hajalioghli[27] further validated this finding in children under 7 years of age with suspected growth disorders, reporting correlation coefficients of 0.98 (boys) and 0.96 (girls) between USBA and GP, which confirms the reliability of USBA assessment in this specific cohort. Consistent with these findings, Torenek[8] developed a GP-guided ultrasound assessment template for healthy adolescents aged 10–17 years, and their results identified strong correlations between USBA and GP (boys: r = 0.745; girls: r = 0.847), thereby confirming the stability of the USBA- GP correlation across different pediatric and adolescent age groups. Direct comparative analysis with prior studies is constrained by discrepancies in the age ranges selected for BA assessment. Wan[25] proposed the sum of ossification ratios of the radius, ulna, and femur (RUF) as an assessment index in a normal population aged 0.1–19 years, which exhibited a high correlation with radiographic bone age evaluated using the Chinese population-modified Tanner-Whitehouse 3 (TW3) scale (boys: r = 0.97; girls: r = 0.96). Consistent with previous findings, the present study confirms that quantitative indicators of ultrasonic ossification rate (e.g., RUP) are highly consistent with GP atlas; therefore, USBA is a reliable alternative method for bone age assessment. A key comparison of RUP and RUF confirms their clinical utility. Both had high correlation with the GP atlas (RUP: r=0.97–0.98; RUF: r=0.96–0.97) and identical excellent reliability (intra- and inter-observer ICC=0.99, p<0.001) with no significant difference in reproducibility. However, RUP has a distinct advantage: it can be completed by single upper limb scanning, eliminating femoral scanning [25] and repeated wrist adjustments[26], which reduces posture change time, subject discomfort (especially for paediatric patients in heavy clothing), shortens preparation time, improves compliance, and is suitable for younger or poorly cooperative paediatric cohorts. Ossification of the proximal radius initiates at 3–6 years, with proximal radial ossification centre fusion at a mean age of 14.8 years (boys) and 12.5 years (girls) [28]. Ossification of the humeral capitellum usually occurs before the age of 1, with fusion occurring before the age of 15 in boys and 14 in girls [28, 29], and both are critical markers for plain elbow radiograph-based skeletal maturity assessment [30, 31]. Shedge’s [24] ultrasound study on elbow ossification centre closure timing concluded that the proximal radial epiphyseal fusion score correlated most strongly with chronological age, making it the optimal age assessment indicator. This aligns with the present study, where the ultrasound-determined proximal radial ossification rate showed the strongest correlation with RBA (boys: r = 0.95; girls: r = 0.94), highlighting radial ossification’s importance in bone age assessment. Thus, the proximal radial ossification rate serves as a key USBA indicator. However, ultrasound measurement of the humeral capitellum for bone age evaluation remains unstudied; its moderate correlation with RBA in this study (boys: r = 0.87; girls: r = 0.81) led to its exclusion as an assessment indicator. Proximal humeral ossification initiates at around 4 months, with full epiphyseal fusion at 12～19 years in females. and 16～20 years in males[29, 32]. However, only a few studies have used this parameter to assess radiographic bone age [29]. Recent studies show that MRI achieves a high accuracy in bone age assessment via proximal humeral epiphyseal ossification staging, thus avoiding radiation[33, 34]. However, it is limited by high costs and operational constraints, making it impractical for repeated assessments. Only a few studies have validated ultrasound for this purpose[14]. In the present study, the ossification ratio of the proximal humerus showed only a moderate correlation with the GP atlas (boys: r = 0.84; girls: r = 0.85), and therefore, this was not retained as the primary outcome. This study has several limitations. Firstly, the single-centre design and near-exclusive inclusion of Han children from central China resulted in a highly homogeneous population, which limits the study's generalisability. Previous research has indicated that GP atlas atrophy charts constructed from historical samples are less applicable to contemporary Asian children[35, 36]. Hence, further validation of this USBA maturity system is required across multi-ethnic, multi-regional modern paediatric populations. Secondly, adolescents with closed epiphyses were excluded, with assessment timelines ending before fusion. Thirdly, variations in individual epiphyseal morphology (e.g., cortical irregularities) and body composition factors (e.g., obesity) may reduce the precision and sensitivity of ultrasound measurements, necessitating quantitative calibration. Ultrasound is also operator-dependent, offering less objectivity than plain radiography. Although standardised scan planes and numeric ossification ratios partly mitigate observer variability, multi-centre and multi-operator studies are still needed to confirm reproducibility and generalisability. In conclusion, the ultrasonic RUP parameter is a reliable, reproducible, and radiation-free indicator for paediatric bone age assessment, with excellent correlation with the GP atlas and high inter/intra-observer reliability. It provides a practical alternative to radiographic bone age determination, particularly suitable for paediatric screening and developmental staging. Further work is required to establish reference values and clinical indications across larger samples, multicentre settings, and multi-ethnic cohorts, to advance the standardised and regulated application of this technique. Declarations Funding: This study was funded by the Soaring Program of Youth Talent Development in Wuhan Children's Hospital (2024TFJH01); Clinical Research Laboratory of Pediatric Orthopedic Diseases (2025FEYJS007); Natural Science Foundation of Wuhan (202602030104158). Competing interests: The authors have no competing interests to declare that are relevant to the content of this article. Author Contribution ZFL performed data analysis, generated the figures, and drafted the manuscript. SXT advised on study methodology and provided substantial manuscript revisions. WX and XX supervised the study, assisted with inter‑rater reliability analysis, and approved the final version of the manuscript. All authors read and approved the final manuscript. References Sanders JO, Browne RH, McConnell SJ, Margraf SA, Cooney TE, Finegold DN (2007) Maturity assessment and curve progression in girls with idiopathic scoliosis. The Journal of bone and joint surgery American volume 89:64-73. Paley D, Bhave A, Herzenberg JE, Bowen JR (2000) Multiplier method for predicting limb-length discrepancy. The Journal of bone and joint surgery American volume 82:1432-1446. Tanner JM, Healy MJR, Cameron N, H G Assessment of skeletal maturity and prediction of adult height (TW3 method), 3rd ed edn. London: W. B. Saunders; 2001. 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Distal radius Distal ulna Medial epicondyle of the femur Proximal radius Proximal humerus Capitulum of humerus First metacarpal RU RP UP RUF RUP Total Boys 0.944 0.946 0.926 0.953 0.842 0.869 0.798 0.979 0.981 0.965 0.980 0.983 0.969 （n=72） (0.912-0.965) (0.915-0.966) (0.883-0.953) (0.926-0.970) (0.758-0.898) (0.799-0.916) (0.694-0.869) (0.966-0.987) (0.970-0.988) (0.944-0.978) (0.968-0.987) (0.974-0.990) (0.951-0.981) Girls 0.909 0.933 0.901 0.935 0.854 0.813 0.765 0.954 0.964 0.958 0.964 0.969 0.956 （n=72） (0.858-0.942) (0.894-0.957) (0.845-0937) (0.897-0.959) (0.775-0.906) (0.717-0.879) (0.649-0.847) (0.927-0.971) (0.942-0.977) (0.934-0.974) (0.943-0.977) (0.952-0.981) (0.931-0.973) Note. Data in parentheses are 95% confidence intervals. *RU=Distal Radius+ Distal Ulna *RP=Distal Radius+ Proximal Radius *UP = Distal Ulna+ Proximal Radius *RUF = Distal Radius+ Distal Ulna+ Medial epicondyle of the Femur *RUP = Distal Radius+ Distal Ulna+ Proximal Radius Table 2. Ossification ratios (× 100) of bones for patients with different bone ages Bone age n Distal radius Distal ulna Proximal radius RUP M F M F M F M F M F 0-2 8 8 0(6.0) 16.2(15.3) 0 0 0 0 0(5.8) 16.5(15.3) 2-4 8 8 29.5(6.8) 36.0(13.9) 0 0(9.9) 0(6.8) 0(8.1) 33.5(9.9) 47.0(19.3) 4-6 8 8 49.2(9.4) 56.7(10.1) 6.2(10.7) 21.2(19.8) 0(17.3) 20.9(14.0) 60.0(27.6) 97.5(29.0) 6-8 8 8 48.6(9.8) 48.3(5.1) 5.0(12.7) 16.5(12.3) 19.5(14.2) 35.9(15.6) 72.0(28.7) 93.5(28.1) 8-10 8 8 58.3(6.4) 57.2(4.5) 25.4(17.7) 40.6(15.4) 32.3(12.2) 46.0(14.7) 107.5(33.0) 150.0(29.2) 10-12 8 8 64.7(8.1) 69.4(11.3) 47.1(7.6) 55.2(14.0) 42.8(6.2) 69.4(13.0) 158.0(15.9) 198.0(28.2) 12-14 8 8 69.7(7.8) 76.2(10.5) 58.9(12.0) 71.1(11.1) 68.4(10.8) 83.0(17.2) 194.0(28.1) 227.5(32.7) 14-16 8 8 82.3(7.6) 90.1(4.0) 61.7(16.0) 81.6(12.2) 79.1(15.2) 76.1(8.3) 232.0(32.5) 247.5(18.3) 16-18 8 8 88.5(3.7) 91.8(4.5) 87.4(5.8) 89.0(4.3) 81.4(4.8) 82.5(9.1) 254.0(10.0) 261.0(10.2) Note. Data are medians, with standard deviation in parentheses. * RUP = sum of ossification ratios from the distal end of radius, ulna and proximal radius. Table 3. Intra-rater and Inter-rater reliability analysis of sonographic parameters Parameter Intra-rater reliability 95%Confidence interval Inter-rater reliability 95%Confidence interval P Value Distal radius 0.95 0.91~0.98 0.95 0.91~0.98 <0.001 Distal ulna 0.98 0.95~0.99 0.97 0.95~0.99 <0.001 Medial epicondyle of the femur 0.98 0.96~0.99 0.97 0.95~0.99 <0.001 Proximal radius 0.96 0.92~0.98 0.91 0.83~0.95 <0.001 Proximal humerus 0.94 0.88~0.97 0.92 0.86~0.96 <0.001 Capitulum of humerus 0.93 0.87~0.96 0.89 0.80~0.94 <0.001 First metacarpal 0.94 0.89~0.97 0.84 0.71~0.91 <0.001 RU 0.99 0.98~0.99 0.98 0.96~0.99 <0.001 RP 0.97 0.95~0.99 0.95 0.90~0.97 <0.001 UP 0.99 0.98~0.99 0.97 0.94~0.99 <0.001 RUF 0.99 0.98~0.99 0.99 0.97~0.99 <0.001 RUP 0.99 0.98~0.99 0.99 0.98~0.99 <0.001 Total 0.99 0.98~0.99 0.98 0.96~0.99 <0.001 Note. *RU = Distal Radius+ Distal Ulna *RP = Distal Radius+ Proximal Radius *UP = Distal Ulna+ Proximal Radius *RUF = Distal Radius+ Distal Ulna+ Medial epicondyle of the Femur *RUP = Distal Radius+ Distal Ulna+ Proximal Radius Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 29 Apr, 2026 Editor assigned by journal 27 Apr, 2026 Submission checks completed at journal 27 Apr, 2026 First submitted to journal 22 Apr, 2026 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-9497803","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":635854895,"identity":"34b363b4-21d7-46d4-bec4-5dd3ab4c1da5","order_by":0,"name":"Fanlun Zeng","email":"","orcid":"","institution":"Wuhan Children's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Fanlun","middleName":"","lastName":"Zeng","suffix":""},{"id":635854896,"identity":"9696e116-be9a-4685-b730-28348a2395e8","order_by":1,"name":"Xiantao Shen","email":"","orcid":"","institution":"Wuhan Children's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiantao","middleName":"","lastName":"Shen","suffix":""},{"id":635854897,"identity":"45dbadc1-a3cb-41e5-94aa-23f1bfdfe154","order_by":2,"name":"Xia Xiao","email":"","orcid":"","institution":"Wuhan Children's Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xia","middleName":"","lastName":"Xiao","suffix":""},{"id":635854898,"identity":"8ac2e7e9-e6d8-4937-b6d6-2475c4d2fe4f","order_by":3,"name":"Xing Wu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIie3QMQqDMBTG8QTBLqF0jEgtPUAhEnASexVDwY517KgIzys49RidUwRdPEBHvUEO0KG6FkrSrUP+8/sN30PIZvvLHClTRgN3VZaTMiOuGFUe8zVpK07NCOFhozJxo2fYEBPAnmnkE9YK8CZAFCXBodCRQWYL4eALGHN04pHUkKgvuoVsZ1IziqS4a0mLYSEYvAdQYkT6ygkblu2BYkNyHDo8KhZzl4j5ycxgi9dclExfNNjV/TSpaxJoyUfst3ObzWazfekNus9ENlgMyiwAAAAASUVORK5CYII=","orcid":"","institution":"Wuhan Children's Hospital","correspondingAuthor":true,"prefix":"","firstName":"Xing","middleName":"","lastName":"Wu","suffix":""}],"badges":[],"createdAt":"2026-04-22 14:40:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9497803/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9497803/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108977267,"identity":"0d9ece9b-4803-4844-b689-2ecf8ed03c91","added_by":"auto","created_at":"2026-05-11 11:31:08","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1154269,"visible":true,"origin":"","legend":"\u003cp\u003eSonographic findings for the first metacarpal (a), distal radius (b), distal ulna (c), proximal radius and capitulum of humerus (d), proximal humerus (e), medial epicondyle of the femur (f) of a 4.4-y-old boy. Radiographic bone age was 5 y after interpreted with the Greulich-Pyle (GP) atlas (g).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9497803/v1/bc0db9c7b20538934d327fa1.jpeg"},{"id":108946332,"identity":"51b167cb-d901-4501-b8b6-c63293ee3395","added_by":"auto","created_at":"2026-05-11 06:22:23","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":340808,"visible":true,"origin":"","legend":"\u003cp\u003eLinear regression between summation of ossification ratios (shown as percenta'ge) of distal radius, distal ulna, and proximal radius calculated from ultrasound images and bone age estimated from radiographs in (a) boys (n= 72) and (b) girls (n= 72). OR=ossification ratio; RUP=radius, ulna and proximal radius.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9497803/v1/d13ff1f8a2e2615ee497463b.jpeg"},{"id":108979636,"identity":"8c26f1fb-4758-4c84-bf0a-982215279b0b","added_by":"auto","created_at":"2026-05-11 12:00:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1841902,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9497803/v1/e5e5d19c-254b-44b9-84fa-5166e5097d3b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"RUP Ultrasonic Ossification Rate: A Novel Parameter for Pediatric Bone Age Assessment","fulltext":[{"header":"Introduction","content":"\u003cp\u003eBone age assessment is critical for evaluating biological development and treating growth-related diseases. It is commonly used to predict limb length in children with leg length discrepancy and to assess idiopathic scoliosis progression [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Furthermore, it can determine growth potential, guide treatment, and predict outcomes in paediatric limb deformities.\u003c/p\u003e \u003cp\u003eBone age assessment relies on radiography, with the Tanner-Whitehouse (TW) method[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] and the Greulich-Pyle (GP) atlas[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] being the gold standards. However, there are risks from ionising radiation[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and MRI is limited by cost, time-consuming, and accessibility[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Recently, ultrasound (US) has emerged as a cost-effective, non-ionizing alternative for bone age estimation[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. It is well-tolerated in paediatric medicine and suitable for unossified epiphyses. Pilot studies have utilized US bone age (USBA) assessment by examining various anatomical sites, including the iliac crest[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], wrist[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], elbow[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], hand[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], clavicle[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], knee[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], shoulder[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], ankle[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], and femoral[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, the USBA is limited by issues of accessibility and overlay effects that can compromise reliability. Additionally, the age range covered by these assessments varies across studies[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], with many studies focusing on defining growth stages rather than precise bone ages. Further validation is needed for USBA to be a \"gold standard.\"\u003c/p\u003e \u003cp\u003eThe USBA has not been applied to estimate the ossification centre rates of the proximal radius and proximal/distal humerus. The presence of bony structures is discernible in US images[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Consequently, the necessity for further research into bone age based on US imaging is paramount. The objective of this study is to analyse the correlation between ultrasonic ossification rate of the wrist, elbow, shoulder, and knee and radiographic findings, with a view to identifying new USBA parameters. It is hypothesised that these parameters will provide an accurate and practical clinical tool.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e\u003cstrong\u003eStudy design and participants\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;This prospective, cross-sectional study was approved by the institutional review board. Written informed consent was obtained from the guardians of all participants. Between September 2023 and September 2024, we prospectively recruited 144 consecutive outpatients (72 girls, 72 boys) aged \u0026lt;18 years. Inclusion required an unremarkable history\u0026mdash;no tumour, trauma, infection, or prior surgery\u0026mdash;at the wrist, elbow, shoulder, or knee. Children with systemic disorders known to alter skeletal maturation were excluded. All participants underwent left-wrist radiography and ultrasound of the wrist, elbow, shoulder, and knee; demographic data were obtained from electronic medical records.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImaging protocols\u003c/strong\u003e\u003cbr\u003e\u003cem\u003eUltrasound Examinations\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAll ultrasound examinations were performed\u0026nbsp;using a GE LOGIQ e ultrasound system (GE Healthcare, Milwaukee, WI, USA) equipped with a 7.0\u0026ndash;12.5 MHz high-frequency linear-array transducer (model L8-12i, GE Healthcare, Tokyo, Japan). A single musculoskeletal sonographer with eight years of paediatric experience acquired every scan while remaining blinded to participants\u0026rsquo; chronological age and radiographic bone age.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRadiography\u003c/em\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cem\u003eExaminations\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eLeft-wrist radiographs were obtained according to Tanner et al[20]. Two paediatric radiologists, blinded to all clinical data, independently assessed bone age using the GP atlas; discrepancies were resolved by averaging the two readings. In cases of discrepancies between the two readings (difference \u0026gt;6 months), a consensus was reached by averaging the two bone age values.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUltrasound measurements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSeven ossification centres/epiphyses were evaluated in this study: the first metacarpal(proximal), distal radius, distal ulna, capitellum of the humerus, proximal radius, proximal humerus, and medial epicondyle of the femur. Participants were positioned supine during all ultrasound examinations, with the elbow fully extended, shoulder abducted, and knees extended with slight abduction to optimise visualisation. Probe positioning and image acquisition followed standardized protocols adapted from prior studies: (1) first metacarpal, distal radius, distal ulna, and medial epicondyle of the femur: as described by Wan et al. [21]; (2) humeral capitellum and proximal radius: as described by Shen et al. [19]; (3) proximal humerus: as described by Sanchez et al.[14]. On ultrasound images, each ossification center appeared as a discrete, variably sized echogenic focus surrounded by a circumferential hypoechoic cartilaginous halo\u0026nbsp;(Fig. 1).\u0026nbsp;The maximum epiphyseal diameter (D) and the corresponding ossification-centre diameter (d) were measured along the longitudinal axis; the ultrasonic ossification ratio (OR = d/D) was calculated immediately after image acquisition.\u0026nbsp;All measurements were performed twice; if the discrepancy between the two measurements exceeded 0.1 mm for either d or D, a third measurement was acquired.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eReliability analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInter- and intra-rater reliability of the ultrasound assessments was evaluated using intraclass correlation coefficients (ICC), which were calculated with ICC interpretations based on standard criteria: ICC\u0026nbsp;＞ 0.75 indicating good agreement, and ICC＞ 0.85 indicating excellent agreement. Inter-rater reliability reflected the consistency between two independently orthopaedic surgeons with 1 and 8 years of experience in musculoskeletal ultrasound and independent, blinded investigators. Intra-rater reliability was determined by blinded reevaluation of 40 randomly selected images by the same investigator. Each surgeon repeated the measurements two months later.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe sample size was estimated a priori for the diagnostic test, with two-sided \u0026alpha; = 0.05 and \u0026beta; = 0.10. Guided by the findings of previous studies (Ultrasound in Med. \u0026amp; Biol. 2020;46(7):1761-1768), it was hypothesised that there would be a strong correlation between the\u0026nbsp;ultrasonic ossification rate and the radiographic bone age scores (expected Pearson r = 0.96). The power analysis of PASS 22.0 indicated that the minimum theoretical sample size required was four. In order to provide a comprehensive overview of the annual age ranges from 0 to 18 years (18 age strata), while ensuring a 1:1 sex ratio, a total of 144 subjects were enrolled in the study (72 males and 72 females).\u003c/p\u003e\n\u003cp\u003eThe data used in this study were analyzed using SPSS 27.0 (IBM Corp., Armonk, NY, USA) and Excel 2013 (Microsoft Corp., Seattle, WA, USA). Pearson correlation was used to examine the relationship between ultrasonic ossification rate and radiographic bone age. A two-tailed p \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 144 consecutive patients (72 boys and 72 girls) were ultimately enrolled. The boys\u0026rsquo; chronological age ranged from 0.2 to 17.8 years, and the girls\u0026rsquo; from 0.4 to 17.8 years.\u003c/p\u003e\n\u003cp\u003eCorrelation analyses between ultrasonic ossification rate and bone age of each bone revealed in Table 1 the first metacarpal had the weakest correlation with radiographic bone age (boys: r=0.80; girls: r=0.77), while the proximal radius had the strongest (boys: r=0.95; girls: r=0.94).\u003c/p\u003e\n\u003cp\u003eUltrasonic ossification rate at the distal radius, distal ulna, and medial epicondyle of the femur were all highly correlated with bone age (r = 0.91\u0026ndash;0.95). Notably, the sum of the ossification rates of the distal radius, distal ulna, and proximal radius (RUP) exhibited excellent correlation with the GP atlas (boys: r=0.98; girls: r=0.97). No obvious increase in Pearson\u0026rsquo;s r was observed when the OR of the other bone was appended. Summing the ossification rates of all assessed bones slightly decreased this correlation (boys: r = 0.97; girls: r = 0.96) (Table 1, Fig. 2).\u003c/p\u003e\n\u003cp\u003eTable 2 presents the percentage ultrasonic ossification rate for the distal radius and ulna, and the proximal radius across different bone-age groups. In adolescence (bone age 14\u0026ndash;16 years), boys exhibited ossification rates of 82.3 %, 61.7 %, and 79.1 % for the distal radius, distal ulna, and proximal radius, respectively, with an RUP of 232 %; corresponding values for girls were 90.1 %, 81.6 %, 76.1 %, and 247.5 %. In 16\u0026ndash;18 years group, rates approached 80\u0026ndash;90% (three bones) and 250\u0026ndash;260% (RUP), indicating near-complete ossification.\u003c/p\u003e\n\u003cp\u003eRUF and RUP showed identical excellent reliability. Intra-observer reproducibility for both parameters was excellent (ICC=0.99 [95% confidence interval: 0.98, 0.99], p\u0026lt;0.001). Inter-observer reproducibility was also high (RUF: ICC=0.99 [95% confidence interval: 0.97, 0.99], p\u0026lt;0.001; RUP: ICC=0.99 [95% confidence interval: 0.98, 0.99], p\u0026lt;0.001). Importantly, the reliability of RUF and RUP was significantly higher than that of single sonographic parameters, among which the first metacarpal had the lowest inter-observer reliability (ICC=0.84) (Table 3).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe ultrasonic ossification rate of the distal radius, distal ulna, and proximal radius was highly correlated with bone age, and the summation of ossification ratios of the RUP exhibited a strongly significant correlation with GP atlas (r = 0.98 for boys, 0.97 for girls), suggesting that RUP can serve as a reliable predictor of bone age in pediatric populations.\u003c/p\u003e\n\u003cp\u003eUltrasound offers the advantages of no ionizing radiation, bedside feasibility, and cost-efficiency, and has become a routine diagnostic modality in pediatric clinical practice. It clearly depicts epiphyseal structures, providing an anatomic basis for quantitative analysis. Compared with radiography, it eliminates radiation exposure(critical for pediatric repeated assessments); in contrast to MRI, it is more convenient and economical, especially for pediatric follow-ups and field assessments in resource-limited settings[13, 22]. Currently, USBA estimation strategies are categorized into four classes: (i) the left-wrist ultrasound atlas method [8]; (ii) measurement of epiphyseal distance or ratio [23]; (iii) ossification staging [14, 24]; and (iv) skeletal maturity scoring [7, 21]. The first two enable direct bone age estimation, while the latter two derive values via standardized staging or scoring. However, 76.7 % of ultrasound studies report only maturity stages rather than specific bone-age values \u003cstrong\u003e[17]\u003c/strong\u003e. Recently, Wan et al.\u0026nbsp;[7, 21, 25]\u0026nbsp;constructed a maturity scoring system based on the ossification ratio (OR) of long-bone ossification centres, which correlates numerically with wrist chronological age, providing a novel quantitative USBA approach. To date, no gold standard USBA method for bone age evaluation has been consensus-based, but its clinical translation potential has attracted considerable academic attention.\u003c/p\u003e\n\u003cp\u003eThe key finding of this study is demonstrated an extremely high correlation between the sum of ultrasonic ossification rate of the RUP and the GP atlas. is that the composite RUP parameter exhibited an excellent correlation with the GP atlas (boys: r = 0.983; girls: r = 0.969), which is comparable to or even superior to previously reported ultrasonic bone age parameters[17]. The ultrasound-based bone age scoring system, established by visually comparing the presence, size, and morphology of ossification centres with reference to the GP atlas, exhibits a strong linear association with RBA in pediatric populations. Bilgili et al[26] demonstrated an extremely significant correlation between USBA adaptation of the GP atlas and GP in normal children aged \u0026le;6 years (boys: r = 0.994; girls: r = 0.986). Hajalioghli[27] further validated this finding in children under 7 years of age with suspected growth disorders, reporting correlation coefficients of 0.98 (boys) and 0.96 (girls) between USBA and GP, which confirms the reliability of USBA assessment in this specific cohort. Consistent with these findings, Torenek[8] developed a GP-guided ultrasound assessment template for healthy adolescents aged 10\u0026ndash;17 years, and their results identified strong correlations between USBA and GP (boys: r = 0.745; girls: r = 0.847), thereby confirming the stability of the USBA- GP correlation across different pediatric and adolescent age groups. Direct comparative analysis with prior studies is constrained by discrepancies in the age ranges selected for BA assessment. Wan[25] proposed the sum of ossification ratios of the radius, ulna, and femur (RUF) as an assessment index in a normal population aged 0.1\u0026ndash;19 years, which exhibited a high correlation with radiographic bone age evaluated using the Chinese population-modified Tanner-Whitehouse 3 (TW3) scale (boys: r = 0.97; girls: r = 0.96). Consistent with previous findings, the present study confirms that quantitative indicators of ultrasonic ossification rate (e.g., RUP) are highly consistent with GP atlas; therefore, USBA is a reliable alternative method for bone age assessment.\u003c/p\u003e\n\u003cp\u003eA key comparison of RUP and RUF confirms their clinical utility. Both had high correlation with the GP atlas (RUP: r=0.97\u0026ndash;0.98; RUF: r=0.96\u0026ndash;0.97) and identical excellent reliability (intra- and inter-observer ICC=0.99, p\u0026lt;0.001) with no significant difference in reproducibility. However, RUP has a distinct advantage: it can be completed by single upper limb scanning, eliminating femoral scanning [25] and repeated wrist adjustments[26], which reduces posture change time, subject discomfort (especially for paediatric patients in heavy clothing), shortens preparation time, improves compliance, and is suitable for younger or poorly cooperative paediatric cohorts.\u003c/p\u003e\n\u003cp\u003eOssification of the proximal radius initiates at 3\u0026ndash;6 years, with proximal radial ossification centre fusion at a mean age of 14.8 years (boys) and 12.5 years (girls) [28]. Ossification of the humeral capitellum usually occurs before the age of 1, with fusion occurring before the age of 15 in boys and 14 in girls\u0026nbsp;[28, 29],\u0026nbsp;and both are critical markers for plain elbow radiograph-based skeletal maturity assessment\u0026nbsp;[30, 31]. Shedge\u0026rsquo;s\u0026nbsp;[24]\u0026nbsp;ultrasound study on elbow ossification centre closure timing concluded that the proximal radial epiphyseal fusion score correlated most strongly with chronological age, making it the optimal age assessment indicator.\u0026nbsp;This aligns with\u0026nbsp;the present study,\u0026nbsp;where the ultrasound-determined proximal radial ossification rate showed the strongest correlation with RBA (boys: r = 0.95; girls: r = 0.94), highlighting radial ossification\u0026rsquo;s importance in bone age assessment.\u0026nbsp;Thus, the proximal radial ossification rate serves as a key USBA indicator. However, ultrasound measurement of the humeral capitellum for bone age evaluation remains unstudied; its moderate correlation with RBA in this study (boys: r = 0.87; girls: r = 0.81) led to its exclusion as an assessment indicator.\u003c/p\u003e\n\u003cp\u003eProximal humeral ossification initiates at around 4 months, with full epiphyseal fusion at 12～19 years in females. and 16～20 years in males[29, 32]. However, only a few studies have used this parameter to assess radiographic bone age [29]. Recent studies show that MRI achieves a high accuracy in bone age assessment via proximal humeral epiphyseal ossification staging, thus avoiding radiation[33, 34]. However, it is limited by high costs and operational constraints, making it impractical for repeated assessments. Only a few studies have validated ultrasound for this purpose[14]. In the present study, the ossification ratio of the proximal humerus showed only a moderate correlation with the GP atlas (boys: r = 0.84; girls: r = 0.85), and therefore, this was not retained as the primary outcome.\u003c/p\u003e\n\u003cp\u003eThis study has several limitations. Firstly, the single-centre design and near-exclusive inclusion of Han children from central China resulted in a highly homogeneous population, which limits the study\u0026apos;s generalisability. Previous research has indicated that GP atlas atrophy charts constructed from historical samples are less applicable to contemporary Asian children[35, 36]. Hence, further validation of this\u0026nbsp;USBA\u0026nbsp;maturity system is required across multi-ethnic, multi-regional modern paediatric populations. Secondly, adolescents with closed epiphyses were\u0026nbsp;excluded, with assessment timelines ending before fusion. Thirdly, variations in individual epiphyseal morphology (e.g., cortical irregularities) and body composition factors (e.g., obesity) may reduce the precision and sensitivity of ultrasound measurements, necessitating quantitative calibration. Ultrasound is also operator-dependent, offering less objectivity than plain radiography. Although standardised scan planes and numeric ossification ratios partly mitigate observer variability, multi-centre and multi-operator studies are still needed to confirm reproducibility and generalisability.\u003c/p\u003e\n\u003cp\u003eIn conclusion, the ultrasonic RUP parameter is a reliable, reproducible, and radiation-free indicator for paediatric bone age assessment, with excellent correlation with the GP atlas and high inter/intra-observer reliability. It provides a practical alternative to radiographic bone age determination, particularly suitable for paediatric screening and developmental staging. Further work is required to establish reference values and clinical indications across larger samples, multicentre settings, and multi-ethnic cohorts, to advance the standardised and regulated application of this technique.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding:\u003c/h2\u003e\n\u003cp\u003eThis study was funded by the Soaring Program of Youth Talent Development in Wuhan Children\u0026apos;s Hospital (2024TFJH01); Clinical Research Laboratory of Pediatric Orthopedic Diseases (2025FEYJS007); Natural Science Foundation of Wuhan (202602030104158).\u003c/p\u003e\n\u003ch2\u003eCompeting interests:\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eThe authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eZFL performed data analysis, generated the figures, and drafted the manuscript. SXT advised on study methodology and provided substantial manuscript revisions. WX and XX supervised the study, assisted with inter‑rater reliability analysis, and approved the final version of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSanders JO, Browne RH, McConnell SJ, Margraf SA, Cooney TE, Finegold DN (2007) Maturity assessment and curve progression in girls with idiopathic scoliosis. The Journal of bone and joint surgery American volume 89:64-73.\u003c/li\u003e\n\u003cli\u003ePaley D, Bhave A, Herzenberg JE, Bowen JR (2000) Multiplier method for predicting limb-length discrepancy. The Journal of bone and joint surgery American volume 82:1432-1446.\u003c/li\u003e\n\u003cli\u003eTanner JM, Healy MJR, Cameron N, H G Assessment of skeletal maturity and prediction of adult height (TW3 method), 3rd ed edn. London: W. B. Saunders; 2001.\u003c/li\u003e\n\u003cli\u003eGreulich WW, Pyle SI (1959) Radiographic atlas of skeletal development of the hand and wrist. Stanford University Press, Stanford, CA.\u003c/li\u003e\n\u003cli\u003eSmith-Bindman R, Alber SA, Kwan ML, Pequeno P, Bolch WE, Bowles EJA, Greenlee RT, Stout NK, Weinmann S, Moy LM, Stewart C, Francisco M, Kofler C, Duncan JR, Ducore J, Mahendra M, Pole JD, Miglioretti DL (2025) Medical Imaging and Pediatric and Adolescent Hematologic Cancer Risk. N Engl J Med 393:1269-1278.\u003c/li\u003e\n\u003cli\u003eTerada Y, Kono S, Uchiumi T, Kose K, Miyagi R, Yamabe E, Fujinaga Y, Yoshioka H (2014) Improved reliability in skeletal age assessment using a pediatric hand MR scanner with a 0.3T permanent magnet. Magn Reson Med Sci 13:215-219.\u003c/li\u003e\n\u003cli\u003eWan J, Zhao Y, Feng Q, Lv P, Hong K, Zhang C (2021) Statistical Confirmation of a Method of US Determination of Bone Age. Radiology 300:176-183.\u003c/li\u003e\n\u003cli\u003eTorenek Agirman K, Bilge OM, Miloglu O (2018) Ultrasonography in determining pubertal growth and bone age. Dentomaxillofac Radiol 47:20170398.\u003c/li\u003e\n\u003cli\u003eDaneff M, Casalis C, Bruno CH, Bruno DA (2015) Bone age assessment with conventional ultrasonography in healthy infants from 1 to 24 months of age. Pediatric radiology 45:1007-1015.\u003c/li\u003e\n\u003cli\u003eWagner UA, Diedrich V, Schmitt O (1995) Determination of skeletal maturity by ultrasound: a preliminary report. Skeletal radiology 24:417-420.\u003c/li\u003e\n\u003cli\u003eSchulz R, Schiborr M, Pfeiffer H, Schmidt S, Schmeling A (2014) Forensic age estimation in living subjects based on ultrasound examination of the ossification of the olecranon. J Forensic Leg Med 22:68-72.\u003c/li\u003e\n\u003cli\u003eSchulz R, Schiborr M, Pfeiffer H, Schmidt S, Schmeling A (2013) Sonographic assessment of the ossification of the medial clavicular epiphysis in 616 individuals. Forensic Sci Med Pathol 9:351-357.\u003c/li\u003e\n\u003cli\u003eHerrmann J, Saring D, Auf der Mauer M, Groth M, Jopp-van Well E (2021) Forensic age assessment of the knee: proposal of a new classification system using two-dimensional ultrasound volumes and comparison to MRI. Eur Radiol 31:3237-3247.\u003c/li\u003e\n\u003cli\u003eSanchez MB, Codinha S, Garcia AM, Sanchez JAS (2017) Estimating legal age based on fusion of The proximal humeral epiphysis. 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Children (Basel) 9.\u003c/li\u003e\n\u003cli\u003eWu X, Xia J, Li X, Chen X, Wang S, Shen X (2025) Ultrasound-guided vs. fluoroscopy-guided percutaneous leverage reduction for severely displaced radial neck fractures in children: a comparative analysis of clinical and radiological outcomes. BMC musculoskeletal disorders 26:106.\u003c/li\u003e\n\u003cli\u003eShen XT, Zhou ZG, Yu LS, Wu X, Chen XL, Xu Y, Sun J (2014) Ultrasound assessment of the elbow joint in infants and toddlers and its clinical significance. Acta radiologica 55:745-752.\u003c/li\u003e\n\u003cli\u003eTanner JM, Healy MJR, Cameron N, Goldstein H (2001) Assessment of skeletal maturity and prediction of adult height (TW3 method). W. B. Saunders, London.\u003c/li\u003e\n\u003cli\u003eWan J, Zhao Y, Feng Q, Sun Z, Zhang C (2019) Potential Value of Conventional Ultrasound in Estimation of Bone Age in Patients from Birth to Near Adulthood. Ultrasound Med Biol 45:2878-2886.\u003c/li\u003e\n\u003cli\u003eUtczas K, Muzsnai A, Cameron N, Zsakai A, Bodzsar EB (2017) A comparison of skeletal maturity assessed by radiological and ultrasonic methods. Am J Hum Biol 29.\u003c/li\u003e\n\u003cli\u003eKarami M, Moshirfatemi A, Daneshvar P (2014) Age determination using ultrasonography in young football players. Adv Biomed Res 3:174.\u003c/li\u003e\n\u003cli\u003eShedge R, Kanchan T, Kushwaha KPS, Krishan K (2021) Ultrasonographic evaluation of the wrist and elbow joints: A pilot study to explore a non-invasive technique for age estimation. Med Sci Law 61:14-22.\u003c/li\u003e\n\u003cli\u003eWan J, Zhao Y, Feng Q, Zhang C (2020) Summation of Ossification Ratios of Radius, Ulna and Femur: A New Parameter to Evaluate Bone Age by Ultrasound. Ultrasound Med Biol 46:1761-1768.\u003c/li\u003e\n\u003cli\u003eBilgili Y, Hizel S, Kara SA, Sanli C, Erdal HH, Altinok D (2003) Accuracy of skeletal age assessment in children from birth to 6 years of age with the ultrasonographic version of the Greulich-Pyle atlas. J Ultrasound Med 22:683-690.\u003c/li\u003e\n\u003cli\u003eHajalioghli P, Tarzamni MK, Arami S, Fouladi DF, Ghojazadeh M (2015) The utility of ultrasonographic bone age determination in detecting growth disturbances; a comparative study with the conventional radiographic technique. Skeletal radiology 44:1351-1356.\u003c/li\u003e\n\u003cli\u003ePatel B, Reed M, Patel S (2009) Gender-specific pattern differences of the ossification centers in the pediatric elbow. Pediatric radiology 39:226-231.\u003c/li\u003e\n\u003cli\u003eRissech C, Lopez-Costas O, Turbon D (2013) Humeral development from neonatal period to skeletal maturity--application in age and sex assessment. Int J Legal Med 127:201-212.\u003c/li\u003e\n\u003cli\u003eSinkler MA, Furdock RJ, Chen DB, Sattar A, Liu RW (2022) The Systematic Isolation of Key Parameters for Estimating Skeletal Maturity on Lateral Elbow Radiographs. The Journal of bone and joint surgery American volume 104:1993-1999.\u003c/li\u003e\n\u003cli\u003eDimeglio A, Charles YP, Daures JP, de Rosa V, Kabore B (2005) Accuracy of the Sauvegrain method in determining skeletal age during puberty. The Journal of bone and joint surgery American volume 87:1689-1696.\u003c/li\u003e\n\u003cli\u003eCardoso HF (2008) Age estimation of adolescent and young adult male and female skeletons II, epiphyseal union at the upper limb and scapular girdle in a modern Portuguese skeletal sample. Am J Phys Anthropol 137:97-105.\u003c/li\u003e\n\u003cli\u003eJiao YS, Tuerhong Y, Chen CX, Dai XH, Lu T, Peng Z, Deng ZH, Fan F (2024) Bone age assessment based on different MRI modalities of the proximal humerus epiphysis: the comparisons of T(1)WI, T(2)WI, and PDWI. Int J Legal Med 138:1509-1521.\u003c/li\u003e\n\u003cli\u003eCekdemir YE, Mutlu U, Karaman G, Guleryuz H (2021) Evaluation of the Ossification Stage of Proximal Humeral Epiphysis by 1.5-T Magnetic Resonance Imaging for Determination of Skeletal Age. Am J Forensic Med Pathol 42:36-41.\u003c/li\u003e\n\u003cli\u003eYuh YS, Chou TY, Tung TH (2023) Bone age assessment: Large-scale comparison of Greulich-Pyle method and Tanner-Whitehouse 3 method for Taiwanese children. J Chin Med Assoc 86:246-253.\u003c/li\u003e\n\u003cli\u003eAlshamrani K, Messina F, Offiah AC (2019) Is the Greulich and Pyle atlas applicable to all ethnicities? A systematic review and meta-analysis. Eur Radiol 29:2910-2923.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"965\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"14\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003eTable 1. Pearson Linear Correlation Coefficients Between Bone Age and Ossification Ratios of the Wrist, Knee, Elbow, and Shoulder Bones.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 8.18653%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eDistal\u0026nbsp;radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eDistal\u0026nbsp;ulna\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003eMedial epicondyle of the femur\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003eProximal radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003eProximal humerus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.49741%;\"\u003e\n \u003cp\u003eCapitulum of humerus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003eFirst metacarpal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eRU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eRP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eUP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eRUF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eRUP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 8.18653%;\"\u003e\n \u003cp\u003eBoys\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.944\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.946\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e0.926\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e0.953\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e0.842\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.49741%;\"\u003e\n \u003cp\u003e0.869\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e0.798\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.979\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.981\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.980\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.983\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.969\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 8.18653%;\"\u003e\n \u003cp\u003e（n=72）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.912-0.965)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.915-0.966)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e(0.883-0.953)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e(0.926-0.970)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e(0.758-0.898)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.49741%;\"\u003e\n \u003cp\u003e(0.799-0.916)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e(0.694-0.869)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.966-0.987)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.970-0.988)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.944-0.978)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.968-0.987)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.974-0.990)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.951-0.981)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 8.18653%;\"\u003e\n \u003cp\u003eGirls\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.909\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.933\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e0.901\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e0.935\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e0.854\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.49741%;\"\u003e\n \u003cp\u003e0.813\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e0.765\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.954\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.964\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.958\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.964\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.969\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e0.956\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 8.18653%;\"\u003e\n \u003cp\u003e（n=72）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.858-0.942)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.894-0.957)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e(0.845-0937)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e(0.897-0.959)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 7.56477%;\"\u003e\n \u003cp\u003e(0.775-0.906)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.49741%;\"\u003e\n \u003cp\u003e(0.717-0.879)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.80829%;\"\u003e\n \u003cp\u003e(0.649-0.847)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.927-0.971)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.942-0.977)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.934-0.974)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.943-0.977)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.952-0.981)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.32124%;\"\u003e\n \u003cp\u003e(0.931-0.973)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"14\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003eNote. Data in parentheses are 95% confidence intervals.\u003c/p\u003e\n \u003cp\u003e*RU=Distal Radius+ Distal Ulna\u003c/p\u003e\n \u003cp\u003e*RP=Distal Radius+\u0026nbsp;Proximal Radius\u003c/p\u003e\n \u003cp\u003e*UP = Distal Ulna+ Proximal Radius\u003c/p\u003e\n \u003cp\u003e*RUF = Distal Radius+ Distal Ulna+ Medial epicondyle of the Femur\u003c/p\u003e\n \u003cp\u003e*RUP = Distal Radius+ Distal Ulna+ Proximal Radius\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"98%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"15\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eTable 2. Ossification ratios (\u0026times; 100) of bones for patients with different bone ages\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003eBone age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 7px;\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003eDistal radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eDistal ulna\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 19px;\"\u003e\n \u003cp\u003eProximal radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003eRUP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e0-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e0(6.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e16.2(15.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e0(5.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e16.5(15.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e2-4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e29.5(6.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e36.0(13.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0(9.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0(6.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0(8.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e33.5(9.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e47.0(19.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e4-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e49.2(9.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e56.7(10.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e6.2(10.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e21.2(19.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e0(17.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e20.9(14.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e60.0(27.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e97.5(29.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e6-8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e48.6(9.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e48.3(5.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e5.0(12.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e16.5(12.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e19.5(14.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e35.9(15.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e72.0(28.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e93.5(28.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e8-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e58.3(6.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e57.2(4.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e25.4(17.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e40.6(15.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e32.3(12.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e46.0(14.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e107.5(33.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e150.0(29.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e10-12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e64.7(8.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e69.4(11.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e47.1(7.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e55.2(14.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e42.8(6.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e69.4(13.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e158.0(15.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e198.0(28.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e12-14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e69.7(7.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e76.2(10.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e58.9(12.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e71.1(11.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e68.4(10.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e83.0(17.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e194.0(28.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e227.5(32.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e14-16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e82.3(7.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e90.1(4.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e61.7(16.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e81.6(12.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e79.1(15.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e76.1(8.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e232.0(32.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e247.5(18.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6px;\"\u003e\n \u003cp\u003e16-18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 3px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8px;\"\u003e\n \u003cp\u003e88.5(3.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e91.8(4.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e87.4(5.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e89.0(4.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e81.4(4.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9px;\"\u003e\n \u003cp\u003e82.5(9.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e254.0(10.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10px;\"\u003e\n \u003cp\u003e261.0(10.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"15\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eNote. Data are medians, with standard deviation in parentheses.\u003c/p\u003e\n \u003cp\u003e* RUP = sum of ossification ratios from the distal end of radius, ulna and proximal radius.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"747\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" valign=\"top\" style=\"width: 746px;\"\u003e\n \u003cp\u003eTable 3. Intra-rater and Inter-rater reliability analysis of sonographic parameters\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003eIntra-rater reliability\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e95%Confidence interval\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003eInter-rater reliability\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e95%Confidence interval\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eDistal\u0026nbsp;radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.91~0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.91~0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eDistal\u0026nbsp;ulna\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.95~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.95~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eMedial epicondyle of the femur\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.96~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.95~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eProximal radius\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.92~0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.83~0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eProximal humerus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.88~0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.86~0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eCapitulum of humerus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.87~0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.80~0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eFirst metacarpal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.89~0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.71~0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eRU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.96~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eRP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.95~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.90~0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eUP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.94~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eRUF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.97~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eRUP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 227px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 130px;\"\u003e\n \u003cp\u003e0.98~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 87px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0.96~0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"top\" style=\"width: 747px;\"\u003e\n \u003cp\u003eNote.\u003c/p\u003e\n \u003cp\u003e*RU = Distal Radius+ Distal Ulna\u003c/p\u003e\n \u003cp\u003e*RP = Distal Radius+ Proximal Radius\u003c/p\u003e\n \u003cp\u003e*UP = Distal Ulna+ Proximal Radius\u003c/p\u003e\n \u003cp\u003e*RUF = Distal Radius+ Distal Ulna+ Medial epicondyle of the Femur\u003c/p\u003e\n \u003cp\u003e*RUP = Distal Radius+ Distal Ulna+ Proximal Radius\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"pediatric-radiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prad","sideBox":"Learn more about [Pediatric Radiology](http://link.springer.com/journal/247)","snPcode":"247","submissionUrl":"https://submission.nature.com/new-submission/247/3","title":"Pediatric Radiology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Ossification rate, Bone age assessment, Ultrasound, Greulich-Pyle (GP) atlas","lastPublishedDoi":"10.21203/rs.3.rs-9497803/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9497803/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe Greulich-Pyle atlas is generally used in clinical practice; however, it involves radiation exposure. Our aim was to clarify the correlation between ultrasonic ossification rate and radiographic bone age, and to develop a repeatable ultrasonic parameter for assessing bone age.\u003c/p\u003e\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo determine the correlation between ultrasonic ossification rates and radiographic bone age, and to test the hypothesis that a summed ultrasonic ossification parameter provides a highly correlated, reproducible, radiation‑free method for pediatric bone age assessment.\u003c/p\u003e\u003ch2\u003eMaterials and methods\u003c/h2\u003e \u003cp\u003eUltrasonic imaging was performed on seven ossification centres and epiphyses in 144 consecutive patients aged 0.1\u0026ndash;18.0 years. The ossification rates were measured and compared with the radiological bone age. The correlation between ultrasonic ossification rate and GP bone age was analyzed by the Pearson correlation coefficient. The intra-observer and inter-observer reliability were evaluated using the intraclass correlation coefficient (ICC).\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe sum of the ossification rates (ORs) of the distal radius, distal ulna, and proximal radius (RUP) was highly correlated with the GP atlas (boys: r\u0026thinsp;=\u0026thinsp;0.98; girls: r\u0026thinsp;=\u0026thinsp;0.97). Appending the ORs of other bones did not increase the value of Pearson's r, while summing the ORs of all assessed bones slightly reduced it (boys: r\u0026thinsp;=\u0026thinsp;0.97; girls: r\u0026thinsp;=\u0026thinsp;0.96). The reliability of RUF and RUP was identical (intra-observer ICC\u0026thinsp;=\u0026thinsp;0.99 [95% CI: 0.98, 0.99], p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; inter-observer: RUF: ICC\u0026thinsp;=\u0026thinsp;0.99 [95% CI: 0.97, 0.99], RUP: ICC\u0026thinsp;=\u0026thinsp;0.99 [95% CI: 0.98, 0.99], both p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), which was significantly higher than that of single sonographic parameters.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe ultrasonic RUP ossification rate is an easy-to-operate, efficient, radiation-free, operator-friendly indicator of bone age with high correlation to skeletal age and excellent reproducibility. It serves as a practical alternative for paediatric screening and developmental staging.\u003c/p\u003e","manuscriptTitle":"RUP Ultrasonic Ossification Rate: A Novel Parameter for Pediatric Bone Age Assessment","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-11 06:22:19","doi":"10.21203/rs.3.rs-9497803/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2026-04-29T10:00:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-27T11:29:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-27T11:28:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Pediatric Radiology","date":"2026-04-22T14:33:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"pediatric-radiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prad","sideBox":"Learn more about [Pediatric Radiology](http://link.springer.com/journal/247)","snPcode":"247","submissionUrl":"https://submission.nature.com/new-submission/247/3","title":"Pediatric Radiology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a3fba73e-c0b3-4db5-97bc-dcb6a28bee24","owner":[],"postedDate":"May 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T06:22:20+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-11 06:22:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9497803","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9497803","identity":"rs-9497803","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}