It is safe to use the ulnar length difference to correct the radial length difference in the 3D-planning process of a radius osteotomy in patients with a distal radius malunion

It is safe to use the ulnar length difference to correct the radial length difference in the 3D-planning process of a radius osteotomy in patients with a distal radius malunion | 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 It is safe to use the ulnar length difference to correct the radial length difference in the 3D-planning process of a radius osteotomy in patients with a distal radius malunion Camiel J Smees, Koen D Oude Nijhuis, Stein van der Heide, Judith olde Heuvel, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4763708/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Aug, 2024 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted 9 You are reading this latest preprint version Abstract Background A corrective radius osteotomy is often performed in patients with a symptomatic distal radius malunion. In 3D-planned osteotomies, the unaffected radius is mirrored over the malunited radius after adjusting for left-right length differences using both ulnae. This approach assumes that ulnar length differences in a malunion population are similar to those in a healthy population. This study was conducted to analyze the difference in ulnar length in a distal radius malunion population and to assess the potential influence of age, sex, or malunion side on this difference. Methods We evaluated 65 adult patients with distal radius malunion using bilateral forearm CT scans. 3D models of both ulnae were constructed, and length differences were determined along a standardized length axis. The results were compared to two populations without a radius malunion. Results The average absolute ulnar length difference was 2.57 mm (SD 1.81), which was comparable to the two healthy populations. This difference was not significantly affected by age, sex, or malunion side. Conclusion This study demonstrated that using the ulnar length difference to correct for radial length difference in the current 3D planning process, before using the contralateral radius as a template for a corrective osteotomy in patients with radius malunion, is safe. Forearm length difference malunion ulnar length 3D models Figures Figure 1 Figure 2 Introduction Secondary displacement of distal radius fractures initially treated with closed reduction and cast immobilization occurs in 36–64% of all patients [1,2]. If not recognized and treated in time, such displacement results in a malunion of the distal radius. Malunion can also occur after primary plate fixation, with rates reported as high as 35% [3]. Pain, limited range of motion, and reduced grip strength are common problems for patients with a distal radius malunion [4-6]. Patients with a symptomatic distal radius malunion can be treated with a corrective osteotomy. To ensure more precise correction of the radius, three-dimensional (3D) planned patient-specific cutting and drilling guides can be used in surgery. In 3D planning, the unaffected contralateral radius is considered the best anatomic representation of the pre-fractured shape of the malunited radius, thus serving as the intended shape to achieve with the osteotomy. The unaffected side is mirrored and projected over the affected radius. However, previous studies have shown that in a healthy population, a substantial difference in radial length between both arms exists [7,8]. Therefore, before comparing the radii, a correction for the radial length difference must be performed. A study by Vroemen et al. found a strong linear relationship between intra-person length differences in the radii and ulnae [8]. Thus, by comparing the ulnar lengths of both arms, the radial length difference can be corrected: the difference in ulnar length is used to adjust the length of the radii. Thereafter, the 3D comparison of the healthy and malunited radius can be made, and the corrective osteotomy planned. In a population of healthy individuals, Vroemen et al. and Hong et al. found a substantial difference in left-right ulnar length: 2.08 mm (SD 2.33) and 2.54 mm (SD 1.88), respectively [7,8]. The current assumption in 3D analysis is that this ulnar length difference in a healthy population is also representative of a population of malunion patients. Clinically, the ulnar length is not typically affected by a distal radius malunion. However, this has never been proven. If the ipsilateral ulna is indeed affected by the radius malunion, using the ulna to correct for length differences in the radius will result in insufficient correction, and an alternative method must be used. The primary goal of this study is to demonstrate that the current clinical practice of using the ulnar length difference to correct the length difference of the radii in the 3D planning process of a corrective osteotomy of a radius malunion is safe. Therefore, an analysis of the left-right difference in ulnar length in a distal radius malunion population, both as an absolute and a relative number, is performed and compared to the data of healthy populations reported by Vroemen et al. and Hong et al. [7,8]. Secondarily, the potential influence of age, sex, or the side of radius malunion (dominant vs. non-dominant hand) on the ulnar length difference was analyzed. Methods For this diagnostic imaging study, approval was obtained from the board of directors of [blinded], and based on national criteria, medical ethics consent was waived. Patients In this analysis, we included all adult patients (aged >18 years) who were treated with a 3D-guided corrective osteotomy for symptomatic distal radius malunion between February 2015 and September 2022 from our prospectively collected cohort of corrective osteotomies. All patients had a bilateral computed tomography (CT) scan of the forearm preoperatively. Patients with forearm pathology other than distal radius malunion, those with bilateral pathology, and those with any previous forearm surgery were excluded. CT scans and segmentation The following CT scan settings were used when obtaining the CT scans: A slice thickness of 0.6 mm was used, with a B60 kernel and a matrix of 512x512. The voltage used was 120 kV, and the tube current was automatically regulated. The CT scans were performed with the patient in prone position with both arms overhead and palms facing each other. Both forearms were segmented to create a 3D surface model using the 3D medical imaging processing software Mimics (Materialise, Leuven, Belgium). The ulnae were segmented with a threshold value of 300 Hounsfield units. A combination of region-growing, mask-splitting and hole-filling functions was used to obtain the 3D surface models of the ulnae. The segmentation method was previously validated and considered to be accurate.[9] All segmentations were performed by a 3D specialist ([author 1]). Measurements The first step in carrying out the measurements is creating a standardised measurement axis. The definitions from the International Society of Biomechanics (ISB) were followed as closely as possible. 12 First, the left ulna was mirrored and aligned with the right ulna from proximal to distal, through a combination of semi-automatic matching and manual adjustment (figure 1a). Matching was deemed successful if the olecranons overlapped and the ulnar domes were aligned. The longest of the two ulnae was used to determine the standardised measurement axis. In the longer ulna, the ulna is cut halfway between the olecranon and the tip of the ulnar dome (figure 1b). To determine the centre of the cut surface, an arc was fit to this surface. The measurement axis was formed between the middle of this arc and the tip of the ulnar dome (green line in figure 1b). The length difference was measured along this axis as a difference between the heights of the ulnar domes (figure 1c). These measurements were taken by a junior researcher ([author 3]) and a 3D specialist ([author 1]). In case of a measurement discrepancy of more than 1 mm, another 3D specialist was consulted who decided which of the two measurements was correct. A detailed explanation of the measurement protocol can be found in Appendix I. Statistical analyses A power analysis was performed to estimate the required patient population size to describe the difference in ulnar length in this cohort. [11] Two previous studies were used to determine a weighted average standard deviation of 1.95 mm with a normal distribution. [7,8] With a desired confidence interval of 0.5 mm and a 5% two-tailed confidence interval, the calculated minimum sample size is 59. To assess the reliability of the measurements, the mean inter-rater differences with standard deviation and the intraclass correlation coefficient (ICC) were calculated. The guidelines for interpretation of the ICC given by Koo and Li were used as standards. [12] Normality of all groups was verified using the Kolmogorov–Smirnov test. All variables were normally distributed. The main outcome of this study was the mean and standard deviation of the absolute length differences of the ulnae. The ulnar length difference relative to the full ulnar length, expressed as a percentage, was also calculated. T-tests were performed to assess whether significant differences in bilateral length differences (absolute and relative) were present in groups based on age, sex and malunion in the dominant vs non-dominant side. Age groups were defined as 18–49 and 50+ years old. Statistical significance was set at p < 0.05. Results Demographics Sixty-five patients were included. The mean age of the population was 47 years (SD 17), 75% was female, and 52% had a malunion of the non-dominant wrist (Table 1). Table 1 : The demographics of the included population. The mean absolute and relative ulnar length differences are given for the entire population, as well for the group divided by age, sex and fracture side and the corresponding p-value. Variables N (%) Absolute ulnar length difference Relative ulnar length difference Mean (SD) (mm) p -value Mean (SD) (%) p -value N 65 (100%) 2.57 (1.81) 0.96 (0.66) Age* 47 ± 17 0.38 0.40 18-49 years 33 (51%) 2.71 (2.07) 1.03 (0.75) 50+ years 32 (49%) 2.31 (1.51) 0.89 (0.55) Sex 0.27 0.59 Male 16 (25%) 2.95 (2.17) 1.04 (0.75) Female 49 (75%) 2.37 (1.68) 0.94 (0.63) Malunion side 0.62 0.63 Dominant side 31 (48%) 2.63 (1.74) 1.00 (0.62) Non-dominant side 34 (52%) 2.41 (1.89) 0.92 (0.70) Intraclass correlation coefficient Two outliers with more than a 1 mm difference were checked by a third observer. The ICC between both observers was always above 0.99, both before and after the two outliers were checked, thus indicating excellent reliability. [12] Absolute ulnar length differences The measured mean absolute length difference in this population was 2.57 mm (SD 1.81). The right arm was, on average, 1.02 mm (SD 2.98) longer than the left arm. Absolute length differences were not significant among groups divided by age, sex, and whether the malunion was present in the dominant or non-dominant side (p = 0.38, 0.27, and 0.62, respectively; see Table 1). Figure 2 presents a violin plot of the absolute length differences, with the minimum difference found being 0.05 mm and the maximum difference being 7.23 mm. Relative bilateral ulnar length differences The mean of the relative length differences in the total study population was 0.96% (SD 0.66). There were no significant differences in relative length differences among groups divided by age, sex and malunion present in the dominant vs the non-dominant hand: p = 0.40, 0.59 and 0.63, respectively (Table 1). Discussion In this paper, we demonstrate that the common practice in 3D planning of a corrective osteotomy - using the ulnar length difference to correct the radial length difference in cases of radius malunion - is safe. This conclusion is based on measurements of the length difference between the left and right ulna in a population with distal radius malunion and comparisons of this difference to previous studies on patients without forearm pathology. We found a length difference of 2.57 mm (SD 1.81), comparable to those in two populations without forearm pathology: 2.54 mm (SD 1.88) and 2.08 mm (SD 2.33) [7,8]. This finding suggests that a distal radius malunion has little to no effect on the ipsilateral ulna, and that the small recorded differences may result from variations in measurement strategies and population differences. In our study, we aligned the ulnae from proximal to distal and determined the length difference along the length axis, constructed based on ISB guidelines. In contrast, Hong et al. calculated the lengths of both ulnae separately within their own coordinate systems before determining the differences [8,10]. Vroemen et al. did not specify the coordinate system used for their measurements [7]. Our observers demonstrated excellent intra-observer reproducibility. Both Vroemen et al. and Hong et al. also included asymmetry measurements in different axes [7,8]. However, they found that only lengthwise differences were significant. Because length is one of the most critical factors to correct for, we opted to consider only the lengthwise differences. Combined with the fact that our method aligns with ISB standards, we propose that future studies should consider methods similar to ours. This study assessed a Dutch population. Vroemen et al. also used a Dutch cohort, while Hong et al. studied a Korean population [7,8]. Given the similarity of results between these studies, we expect our findings to be generalizable to other populations. Bilateral length differences (absolute and relative) were not significantly different among groups based on age, sex, or side of radius malunion (dominant vs. non-dominant). The population size for the power analysis was based on the mean bilateral length difference, not on subanalyses. It is therefore unclear whether age, sex, or side of radius malunion significantly affects bilateral length differences in a larger population. In addition to the studies by Hong et al. and Vroemen et al., we presented relative length measurements, considering the expectation that taller individuals might have longer forearms and that significant height differences may exist among different populations [7,8]. However, this percentage was very small, rendering this assumption irrelevant. Limitations Our study verified the importance of correcting for left-right length differences. However, the maximum bilateral length difference for which a simple length correction is sufficient and the threshold at which alternative methods, such as statistical shape modeling, should be used remain unknown. Additionally, this study analyzed only ulnar length, as malunion was present in one of the radii. It is expected that ulnar length is a useful indicator of radial length, as previously demonstrated by Vroemen et al. [8] However, the linear relationship identified by Vroemen et al. between inter-person length differences in the radii and ulnae is currently based on 20 healthy volunteers and is assumed to hold for all patients. In our population, the largest reported length difference in the radii was 7.30 mm, making it unclear whether this relationship is maintained when length differences exceed the currently observed range. To gain a better understanding of the relationship between radial and ulnar lengths and potential variations, further investigation in a larger healthy population is necessary. Conclusion The substantial difference between the left and right ulna in patients with distal radius malunion that we found was similar to that in people without forearm pathology [7,8] Previous research has shown a strong correlation between intra-patient ulnar and radial left-right length differences [8] . Therefore, this study demonstrated that it is safe to use the left-right length difference of the ulna to correct for the radial length difference in 3D-planned corrective osteotomy of a radius malunion, which uses the contralateral radius as a template. Abbreviations 3D – three-dimensional CT – Computed Tomography ISB - International Society of Biomechanics ICC - intraclass correlation coefficient Declarations Ethics approval and consent to participate Ethical approval: The study was approved by the institutional review board. Informed consent: No consent was required, as the study was performed in a retrospective manner with no intervention. Consent for publication No individual person’s data was used. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests Funding The authors received no financial support for the research, authorship, and/or publication of this article. Authors' contributions Study design: CJS, SvdH, AJHV, GJMT Data assembly: CJS, SvdH, JoH Data analysis: CJS, KON, JoH, JND, AJHV, GJMT Initial draft: CJS, KON, JND, JoH Final approval of manuscript: CJS, KON, SvdH, JoH, JND, AJHV, GJMT Acknowledgements Not applicable References Jung HW, Hong H, Jung HJ, et al. Redisplacement of Distal Radius Fracture after Initial Closed Reduction: Analysis of Prognostic Factors. Clin Orthop Surg . 2015;7(3):377. Makhni EC, Ewald TJ, Kelly S, Day CS. Effect of Patient Age on the Radiographic Outcomes of Distal Radius Fractures Subject to Nonoperative Treatment. J Hand Surg Am . 2008;33(8):1301-1308. Hollevoet N. Effect of patient age on malunion of operatively treated distal radius fractures. Acta Orthop Belg . 2010;76(6):743-750. Bushnell BD, Bynum DK. Malunion of the distal radius. J Am Acad Orthop Surg . 2007;15(1):27-40. Forward DP, Davis TRC, Sithole JS. Do young patients with malunited fractures of the distal radius inevitably develop symptomatic post-traumatic osteoarthritis? J Bone Joint Surg Br . 2008;90-B(5):629-637. Wadsten MÅ, Sjödén GO, Buttazzoni GG, Buttazzoni C, Englund E, Sayed-Noor AS. The influence of late displacement in distal radius fractures on function, grip strength, range of motion and quality of life. J Hand Surg Eur Vol . 2018;43(2):131-136. Hong E, Kwak DS, Kim IB. Morphological symmetry of the radius and ulna—Can contralateral forearm bones utilize as a reliable template for the opposite side? Simmen HP, ed. PLoS One . 2021;16(10):e0258232. Vroemen JC, Dobbe JGG, Jonges R, Strackee SD, Streekstra GJ. Three-Dimensional Assessment of Bilateral Symmetry of the Radius and Ulna for Planning Corrective Surgeries. J Hand Surg Am . 2012;37(5):982-988. Van den Broeck J, Vereecke E, Wirix-Speetjens R, Vander Sloten J. Segmentation accuracy of long bones. Med Eng Phys . 2014;36(7):949-953. Wu G, van der Helm FCT, (DirkJan) Veeger HEJ, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion—Part II: shoulder, elbow, wrist and hand. J Biomech . 2005;38(5):981-992. Arifin WN. Introduction to sample size calculation. Education in Medicine Journal . 2013;5(2). Koo TK, Li MY. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. J Chiropr Med . 2016;15(2):155-163. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Aug, 2024 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted Editorial decision: Revision requested 09 Aug, 2024 Reviews received at journal 08 Aug, 2024 Reviews received at journal 01 Aug, 2024 Reviewers agreed at journal 29 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers invited by journal 22 Jul, 2024 Editor assigned by journal 22 Jul, 2024 Submission checks completed at journal 22 Jul, 2024 First submitted to journal 18 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4763708","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":338011616,"identity":"20ca05f4-1c18-4574-be72-95e1273aa6d3","order_by":0,"name":"Camiel J Smees","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAoklEQVRIiWNgGAWjYBADOShtQbwWYygtQbyWxAaitfA3sD/d8KGiLr2f/fCxB4w7iNAicYDH7OaMM4dzZ/akpRswniFCiwEDD9tt3rYDuRtu8JhJMLYRpYX92e2//+rSDUjQwmB2m7GBOYF4LRKHgX7pOXbYEOiXNIlEYrTwt7c/u/Gjpk6eHxhiEh/bbAhrYWBG5iQQoWEUjIJRMApGAREAACp8Mcv4rHm0AAAAAElFTkSuQmCC","orcid":"","institution":"OCON Orthopedische kliniek","correspondingAuthor":true,"prefix":"","firstName":"Camiel","middleName":"J","lastName":"Smees","suffix":""},{"id":338011623,"identity":"f7e62b56-cbcd-49f1-b045-01f71a3db189","order_by":1,"name":"Koen D Oude Nijhuis","email":"","orcid":"","institution":"University Medical Center Groningen","correspondingAuthor":false,"prefix":"","firstName":"Koen","middleName":"D Oude","lastName":"Nijhuis","suffix":""},{"id":338011625,"identity":"92ca94a2-08e0-429f-8004-4dbb9a153cf5","order_by":2,"name":"Stein van der Heide","email":"","orcid":"","institution":"OCON Orthopedische kliniek","correspondingAuthor":false,"prefix":"","firstName":"Stein","middleName":"van der","lastName":"Heide","suffix":""},{"id":338011627,"identity":"0a0e331c-960b-4d39-8aa3-da9d2c72b3ea","order_by":3,"name":"Judith olde Heuvel","email":"","orcid":"","institution":"OCON Orthopedische kliniek","correspondingAuthor":false,"prefix":"","firstName":"Judith","middleName":"olde","lastName":"Heuvel","suffix":""},{"id":338011629,"identity":"f654625b-a50f-42fd-bdb1-17bb9ea7e375","order_by":4,"name":"Job N Doornberg","email":"","orcid":"","institution":"University Medical Center Groningen","correspondingAuthor":false,"prefix":"","firstName":"Job","middleName":"N","lastName":"Doornberg","suffix":""},{"id":338011632,"identity":"45130885-d523-4eff-a290-36eeebd6a8b4","order_by":5,"name":"Anne J H Vochteloo","email":"","orcid":"","institution":"OCON Orthopedische kliniek","correspondingAuthor":false,"prefix":"","firstName":"Anne","middleName":"J H","lastName":"Vochteloo","suffix":""},{"id":338011633,"identity":"d071a1ae-b0ed-469f-8799-16437beb2dc5","order_by":6,"name":"Gabriëlle J M Tuijthof","email":"","orcid":"","institution":"University of Twente","correspondingAuthor":false,"prefix":"","firstName":"Gabriëlle","middleName":"J M","lastName":"Tuijthof","suffix":""}],"badges":[],"createdAt":"2024-07-18 15:37:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4763708/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4763708/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13018-024-05012-3","type":"published","date":"2024-08-30T15:57:26+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62528462,"identity":"8a1b0c46-6642-41ab-99e6-2417b99a6534","added_by":"auto","created_at":"2024-08-15 12:01:47","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":166572,"visible":true,"origin":"","legend":"\u003cp\u003eMeasuring the ulnae length difference. A) The left ulna (cyan) is mirrored and aligned with the contralateral ulna (white). The longest ulna is then determined. B) On the longest ulna, the halfway point is defined as the point between the tip of the olecranon and the ulnar dome (red). The length axis (green) is defined between the halfway point of the ulna and the tip of the ulnar dome. C) The ulnar length difference is measured on the length axis between the two ulnae.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4763708/v1/b9d58bc960fade6da89b0629.png"},{"id":62528461,"identity":"501485ff-75a4-4b53-a4ef-3015a4d1457c","added_by":"auto","created_at":"2024-08-15 12:01:47","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":27254,"visible":true,"origin":"","legend":"\u003cp\u003eThe spread in absolute bilateral length differences. The violin plot depicts the absolute length differences in the entire population as mean values of both observers. Every dot represents the measurement in one patient. The mean length difference is 2.57 mm (SD 1.81).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4763708/v1/b91719a484a1b8c7e68236ca.png"},{"id":63820910,"identity":"345f9a83-8d4a-476b-a288-4c8db42459af","added_by":"auto","created_at":"2024-09-02 16:10:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":606755,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4763708/v1/78eabd91-cb9d-44ba-a9b7-729a2939287a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"It is safe to use the ulnar length difference to correct the radial length difference in the 3D-planning process of a radius osteotomy in patients with a distal radius malunion","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSecondary displacement of distal radius fractures initially treated with closed reduction and cast immobilization occurs in 36\u0026ndash;64% of all patients [1,2]. If not recognized and treated in time, such displacement results in a malunion of the distal radius. Malunion can also occur after primary plate fixation, with rates reported as high as 35% [3]. Pain, limited range of motion, and reduced grip strength are common problems for patients with a distal radius malunion [4-6]. Patients with a symptomatic distal radius malunion can be treated with a corrective osteotomy.\u003c/p\u003e\n\u003cp\u003eTo ensure more precise correction of the radius, three-dimensional (3D) planned patient-specific cutting and drilling guides can be used in surgery. In 3D planning, the unaffected contralateral radius is considered the best anatomic representation of the pre-fractured shape of the malunited radius, thus serving as the intended shape to achieve with the osteotomy. The unaffected side is mirrored and projected over the affected radius. However, previous studies have shown that in a healthy population, a substantial difference in radial length between both arms exists [7,8].\u003c/p\u003e\n\u003cp\u003eTherefore, before comparing the radii, a correction for the radial length difference must be performed. A study by Vroemen et al. found a strong linear relationship between intra-person length differences in the radii and ulnae [8]. Thus, by comparing the ulnar lengths of both arms, the radial length difference can be corrected: the difference in ulnar length is used to adjust the length of the radii. Thereafter, the 3D comparison of the healthy and malunited radius can be made, and the corrective osteotomy planned.\u003c/p\u003e\n\u003cp\u003eIn a population of healthy individuals, Vroemen et al. and Hong et al. found a substantial difference in left-right ulnar length: 2.08 mm (SD 2.33) and 2.54 mm (SD 1.88), respectively [7,8]. The current assumption in 3D analysis is that this ulnar length difference in a healthy population is also representative of a population of malunion patients. Clinically, the ulnar length is not typically affected by a distal radius malunion. However, this has never been proven. If the ipsilateral ulna is indeed affected by the radius malunion, using the ulna to correct for length differences in the radius will result in insufficient correction, and an alternative method must be used.\u003c/p\u003e\n\u003cp\u003eThe primary goal of this study is to demonstrate that the current clinical practice of using the ulnar length difference to correct the length difference of the radii in the 3D planning process of a corrective osteotomy of a radius malunion is safe. Therefore, an analysis of the left-right difference in ulnar length in a distal radius malunion population, both as an absolute and a relative number, is performed and compared to the data of healthy populations reported by Vroemen et al. and Hong et al. [7,8]. Secondarily, the potential influence of age, sex, or the side of radius malunion (dominant vs. non-dominant hand) on the ulnar length difference was analyzed.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eFor this diagnostic imaging study, approval was obtained from the board of directors of [blinded], and based on national criteria, medical ethics consent was waived.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePatients\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIn this analysis, we included all adult patients (aged \u0026gt;18 years) who were treated with a 3D-guided corrective osteotomy for symptomatic distal radius malunion between February 2015 and September 2022 from our prospectively collected cohort of corrective osteotomies. All patients had a bilateral computed tomography (CT) scan of the forearm preoperatively. Patients with forearm pathology other than distal radius malunion, those with bilateral pathology, and those with any previous forearm surgery were excluded.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCT scans and segmentation\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe following CT scan settings were used when obtaining the CT scans: A slice thickness of 0.6 mm was used, with a B60 kernel and a matrix of 512x512. The voltage used was 120 kV, and the tube current was automatically regulated. The CT scans were performed with the patient in prone position with both arms overhead and palms facing each other.\u003c/p\u003e\n\u003cp\u003eBoth forearms were segmented to create a 3D surface model using the 3D medical imaging processing software Mimics (Materialise, Leuven, Belgium). The ulnae were segmented with a threshold value of 300 Hounsfield units. A combination of region-growing, mask-splitting and hole-filling functions was used to obtain the 3D surface models of the ulnae. The segmentation method was previously validated and considered to be accurate.[9] All segmentations were performed by a 3D specialist ([author 1]).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMeasurements\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe first step in carrying out the measurements is creating a standardised measurement axis. The definitions from the International Society of Biomechanics (ISB) were followed as closely as possible.\u003csup\u003e12\u003c/sup\u003e First, the left ulna was mirrored and aligned with the right ulna from proximal to distal, through a combination of semi-automatic matching and manual adjustment (figure 1a). Matching was deemed successful if the olecranons overlapped and the ulnar domes were aligned. The longest of the two ulnae was used to determine the standardised measurement axis. In the longer ulna, the ulna is cut halfway between the olecranon and the tip of the ulnar dome (figure 1b). To determine the centre of the cut surface, an arc was fit to this surface. The measurement axis was formed between the middle of this arc and the tip of the ulnar dome (green line in figure 1b). The length difference was measured along this axis as a difference between the heights of the ulnar domes (figure 1c). These measurements were taken by a junior researcher ([author 3]) and a 3D specialist ([author 1]). In case of a measurement discrepancy of more than 1 mm, another 3D specialist was consulted who decided which of the two measurements was correct. A detailed explanation of the measurement protocol can be found in Appendix I.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStatistical analyses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eA power analysis was performed to estimate the required patient population size to describe the difference in ulnar length in this cohort. [11] Two previous studies were used to determine a weighted average standard deviation of 1.95 mm with a normal distribution. [7,8] With a desired confidence interval of 0.5 mm and a 5% two-tailed confidence interval, the calculated minimum sample size is 59.\u003c/p\u003e\n\u003cp\u003eTo assess the reliability of the measurements, the mean inter-rater differences with standard deviation and the intraclass correlation coefficient (ICC) were calculated. The guidelines for interpretation of the ICC given by Koo and Li were used as standards. [12]\u003c/p\u003e\n\u003cp\u003eNormality of all groups was verified using the Kolmogorov\u0026ndash;Smirnov test. All variables were normally distributed. The main outcome of this study was the mean and standard deviation of the absolute length differences of the ulnae. The ulnar length difference relative to the full ulnar length, expressed as a percentage, was also calculated. T-tests were performed to assess whether significant differences in bilateral length differences (absolute and relative) were present in groups based on age, sex and malunion in the dominant vs non-dominant side. Age groups were defined as 18\u0026ndash;49 and 50+ years old. Statistical significance was set at \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05.\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eDemographics\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSixty-five patients were included. The mean age of the population was 47 years (SD 17), 75% was female, and 52% had a malunion of the non-dominant wrist (Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eTable 1\u003c/em\u003e: The demographics of the included population. The mean absolute and relative ulnar length differences are given for the entire population, as well for the group divided by age, sex and fracture side and the corresponding p-value. \u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"604\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.237623762376238%\" rowspan=\"2\"\u003e\n \u003cp\u003eVariables\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.036303630363037%\" rowspan=\"2\"\u003e\n \u003cp\u003eN (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.363036303630363%\" colspan=\"2\"\u003e\n \u003cp\u003eAbsolute ulnar length difference\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.363036303630363%\" colspan=\"2\"\u003e\n \u003cp\u003eRelative ulnar length difference\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.15258855585831%\"\u003e\n \u003cp\u003eMean (SD) (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.71117166212534%\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"29.155313351498638%\"\u003e\n \u003cp\u003eMean (SD) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.980926430517712%\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e65 (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.57 (1.81)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e0.96 (0.66)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003eAge*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e47 \u0026plusmn; 17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;18-49 years\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e33 (51%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.71 (2.07)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e1.03 (0.75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;50+ years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e32 (49%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.31 (1.51)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e0.89 (0.55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e16 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.95 (2.17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e1.04 (0.75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; Female\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e49 (75%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.37 (1.68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e0.94 (0.63)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003eMalunion side\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e0.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Dominant side\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e31 (48%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.63 (1.74)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e1.00 (0.62)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.28099173553719%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; Non-dominant side\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.057851239669422%\"\u003e\n \u003cp\u003e34 (52%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.50413223140496%\"\u003e\n \u003cp\u003e2.41 (1.89)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.743801652892563%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.68595041322314%\"\u003e\n \u003cp\u003e0.92 (0.70)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.727272727272727%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eIntraclass correlation coefficient\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTwo outliers with more than a 1 mm difference were checked by a third observer. The ICC between both observers was always above 0.99, both before and after the two outliers were checked, thus indicating excellent reliability. [12]\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAbsolute ulnar length differences\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe measured mean absolute length difference in this population was 2.57 mm (SD 1.81). The right arm was, on average, 1.02 mm (SD 2.98) longer than the left arm. Absolute length differences were not significant among groups divided by age, sex, and whether the malunion was present in the dominant or non-dominant side (p = 0.38, 0.27, and 0.62, respectively; see Table 1). Figure 2 presents a violin plot of the absolute length differences, with the minimum difference found being 0.05 mm and the maximum difference being 7.23 mm.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRelative bilateral ulnar length differences\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe mean of the relative length differences in the total study population was 0.96% (SD 0.66). There were no significant differences in relative length differences among groups divided by age, sex and malunion present in the dominant vs the non-dominant hand: \u003cem\u003ep\u0026nbsp;\u003c/em\u003e= 0.40, 0.59 and 0.63, respectively (Table 1).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this paper, we demonstrate that the common practice in 3D planning of a corrective osteotomy - using the ulnar length difference to correct the radial length difference in cases of radius malunion - is safe. This conclusion is based on measurements of the length difference between the left and right ulna in a population with distal radius malunion and comparisons of this difference to previous studies on patients without forearm pathology. We found a length difference of 2.57 mm (SD 1.81), comparable to those in two populations without forearm pathology: 2.54 mm (SD 1.88) and 2.08 mm (SD 2.33) [7,8]. This finding suggests that a distal radius malunion has little to no effect on the ipsilateral ulna, and that the small recorded differences may result from variations in measurement strategies and population differences.\u003c/p\u003e\n\u003cp\u003eIn our study, we aligned the ulnae from proximal to distal and determined the length difference along the length axis, constructed based on ISB guidelines. In contrast, Hong et al. calculated the lengths of both ulnae separately within their own coordinate systems before determining the differences [8,10]. Vroemen et al. did not specify the coordinate system used for their measurements [7].\u003c/p\u003e\n\u003cp\u003eOur observers demonstrated excellent intra-observer reproducibility. Both Vroemen et al. and Hong et al. also included asymmetry measurements in different axes [7,8]. However, they found that only lengthwise differences were significant. Because length is one of the most critical factors to correct for, we opted to consider only the lengthwise differences. Combined with the fact that our method aligns with ISB standards, we propose that future studies should consider methods similar to ours.\u003c/p\u003e\n\u003cp\u003eThis study assessed a Dutch population. Vroemen et al. also used a Dutch cohort, while Hong et al. studied a Korean population [7,8]. Given the similarity of results between these studies, we expect our findings to be generalizable to other populations.\u003c/p\u003e\n\u003cp\u003eBilateral length differences (absolute and relative) were not significantly different among groups based on age, sex, or side of radius malunion (dominant vs. non-dominant). The population size for the power analysis was based on the mean bilateral length difference, not on subanalyses. It is therefore unclear whether age, sex, or side of radius malunion significantly affects bilateral length differences in a larger population.\u003c/p\u003e\n\u003cp\u003eIn addition to the studies by Hong et al. and Vroemen et al., we presented relative length measurements, considering the expectation that taller individuals might have longer forearms and that significant height differences may exist among different populations [7,8]. However, this percentage was very small, rendering this assumption irrelevant.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eLimitations\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eOur study verified the importance of correcting for left-right length differences. However, the maximum bilateral length difference for which a simple length correction is sufficient and the threshold at which alternative methods, such as statistical shape modeling, should be used remain unknown. Additionally, this study analyzed only ulnar length, as malunion was present in one of the radii. It is expected that ulnar length is a useful indicator of radial length, as previously demonstrated by Vroemen et al. [8] However, the linear relationship identified by Vroemen et al. between inter-person length differences in the radii and ulnae is currently based on 20 healthy volunteers and is assumed to hold for all patients. In our population, the largest reported length difference in the radii was 7.30 mm, making it unclear whether this relationship is maintained when length differences exceed the currently observed range. To gain a better understanding of the relationship between radial and ulnar lengths and potential variations, further investigation in a larger healthy population is necessary.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe substantial difference between the left and right ulna in patients with distal radius malunion that we found was similar to that in people without forearm pathology [7,8] \u0026nbsp;Previous research has shown a strong correlation between intra-patient ulnar and radial left-right length differences [8]\u003csup\u003e. \u0026nbsp;\u003c/sup\u003eTherefore, this study demonstrated that it is safe to use the left-right length difference of the ulna to correct for the radial length difference in 3D-planned corrective osteotomy of a radius malunion, which uses the contralateral radius as a template.\u0026nbsp;\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e3D \u0026ndash; three-dimensional\u003c/p\u003e\n\u003cp\u003eCT \u0026ndash; Computed Tomography\u003c/p\u003e\n\u003cp\u003eISB -\u0026nbsp;International Society of Biomechanics\u003c/p\u003e\n\u003cp\u003eICC - intraclass correlation coefficient\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval: \u003c/strong\u003eThe study was approved by the institutional review board.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent:\u003c/strong\u003e No consent was required, as the study was performed in a retrospective manner with no intervention.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNo individual person\u0026rsquo;s data was used.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no financial support for the research, authorship, and/or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy design: \u003c/strong\u003eCJS, SvdH, AJHV, GJMT\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData assembly:\u003c/strong\u003e CJS, SvdH, JoH\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData analysis:\u003c/strong\u003e CJS, KON, JoH, JND, AJHV, GJMT\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInitial draft: \u003c/strong\u003eCJS, KON, JND, JoH\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFinal approval of manuscript:\u003c/strong\u003e CJS, KON, SvdH, JoH, JND, AJHV, GJMT\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eJung HW, Hong H, Jung HJ, et al. Redisplacement of Distal Radius Fracture after Initial Closed Reduction: Analysis of Prognostic Factors. \u003cem\u003eClin Orthop Surg\u003c/em\u003e. 2015;7(3):377. \u003c/li\u003e\n\u003cli\u003eMakhni EC, Ewald TJ, Kelly S, Day CS. Effect of Patient Age on the Radiographic Outcomes of Distal Radius Fractures Subject to Nonoperative Treatment. \u003cem\u003eJ Hand Surg Am\u003c/em\u003e. 2008;33(8):1301-1308. \u003c/li\u003e\n\u003cli\u003eHollevoet N. Effect of patient age on malunion of operatively treated distal radius fractures. \u003cem\u003eActa Orthop Belg\u003c/em\u003e. 2010;76(6):743-750. \u003c/li\u003e\n\u003cli\u003eBushnell BD, Bynum DK. Malunion of the distal radius. \u003cem\u003eJ Am Acad Orthop Surg\u003c/em\u003e. 2007;15(1):27-40.\u003c/li\u003e\n\u003cli\u003eForward DP, Davis TRC, Sithole JS. Do young patients with malunited fractures of the distal radius inevitably develop symptomatic post-traumatic osteoarthritis? \u003cem\u003eJ Bone Joint Surg Br\u003c/em\u003e. 2008;90-B(5):629-637.\u003c/li\u003e\n\u003cli\u003eWadsten M\u0026Aring;, Sj\u0026ouml;d\u0026eacute;n GO, Buttazzoni GG, Buttazzoni C, Englund E, Sayed-Noor AS. The influence of late displacement in distal radius fractures on function, grip strength, range of motion and quality of life. \u003cem\u003eJ Hand Surg Eur Vol\u003c/em\u003e. 2018;43(2):131-136.\u003c/li\u003e\n\u003cli\u003eHong E, Kwak DS, Kim IB. Morphological symmetry of the radius and ulna\u0026mdash;Can contralateral forearm bones utilize as a reliable template for the opposite side? Simmen HP, ed. \u003cem\u003ePLoS One\u003c/em\u003e. 2021;16(10):e0258232.\u003c/li\u003e\n\u003cli\u003eVroemen JC, Dobbe JGG, Jonges R, Strackee SD, Streekstra GJ. Three-Dimensional Assessment of Bilateral Symmetry of the Radius and Ulna for Planning Corrective Surgeries. \u003cem\u003eJ Hand Surg Am\u003c/em\u003e. 2012;37(5):982-988.\u003c/li\u003e\n\u003cli\u003eVan den Broeck J, Vereecke E, Wirix-Speetjens R, Vander Sloten J. Segmentation accuracy of long bones. \u003cem\u003eMed Eng Phys\u003c/em\u003e. 2014;36(7):949-953.\u003c/li\u003e\n\u003cli\u003eWu G, van der Helm FCT, (DirkJan) Veeger HEJ, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion\u0026mdash;Part II: shoulder, elbow, wrist and hand. \u003cem\u003eJ Biomech\u003c/em\u003e. 2005;38(5):981-992.\u003c/li\u003e\n\u003cli\u003eArifin WN. Introduction to sample size calculation. \u003cem\u003eEducation in Medicine Journal\u003c/em\u003e. 2013;5(2).\u003c/li\u003e\n\u003cli\u003eKoo TK, Li MY. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. \u003cem\u003eJ Chiropr Med\u003c/em\u003e. 2016;15(2):155-163. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Forearm length difference, malunion, ulnar length, 3D models","lastPublishedDoi":"10.21203/rs.3.rs-4763708/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4763708/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eA corrective radius osteotomy is often performed in patients with a symptomatic distal radius malunion. In 3D-planned osteotomies, the unaffected radius is mirrored over the malunited radius after adjusting for left-right length differences using both ulnae. This approach assumes that ulnar length differences in a malunion population are similar to those in a healthy population. This study was conducted to analyze the difference in ulnar length in a distal radius malunion population and to assess the potential influence of age, sex, or malunion side on this difference.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe evaluated 65 adult patients with distal radius malunion using bilateral forearm CT scans. 3D models of both ulnae were constructed, and length differences were determined along a standardized length axis. The results were compared to two populations without a radius malunion.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe average absolute ulnar length difference was 2.57 mm (SD 1.81), which was comparable to the two healthy populations. This difference was not significantly affected by age, sex, or malunion side.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study demonstrated that using the ulnar length difference to correct for radial length difference in the current 3D planning process, before using the contralateral radius as a template for a corrective osteotomy in patients with radius malunion, is safe.\u003c/p\u003e","manuscriptTitle":"It is safe to use the ulnar length difference to correct the radial length difference in the 3D-planning process of a radius osteotomy in patients with a distal radius malunion","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-15 12:01:42","doi":"10.21203/rs.3.rs-4763708/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-09T07:14:01+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-08T11:40:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-01T07:36:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"287734195275201485436350045915425222093","date":"2024-07-29T07:43:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"135230771545931926926389512724306717767","date":"2024-07-22T16:02:14+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-22T10:52:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-22T08:43:38+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-22T08:03:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2024-07-18T15:36:17+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8e24a4c0-9d1c-4b32-9dd7-09587e1eb008","owner":[],"postedDate":"August 15th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-09-02T16:01:55+00:00","versionOfRecord":{"articleIdentity":"rs-4763708","link":"https://doi.org/10.1186/s13018-024-05012-3","journal":{"identity":"journal-of-orthopaedic-surgery-and-research","isVorOnly":false,"title":"Journal of Orthopaedic Surgery and Research"},"publishedOn":"2024-08-30 15:57:26","publishedOnDateReadable":"August 30th, 2024"},"versionCreatedAt":"2024-08-15 12:01:42","video":"","vorDoi":"10.1186/s13018-024-05012-3","vorDoiUrl":"https://doi.org/10.1186/s13018-024-05012-3","workflowStages":[]},"version":"v1","identity":"rs-4763708","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4763708","identity":"rs-4763708","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}