Anatomical fit of volar locking plates for the distal radius and the influence of plate size

Anatomical fit of volar locking plates for the distal radius and the influence of plate size | 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 Anatomical fit of volar locking plates for the distal radius and the influence of plate size Hiroshi Hasegawa, Kotaro Sato, Kenya Murakami, Tomoyuki Saino, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4481905/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 3 You are reading this latest preprint version Abstract Purpose The volar locking plate system is the standard surgical treatment for patients with unstable distal radius fractures. Volar locking plates are currently available in different shapes and 2–3 size options. In this study, we investigated whether the anatomical fit and plate size of volar locking plates affect their proper placement. Methods Two sizes of Acu-Loc2 Proximal Plates (AcuLoc), three sizes of Variable Angle LCP Two-Column Volar Distal Radius Plate 2.4 (VALCP), and 16 formalin-fixed cadaver specimens were studied. The plates and forearms were scanned using computed tomography. The plate was fixed to a radius within the watershed line, and radiographs were obtained using fluoroscopy. X-rays were superimposed, and a three-dimensional image of the plate and bone was created. The distance from the plate to the volar surface of each distal locking hole (PBD) was measured. To investigate the anatomical fitting of the plate, the contact area between the bone and plate was analyzed on three-dimensional images. We measured the distance between the distal end of the plate and the watershed line in three-dimensional images, defining it as watershed overlap. Results The PBD in the radial column was significantly smaller than that in the ulnar column in the narrow and standard VALCP and narrow in the AcuLoc. For the other plates, the PBD in the radial column tended to be smaller than that in the ulnar column. The contact area was 6.6–20.0% of the plate. The average value of the watershed overlap was negative for both plates. However, no significant differences were observed in PBD, contact area, or watershed overlap among the plate sizes for either plate. Conclusion Although the small plate size affected the fitting to the distal radius, the variance was small; therefore, each plate size may be selected depending on the circumstances of the fracture. anatomy cadaver radius tomography computers Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Distal radius fractures commonly occur in elderly people with osteoporosis [ 15 ]. The volar locking plate (VLP) system provides stable fixation for early rehabilitation and is the mainstream surgical treatment for patients with unstable distal radius fractures [ 5 , 9 ]. The watershed line, a ridge located on the volar surface of the distal radius, is a good landmark to determine the distal limit of the VLP [ 8 , 17 ]. The projection of a plate beyond the watershed line may cause flexor pollicis longus tendon rupture [ 4 , 10 , 19 ]. Therefore, surgeons attempt to attach the VLP within the watershed line to prevent tendon irritation; hence, anatomical fitting is an important issue. The fit of the VLP may depend on plate contour and individual differences in the distal radius. Many authors have attempted to clarify plate-to-bone fitting using commercial VLPs [ 3 , 22 ]. Various VLP shapes are available, and surgeons can select among them depending on the fracture type. These plates are available in two or three size options. Larger plates are difficult to apply and sensitive placement imperfections, prompting surgeons to prefer smaller plates to larger ones [ 14 ]. We aimed to investigate the potential impact of anatomical fitting between VLP and distal radius on its proper placement and to assess whether plate size affects plate placement. We hypothesized that plate size would affect the anatomical fit to the volar surface of the radius. Materials And Methods 2.1. Materials This study was approved by the Ethics Committee of our institution. We used the current designs of fixed and variable angle locking plates. The fixed locking plate was the Acu-Loc®︎2 Proximal Plate (AcuLoc; Acumed, Hillsboro, OR, USA), and two plate sizes (narrow and standard) were used (Fig. 1). The variable angle locking plate was Variable Angle LCP® Two-Column Volar Distal Radius Plate 2.4 (VALCP; DePuySynthes, Raynham, MA, USA), and three plate sizes (narrow, standard, and wide) were used (Fig. 1). We studied 16 unpaired formalin-fixed right upper limbs (nine male and seven female individuals; average age, 82.3 years) without severe degenerative or traumatic changes. All specimens were fixed with 10% formalin and preserved in 50% alcohol for 6 months. The specimens were donated to our institute for educational and research purposes. For cadaver preparation, the radius was cut from the forearm and exposed by dissecting the skin, subcutaneous tissue, and muscles. The ulna, carpal bones, and surrounding soft tissues were removed to obtain clear bone images. The radii and plates were scanned using 16-row computed tomography (CT) (ALEXION TSX-032A; CANON, Tochigi, Japan). The mean maximum width of the distal radius was 32.5 mm (range, 29–37 mm). 2.2. Methods 2.2.1. Plate placement and X-ray examination All plate fixations were performed by an experienced hand surgeon. Plate placement at the distal limit was set on the watershed line. The plates were placed with the best anatomical fit in the radial-ulnar position with axial alignment. First, the plates were fixed with a cortical screw in the oval hole. Then, the plate position was adjusted using the watershed line as a reference. Finally, the plates were tightly fixed. Thereafter, another orthopedic surgeon confirmed plate placement. The plate was fixed through the same drill hole to maintain rigid fixation. In the case of screw loosening, another hole was used for secure fixation. After plate placement, accurate posterior-anterior (PA) and lateral radiographs (X-rays) were obtained using fluoroscopy (EXAVISTA; HITACHI, Tokyo, Japan). 2.2.2. Computer simulation CT data of the bones and plates were transferred to the Mimics software (version 25.0; Materialise, Leuven, Belgium) and 3-matic version 17.0 (Materialise) to simulate three-dimensional (3D) models on the computer. The PA X-rays were overlaid onto 3D models of the distal radius to place the virtual plate on the distal radius (Fig. 2a). Thereafter, the plate was adjusted in the sagittal view to obtain an optimal fit without plate-bone intersections using lateral X-rays as a reference (Fig. 2b). 2.3. Methods of assessment Regarding plate and bone images, we defined each distal locking hole as U1, U2, R1, or R2 (Fig. 3a). U1 and U2 were on the ulnar column, whereas R1 and R2 were on the radial column, excluding the wide size of the VALCP. In the case of a plate with five distal locking holes, the center hole was defined as C. We created images of the sagittal plane at the center of the distal locking hole. In this image, the volar cortical angle (VCA) was measured as the angle formed by a line drawn along the volar surface and a line drawn on the radial shaft at U1, U2, C, R1, and R2 (Fig. 3b). The distance from the plate to the nearest point on the bone was measured at each distal locking hole. This value was defined as the plate-to-bone distance (PBD) in U1, U2, C, R1, and R2 (Fig. 3c). To investigate the anatomical fitting of the plate, the contact area between the bone and plate was analyzed on 3D images. The contact area was defined as the PBD within a 0.1-mm threshold, signifying the region where the plate was deemed to be in direct contact with the bone surface [22]. The contact area and PBD images are shown as color maps (Fig. 4). We measured the 3D images to confirm whether the plate ends were within the watershed line or overlapped. The watershed line was defined as the most distal bony prominence and was marked. We measured the distance between the distal end of the plate and the watershed line in the 3D images, terming it watershed overlap (Fig. 5). We measured all parameters twice. The second measurement was performed at more than one week after the first measurement, and the average of both values was used for analysis. 2.4. Statistical analysis Data analyses were performed using StatMate version 4.01 (Tokyo, Japan). The one-way analysis of variance (ANOVA) with Tukey’s test was used to evaluate the PBD and VCA among each distal locking hole. The Mann–Whitney U test was performed to analyze the PBD, contact area, and watershed overlap in the AcuLoc. ANOVA with Tukey’s test was used to analyze the PBD, contact area, and watershed overlap in the VALCP. Statistical significance was set at a P-value of less than 0.05. Results The contact area was 6.6–20.0%, and there was no significant difference among the various plate sizes in both plates (Fig. 4). The VCAs for each value are listed in Table 1. The VCA of the radial column was significantly smaller than that of the ulnar column. PBD results are shown in Fig. 6a and 6b. Regarding VALCP, the PBD in the radial column was significantly smaller than that in the ulnar column in the narrow and standard plates. For the other plates, the PBD in the radial column tended to be smaller than that in the ulnar column. Watershed overlap was observed, especially for AcuLoc, although the average value was negative for both plates. There was no significant difference in the watershed overlap among the plate sizes in both plates (Table 2). Discussion This study revealed that the VCA in the radial column was significantly smaller than that in the ulnar column. A previous study investigated the VCA at the midpoint of the scaphoid fossa and at the lateral and medial edges of the lunate fossa [6]. In their measurements, VCA was significantly lower at the midpoint of the scaphoid fossa than at the lunate fossa, similar to our findings. The PBD at the distal locking hole was closer to the radial column than the ulnar column. Previous studies have investigated the compatibility of the distal radius and currently available plates. Although the current commercial plates are designed to fit the volar surface of the radius, a previous study revealed that the plates do not match the volar surface. Kwak et al. [11] reported the VCA of a commercial plate containing the VALCP and AcuLoc. In their report, the VCA in the radial and ulnar columns for the wide type was 23° and 30°, and in the narrow type, it was 21° and 27°, respectively, in the VALCP. For the AcuLoc plate, the VCA in the radial and ulnar columns for the wide type were 24° and 29°, and those for the narrow type were 22° and 27°, respectively. Hence, the difference in the plate angle between the radial and ulnar columns was 5–6°. Although these angles were similar to our VCA measurements, a more anatomical fit needs to be explored. The ulnar column supports the lunate fossa and plays an important role in treating challenging fractures of the distal radius with volar rim fragments [2]. Gandhi et al. [7] reported that the VCA increases with age until 51 years of age, followed by a decline. The morphology of human bones changes with age [1,20,21]. The decrease in VCA with age could explain the remodeling of the distal radius due to chronic microtrauma caused by repetitive load during activities of daily life [16]. Yoneda et al. [13] reported on the angle between the volar prominence and radial shaft. They concluded that the angle had a wide range with a coefficient of variance of 24.5%. These individual differences in the morphology of the distal radius make it difficult to develop commercial plates with an anatomical fit. Previous reports have revealed a less than 10% plate-bone contact area between the VLPs and distal radius. Buzzell et al. [3] studied seven plates using pressure-sensitive film and reported a contact area of 3–6%. Yoneda et al. [22] used a computer model to investigate the contact area and reported it to be 1.8–8.0%. In our 3D simulation study, the contact area was 6.6–20.0% of the plate, which was similar to a previous study. The difference between plate sizes was small; therefore, compatibility by size was not determined in this study. Many recent plates are designed to fit the morphology of the radius to avoid irritating the flexor tendons. Limthongthang et al. [13] investigated the plate-to-bone interactions using cadavers and several commercially available VLPs. They reported that all plates protruded beyond the watershed line, even though they were placed in a position to achieve a proper anatomic fit as close to the watershed line as possible. Perrin et al. [18] conducted a similar study, in which plates were placed in a computer simulation model, and watershed line overlap was found in 17 of 40 patients. The current study revealed that some plates protruded beyond the watershed line, especially the AcuLoc, although the difference in values between the plate sizes was small. There were no significant differences in the PBD, contact area, or watershed overlap among the plates of different sizes. There is a potential for surgeons to select smaller or bigger plates than those matched because smaller plates are easier to apply and surgeons are reluctant to place them beyond the watershed line [14]. Wider plates provide more stability than smaller plates, and narrow plates may not completely capture small bone fragments in comminuted fractures [14]. We found no advantage in selecting a smaller size. Every plate size showed a small PBD without excessive watershed overlap. Although the plate size affected the fit to the distal radius, the variance was small; hence, each plate size could be developed with anatomical consistency. Surgeons may select the plate size necessary for a specific fracture situation with optimal fitting. Smaller plates had no advantage concerning the PBD, contact area, or watershed overlap. This study has some limitations. First, the sample size was small. Second, the mean cadaver age was 82.3 years; hence, our results may have been affected by degenerative changes. Third, each specimen was tested several times. The order of plate placement can affect the fixing force associated with screw loosening. Fourth, although we attached the best-fitting plate with the help of a single surgeon, the placement may not have been perfectly straight. This may have affected the measurement results. Thus, two surgeons confirmed the VLP placement. Fifth, all specimens were normal, without a wrist fracture. Patients with loss of reduction or inadequate reduction may have different results that cannot be assessed using a non-fracture model. Finally, we used plates from Western countries and Japanese cadavers. A previous study reported that the VCA was larger in Caucasians than in Koreans [12]. Hence, using specimens from Western countries may have produced different results. Conclusion Although the plate size affected the fit to the distal radius, the variability observed was minimal, suggesting that each plate size may be selected depending on the fracture circumstances. Our data may provide surgeons with accurate knowledge regarding the VLP and bone interactions, particularly regarding implant size. Future studies with larger sample sizes and implant-specimen congruency are required to validate our findings. Abbreviations VLP; volar locking plate AcuLoc; Acu-Loc®︎2 Proximal Plate VALCP; Variable Angle LCP® Two-Column Volar Distal Radius Plate 2.4 CT; computed tomography 3D; three-dimensional PA; posterior-anterior X-rays; radiographs VCA; volar cortical angle PBD; plate-to-bone distance ANOVA; one-way analysis of variance Declarations Contributions Protocol/project development: K. Sato, G. Takahashi, and M. Doita Data collection or management: H. Hasegawa Data analysis: H. Hasegawa and K. Sato Manuscript writing/editing: H. Hasegawa, K. Murakami, and M Matsuura Ethics approval and consent to participate This study was approved by the Ethics Committee of our institution. Funding and/or Competing interests No funds, grants, or other support was received. Acknowledgements The authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase mankind's overall knowledge that can then improve patient care. Therefore, these donors and their families deserve our highest gratitude. The authors wish to thank associate Jun Kanazawa from the Department of Anatomy of Iwate Medial University for his technical assistance and Professors Jiro Hitomi for his continuous support of this study. References Aaron JE, Makins NB, Sagreiya K. The microanatomy of trabecular bone loss in normal aging men and women. Clin Orthop Relat Res. 1987;(215):260-71. doi: 10.1097/00003086-199702000-00038 Beck JD, Harness NG, Spencer HT. Volar plate fixation failure for volar shearing distal radius fractures with small lunate facet fragments. J Hand Surg Am. 2014;39:670-8. doi: 10.1016/j.jhsa.2014.01.006. Buzzell JE, Weikert DR, Watson JT, Lee DH. Precontoured fixed-angle volar distal radius plates: a comparison of anatomic fit. J Hand Surg Am. 2008;33:1144-52. doi: 10.1016/j.jhsa.2008.02.029. Casaletto JA, Machin D, Leung R, Brown DJ. Flexor pollicis longus tendon ruptures after palmar plate fixation of fractures of the distal radius. J Hand Surg Eur Vol. 2009;34:471–4. doi: 10.1177/1753193408100964. Chung KC, Watt AJ, Kotsis SV, Margaliot Z, Haase SC, Kim HM. Treatment of unstable distal radial fractures with the volar locking plating system. J Bone Joint Surg Am. 2006;88.2687–94;88:2687–94. doi: 10.2106/JBJS.E.01298. Evans S, Ramasamy A, Deshmukh SC. Distal volar radial plates: how anatomical are they? Orthop Traumatol Surg Res. 2014;100:293-5. doi: 10.1016/j.otsr.2013.11.014. Gandhi RA, Hesketh PJ, Bannister ER, Sebro R, Mehta S. Age-related variations in volar cortical angle of the distal radius. Hand (N Y). 2020;15:573-7. doi: 10.1177/1558944718820962. Imatani J, Akita K, Yamaguchi K, Shimizu H, Kondou H, Ozaki T. An anatomical study of the watershed line on the volar, distal aspect of the radius: implications for plate placement and avoidance of tendon ruptures. J Hand Surg Am. 2012;37:1550–4. doi: 10.1016/j.jhsa.2012.05.011. Jose A, Suranigi SM, Deniese PN, Babu AT, Rengasamy K, Najimudeen S. Unstable distal radius fractures treated by volar locking anatomical plates. J Clin Diagn Res. 2017;11:RC04–8. doi: 10.7860/JCDR/2017/24114.9261. Kitay A, Swanstrom M, Schreiber JJ, Carlson MG, Nguyen JT, Weiland AJ, et al. Volar plate position and flexor tendon rupture following distal radius fracture fixation. J Hand Surg Am. 2013;38:1091-6. doi: 10.1016/j.jhsa.2013.03.011. Kwak DS, Lee JY, Im JH, Song HJ, Park D. Do volar locking plates fit the volar cortex of the distal radius? J Hand Surg Eur Vol. 2017;42:266-70. doi: 10.1177/1753193416676704. Kwon BC, Lee JK, Lee SY, Hwang JY, Seo JH. Morphometric variations in the volar aspect of the distal radius. Clin Orthop Surg. 2018;10:462-7. doi: 10.4055/cios.2018.10.4.462. Limthongthang R, Bachoura A, Jacoby SM, Osterman AL. Distal radius volar locking plate design and associated vulnerability of the flexor pollicis longus. J Hand Surg Am. 2014;39:852-60. doi: 10.1016/j.jhsa.2014.01.038. McIver ND, Salas C, Menon N, Heifner J, Mercer D. Appropriately matched fixed-angle locking plates improve stability in volar distal radius fixation. J Hand Surg Glob Online. 2022;4:135-40. doi: 10.1016/j.jhsg.2022.02.007. Nellans KW, Kowalski E, Chung KC. The epidemiology of distal radius fractures. Hand Clin. 2012;28:113–25. doi: 10.1016/j.hcl.2012.02.001. O’Brien FJ, Brennan O, Kennedy OD, Lee TC. Microcracks in cortical bone: how do they affect bone biology? Curr Osteoporos Rep. 2005;3:39-45. doi: 10.1007/s11914-005-0002-1. Orbay JL, Touhami A. Current concepts in volar fixed-angle fixation of unstable distal radius fractures. Clin Orthop Relat Res. 2006;445:58–67. doi: 10.1097/01.blo.0000205891.96575.0f. Perrin M, Badre A, Suh N, Lalone EA. Analysis of three-dimensional anatomical variance and fit of the distal radius to current volar locking plate designs. J Hand Surg Glob Online. 2020;2:277-85. doi: 10.1016/j.jhsg.2020.07.003. Soong M, Earp BE, Bishop G, Leung A, Blazar P. Volar locking plate implant prominence and flexor tendon rupture. J Bone Joint Surg Am. 2011;93:328-35. doi: 10.2106/JBJS.J.00193. Tommasini SM, Nasser P, Jepsen KJ. Sexual dimorphism affects tibia size and shape but not tissue-level mechanical properties. Bone. 2007;40:498-505. doi: 10.1016/j.bone.2006.08.012. Tommasini SM, Nasser P, Schaffler MB, Jepsen KJ. Relationship between bone morphology and bone quality in male tibias: implications for stress fracture risk. J Bone Miner Res. 2005;20:1372-80. doi: 10.1359/JBMR.050326. Yoneda H, Iwatsuki K, Hara T, Kurimoto S, Yamamoto M, Hirata H. Interindividual anatomical variations affect the plate-to-bone fit during osteosynthesis of distal radius fractures. J Orthop Res. 2016;34:953-60. doi: 10.1002/jor.23125. Tables Tables are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Tablevol.6.pptx Cite Share Download PDF Status: Under Review Version 1 posted Editor assigned by journal 30 May, 2024 Submission checks completed at journal 30 May, 2024 First submitted to journal 26 May, 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-4481905","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":308749391,"identity":"d5cc1d75-65fc-4b05-9a86-a9a0ed7fc873","order_by":0,"name":"Hiroshi Hasegawa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1ElEQVRIiWNgGAWjYBACAyBmRmLYACnGxgOkaEkDaWkgScthsCheLebsxx8+Lqipk4MyztutbT8MtKXGJhqXFsueHGPjGccOG0MZt5O3nUkEajmWltuAy2EHctikedgOJG6AMG4nmx0AamFsOIxby/nnz3/z/Kur3wBhnEs2O/+QgJYbCWbMvG3MCVDGATuzG4RsufHGWJq377DhBggjOcHsBtCWBHx+OZ/+8DPPtzp5KMPO3gzIePChxganFgyQCFaZQKxyELAnRfEoGAWjYBSMDAAAjmpmFn/o4kQAAAAASUVORK5CYII=","orcid":"","institution":"Iwate Medical University","correspondingAuthor":true,"prefix":"","firstName":"Hiroshi","middleName":"","lastName":"Hasegawa","suffix":""},{"id":308749392,"identity":"b79a41dc-241a-4000-925a-ceb8e2a1e018","order_by":1,"name":"Kotaro Sato","email":"","orcid":"","institution":"Iwate Medical University","correspondingAuthor":false,"prefix":"","firstName":"Kotaro","middleName":"","lastName":"Sato","suffix":""},{"id":308749393,"identity":"998ea6e0-fab1-48f4-90ee-37c9328ea171","order_by":2,"name":"Kenya Murakami","email":"","orcid":"","institution":"Iwate Medical University","correspondingAuthor":false,"prefix":"","firstName":"Kenya","middleName":"","lastName":"Murakami","suffix":""},{"id":308749394,"identity":"a9fe32a2-926f-4c18-a44d-6a5ba61bf163","order_by":3,"name":"Tomoyuki Saino","email":"","orcid":"","institution":"Iwate Medical University","correspondingAuthor":false,"prefix":"","firstName":"Tomoyuki","middleName":"","lastName":"Saino","suffix":""},{"id":308749395,"identity":"d46ccb20-0bc5-4219-b0b1-d789eda0b791","order_by":4,"name":"Minoru Doita","email":"","orcid":"","institution":"Iwate Medical University","correspondingAuthor":false,"prefix":"","firstName":"Minoru","middleName":"","lastName":"Doita","suffix":""}],"badges":[],"createdAt":"2024-05-27 02:54:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4481905/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4481905/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58309250,"identity":"1a1a850d-a85f-4fb7-9d03-cb9034a713f7","added_by":"auto","created_at":"2024-06-13 18:53:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":847100,"visible":true,"origin":"","legend":"\u003cp\u003eThe five plates used.\u003c/p\u003e\n\u003cp\u003eThe Acu-Loc®︎2 Proximal Plate (AcuLoc) has two sizes: narrow and standard. The Variable Angle LCP® Two-Column Volar Distal Radius Plate 2.4 (VALCP) has three sizes: narrow, standard, and wide.\u003c/p\u003e","description":"","filename":"Figurevol.71.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/15af7b3122e2bffb039d8ee7.png"},{"id":58307958,"identity":"addb1423-165c-4ac4-a440-ddff1a569b0a","added_by":"auto","created_at":"2024-06-13 18:45:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":727448,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray and 3D models of the bones and plates.\u003c/p\u003e\n\u003cp\u003e(a) Posterior-anterior (PA) view.\u003c/p\u003e\n\u003cp\u003ePlate the virtual plate to the virtual distal radius.\u003c/p\u003e\n\u003cp\u003e(b) Sagittal view.\u003c/p\u003e\n\u003cp\u003eDetermine the best-fit placement of the virtual plate.\u003c/p\u003e\n\u003cp\u003e3D, three-dimensional\u003c/p\u003e","description":"","filename":"Figurevol.72.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/7e1cae47d71259531d775d84.png"},{"id":58307960,"identity":"6e9b2a6f-56e5-4f7a-aa46-b054395b639f","added_by":"auto","created_at":"2024-06-13 18:45:27","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1009927,"visible":true,"origin":"","legend":"\u003cp\u003ePlate and bone imaging markings.\u003c/p\u003e\n\u003cp\u003e(a) The distal locking holes indicate U1, U2, C, R1, and R2: the sagittal planes are created at the center of each hole.\u003c/p\u003e\n\u003cp\u003e(b) The *VCA at each sagittal plane in the VALCP (wide).\u003c/p\u003e\n\u003cp\u003e(c) The *PBD at each distal locking hole.\u003c/p\u003e\n\u003cp\u003ePBD, plate-to-bone distance; VCA, volar cortical angle VALCP, Variable Angle LCP® Two-Column Volar Distal Radius Plate 2.4.\u003c/p\u003e","description":"","filename":"Figurevol.73.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/c5b6216f2a47bb41f5bc258a.png"},{"id":58307955,"identity":"a292a13d-2108-4bf9-b6dd-3370622edfaa","added_by":"auto","created_at":"2024-06-13 18:45:27","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":580697,"visible":true,"origin":"","legend":"\u003cp\u003eContact area and PBD with color maps.\u003c/p\u003e\n\u003cp\u003eAs the PBD shortens, the color shifts from green to red. The non-colored regions represent the area where the PBD is more than 1.0 mm. The contact ratio is calculated by dividing the contact area by the plate’s surface area.\u003c/p\u003e\n\u003cp\u003ePBD, plate-to-bone distance.\u003c/p\u003e","description":"","filename":"Figurevol.74.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/f1b6ad78c2d8d6b19429dfd2.png"},{"id":58307959,"identity":"549b69d5-08f3-4be8-8c3b-5bf01aaf05ee","added_by":"auto","created_at":"2024-06-13 18:45:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":938679,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of watershed overlap.\u003c/p\u003e\n\u003cp\u003eThe two-headed arrow shows how watershed overlap is measured between the two central distal locking holes. The blue dotted line illustrates the watershed line.\u003c/p\u003e","description":"","filename":"Figurevol.75.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/35e33d7064ec9942344fb552.png"},{"id":58307954,"identity":"c8662443-1282-41d7-b816-dba840fbe0fc","added_by":"auto","created_at":"2024-06-13 18:45:26","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":45324,"visible":true,"origin":"","legend":"\u003cp\u003ePBD in the two plates.\u003c/p\u003e\n\u003cp\u003e(a) The PBD in the AcuLoc: The PBD in the radial column is smaller than that in the ulnar column in narrow plates.\u003c/p\u003e\n\u003cp\u003e(b) The PBD in the VALCP: The PBD in the radial column is smaller than that in the ulnar column in narrow and standard plates.\u003c/p\u003e\n\u003cp\u003e* \u003cem\u003ep\u003c/em\u003e\u0026lt;0.05.\u003c/p\u003e\n\u003cp\u003eAcuLoc, Acu-Loc®︎2 Proximal Plate; PBD, plate-to-bone distance; VALCP, Variable Angle LCP® Two-Column Volar Distal Radius Plate 2.4.\u003c/p\u003e","description":"","filename":"Figurevol.76.png","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/a3c6d6f46df8adaf5f77c724.png"},{"id":58309273,"identity":"3c2bad10-9cb9-4c13-9be8-c9bef4dd5605","added_by":"auto","created_at":"2024-06-13 18:53:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4372496,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/918f12bd-9283-44bc-b718-296155c704b0.pdf"},{"id":58307957,"identity":"86e0460a-06b4-4fc0-b455-6d9c92193c17","added_by":"auto","created_at":"2024-06-13 18:45:27","extension":"pptx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":124824,"visible":true,"origin":"","legend":"","description":"","filename":"Tablevol.6.pptx","url":"https://assets-eu.researchsquare.com/files/rs-4481905/v1/0a43108c198fdf3c7e7a161b.pptx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anatomical fit of volar locking plates for the distal radius and the influence of plate size","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDistal radius fractures commonly occur in elderly people with osteoporosis [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The volar locking plate (VLP) system provides stable fixation for early rehabilitation and is the mainstream surgical treatment for patients with unstable distal radius fractures [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The watershed line, a ridge located on the volar surface of the distal radius, is a good landmark to determine the distal limit of the VLP [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The projection of a plate beyond the watershed line may cause flexor pollicis longus tendon rupture [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Therefore, surgeons attempt to attach the VLP within the watershed line to prevent tendon irritation; hence, anatomical fitting is an important issue. The fit of the VLP may depend on plate contour and individual differences in the distal radius. Many authors have attempted to clarify plate-to-bone fitting using commercial VLPs [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Various VLP shapes are available, and surgeons can select among them depending on the fracture type. These plates are available in two or three size options. Larger plates are difficult to apply and sensitive placement imperfections, prompting surgeons to prefer smaller plates to larger ones [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. We aimed to investigate the potential impact of anatomical fitting between VLP and distal radius on its proper placement and to assess whether plate size affects plate placement. We hypothesized that plate size would affect the anatomical fit to the volar surface of the radius.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003e\u003cem\u003e2.1. Materials\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of our institution. We used the current designs of fixed and variable angle locking plates. The fixed locking plate was the Acu-Loc\u0026reg;︎2 Proximal Plate (AcuLoc; Acumed, Hillsboro, OR, USA), and two plate sizes (narrow and standard) were used (Fig. 1). The variable angle locking plate was Variable Angle LCP\u0026reg; Two-Column Volar Distal Radius Plate 2.4 (VALCP; DePuySynthes, Raynham, MA, USA), and three plate sizes (narrow, standard, and wide) were used (Fig. 1). We studied 16 unpaired formalin-fixed right upper limbs (nine male and seven female individuals; average age, 82.3 years) without severe degenerative or traumatic changes. All specimens were fixed with 10% formalin and preserved in 50% alcohol for 6 months. The specimens were donated to our institute for educational and research purposes. For cadaver preparation, the radius was cut from the forearm and exposed by dissecting the skin, subcutaneous tissue, and muscles. The ulna, carpal bones, and surrounding soft tissues were removed to obtain clear bone images. The radii and plates were scanned using 16-row computed tomography (CT) (ALEXION TSX-032A; CANON, Tochigi, Japan). The mean maximum width of the distal radius was 32.5 mm (range, 29\u0026ndash;37 mm).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.2. Methods\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.2.1. Plate placement and X-ray examination\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAll plate fixations were performed by an experienced hand surgeon. Plate placement at the distal limit was set on the watershed line. The plates were placed with the best anatomical fit in the radial-ulnar position with axial alignment. First, the plates were fixed with a cortical screw in the oval hole. Then, the plate position was adjusted using the watershed line as a reference. Finally, the plates were tightly fixed. Thereafter, another orthopedic surgeon confirmed plate placement. The plate was fixed through the same drill hole to maintain rigid fixation. In the case of screw loosening, another hole was used for secure fixation. After plate placement, accurate posterior-anterior (PA) and lateral radiographs (X-rays) were obtained using fluoroscopy (EXAVISTA; HITACHI, Tokyo, Japan).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.2.2. Computer simulation\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eCT data of the bones and plates were transferred to the Mimics software (version 25.0; Materialise, Leuven, Belgium) and 3-matic version 17.0 (Materialise) to simulate three-dimensional (3D) models on the computer. The PA X-rays were overlaid onto 3D models of the distal radius to place the virtual plate on the distal radius (Fig. 2a). Thereafter, the plate was adjusted in the sagittal view to obtain an optimal fit without plate-bone intersections using lateral X-rays as a reference (Fig. 2b).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.3. Methods of assessment\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eRegarding plate and bone images, we defined each distal locking hole as U1, U2, R1, or R2 (Fig. 3a). U1 and U2 were on the ulnar column, whereas R1 and R2 were on the radial column, excluding the wide size of the VALCP. In the case of a plate with five distal locking holes, the center hole was defined as C. We created images of the sagittal plane at the center of the distal locking hole. In this image, the volar cortical angle (VCA) was measured as the angle formed by a line drawn along the volar surface and a line drawn on the radial shaft at U1, U2, C, R1, and R2 (Fig. 3b). The distance from the plate to the nearest point on the bone was measured at each distal locking hole. This value was defined as the plate-to-bone distance (PBD) in U1, U2, C, R1, and R2 (Fig. 3c).\u003c/p\u003e\n\u003cp\u003eTo investigate the anatomical fitting of the plate, the contact area between the bone and plate was analyzed on 3D images. The contact area was defined as the PBD within a 0.1-mm threshold, signifying the region where the plate was deemed to be in direct contact with the bone surface [22]. The contact area and PBD images are shown as color maps (Fig. 4).\u003c/p\u003e\n\u003cp\u003eWe measured the 3D images to confirm whether the plate ends were within the watershed line or overlapped. The watershed line was defined as the most distal bony prominence and was marked. We measured the distance between the distal end of the plate and the watershed line in the 3D images, terming it watershed overlap (Fig. 5). We measured all parameters twice. The second measurement was performed at more than one week after the first measurement, and the average of both values was used for analysis.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.4. Statistical analysis\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eData analyses were performed using StatMate version 4.01 (Tokyo, Japan). The one-way analysis of variance (ANOVA) with Tukey\u0026rsquo;s test was used to evaluate the PBD and VCA among each distal locking hole. The Mann\u0026ndash;Whitney U test was performed to analyze the PBD, contact area, and watershed overlap in the AcuLoc. ANOVA with Tukey\u0026rsquo;s test was used to analyze the PBD, contact area, and watershed overlap in the VALCP. Statistical significance was set at a P-value of less than 0.05.\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe contact area was 6.6\u0026ndash;20.0%, and there was no significant difference among the various plate sizes in both plates (Fig. 4). The VCAs for each value are listed in Table 1. The VCA of the radial column was significantly smaller than that of the ulnar column. PBD results are shown in Fig. 6a and 6b. Regarding VALCP, the PBD in the radial column was significantly smaller than that in the ulnar column in the narrow and standard plates. For the other plates, the PBD in the radial column tended to be smaller than that in the ulnar column.\u003c/p\u003e\n\u003cp\u003eWatershed overlap was observed, especially for AcuLoc, although the average value was negative for both plates. There was no significant difference in the watershed overlap among the plate sizes in both plates (Table 2).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study revealed that the VCA in the radial column was significantly smaller than that in the ulnar column. A previous study investigated the VCA at the midpoint of the scaphoid fossa and at the lateral and medial edges of the lunate fossa [6]. In their measurements, VCA was significantly lower at the midpoint of the scaphoid fossa than at the lunate fossa, similar to our findings.\u003c/p\u003e\n\u003cp\u003eThe PBD at the distal locking hole was closer to the radial column than the ulnar column. Previous studies have investigated the compatibility of the distal radius and currently available plates. Although the current commercial plates are designed to fit the volar surface of the radius, a previous study revealed that the plates do not match the volar surface. Kwak et al. [11] reported the VCA of a commercial plate containing the VALCP and AcuLoc. In their report, the VCA in the radial and ulnar columns for the wide type was 23\u0026deg; and 30\u0026deg;, and in the narrow type, it was 21\u0026deg; and 27\u0026deg;, respectively, in the VALCP. For the AcuLoc plate, the VCA in the radial and ulnar columns for the wide type were 24\u0026deg; and 29\u0026deg;, and those for the narrow type were 22\u0026deg; and 27\u0026deg;, respectively. Hence, the difference in the plate angle between the radial and ulnar columns was 5\u0026ndash;6\u0026deg;. Although these angles were similar to our VCA measurements, a more anatomical fit needs to be explored. The ulnar column supports the lunate fossa and plays an important role in treating challenging fractures of the distal radius with volar rim fragments [2].\u003c/p\u003e\n\u003cp\u003eGandhi et al. [7] reported that the VCA increases with age until 51 years of age, followed by a decline. The morphology of human bones changes with age [1,20,21]. The decrease in VCA with age could explain the remodeling of the distal radius due to chronic microtrauma caused by repetitive load during activities of daily life [16]. Yoneda et al. [13] reported on the angle between the volar prominence and radial shaft. They concluded that the angle had a wide range with a coefficient of variance of 24.5%. These individual differences in the morphology of the distal radius make it difficult to develop commercial plates with an anatomical fit.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePrevious reports have revealed a less than 10% plate-bone contact area between the VLPs and distal radius. Buzzell et al. [3] studied seven plates using pressure-sensitive film and reported a contact area of 3\u0026ndash;6%. Yoneda et al. [22] used a computer model to investigate the contact area and reported it to be 1.8\u0026ndash;8.0%. In our 3D simulation study, the contact area was 6.6\u0026ndash;20.0% of the plate, which was similar to a previous study. The difference between plate sizes was small; therefore, compatibility by size was not determined in this study.\u003c/p\u003e\n\u003cp\u003eMany recent plates are designed to fit the morphology of the radius to avoid irritating the flexor tendons. Limthongthang et al. [13] investigated the plate-to-bone interactions using cadavers and several commercially available VLPs. They reported that all plates protruded beyond the watershed line, even though they were placed in a position to achieve a proper anatomic fit as close to the watershed line as possible. Perrin et al. [18] conducted a similar study, in which plates were placed in a computer simulation model, and watershed line overlap was found in 17 of 40 patients. The current study revealed that some plates protruded beyond the watershed line, especially the AcuLoc, although the difference in values between the plate sizes was small.\u003c/p\u003e\n\u003cp\u003eThere were no significant differences in the PBD, contact area, or watershed overlap among the plates of different sizes. There is a potential for surgeons to select smaller or bigger plates than those matched because smaller plates are easier to apply and surgeons are reluctant to place them beyond the watershed line [14]. Wider plates provide more stability than smaller plates, and narrow plates may not completely capture small bone fragments in comminuted fractures [14]. We found no advantage in selecting a smaller size. Every plate size showed a small PBD without excessive watershed overlap. Although the plate size affected the fit to the distal radius, the variance was small; hence, each plate size could be developed with anatomical consistency. Surgeons may select the plate size necessary for a specific fracture situation with optimal fitting. Smaller plates had no advantage concerning the PBD, contact area, or watershed overlap.\u003c/p\u003e\n\u003cp\u003eThis study has some limitations. First, the sample size was small. Second, the mean cadaver age was 82.3 years; hence, our results may have been affected by degenerative changes. Third, each specimen was tested several times. The order of plate placement can affect the fixing force associated with screw loosening. Fourth, although we attached the best-fitting plate with the help of a single surgeon, the placement may not have been perfectly straight. This may have affected the measurement results. Thus, two surgeons confirmed the VLP placement. Fifth, all specimens were normal, without a wrist fracture. Patients with loss of reduction or inadequate reduction may have different results that cannot be assessed using a non-fracture model. Finally, we used plates from Western countries and Japanese cadavers. A previous study reported that the VCA was larger in Caucasians than in Koreans [12]. Hence, using specimens from Western countries may have produced different results.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAlthough the plate size affected the fit to the distal radius, the variability observed was minimal, suggesting that each plate size may be selected depending on the fracture circumstances. Our data may provide surgeons with accurate knowledge regarding the VLP and bone interactions, particularly regarding implant size. Future studies with larger sample sizes and implant-specimen congruency are required to validate our findings.\u003c/p\u003e\n"},{"header":"Abbreviations","content":"\u003cp\u003eVLP; volar locking plate\u003c/p\u003e\n\u003cp\u003eAcuLoc; Acu-Loc\u0026reg;︎2 Proximal Plate\u003c/p\u003e\n\u003cp\u003eVALCP; Variable Angle LCP\u0026reg; Two-Column Volar Distal Radius Plate 2.4\u003c/p\u003e\n\u003cp\u003eCT; computed tomography\u003c/p\u003e\n\u003cp\u003e3D; three-dimensional\u003c/p\u003e\n\u003cp\u003ePA; posterior-anterior\u003c/p\u003e\n\u003cp\u003eX-rays; radiographs\u003c/p\u003e\n\u003cp\u003eVCA; volar cortical angle\u003c/p\u003e\n\u003cp\u003ePBD; plate-to-bone distance\u003c/p\u003e\n\u003cp\u003eANOVA; one-way analysis of variance\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eContributions\u003c/p\u003e\n\u003cp\u003eProtocol/project development: K. Sato, G. Takahashi, and M. Doita\u003c/p\u003e\n\u003cp\u003eData collection or management: H. Hasegawa\u003c/p\u003e\n\u003cp\u003eData analysis: H. Hasegawa and K. Sato\u003c/p\u003e\n\u003cp\u003eManuscript writing/editing: H. Hasegawa, K. Murakami, and M Matsuura\u0026nbsp;\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eEthics approval and consent to participate\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of our institution.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eFunding and/or Competing interests\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eNo funds, grants, or other support was received.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eAcknowledgements\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase mankind\u0026apos;s overall knowledge that can then improve patient care. Therefore, these donors and their families deserve our highest gratitude.\u003c/p\u003e\n\u003cp\u003eThe authors wish to thank associate Jun Kanazawa from the Department of Anatomy of Iwate Medial University for his technical assistance and Professors Jiro Hitomi for his continuous support of this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAaron JE, Makins NB, Sagreiya K. The microanatomy of trabecular bone loss in normal aging men and women. Clin Orthop Relat Res. 1987;(215):260-71. doi: 10.1097/00003086-199702000-00038\u003c/li\u003e\n\u003cli\u003eBeck JD, Harness NG, Spencer HT. Volar plate fixation failure for volar shearing distal radius fractures with small lunate facet fragments. J Hand Surg Am. 2014;39:670-8. doi: 10.1016/j.jhsa.2014.01.006.\u003c/li\u003e\n\u003cli\u003eBuzzell JE, Weikert DR, Watson JT, Lee DH. Precontoured fixed-angle volar distal radius plates: a comparison of anatomic fit. J Hand Surg Am. 2008;33:1144-52. doi: 10.1016/j.jhsa.2008.02.029.\u003c/li\u003e\n\u003cli\u003eCasaletto JA, Machin D, Leung R, Brown DJ. Flexor pollicis longus tendon ruptures after palmar plate fixation of fractures of the distal radius. J Hand Surg Eur Vol. 2009;34:471\u0026ndash;4. doi: 10.1177/1753193408100964.\u003c/li\u003e\n\u003cli\u003eChung KC, Watt AJ, Kotsis SV, Margaliot Z, Haase SC, Kim HM. Treatment of unstable distal radial fractures with the volar locking plating system. J Bone Joint Surg Am. 2006;88.2687\u0026ndash;94;88:2687\u0026ndash;94. doi: 10.2106/JBJS.E.01298.\u003c/li\u003e\n\u003cli\u003eEvans S, Ramasamy A, Deshmukh SC. Distal volar radial plates: how anatomical are they? Orthop Traumatol Surg Res. 2014;100:293-5. doi: 10.1016/j.otsr.2013.11.014.\u003c/li\u003e\n\u003cli\u003eGandhi RA, Hesketh PJ, Bannister ER, Sebro R, Mehta S. Age-related variations in volar cortical angle of the distal radius. Hand (N Y). 2020;15:573-7. doi: 10.1177/1558944718820962.\u003c/li\u003e\n\u003cli\u003eImatani J, Akita K, Yamaguchi K, Shimizu H, Kondou H, Ozaki T. An anatomical study of the watershed line on the volar, distal aspect of the radius: implications for plate placement and avoidance of tendon ruptures. J Hand Surg Am. 2012;37:1550\u0026ndash;4. doi: 10.1016/j.jhsa.2012.05.011.\u003c/li\u003e\n\u003cli\u003eJose A, Suranigi SM, Deniese PN, Babu AT, Rengasamy K, Najimudeen S. Unstable distal radius fractures treated by volar locking anatomical plates. J Clin Diagn Res. 2017;11:RC04\u0026ndash;8. doi: 10.7860/JCDR/2017/24114.9261.\u003c/li\u003e\n\u003cli\u003eKitay A, Swanstrom M, Schreiber JJ, Carlson MG, Nguyen JT, Weiland AJ, et al. Volar plate position and flexor tendon rupture following distal radius fracture fixation. J Hand Surg Am. 2013;38:1091-6. doi: 10.1016/j.jhsa.2013.03.011.\u003c/li\u003e\n\u003cli\u003eKwak DS, Lee JY, Im JH, Song HJ, Park D. Do volar locking plates fit the volar cortex of the distal radius? J Hand Surg Eur Vol. 2017;42:266-70. doi: 10.1177/1753193416676704.\u003c/li\u003e\n\u003cli\u003eKwon BC, Lee JK, Lee SY, Hwang JY, Seo JH. Morphometric variations in the volar aspect of the distal radius. Clin Orthop Surg. 2018;10:462-7. doi: 10.4055/cios.2018.10.4.462.\u003c/li\u003e\n\u003cli\u003eLimthongthang R, Bachoura A, Jacoby SM, Osterman AL. Distal radius volar locking plate design and associated vulnerability of the flexor pollicis longus. J Hand Surg Am. 2014;39:852-60. doi: 10.1016/j.jhsa.2014.01.038.\u003c/li\u003e\n\u003cli\u003eMcIver ND, Salas C, Menon N, Heifner J, Mercer D. Appropriately matched fixed-angle locking plates improve stability in volar distal radius fixation. J Hand Surg Glob Online. 2022;4:135-40. doi: 10.1016/j.jhsg.2022.02.007.\u003c/li\u003e\n\u003cli\u003eNellans KW, Kowalski E, Chung KC. The epidemiology of distal radius fractures. Hand Clin. 2012;28:113\u0026ndash;25. doi: 10.1016/j.hcl.2012.02.001.\u003c/li\u003e\n\u003cli\u003eO\u0026rsquo;Brien FJ, Brennan O, Kennedy OD, Lee TC. Microcracks in cortical bone: how do they affect bone biology? Curr Osteoporos Rep. 2005;3:39-45. doi: 10.1007/s11914-005-0002-1.\u003c/li\u003e\n\u003cli\u003eOrbay JL, Touhami A. Current concepts in volar fixed-angle fixation of unstable distal radius fractures. Clin Orthop Relat Res. 2006;445:58\u0026ndash;67. doi: 10.1097/01.blo.0000205891.96575.0f.\u003c/li\u003e\n\u003cli\u003ePerrin M, Badre A, Suh N, Lalone EA. Analysis of three-dimensional anatomical variance and fit of the distal radius to current volar locking plate designs. J Hand Surg Glob Online. 2020;2:277-85. doi: 10.1016/j.jhsg.2020.07.003.\u003c/li\u003e\n\u003cli\u003eSoong M, Earp BE, Bishop G, Leung A, Blazar P. Volar locking plate implant prominence and flexor tendon rupture. J Bone Joint Surg Am. 2011;93:328-35. doi: 10.2106/JBJS.J.00193.\u003c/li\u003e\n\u003cli\u003eTommasini SM, Nasser P, Jepsen KJ. Sexual dimorphism affects tibia size and shape but not tissue-level mechanical properties. Bone. 2007;40:498-505. doi: 10.1016/j.bone.2006.08.012.\u003c/li\u003e\n\u003cli\u003eTommasini SM, Nasser P, Schaffler MB, Jepsen KJ. Relationship between bone morphology and bone quality in male tibias: implications for stress fracture risk. J Bone Miner Res. 2005;20:1372-80. doi: 10.1359/JBMR.050326.\u003c/li\u003e\n\u003cli\u003eYoneda H, Iwatsuki K, Hara T, Kurimoto S, Yamamoto M, Hirata H. Interindividual anatomical variations affect the plate-to-bone fit during osteosynthesis of distal radius fractures. J Orthop Res. 2016;34:953-60. doi: 10.1002/jor.23125.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables are available in the Supplementary Files section.\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":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"anatomy, cadaver, radius, tomography, computers","lastPublishedDoi":"10.21203/rs.3.rs-4481905/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4481905/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThe volar locking plate system is the standard surgical treatment for patients with unstable distal radius fractures. Volar locking plates are currently available in different shapes and 2\u0026ndash;3 size options. In this study, we investigated whether the anatomical fit and plate size of volar locking plates affect their proper placement.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTwo sizes of Acu-Loc2 Proximal Plates (AcuLoc), three sizes of Variable Angle LCP Two-Column Volar Distal Radius Plate 2.4 (VALCP), and 16 formalin-fixed cadaver specimens were studied. The plates and forearms were scanned using computed tomography. The plate was fixed to a radius within the watershed line, and radiographs were obtained using fluoroscopy. X-rays were superimposed, and a three-dimensional image of the plate and bone was created. The distance from the plate to the volar surface of each distal locking hole (PBD) was measured. To investigate the anatomical fitting of the plate, the contact area between the bone and plate was analyzed on three-dimensional images. We measured the distance between the distal end of the plate and the watershed line in three-dimensional images, defining it as watershed overlap.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe PBD in the radial column was significantly smaller than that in the ulnar column in the narrow and standard VALCP and narrow in the AcuLoc. For the other plates, the PBD in the radial column tended to be smaller than that in the ulnar column. The contact area was 6.6\u0026ndash;20.0% of the plate. The average value of the watershed overlap was negative for both plates. However, no significant differences were observed in PBD, contact area, or watershed overlap among the plate sizes for either plate.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAlthough the small plate size affected the fitting to the distal radius, the variance was small; therefore, each plate size may be selected depending on the circumstances of the fracture.\u003c/p\u003e","manuscriptTitle":"Anatomical fit of volar locking plates for the distal radius and the influence of plate size","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-13 18:45:18","doi":"10.21203/rs.3.rs-4481905/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorAssigned","content":"","date":"2024-05-30T15:52:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-30T08:38:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2024-05-27T02:53:04+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d93f3947-10c5-4f60-9117-56bce575b00e","owner":[],"postedDate":"June 13th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-06-13T18:45:18+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-13 18:45:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4481905","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4481905","identity":"rs-4481905","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}