Investigation of the Biomechanical Properties of Circular Frames for the Foot

Investigation of the Biomechanical Properties of Circular Frames for the Foot | 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 Investigation of the Biomechanical Properties of Circular Frames for the Foot Sarah Johnson-Lynn, Tom Irish, Peter Watson, Paul Harwood, Todd Stewart This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8532775/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Circular frames are used for the treatment of complex foot injuries, including those with bone and soft tissue loss and deformities requiring gradual correction. The most frequently used foot frame constructs are a Charcot frame, a Butt frame and a Mitre frame. The aim of this study was to provide data on the biomechanical properties of the most common configurations of foot frames in axial loading, to simulate the mechanism of loading when in use in the patient. This will provide surgeons with the necessary information to assist in selecting the most appropriate frame for a given circumstance and will facilitate further biomechanics research in this developing area. Three frame fixation model geometries were constructed using Orthofix TL-HEX components and analysed with 3 frames of each geometry constructed for a total of 9 frames. 3D foot models for use in the study were manufactured using 3D printing. The Charcot frame showed the least frame construct stiffness throughout the range of load applied with a stiffness increasing from 31 N/mm at 50N load to 93N/mm at a load of 700N, whereas the Butt frame generally produced the greatest construct stiffness increasing from 47 N/mm at 50N load to 122 N/mm at a load of 700N. The Mitre frame had the greatest initial stiffness of 53N/mm at 50N but it only increased to 105 N/mm at 700N. The Charcot frame construct presents the lowest resistance to axial loading of all the common constructs, which has implications for it’s use in patients with higher body mass index and peripheral neuropathy. The results of this study have important clinical implications, specifically with regards weightbearing instructions given to patients living with a frame. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Circular frames are used for the treatment of complex foot injuries, including those with bone and soft tissue loss and deformities requiring gradual correction. As they are highly customisable, they allow precise manipulation of bone segments and the surrounding mechanical environment. The most frequently used foot frame constructs are a Charcot frame, a Butt frame and a Mitre frame (Cherkashin, 2018). These can be employed to treat ankle, hindfoot and midfoot injuries, congenital and acquired deformities and be employed to stabilise osteotomies and fusion sites. The Charcot frame is frequently employed to provide stability following correction of a rocker-bottom foot in the context of Charcot arthropathy, sometimes employed alongside internal fixation as a hybrid construct and can also be used for gradual correction of an equinous deformity (Martin, 2021 ). The butt frame is used primarily for the correction of midfoot deformities, with the hindfoot stabilised, and may be combined with additional elements to provide correction at the supramalleolar level. The mitre frame is most frequently employed for the simultaneous correction of hindfoot and midfoot deformities. Some of these uses require soft tissue correction only but others rely on healing of osteotomy or arthrodesis sites for their success (Eidelman, 2011 ). The strain environment is considered to be the primary determinant of union at fracture, osteotomy and arthrodesis sites (Elliott, 2016), with axial micromotion broadly having a positive effect on bone healing and shear forces inhibiting bone healing (Mavcic, 2012 ). It is therefore important that we understand the strain environment created by the different foot frame constructs. Previous studies have shown that stiffness of constructs to axial loading, bending and torsion is dependent on the interaction between multiple elements of the frame (Bronson, 1998). It is also dependent on whether an Ilizarov or hexapod construct is used (Fenton, 2021) and on whether fine wires or half pins are used as fixation elements (Henderson, 2016). There is no currently available literature on the biomechanical properties of foot frame constructs but extensive previous work on the biomechanics of tibial frames (Mao, 2023), has established much of the necessary testing protocols (Henderson 2016, Henderson 2017). Testing of the frame in isolation has been superseded by the use of mechanically consistent synthetic bone substitute to allow a more accurate representation of the behaviour of the frame when affixed to the bone segments in vivo (Lenarz, 2008). The aim of this study was to provide data on the biomechanical properties of the most common configurations of foot frames in axial loading, to simulate the mechanism of loading when in use in the patient. This will provide surgeons with the necessary information to assist in selecting the most appropriate frame for a given circumstance and will facilitate further biomechanics research in this developing area. Methods 3D foot models for use in the study were manufactured using 3D printing as no structural foot models could be sourced commercially. The suitability of 3D printing as a surrogate for bone modelling was validated by constructing comparable symmetrically tensioned Illizarov style two-layer frames from commercial polycarbonate tubing and from 3D printed tubing of the same diameter and section thickness. 3D Printed bone models were manufactured from Polylactic Acid (PLA) filament using a Bambu Labs H2D AMS 2 PRO 3D Printer (Bambu Labs, USA). Three 180mm diameter frame models were manufactured with each material type surrogate bone. Wires were tensioned at 130 kg and loaded to 500N axially with the maximum deformation reported in Fig. 1 . The difference in the construct deformation in frames manufactured with 3D printed tubing compared to the commercially available polycarbonate tubing was not statistically significant. Three frame fixation model geometries (Fig. 2 ) were analysed with 3 frames of each geometry constructed for a total of 9 frames. Frames were constructed using Orthofix TL-HEX components (Orthofix Medical inc., Lewisville, Texas, USA). All frames consisted of a standardised two-layer 4 K-wire 4 vertical rod tibial fixation incorporating a variation in hexapod foot fixation. The tibia/foot bone model geometry was downloaded from Grabcad (Tibia bone by Claudio Soria). A superior plate was added to the proximal surfaces of the tibia/fibula to provide support for load application and additional fusing of the individual foot metacarpal joints was completed within the print model to improve the structural integrity. All models were made from Polylactic Acid (PLA) filament. To facilitate testing the frames were constructed to incorporate an 8mm gap between the distal tibia and the proximal talus with the tibia mounted centrally and vertically and recreating a standing posture. All frames had a two-ring proximal block using 160mm rings with 100mm between the rings, and four threaded rods between the rings. The rings were attached to the tibias of the models using two plain 1.8mm Ilizarov wires, tensioned to 130kg. The Charcot frame was constructed with a flat foot plate attached to the tibial rings with six hexapod struts. The Butt frame was constructed with the tibial ring block attached directly to a foot plate at 90 degrees to the rings. This was then attached to the calcaneum of the model with two 1.8mm Ilizarov wires using wire corridors mimicking safe corridors used in vivo and standardised between models. Six hexapod struts then attached a full, 130mm ring at the forefoot, again attached using two 1.8mm wires using clinically relevant wire corridors. The Mitre frame was constructed by attaching the standard tibial block to a further 160mm ring at 45 degrees with six hexapod struts. There was then a further 130mm ring positioned at the forefoot attached using a set of six hexapod struts. Wire attachments to the calcaneum and forefoot were as for Butt frame. The Mitre frame was additionally used with the bony anatomy cut to mimic a midfoot osteotomy through the cuneiforms, as it would be performed in vivo . Vertical axial loading was applied to simulate standing using an Instron E10000 Universal Testing machine (Instron, High Wycombe UK) (Fig. 3 ). A base platform was constructed such that the 1st and 5th metatarsals and calcaneus contacted at the base forming three points of inferior support. The tibia and fibula protruded from the proximal end of the frames and were loaded together in compression via the Instron actuator through the load steps of 50, 100, 200, 300, 400, 500, 600 and 700N for 3 cycles. Each load was held for 5 seconds whilst data was collected at a frequency of 100Hz. Data collection resulted in axial load and position data with a measure of variability at each load step for each frame. Finally, to understand the variation across the three frames, the data points across each load step and for each frame were pooled together and the average value with standard deviation calculated. To obtain a value of stiffness, a line of best fit was applied to the load-position graphs for each frame as well as the combined frames curve. In the Mitre frame the forefoot foot was additionally sectioned to investigate internal frame stability (Fig. 3 – right). Results 3D printed models performed well with no permanent deformation or wear observed at pin contact points following testing. Frames showed a typical variation of +/- 1 mm at each loading step despite being re-tested 3 times. This suggests that the frames kept their wire stiffness throughout testing and that the bone models represented the true frame stiffness. Frame average axial deformation is shown in Fig. 4 for the four frame geometries at each loading step. The deformation measured in all of the frames increased with applied load. At very low loads the deformation was highly variable in all of the frames. Determination of a reliable zero load involved the inherent frame laxity to be supported. Therefore, the displacement magnitudes were normalised at 50N to allow a comparable determination of mechanical properties. The greatest initial laxity (average of ~ 4mm) was observed in the Mitre frame where the foot was sectioned. This frame additionally had the greatest variability in results of deformation and stiffness. The remaining frames showed reduced initial laxity and generally reduced variability (+/- 1mm) that was consistent throughout the range of load applied. The greatest deformation was observed in the Charcot frame with the least in the Butt frame, this trend was consistent throughout the testing. The variability in initial load support was also evident in the frame stiffness, as shown in Fig. 5 , where all frames were observed to increase in stiffness as the applied load increased. The Charcot frame showed the least frame construct stiffness throughout the range of load applied with a stiffness increasing from 31 N/mm at 50N load to 93N/mm at a load of 700N, whereas the Butt frame generally produced the greatest construct stiffness increasing from 47 N/mm at 50N load to 122 N/mm at a load of 700N. The Mitre frame had the greatest initial stiffness of 53N/mm at 50N but it only increased to 105 N/mm at 700N. The Mitre frame with the sectioned foot had a reduced stiffness under the lower loads (32 N/mm), but despite having a sectioned foot, the stiffness was comparable to the standard Mitre frame at the greater 700N (104 N/mm). Discussion 3D printed manufacture of materials was validated prior to use by comparing them to traditional polycarbonate tubing in a simple frame geometry; no adverse effects were observed in their ability to support forces exhibited in trauma frames in-vitro. 3D printed foot geometries are not commercially available with structural properties that allow clinical magnitudes of loading. However, improvements in 3D printing have made it feasible to manufacture cost effective custom anatomical models that in the testing completed in this study showed excellent suitability. Error bars in deformation from model to model in each frame geometry type showed a variation in the region of +/- 1mm in an overall frame deformation of 10mm suggesting that the variability within a specific model was far less than between the different model types thus validating the test and supporting the usage of 3d Printing. With regards to fixation type, the three frames appeared to have similar levels of deformation under the loads applied. At 700N the greatest difference in deformation between the frames was only ~ 0.8mm. The 8mm gap in the ankle was observed to close between 500-600N during the experiments. This specific gap would likely not occur clinically; however, it is likely that other variations may be present, hence, it is a useful repeatable feature of the testing. It is understood that as these types of tripod frames experience greater load, they become stiffer with tightening of the component parts under deformation leading to reduced variation; this pattern was observed in the results (Fenton, 2021). Interestingly in the past, traditional frames with vertical rods only have shown more consistent stiffness under lower loads with reduced deformation (Henderson, 2016). The results of this study have important clinical implications, specifically with regards weightbearing instructions given to patients living with a frame. It is interesting to note that the Charcot frame had the lowest stiffness, as this frame is the construct most frequently employed for patients with diabetic foot problems to correct Charcot deformities and offload ulcers. This is key information as these patients frequently have peripheral neuropathy meaning that they will load their frames without being limited by pain inhibition and the patients are frequently of high body mass index. These frames frequently fail early as they experience greater loading earlier in their use. This study, therefore, adds supporting biomechanical data to the emerging clinical picture of issues with frame use in this population and emphasises the importance of adding additional reinforcing frame elements or changing the frame construct. The Butt frame had the greatest stiffness under load, which would be expected as the resistance to axial loading is not dependent on the hexapod struts. However, clinically this is a difficult frame for patients to weightbear on as the 90-degree foot plate extends the length of the limb by several centimetres. If the patient is able to weightbear, the forefoot ring should be clear of the floor and force should only be applied through end loading the foot plate, making this a very strong construct. It is also usual for patients to be kept non-weightbearing with a Mitre frame applied as balance is very difficult with edge loading on the 45 degree tilted heel ring, therefore resistance to applied axial load is often less important than for the other frame constructs, although the frame will frequently be rested on the floor with the patient in standing. Whilst the sectioned Mitre frame foot model showed comparable stiffness at higher loads to the un-sectioned counterpart there were some noted differences. At lower loads the sectioned foot had greater instability. Specifically with the foot cut, the forefoot and hindfoot were each only supported by a single set of wires resulting in greater plantarflexion of the hindfoot under heel contact and greater dorsiflexion of the forefoot under toe contact. This would behave differently in a clinical scenario, as the soft tissues surrounding the osteotomy would add significant stiffness to the construct overall, particularly the plantar fascia behaving as a tension band, resisting forefoot dorsiflexion. As gradual corrections proceed during treatment, bone contact is restored in the modified position, also adding intrinsic stability. Conclusion Hexapod circular frame constructs can be an effective method of treating complex foot deformities, trauma and infection. The Charcot frame construct presents the lowest resistance to axial loading of all the common constructs, which has implications for it’s use in patients with higher body mass index and peripheral neuropathy. Declarations Ethics approval and consent to participate This study does not involve human subjects, information or tissue and therefore does not require Local Ethics Committee approval or participant consent. Consent for publication Not applicable Author contribution statement The investigation was planned by SJL, PH and TS. Frames were assembled by SJL and PH. Experiments were conducted by TS, TI and PW. TS and SJL wrote the initial draft. All authors reviewed and contributed to the editing of the paper. Funding statement This work was supported by the British Orthopaedic Foot and Ankle Society and frame materials for testing were supplied by Orthofix. Author Contribution The investigation was planned by SJL, PH and TS. Frames were assembled by SJL and PH. Experiments were conducted by TS, TI and PW. TS and SJL wrote the initial draft. All authors reviewed and contributed to the editing of the paper. Data Availability The authors declare that the data supporting the findings of this study are available within the paper and its supplementary information files. References Bronson DG, Samchukov ML, Birch JG, Browne RH, Ashman RB. Stability of circular external fixation: a multi-variable biomechanical analysis. Clin Biomech Elsevier Ltd. 1998;13:441–8. Cherkashin AM, Samchukov ML, Birkholts F. Treatment Strategies and Frame Configurations in the Management of Foot and Ankle Deformities. Clin Podiatr Med Surg. 2018;35(4):423–42. Eidelman M, Katzman A. Treatment of Arthrogrypotic Foot Deformities With the Taylor Spatial Frame. J Pediatr Orthop. 2011;31(4):429–34. 10.1097/BPO.0b013e3182172392 . Elliott DS, Newman KJH, Forward DP, Hahn DM, Ollivere B, Kojima K, Handley R, Rossiter ND, Wixted JJ, Smith RM, Moran CG. (2016) A unified theory of bone healing and nonunion: BHN theory. Bone and Joint Journal; 98-B (7): 884–91. Fenton C, Henderson D, Samchukov M, Cherkashin A, Sharma H. Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs. Strategies Trauma Limb Reconstruction. 2021;16(3):138–43. Henderson DJ, Rushbrook JL, Stewart TD, Harwood PJ. (2016) What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames? Clinical Orthopaedics and Related Research; 474: 1041–9. Henderson DJ, Rushbrook JL, Harwood PJ, Stewart TD. (2017) What Are the Biomechanical Properties of the Taylor Spatial Frame™? Clinical Orthopaedics and Related Research; 475: 1472–82. Lenarz C, Bledsoe G, Watson JT. Circular External Fixation Frames with Divergent Half Pins A Pilot Biomechanical Study. Clin Orthop Relat Res. 2008;466:2933–9. Mao Y, Lin Q, Yang Q. The Relation between the Dynamization of Hexapod Circular External Fixator and Tibial Mechanical Properties. Orthop Surg. 2023;15:1677–84. Martin B, Chow J. The use of circular frame external fixation in the treatment of ankle/hindfoot Charcot Neuroarthropathy. J Clin Orthop Trauma. 2021;16:269–76. 10.1016/j.jcot.2021.02.016 . Mavcic B, Antolic V. Optimal mechanical environment of the healing bone fracture / osteotomy. Int Orthop. 2012;36:689–95. Sarpel Y, Gulsen M, Togrul E, Capa M, Herdem M. Comparison of mechanical performance among different frame configurations of the Ilizarov external fixator: experimental study. J Trauma. 2005;58:546–52. Additional Declarations No competing interests reported. Supplementary Files Originaldatafootframes.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 15 Feb, 2026 Reviewers invited by journal 11 Feb, 2026 Editor assigned by journal 21 Jan, 2026 Submission checks completed at journal 20 Jan, 2026 First submitted to journal 13 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8532775","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":591636481,"identity":"f5fb2312-ecf1-4426-a9d9-6d126bbcbcbc","order_by":0,"name":"Sarah Johnson-Lynn","email":"data:image/png;base64,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","orcid":"","institution":"University of York","correspondingAuthor":true,"prefix":"","firstName":"Sarah","middleName":"","lastName":"Johnson-Lynn","suffix":""},{"id":591636482,"identity":"7e09beb3-f4f3-4fcf-aee2-0a53eb7cbf38","order_by":1,"name":"Tom Irish","email":"","orcid":"","institution":"University of Leeds","correspondingAuthor":false,"prefix":"","firstName":"Tom","middleName":"","lastName":"Irish","suffix":""},{"id":591636483,"identity":"a096cbda-2d42-4f89-8d07-bf6160c51add","order_by":2,"name":"Peter Watson","email":"","orcid":"","institution":"University of Leeds","correspondingAuthor":false,"prefix":"","firstName":"Peter","middleName":"","lastName":"Watson","suffix":""},{"id":591636484,"identity":"188b0cd8-9557-4d1b-8d87-142c4da0c5bf","order_by":3,"name":"Paul Harwood","email":"","orcid":"","institution":"University of Leeds","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Harwood","suffix":""},{"id":591636485,"identity":"bbd6633d-7df0-418b-936b-c37ae119bb56","order_by":4,"name":"Todd Stewart","email":"","orcid":"","institution":"University of Leeds","correspondingAuthor":false,"prefix":"","firstName":"Todd","middleName":"","lastName":"Stewart","suffix":""}],"badges":[],"createdAt":"2026-01-06 15:08:58","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8532775/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8532775/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102853992,"identity":"2009aa26-2c57-479c-842e-49da93bef36c","added_by":"auto","created_at":"2026-02-17 14:46:45","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":68982,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eMaximum wire deformation in models with 3D printed tubing vs commercial polycarbonate tubing bone models of the same geometry showing comparable performance. Mean values of three tests are shown with error bars representing standard deviation.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/e21ac786bcb4bf1b597b159c.jpg"},{"id":102853993,"identity":"59a892e7-497c-4b97-a282-e9a9bf48c89a","added_by":"auto","created_at":"2026-02-17 14:46:45","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":125210,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eFoot frame geometries for analysis. Charcot frame (left) , Butt frame (Centre), Mitre frame (Right)\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/271e38d264d4b6cdf42e854f.jpg"},{"id":102853997,"identity":"ebe18d9b-c142-4ad9-bd87-a01274a8b8c2","added_by":"auto","created_at":"2026-02-17 14:46:45","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":182156,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eCharcot frame mounted in the Instron showing proximal loading of the Tibia/Fibula and inferior three-point contact with the calcaneus and the 1\u003c/em\u003e\u003csup\u003e\u003cem\u003est\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e and 5\u003c/em\u003e\u003csup\u003e\u003cem\u003eth\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e metatarsals to simulate standing ( Left).\u0026nbsp; Mitre frame with sectioned forefoot (right).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/1c12c7b58b4fc96918487d0a.jpg"},{"id":102853995,"identity":"c364b9de-753c-4f81-a386-71a3fb3a807a","added_by":"auto","created_at":"2026-02-17 14:46:45","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":243980,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eAverage displacement recorded at each of the 7 loading steps. Displacement was zeroed at a 50N load to normalise the results. Error bars represent standard deviations of the three frames of each geometry tested.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/615c0931816721b5cf44224a.jpg"},{"id":102853996,"identity":"597285ca-7300-46e3-8848-81cac69e0746","added_by":"auto","created_at":"2026-02-17 14:46:45","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":275176,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eAverage frame stiffness recorded at each of the 7 loading steps. Error bars represent standard deviations of the three frames of each geometry tested.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/6c9303cbc85c942021aa6cdb.jpg"},{"id":103049615,"identity":"60b6bd99-b993-4e60-89fa-18b56875fa82","added_by":"auto","created_at":"2026-02-20 07:43:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1244191,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/4b1907fd-a1e6-4f0f-b062-479afe98e5ce.pdf"},{"id":102963407,"identity":"df1b8bf6-1f84-43d0-98d0-7c371f39d9bc","added_by":"auto","created_at":"2026-02-19 04:17:42","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":165964,"visible":true,"origin":"","legend":"","description":"","filename":"Originaldatafootframes.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-8532775/v1/b0c2e09e8ad93a389d1d8727.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigation of the Biomechanical Properties of Circular Frames for the Foot","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCircular frames are used for the treatment of complex foot injuries, including those with bone and soft tissue loss and deformities requiring gradual correction. As they are highly customisable, they allow precise manipulation of bone segments and the surrounding mechanical environment. The most frequently used foot frame constructs are a Charcot frame, a Butt frame and a Mitre frame (Cherkashin, 2018). These can be employed to treat ankle, hindfoot and midfoot injuries, congenital and acquired deformities and be employed to stabilise osteotomies and fusion sites. The Charcot frame is frequently employed to provide stability following correction of a rocker-bottom foot in the context of Charcot arthropathy, sometimes employed alongside internal fixation as a hybrid construct and can also be used for gradual correction of an equinous deformity (Martin, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The butt frame is used primarily for the correction of midfoot deformities, with the hindfoot stabilised, and may be combined with additional elements to provide correction at the supramalleolar level. The mitre frame is most frequently employed for the simultaneous correction of hindfoot and midfoot deformities. Some of these uses require soft tissue correction only but others rely on healing of osteotomy or arthrodesis sites for their success (Eidelman, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe strain environment is considered to be the primary determinant of union at fracture, osteotomy and arthrodesis sites (Elliott, 2016), with axial micromotion broadly having a positive effect on bone healing and shear forces inhibiting bone healing (Mavcic, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). It is therefore important that we understand the strain environment created by the different foot frame constructs.\u003c/p\u003e \u003cp\u003ePrevious studies have shown that stiffness of constructs to axial loading, bending and torsion is dependent on the interaction between multiple elements of the frame (Bronson, 1998). It is also dependent on whether an Ilizarov or hexapod construct is used (Fenton, 2021) and on whether fine wires or half pins are used as fixation elements (Henderson, 2016).\u003c/p\u003e \u003cp\u003eThere is no currently available literature on the biomechanical properties of foot frame constructs but extensive previous work on the biomechanics of tibial frames (Mao, 2023), has established much of the necessary testing protocols (Henderson 2016, Henderson 2017). Testing of the frame in isolation has been superseded by the use of mechanically consistent synthetic bone substitute to allow a more accurate representation of the behaviour of the frame when affixed to the bone segments in vivo (Lenarz, 2008).\u003c/p\u003e \u003cp\u003eThe aim of this study was to provide data on the biomechanical properties of the most common configurations of foot frames in axial loading, to simulate the mechanism of loading when in use in the patient. This will provide surgeons with the necessary information to assist in selecting the most appropriate frame for a given circumstance and will facilitate further biomechanics research in this developing area.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e3D foot models for use in the study were manufactured using 3D printing as no structural foot models could be sourced commercially. The suitability of 3D printing as a surrogate for bone modelling was validated by constructing comparable symmetrically tensioned Illizarov style two-layer frames from commercial polycarbonate tubing and from 3D printed tubing of the same diameter and section thickness. 3D Printed bone models were manufactured from Polylactic Acid (PLA) filament using a Bambu Labs H2D AMS 2 PRO 3D Printer (Bambu Labs, USA). Three 180mm diameter frame models were manufactured with each material type surrogate bone. Wires were tensioned at 130 kg and loaded to 500N axially with the maximum deformation reported in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The difference in the construct deformation in frames manufactured with 3D printed tubing compared to the commercially available polycarbonate tubing was not statistically significant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThree frame fixation model geometries (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) were analysed with 3 frames of each geometry constructed for a total of 9 frames. Frames were constructed using Orthofix TL-HEX components (Orthofix Medical inc., Lewisville, Texas, USA). All frames consisted of a standardised two-layer 4 K-wire 4 vertical rod tibial fixation incorporating a variation in hexapod foot fixation. The tibia/foot bone model geometry was downloaded from Grabcad (Tibia bone by Claudio Soria). A superior plate was added to the proximal surfaces of the tibia/fibula to provide support for load application and additional fusing of the individual foot metacarpal joints was completed within the print model to improve the structural integrity. All models were made from Polylactic Acid (PLA) filament. To facilitate testing the frames were constructed to incorporate an 8mm gap between the distal tibia and the proximal talus with the tibia mounted centrally and vertically and recreating a standing posture.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAll frames had a two-ring proximal block using 160mm rings with 100mm between the rings, and four threaded rods between the rings. The rings were attached to the tibias of the models using two plain 1.8mm Ilizarov wires, tensioned to 130kg. The Charcot frame was constructed with a flat foot plate attached to the tibial rings with six hexapod struts. The Butt frame was constructed with the tibial ring block attached directly to a foot plate at 90 degrees to the rings. This was then attached to the calcaneum of the model with two 1.8mm Ilizarov wires using wire corridors mimicking safe corridors used \u003cem\u003ein vivo\u003c/em\u003e and standardised between models. Six hexapod struts then attached a full, 130mm ring at the forefoot, again attached using two 1.8mm wires using clinically relevant wire corridors. The Mitre frame was constructed by attaching the standard tibial block to a further 160mm ring at 45 degrees with six hexapod struts. There was then a further 130mm ring positioned at the forefoot attached using a set of six hexapod struts. Wire attachments to the calcaneum and forefoot were as for Butt frame. The Mitre frame was additionally used with the bony anatomy cut to mimic a midfoot osteotomy through the cuneiforms, as it would be performed \u003cem\u003ein vivo\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eVertical axial loading was applied to simulate standing using an Instron E10000 Universal Testing machine (Instron, High Wycombe UK) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). A base platform was constructed such that the 1st and 5th metatarsals and calcaneus contacted at the base forming three points of inferior support. The tibia and fibula protruded from the proximal end of the frames and were loaded together in compression via the Instron actuator through the load steps of 50, 100, 200, 300, 400, 500, 600 and 700N for 3 cycles. Each load was held for 5 seconds whilst data was collected at a frequency of 100Hz.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eData collection resulted in axial load and position data with a measure of variability at each load step for each frame. Finally, to understand the variation across the three frames, the data points across each load step and for each frame were pooled together and the average value with standard deviation calculated. To obtain a value of stiffness, a line of best fit was applied to the load-position graphs for each frame as well as the combined frames curve. In the Mitre frame the forefoot foot was additionally sectioned to investigate internal frame stability (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u0026ndash; right).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e3D printed models performed well with no permanent deformation or wear observed at pin contact points following testing. Frames showed a typical variation of +/- 1 mm at each loading step despite being re-tested 3 times. This suggests that the frames kept their wire stiffness throughout testing and that the bone models represented the true frame stiffness.\u003c/p\u003e \u003cp\u003eFrame average axial deformation is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e for the four frame geometries at each loading step. The deformation measured in all of the frames increased with applied load. At very low loads the deformation was highly variable in all of the frames. Determination of a reliable zero load involved the inherent frame laxity to be supported. Therefore, the displacement magnitudes were normalised at 50N to allow a comparable determination of mechanical properties. The greatest initial laxity (average of ~\u0026thinsp;4mm) was observed in the Mitre frame where the foot was sectioned. This frame additionally had the greatest variability in results of deformation and stiffness. The remaining frames showed reduced initial laxity and generally reduced variability (+/- 1mm) that was consistent throughout the range of load applied. The greatest deformation was observed in the Charcot frame with the least in the Butt frame, this trend was consistent throughout the testing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe variability in initial load support was also evident in the frame stiffness, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, where all frames were observed to increase in stiffness as the applied load increased. The Charcot frame showed the least frame construct stiffness throughout the range of load applied with a stiffness increasing from 31 N/mm at 50N load to 93N/mm at a load of 700N, whereas the Butt frame generally produced the greatest construct stiffness increasing from 47 N/mm at 50N load to 122 N/mm at a load of 700N. The Mitre frame had the greatest initial stiffness of 53N/mm at 50N but it only increased to 105 N/mm at 700N. The Mitre frame with the sectioned foot had a reduced stiffness under the lower loads (32 N/mm), but despite having a sectioned foot, the stiffness was comparable to the standard Mitre frame at the greater 700N (104 N/mm).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e3D printed manufacture of materials was validated prior to use by comparing them to traditional polycarbonate tubing in a simple frame geometry; no adverse effects were observed in their ability to support forces exhibited in trauma frames in-vitro. 3D printed foot geometries are not commercially available with structural properties that allow clinical magnitudes of loading. However, improvements in 3D printing have made it feasible to manufacture cost effective custom anatomical models that in the testing completed in this study showed excellent suitability. Error bars in deformation from model to model in each frame geometry type showed a variation in the region of +/- 1mm in an overall frame deformation of 10mm suggesting that the variability within a specific model was far less than between the different model types thus validating the test and supporting the usage of 3d Printing.\u003c/p\u003e \u003cp\u003eWith regards to fixation type, the three frames appeared to have similar levels of deformation under the loads applied. At 700N the greatest difference in deformation between the frames was only\u0026thinsp;~\u0026thinsp;0.8mm. The 8mm gap in the ankle was observed to close between 500-600N during the experiments. This specific gap would likely not occur clinically; however, it is likely that other variations may be present, hence, it is a useful repeatable feature of the testing. It is understood that as these types of tripod frames experience greater load, they become stiffer with tightening of the component parts under deformation leading to reduced variation; this pattern was observed in the results (Fenton, 2021). Interestingly in the past, traditional frames with vertical rods only have shown more consistent stiffness under lower loads with reduced deformation (Henderson, 2016).\u003c/p\u003e \u003cp\u003eThe results of this study have important clinical implications, specifically with regards weightbearing instructions given to patients living with a frame. It is interesting to note that the Charcot frame had the lowest stiffness, as this frame is the construct most frequently employed for patients with diabetic foot problems to correct Charcot deformities and offload ulcers. This is key information as these patients frequently have peripheral neuropathy meaning that they will load their frames without being limited by pain inhibition and the patients are frequently of high body mass index. These frames frequently fail early as they experience greater loading earlier in their use. This study, therefore, adds supporting biomechanical data to the emerging clinical picture of issues with frame use in this population and emphasises the importance of adding additional reinforcing frame elements or changing the frame construct.\u003c/p\u003e \u003cp\u003eThe Butt frame had the greatest stiffness under load, which would be expected as the resistance to axial loading is not dependent on the hexapod struts. However, clinically this is a difficult frame for patients to weightbear on as the 90-degree foot plate extends the length of the limb by several centimetres. If the patient is able to weightbear, the forefoot ring should be clear of the floor and force should only be applied through end loading the foot plate, making this a very strong construct.\u003c/p\u003e \u003cp\u003eIt is also usual for patients to be kept non-weightbearing with a Mitre frame applied as balance is very difficult with edge loading on the 45 degree tilted heel ring, therefore resistance to applied axial load is often less important than for the other frame constructs, although the frame will frequently be rested on the floor with the patient in standing.\u003c/p\u003e \u003cp\u003eWhilst the sectioned Mitre frame foot model showed comparable stiffness at higher loads to the un-sectioned counterpart there were some noted differences. At lower loads the sectioned foot had greater instability. Specifically with the foot cut, the forefoot and hindfoot were each only supported by a single set of wires resulting in greater plantarflexion of the hindfoot under heel contact and greater dorsiflexion of the forefoot under toe contact. This would behave differently in a clinical scenario, as the soft tissues surrounding the osteotomy would add significant stiffness to the construct overall, particularly the plantar fascia behaving as a tension band, resisting forefoot dorsiflexion. As gradual corrections proceed during treatment, bone contact is restored in the modified position, also adding intrinsic stability.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eHexapod circular frame constructs can be an effective method of treating complex foot deformities, trauma and infection. The Charcot frame construct presents the lowest resistance to axial loading of all the common constructs, which has implications for it\u0026rsquo;s use in patients with higher body mass index and peripheral neuropathy.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eThis study does not involve human subjects, information or tissue and therefore does not require Local Ethics Committee approval or participant consent.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eAuthor contribution statement\u003c/h2\u003e \u003cp\u003eThe investigation was planned by SJL, PH and TS. Frames were assembled by SJL and PH. Experiments were conducted by TS, TI and PW. TS and SJL wrote the initial draft. All authors reviewed and contributed to the editing of the paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding statement\u003c/h2\u003e \u003cp\u003eThis work was supported by the British Orthopaedic Foot and Ankle Society and frame materials for testing were supplied by Orthofix.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eThe investigation was planned by SJL, PH and TS. Frames were assembled by SJL and PH. Experiments were conducted by TS, TI and PW. TS and SJL wrote the initial draft. All authors reviewed and contributed to the editing of the paper.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe authors declare that the data supporting the findings of this study are available within the paper and its supplementary information files.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBronson DG, Samchukov ML, Birch JG, Browne RH, Ashman RB. Stability of circular external fixation: a multi-variable biomechanical analysis. Clin Biomech Elsevier Ltd. 1998;13:441\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCherkashin AM, Samchukov ML, Birkholts F. Treatment Strategies and Frame Configurations in the Management of Foot and Ankle Deformities. Clin Podiatr Med Surg. 2018;35(4):423\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEidelman M, Katzman A. Treatment of Arthrogrypotic Foot Deformities With the Taylor Spatial Frame. J Pediatr Orthop. 2011;31(4):429\u0026ndash;34. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/BPO.0b013e3182172392\u003c/span\u003e\u003cspan address=\"10.1097/BPO.0b013e3182172392\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElliott DS, Newman KJH, Forward DP, Hahn DM, Ollivere B, Kojima K, Handley R, Rossiter ND, Wixted JJ, Smith RM, Moran CG. (2016) A unified theory of bone healing and nonunion: BHN theory. Bone and Joint Journal; 98-B (7): 884\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFenton C, Henderson D, Samchukov M, Cherkashin A, Sharma H. Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs. Strategies Trauma Limb Reconstruction. 2021;16(3):138\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHenderson DJ, Rushbrook JL, Stewart TD, Harwood PJ. (2016) What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames? Clinical Orthopaedics and Related Research; 474: 1041\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHenderson DJ, Rushbrook JL, Harwood PJ, Stewart TD. (2017) What Are the Biomechanical Properties of the Taylor Spatial Frame\u0026trade;? Clinical Orthopaedics and Related Research; 475: 1472\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLenarz C, Bledsoe G, Watson JT. Circular External Fixation Frames with Divergent Half Pins A Pilot Biomechanical Study. Clin Orthop Relat Res. 2008;466:2933\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMao Y, Lin Q, Yang Q. The Relation between the Dynamization of Hexapod Circular External Fixator and Tibial Mechanical Properties. Orthop Surg. 2023;15:1677\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMartin B, Chow J. The use of circular frame external fixation in the treatment of ankle/hindfoot Charcot Neuroarthropathy. J Clin Orthop Trauma. 2021;16:269\u0026ndash;76. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jcot.2021.02.016\u003c/span\u003e\u003cspan address=\"10.1016/j.jcot.2021.02.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMavcic B, Antolic V. Optimal mechanical environment of the healing bone fracture / osteotomy. Int Orthop. 2012;36:689\u0026ndash;95.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSarpel Y, Gulsen M, Togrul E, Capa M, Herdem M. Comparison of mechanical performance among different frame configurations of the Ilizarov external fixator: experimental study. J Trauma. 2005;58:546\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e\u003c/ol\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":"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":"","lastPublishedDoi":"10.21203/rs.3.rs-8532775/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8532775/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCircular frames are used for the treatment of complex foot injuries, including those with bone and soft tissue loss and deformities requiring gradual correction. The most frequently used foot frame constructs are a Charcot frame, a Butt frame and a Mitre frame. The aim of this study was to provide data on the biomechanical properties of the most common configurations of foot frames in axial loading, to simulate the mechanism of loading when in use in the patient. This will provide surgeons with the necessary information to assist in selecting the most appropriate frame for a given circumstance and will facilitate further biomechanics research in this developing area. Three frame fixation model geometries were constructed using Orthofix TL-HEX components and analysed with 3 frames of each geometry constructed for a total of 9 frames. 3D foot models for use in the study were manufactured using 3D printing. The Charcot frame showed the least frame construct stiffness throughout the range of load applied with a stiffness increasing from 31 N/mm at 50N load to 93N/mm at a load of 700N, whereas the Butt frame generally produced the greatest construct stiffness increasing from 47 N/mm at 50N load to 122 N/mm at a load of 700N. The Mitre frame had the greatest initial stiffness of 53N/mm at 50N but it only increased to 105 N/mm at 700N. The Charcot frame construct presents the lowest resistance to axial loading of all the common constructs, which has implications for it\u0026rsquo;s use in patients with higher body mass index and peripheral neuropathy. The results of this study have important clinical implications, specifically with regards weightbearing instructions given to patients living with a frame.\u003c/p\u003e","manuscriptTitle":"Investigation of the Biomechanical Properties of Circular Frames for the Foot","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-17 14:46:40","doi":"10.21203/rs.3.rs-8532775/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"134310153370203669726712489537644833245","date":"2026-02-15T13:22:03+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-11T16:34:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-21T10:41:50+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-20T22:55:36+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2026-01-13T13:28:46+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":"dfbed896-0e31-4005-9a1f-b9ecf6d39737","owner":[],"postedDate":"February 17th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-17T14:46:40+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-17 14:46:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8532775","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8532775","identity":"rs-8532775","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}