Preliminary Application of 3D-Printed Interbody Fusion Devices in the Treatment of Lumbar Degenerative Diseases

Preliminary Application of 3D-Printed Interbody Fusion Devices in the Treatment of Lumbar Degenerative Diseases | 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 Preliminary Application of 3D-Printed Interbody Fusion Devices in the Treatment of Lumbar Degenerative Diseases Jingtao Ji, Guangdong Chen, Jun Miao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4593148/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objectives : To investigate the effectiveness, safety, and usability of 3D-printed interbody fusion cages in posterior lumbar fusion surgery. Methods : This randomized controlled trial included 36 patients with single-stage lumbar degenerative disease undergoing PLIF surgery. The patients were divided into two groups: the control group (17 patients) used PEEK (polyetheretherketone) cages for interbody fusion, while the experimental group (19 patients) used 3D-printed cages. The study aimed to assess the postoperative effectiveness and safety of the surgeries using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores, and to evaluate the stability and fusion effect of the cages through postoperative imaging. Results : All patients were followed up for 3 to 26 months. There were statistically significant differences (P0.01) were found between the preoperative VAS and ODI scores of the two groups. However, there were statistically significant differences (P<0.01) in the postoperative VAS and ODI scores between the two groups. Postoperative X-rays and CT scans showed satisfactory placement of the anterior cages and pedicle screws in all patients. During the follow-up period, 3 out of 17 patients (17.6%) in the PEEK cage group experienced cage migration, and 1 patient (5.9%) showed signs of pedicle screw loosening, while the remaining pedicle screws were stable. In contrast, none of the 19 patients with 3D-printed cages experienced cage migration, and no signs of pedicle screw loosening were observed. 3D printing interbody fusion cage posterior lumbar fusion surgery bone fusion Figures Figure 1 Figure 2 Figure 3 Introduction Since its first reported by Cloward in 1981[ 1 ], Posterior Lumbar Interbody Fusion (PLIF) surgery has been widely used in the treatment of degenerative lumbar diseases due to its features of adequate decompression and reconstruction of spinal stability. Interbody fusion cages play a crucial role in PLIF surgery, as they can expand the intervertebral space, better restore the physiological curvature of the lumbar spine, and provide greater space for interbody bone grafting. For unstable vertebral bodies, interbody fusion cages can enhance the stability of the anterior and middle columns, reducing the occurrence of loosening and fracture of pedicle screw-rod systems[ 2 ]. In the 1950s, Cloward attempted to achieve intervertebral fusion by using vertebral body grafting, but it had a low fusion rate[ 3 ]. In response, Bagby designed a cage-like interbody fusion device made of stainless steel, which laid the groundwork for the modern cage[ 4 ]. With continuous advancements in materials and manufacturing techniques, cages made of various materials have emerged. Currently, polyetheretherketone (PEEK) interbody fusion devices are the most widely used due to their excellent elastic modulus and tissue compatibility, which help maintain intervertebral height and prevent cage subsidence caused by stress shielding[ 5 ]. However, PEEK materials have poor surface bone integration capability, resulting in a lower interbody fusion rate. Among metal fusion devices, titanium alloys exhibit corrosion resistance, good tissue compatibility, and strong bone integration capabilities. Cuzzocrea et al. found that titanium alloys have a better interbody fusion rate compared to PEEK materials. However, due to the significant difference in elastic modulus between titanium alloys and vertebral bodies, subsidence of the fusion device may occur due to stress shielding[ 6 ]. 3D printing, an important technology that emerged in the 1980s, has rapidly developed over the past 30 years. Unlike traditional subtractive manufacturing and casting techniques, 3D printing not only alters the physical structure of products but also allows for customization according to individual needs. This capability enables a complete match between materials and affected areas, making it particularly promising for medical applications. Customized implantable 3D-printed prosthetics can achieve both structural integrity and functional reconstruction for complex anatomical defects. They have been utilized in maxillofacial reconstruction, neurosurgical cranial reconstruction, vertebral body reconstruction following spinal tumor resection, and other procedures[ 7 – 9 ]. Currently, domestically certified 3D-printed titanium alloy cages, such as those produced by Aike Medical in China, have superior individualized designs compared to PEEK material cages. They offer a larger contact area, resulting in tighter adhesion to adjacent vertebrae and reducing the probability of settling due to cutting forces. With a porous design resembling trabecular bone structure, these cages have an elastic modulus similar to cancellous bone, facilitating bone ingrowth and promoting fusion. From November 2018 to April 2023, our hospital conducted a randomized controlled study comparing the use of 3D-printed titanium alloy cages for intervertebral fusion in posterior lumbar fusion surgery with the application of PEEK material cages. The study aimed to evaluate the effectiveness, safety, and usability of 3D-printed cages in posterior lumbar fusion surgery and assess their long-term fusion outcomes through radiographic evaluation. Materials and methods This study has been approved by the Ethics Committee of Tianjin Hospital, and all patients participating in the study have provided informed consent. All methods were conducted in accordance with relevant guidelines and regulations. Design and patients Selection This study included 36 patients with single-level degenerative diseases of the lumbar spine. Inclusion criteria were as follows: (1) Patients with lumbar disc herniation experiencing lumbago or sciatica with ineffective conservative treatment; patients with lumbar spinal stenosis experiencing intermittent claudication, with or without lumbago or sciatica, with ineffective conservative treatment. (2) Preoperative confirmation through lumbar spine anteroposterior, lateral, and dynamic X-rays, lumbar spine CT, and lumbar spine MRI. (3) All patients had single-level lesions. (4) No history of previous lumbar spine surgery. The patients were divided into two groups: a control group comprising 17 cases who underwent intervertebral fusion using PEEK material cages, including 11 males and 6 females, with ages ranging from 22 to 71 years and an average age of 59.6 years. The lesion distribution was as follows: 9 cases at the level of the L4/5 intervertebral disc, 7 cases at the level of the L5/S1 intervertebral disc, and 1 case at the level of the L2/3 intervertebral disc. The disease types were as follows: 13 cases of lumbar disc herniation and 4 cases of lumbar spinal stenosis. The experimental group comprised 19 cases who underwent intervertebral fusion using 3D-printed cages, including 14 males and 5 females, with ages ranging from 45 to 77 years and an average age of 63.3 years. The lesion distribution was as follows: 8 cases at the level of the L4/5 intervertebral disc and 11 cases at the level of the L5/S1 intervertebral disc. The disease types were as follows: 10 cases of lumbar disc herniation and 9 cases of lumbar spinal stenosis. Surgical technique After general anesthesia, the patient was placed in a prone position, sterilized, and draped with sterile towels. A midline incision was made at the posterior lumbar spine, and the skin, subcutaneous tissue, and deep fascia were incised. The paraspinal muscles were dissected bilaterally under the bone membrane to the outer edge of the articular process. Four pedicle screws were implanted into the vertebral bodies above and below the responsible segment. Decompression of the entire lamina was performed using bone chisels, bone rongeurs, and laminectomy rongeurs. For patients with lumbar spinal stenosis, a substantial portion of the bilateral inferior articular processes was removed, and the hypertrophied ligamentum flavum was excised, followed by bilateral foraminal decompression. The dura mater was gently retracted and protected. The annulus fibrosus between the responsible segments was incised with a scalpel, and the nucleus pulposus tissue and cartilaginous endplates were removed. Cage sizing was determined by trial implantation, and autologous cancellous bone was placed in the intervertebral space. The cage was then implanted and impacted into the intervertebral space. After satisfactory positioning was confirmed under fluoroscopy, the rod and top cap were placed. Compression was applied to the responsible segment, and the top cap was tightened. Nerve root decompression was rechecked, irrigation was performed, and after no significant bleeding, a single drainage tube was left in place. The incision was closed in layers. Postoperative management The patient remained bedridden for 24 hours, followed by ambulation with a lumbar support. If wound drainage was less than 50ml, the drainage tube was removed. Follow‑up index and Statistical analysis The efficacy of the experimental and control groups was evaluated by comparing preoperative and postoperative pain visual analog scale (VAS) scores and Oswestry Disability Index (ODI). Statistical analysis was performed using SPSS 19 software (SPSS Inc., USA). Paired-sample t-tests were conducted to compare postoperative VAS and ODI scores with preoperative scores, with a significance level set at 0.01 for bilateral testing. Radiologic analysis Following surgery, all 36 patients underwent X-ray and CT examinations at 3 months and 1 year postoperatively to assess the stability and fusion status of the cages. Results Baseline clinical data In this group of 36 patients, single-stage posterior lumbar fusion surgery was performed. In the experimental group, the surgical duration ranged from 70 to 140 minutes, with an average of 130 minutes. Intraoperative blood loss ranged from 200 to 600ml, with an average of 260ml. In the control group, the surgical duration ranged from 75 to 135 minutes, with an average of 135 minutes. Intraoperative blood loss ranged from 150 to 700ml, with an average of 240ml. Clinical efficacy assessment After 24 hours postoperatively, symptoms of lumbago and leg pain were alleviated to varying degrees in all 36 patients. 8 patients experienced unilateral lower limb pain and numbness after the removal of the drainage tube, which were relieved after treatment with nerve nutrition, dehydration medications, and low-dose steroids. In the experimental group, 3 patients occasionally experienced discomfort in the lumbar region during follow-up, which could be alleviated by rest or oral non-steroidal anti-inflammatory drugs. 17 patients in the experimental group did not experience a recurrence of preoperative symptoms during follow-up. In the control group, 5 patients reported discomfort in the lumbar region when lying flat, and 2 patients experienced significant lumbar pain, requiring the use of lumbar support or oral non-steroidal anti-inflammatory drugs for relief. After 24 hours postoperatively, pain symptoms were alleviated to varying degrees in all 36 patients. Both the preoperative and postoperative 24-hour and 3-month VAS scores showed statistically significant differences (P < 0.01) when comparing the experimental group and the control group (Table 2 ). There were no statistically significant differences in VAS scores between the two groups before surgery, at 24 hours postoperatively, and at 3 months postoperatively (P > 0.01) (Table 3 ). Table 2 Preoperative and Postoperative VAS Scores at 24 Hours and 3 Months Preoperative VAS Scores Postoperative VAS Scores statistical results Control group 7.0 ± 1.8 Postoperative VAS Scores at 24 Hours 3.6 ± 1.0 t = 9.025, P < 0.01 Postoperative VAS Scores at 3 Months 1.7 ± 1.9 t = 9.324, P < 0.01 Experimental Group 6.8 ± 0.8 ostoperative VAS Scores at 24 Hours 2.8 ± 1.0 t = 16.971, P < 0.01 Postoperative VAS Scores at 3 Months 2.1 ± 1.8 t = 9.899, P < 0.01 Table 3 Preoperative VAS Scores and Postoperative VAS Scores at 24 Hours and 3 Months Preoperative VAS Postoperative VAS Scores at 24 Hours Postoperative VAS Scores at 3 Months Control group 6.8 ± 0.8 2.8 ± 1.0 2.1 ± 1.8 Experimental Group 6.9 ± 2.0 3.7 ± 1.1 1.0 ± 2.0 统计结果 t = 0.103, P > 0.01 t = 1.650, P > 0.01 t = 1.048, P > 0.01 In the statistical results, both the experimental group and the control group showed significant differences in ODI scores between the preoperative and 3-month postoperative assessments (P 0.01)(Table 4 ).. Table 4 ODI Scores for the Experimental and Control Groups Preoperative ODI Scores Postoperative ODI Scores 统计结果 Control group 88.4 ± 5.2 7.7 ± 3.6 t = 58.250, P < 0.01 Experimental Group 88.0 ± 5.0 7.0 ± 4.2 t = 53.637, P < 0.01 统计值 t = 0.641, P = 0.530 t = 0.270, P = 0.791 Radiological Results Postoperative X-rays and CT scans of the 36 patients in this group showed satisfactory positions of the anterior cages and pedicle screws. Follow-up X-rays taken between 3 and 26 months postoperatively were compared with immediate postoperative X-rays to assess screw loosening and cage migration. Among the 17 patients who received PEEK cages, 3 experienced cage migration (17.6%), and 1 showed signs of posterior pedicle screw loosening (5.9%), while the remaining 2 pedicle screws were stable. In the 19 patients who received 3D-printed cages, no cage migration or pedicle screw loosening was observed. Discussion 3D printed intervertebral fusion cages have excellent biocompatibility The concept of three-dimensional printing (3DP) originated in the 1980s and has rapidly developed across various industries in recent years. It has found extensive applications particularly in military manufacturing, automotive manufacturing, and biological human tissues[ 10 ]. In the medical field, high-resolution imaging technologies such as CT and MRI are used to generate 3D data files, enabling 3D printing in medicine. This allows for the production of a range of 3D printed prosthetics that meet specific anatomical structures and shape requirements. 3D printing technology in medicine can be categorized into four types: 1. anatomical models for teaching or surgical planning; 2. tissue bioengineering; 3. external fixation devices; 4. internal fixation prostheses[ 11 – 13 ]. Among these, 3D printed prostheses implanted within the body have developed rapidly in recent years, particularly in the field of spinal surgery. This technology addresses the challenges of reconstruction caused by the complex anatomical structures and the proximity of critical neural tissues. Due to its excellent properties, titanium alloy is widely used in orthopedic and dental fields: 1) good biocompatibility; 2) high strength-to-weight ratio; 3) relatively low elastic modulus; and 4) excellent corrosion resistance[ 14 – 15 ]. The biocompatibility of Ti6Al4V has been confirmed in numerous in vivo and in vitro studies[ 16 – 19 ]. In this study, the 3D printed intervertebral fusion cage was produced using electron beam melting (EBM) 3D printing technology, which forms the porous metal fusion cage with specific shapes and microporous structures by melting Ti6Al4V powder, creating a rough surface. Xue et al. demonstrated that this rough surface enhances cell adhesion and stimulates cell differentiation, with improved cell adhesion being a necessary condition for inducing bone ingrowth[ 20 ]. Haslauer et al. found that porous titanium alloy prostheses manufactured by EBM technology exhibit good biocompatibility and facilitate bone tissue ingrowth to achieve fusion[ 21 ]. Additionally, Sinclair et al. compared the host bone response to porous implants and polyether ether ketone implants in a goat cervical fusion model[ 22 ]. The results showed that animals implanted with porous titanium implants had a higher average mineral apposition rate of bone ingrowth compared to those with polyether ether ketone implants. Yang et al. used EBM-manufactured artificial vertebrae for vertebral reconstruction in a sheep model. X-ray, micro-CT, and histological examinations confirmed that the porous titanium artificial vertebrae manufactured using 3D printing technology possess good biocompatibility and mechanical stability, making them suitable for vertebral reconstruction post-vertebrectomy[ 23 ]. 3D printed intervertebral fusion cages can reduce the subsidence rate of internal fixation Currently, the elastic modulus of all metal implants is higher than that of bone, which may lead to endplate fractures or implant collapse. The compressive strength of the implant increases as porosity decreases, but the bone fusion rate decreases as porosity decreases, and the elastic modulus increases. The mismatch between the elastic modulus of the implant and that of the host bone can result in stress shielding effects, ultimately leading to implant failure. In this study, the 3D printed intervertebral fusion cage was designed to mimic the trabecular structure of human cancellous bone, with a porosity of up to 80%. Its microstructure is highly organized, with uniform pore size and shape, and it possesses mechanical properties similar to cancellous bone, reducing the stress shielding effect. Parthasarathy et al. noted that the strength of porous implants depends on their volume and porosity[ 24 ]. Once bone grows into the implant, it transforms into a "reinforced concrete structure," significantly increasing compressive strength. Therefore, the elastic modulus of the implant is crucial, playing a key role in early bone fusion. In addition to its microporous design, the 3D printed intervertebral fusion cage is covered with melted titanium alloy particles on its surface, significantly increasing the bone-metal interface area, which is more conducive to bone tissue cell attachment. Furthermore, utilizing digital technology during the manufacturing of the fusion cage allows for full consideration of the actual dimensions and unique geometry of the implantation site, increasing the contact area between the fusion cage and the implantation site. This enhances the stability between the two, thereby reducing the incidence of endplate fractures and implant collapse. 3D printed intervertebral fusion cages can promote bone ingrowth The porous structure of 3D printed intervertebral fusion cages facilitates bone ingrowth, achieving stability through the mechanical interlock formed by bone growth into the porous structure[ 25 , 26 ]. The bone ingrowth capacity of such porous implants depends mainly on parameters such as porosity, pore size, shape, and distribution. Porosity and pore size play crucial roles in bone ingrowth[ 27 ]. Due to cellular size and migration requirements, the minimum diameter of pores should be greater than or equal to 100 µm; higher porosity and larger pore size facilitate greater bone ingrowth[ 28 ]. However, excessively high porosity can lead to lower mechanical strength, thus appropriate porosity and pore size are key factors for achieving effective bone ingrowth with porous implants. The 3D printed intervertebral fusion cages used in this study have a porosity of 80% and a pore size structure of 800 ± 200µm, which is conducive to bone cell migration and proliferation. Additionally, these implants feature a three-dimensional open porous structure with interconnected pores, which plays a vital role in bone formation and growth processes, facilitating cell seeding, attachment, proliferation, differentiation, and tissue growth[ 29 ]. The surface of 3D printed intervertebral fusion cages appears rough due to the presence of melted titanium alloy particles covering it. Anselme et al. observed that the adhesion and differentiation levels of osteoblasts on the rough surface of metal implants were higher than those on smooth surfaces[ 30 ]. A finding corroborated by other studies which showed a greater quantity of osteoblasts on rough surfaces compared to smooth ones[ 31 , 32 ]. Yang et al. investigated the effects of surface-treated porous titanium implants on the attachment and differentiation of mesenchymal stem cells (MSCs) in simulated body fluid cultures. The results indicated that the rough surface had greater potential to promote osteogenic differentiation of MSCs[ 33 ]. Subsequent studies further demonstrated the osteoinductive capabilities of rough or porous titanium alloy materials[ 34 , 35 ]. Therefore, the design of 3D printed intervertebral fusion cages with a three-dimensional open porous structure and a rough surface covering provides excellent osteoinductive properties and promotes bone ingrowth, thereby improving the fusion rate post-implantation and offering better biological stability. A limitation of this study is the relatively small number of cases in the group, as well as the short follow-up time, due to restrictions such as patient enrollment criteria, economic conditions, and cognitive abilities. Further research is needed to investigate the long-term efficacy of this technique and to continue refining it in future studies. Conclusion Intervertebral fusion cages manufactured using 3D printing technology exhibit excellent biocompatibility and mechanical stability. Their use in posterior lumbar fusion surgery is effective, safe, and feasible, offering a new option for intervertebral fusion cages in posterior lumbar fusion procedures. Declarations Ethics approval and consent to participate: All clinical investigations had been conducted according to the principles expressed in the Declaration of Helsinki. This study was conducted with approval from the Ethics Committee of Tianjin Hospital. Informed consent to participate in the study was obtained from the participant. Consent for publication : Written informed consent for publication was obtained from all participants. Availability of data and materials : The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request. Competing interests : The authors declare that they have no competing interests. Authors' contributions : Jun Miao conceived the original ideas of this manuscript. Jingtao Ji wrote the manuscript. Jingtao Ji and Guangdong Chen performed the experiments. Jingtao Ji and Guangdong Chen were responsible for image production. All authors read and approved the final manuscript. References Cloward RB. 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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-4593148","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":320128476,"identity":"426f05d8-0972-41d7-8ffe-444ca23d84de","order_by":0,"name":"Jingtao Ji","email":"","orcid":"","institution":"Department of Spine Surgery of Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jingtao","middleName":"","lastName":"Ji","suffix":""},{"id":320128479,"identity":"df400ac6-3812-43b1-bfe3-d8fae3957bfe","order_by":1,"name":"Guangdong Chen","email":"","orcid":"","institution":"Academy of Medical Engineering and Translational Medicine, Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Guangdong","middleName":"","lastName":"Chen","suffix":""},{"id":320128480,"identity":"80638739-e314-4e09-b840-a3ec0f093e81","order_by":2,"name":"Jun Miao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAqklEQVRIiWNgGAWjYFCCwwcffKiw4eHnbyBay7Fkwxln0mQkZxwgWguPmjBv22Ebg4YEIjXoNp5hY5xx5jyPAcMBxg8fc4jQYnbg7DGgX27zmDM3MEvO3EaUlnPpQL/c5rFsOMDGzEucljNm0rxt53gMDiSQpuUASVrAgZzMIznjYDORfrkBjko7e37+5oMfPhKjhUHiAIzF2ECMeiAgIZ2MglEwCkbBSAUA2Dg/9CBPyQAAAAAASUVORK5CYII=","orcid":"","institution":"Department of Spine Surgery of Tianjin Hospital","correspondingAuthor":true,"prefix":"","firstName":"Jun","middleName":"","lastName":"Miao","suffix":""}],"badges":[],"createdAt":"2024-06-17 09:26:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4593148/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4593148/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":60597019,"identity":"4343bab1-a5df-433b-935b-be87702dd90a","added_by":"auto","created_at":"2024-07-18 15:46:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1929239,"visible":true,"origin":"","legend":"\u003cp\u003eSurgical Diagram A, B: Pedicle screws implanted into the upper and lower vertebrae; C, D: 3D-printed intervertebral cage;E: 3D-printed intervertebral cage implanted into the intervertebral space; F, G, H: Illustrations of the 3D-printed intervertebral cage after implantation.\u003c/p\u003e","description":"","filename":"figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4593148/v1/41248a034dbb58aa3b21f19e.png"},{"id":60597020,"identity":"03c82d96-af3b-4b2c-8916-5ecd37ec8dcd","added_by":"auto","created_at":"2024-07-18 15:46:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2145709,"visible":true,"origin":"","legend":"\u003cp\u003eA 64-year-old male with lumbar spinal stenosis. A, B: Preoperative X-rays; C: Preoperative CT showing L4/5 disc herniation and spinal canal stenosis at the same level; D, E, F: Preoperative lumbar MRI showing L4/5 disc herniation, spinal stenosis, and dural sac compression; G: Postoperative CT showing adequate decompression of the spinal canal, with stable 3D-printed artificial vertebra and pedicle screws; H, I: Postoperative X-rays showing stable fixation of pedicle screws and intervertebral cage; J, K: Postoperative CT showing adequate decompression of the spinal canal, with stable 3D-printed intervertebral cage and pedicle screws; L, M: X-rays 3 months postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage; N, O: X-rays 6 months postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage; P, Q: X-rays 1 year postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage.\u003c/p\u003e","description":"","filename":"figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4593148/v1/3c3fe7680fc86a00448c0f1b.png"},{"id":60597018,"identity":"269cfa46-5b71-461c-9187-953fe171e4ea","added_by":"auto","created_at":"2024-07-18 15:46:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2330007,"visible":true,"origin":"","legend":"\u003cp\u003eA 60-year-old female with L4 vertebral spondylolisthesis and lumbar spinal stenosis. A, B: Preoperative X-rays; C: Preoperative CT showing L4 vertebral anterolisthesis and spinal canal stenosis at the same level; D, E, F: Preoperative lumbar MRI showing L4 vertebral anterolisthesis, spinal stenosis, and dural sac compression; G: Postoperative CT showing adequate decompression of the spinal canal, with stable 3D-printed artificial vertebra and pedicle screws; H, I: Postoperative X-rays showing stable fixation of pedicle screws and intervertebral cage; J, K: Postoperative CT showing adequate decompression of the spinal canal, with stable 3D-printed intervertebral cage and pedicle screws; L, M: X-rays 3 months postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage; N, O: X-rays 6 months postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage; P, Q: X-rays 1 year postoperatively showing stable lumbar internal fixation and 3D-printed intervertebral cage.\u003c/p\u003e","description":"","filename":"figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4593148/v1/123c1cb80335f05e1b5dca98.png"},{"id":62027397,"identity":"0742d9b2-8dac-45c6-9000-5eee773d7a4d","added_by":"auto","created_at":"2024-08-08 11:19:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9474254,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4593148/v1/2a6867aa-ed4f-4976-b2b9-a52df985b05f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preliminary Application of 3D-Printed Interbody Fusion Devices in the Treatment of Lumbar Degenerative Diseases","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSince its first reported by Cloward in 1981[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], Posterior Lumbar Interbody Fusion (PLIF) surgery has been widely used in the treatment of degenerative lumbar diseases due to its features of adequate decompression and reconstruction of spinal stability. Interbody fusion cages play a crucial role in PLIF surgery, as they can expand the intervertebral space, better restore the physiological curvature of the lumbar spine, and provide greater space for interbody bone grafting. For unstable vertebral bodies, interbody fusion cages can enhance the stability of the anterior and middle columns, reducing the occurrence of loosening and fracture of pedicle screw-rod systems[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the 1950s, Cloward attempted to achieve intervertebral fusion by using vertebral body grafting, but it had a low fusion rate[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In response, Bagby designed a cage-like interbody fusion device made of stainless steel, which laid the groundwork for the modern cage[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. With continuous advancements in materials and manufacturing techniques, cages made of various materials have emerged. Currently, polyetheretherketone (PEEK) interbody fusion devices are the most widely used due to their excellent elastic modulus and tissue compatibility, which help maintain intervertebral height and prevent cage subsidence caused by stress shielding[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, PEEK materials have poor surface bone integration capability, resulting in a lower interbody fusion rate. Among metal fusion devices, titanium alloys exhibit corrosion resistance, good tissue compatibility, and strong bone integration capabilities. Cuzzocrea et al. found that titanium alloys have a better interbody fusion rate compared to PEEK materials. However, due to the significant difference in elastic modulus between titanium alloys and vertebral bodies, subsidence of the fusion device may occur due to stress shielding[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e3D printing, an important technology that emerged in the 1980s, has rapidly developed over the past 30 years. Unlike traditional subtractive manufacturing and casting techniques, 3D printing not only alters the physical structure of products but also allows for customization according to individual needs. This capability enables a complete match between materials and affected areas, making it particularly promising for medical applications. Customized implantable 3D-printed prosthetics can achieve both structural integrity and functional reconstruction for complex anatomical defects. They have been utilized in maxillofacial reconstruction, neurosurgical cranial reconstruction, vertebral body reconstruction following spinal tumor resection, and other procedures[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Currently, domestically certified 3D-printed titanium alloy cages, such as those produced by Aike Medical in China, have superior individualized designs compared to PEEK material cages. They offer a larger contact area, resulting in tighter adhesion to adjacent vertebrae and reducing the probability of settling due to cutting forces. With a porous design resembling trabecular bone structure, these cages have an elastic modulus similar to cancellous bone, facilitating bone ingrowth and promoting fusion.\u003c/p\u003e \u003cp\u003eFrom November 2018 to April 2023, our hospital conducted a randomized controlled study comparing the use of 3D-printed titanium alloy cages for intervertebral fusion in posterior lumbar fusion surgery with the application of PEEK material cages. The study aimed to evaluate the effectiveness, safety, and usability of 3D-printed cages in posterior lumbar fusion surgery and assess their long-term fusion outcomes through radiographic evaluation.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e This study has been approved by the Ethics Committee of Tianjin Hospital, and all patients participating in the study have provided informed consent. All methods were conducted in accordance with relevant guidelines and regulations.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eDesign and patients Selection\u003c/h2\u003e \u003cp\u003eThis study included 36 patients with single-level degenerative diseases of the lumbar spine. Inclusion criteria were as follows: (1) Patients with lumbar disc herniation experiencing lumbago or sciatica with ineffective conservative treatment; patients with lumbar spinal stenosis experiencing intermittent claudication, with or without lumbago or sciatica, with ineffective conservative treatment. (2) Preoperative confirmation through lumbar spine anteroposterior, lateral, and dynamic X-rays, lumbar spine CT, and lumbar spine MRI. (3) All patients had single-level lesions. (4) No history of previous lumbar spine surgery.\u003c/p\u003e \u003cp\u003eThe patients were divided into two groups: a control group comprising 17 cases who underwent intervertebral fusion using PEEK material cages, including 11 males and 6 females, with ages ranging from 22 to 71 years and an average age of 59.6 years. The lesion distribution was as follows: 9 cases at the level of the L4/5 intervertebral disc, 7 cases at the level of the L5/S1 intervertebral disc, and 1 case at the level of the L2/3 intervertebral disc. The disease types were as follows: 13 cases of lumbar disc herniation and 4 cases of lumbar spinal stenosis.\u003c/p\u003e \u003cp\u003eThe experimental group comprised 19 cases who underwent intervertebral fusion using 3D-printed cages, including 14 males and 5 females, with ages ranging from 45 to 77 years and an average age of 63.3 years. The lesion distribution was as follows: 8 cases at the level of the L4/5 intervertebral disc and 11 cases at the level of the L5/S1 intervertebral disc. The disease types were as follows: 10 cases of lumbar disc herniation and 9 cases of lumbar spinal stenosis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eSurgical technique\u003c/h2\u003e \u003cp\u003eAfter general anesthesia, the patient was placed in a prone position, sterilized, and draped with sterile towels. A midline incision was made at the posterior lumbar spine, and the skin, subcutaneous tissue, and deep fascia were incised. The paraspinal muscles were dissected bilaterally under the bone membrane to the outer edge of the articular process. Four pedicle screws were implanted into the vertebral bodies above and below the responsible segment. Decompression of the entire lamina was performed using bone chisels, bone rongeurs, and laminectomy rongeurs. For patients with lumbar spinal stenosis, a substantial portion of the bilateral inferior articular processes was removed, and the hypertrophied ligamentum flavum was excised, followed by bilateral foraminal decompression. The dura mater was gently retracted and protected. The annulus fibrosus between the responsible segments was incised with a scalpel, and the nucleus pulposus tissue and cartilaginous endplates were removed. Cage sizing was determined by trial implantation, and autologous cancellous bone was placed in the intervertebral space. The cage was then implanted and impacted into the intervertebral space. After satisfactory positioning was confirmed under fluoroscopy, the rod and top cap were placed. Compression was applied to the responsible segment, and the top cap was tightened. Nerve root decompression was rechecked, irrigation was performed, and after no significant bleeding, a single drainage tube was left in place. The incision was closed in layers.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative management\u003c/h2\u003e \u003cp\u003eThe patient remained bedridden for 24 hours, followed by ambulation with a lumbar support. If wound drainage was less than 50ml, the drainage tube was removed.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eFollow‑up index and Statistical analysis\u003c/h2\u003e \u003cp\u003eThe efficacy of the experimental and control groups was evaluated by comparing preoperative and postoperative pain visual analog scale (VAS) scores and Oswestry Disability Index (ODI). Statistical analysis was performed using SPSS 19 software (SPSS Inc., USA). Paired-sample t-tests were conducted to compare postoperative VAS and ODI scores with preoperative scores, with a significance level set at 0.01 for bilateral testing.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eRadiologic analysis\u003c/h2\u003e \u003cp\u003eFollowing surgery, all 36 patients underwent X-ray and CT examinations at 3 months and 1 year postoperatively to assess the stability and fusion status of the cages.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eBaseline clinical data\u003c/h2\u003e \u003cp\u003eIn this group of 36 patients, single-stage posterior lumbar fusion surgery was performed. In the experimental group, the surgical duration ranged from 70 to 140 minutes, with an average of 130 minutes. Intraoperative blood loss ranged from 200 to 600ml, with an average of 260ml. In the control group, the surgical duration ranged from 75 to 135 minutes, with an average of 135 minutes. Intraoperative blood loss ranged from 150 to 700ml, with an average of 240ml.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eClinical efficacy assessment\u003c/h2\u003e \u003cp\u003eAfter 24 hours postoperatively, symptoms of lumbago and leg pain were alleviated to varying degrees in all 36 patients. 8 patients experienced unilateral lower limb pain and numbness after the removal of the drainage tube, which were relieved after treatment with nerve nutrition, dehydration medications, and low-dose steroids. In the experimental group, 3 patients occasionally experienced discomfort in the lumbar region during follow-up, which could be alleviated by rest or oral non-steroidal anti-inflammatory drugs. 17 patients in the experimental group did not experience a recurrence of preoperative symptoms during follow-up. In the control group, 5 patients reported discomfort in the lumbar region when lying flat, and 2 patients experienced significant lumbar pain, requiring the use of lumbar support or oral non-steroidal anti-inflammatory drugs for relief.\u003c/p\u003e \u003cp\u003eAfter 24 hours postoperatively, pain symptoms were alleviated to varying degrees in all 36 patients. Both the preoperative and postoperative 24-hour and 3-month VAS scores showed statistically significant differences (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) when comparing the experimental group and the control group (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e2\u003c/span\u003e). There were no statistically significant differences in VAS scores between the two groups before surgery, at 24 hours postoperatively, and at 3 months postoperatively (P\u0026thinsp;\u0026gt;\u0026thinsp;0.01) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePreoperative and Postoperative VAS Scores at 24 Hours and 3 Months\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative VAS Scores\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative VAS Scores\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003estatistical results\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eControl group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative VAS Scores at 24 Hours\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;9.025, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative VAS Scores at 3 Months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;9.324, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eExperimental Group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e6.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eostoperative VAS Scores at 24 Hours\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;16.971, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative VAS Scores at 3 Months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;9.899, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePreoperative VAS Scores and Postoperative VAS Scores at 24 Hours and 3 Months\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative VAS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative VAS Scores at 24 Hours\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePostoperative VAS Scores at 3 Months\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExperimental Group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e统计结果\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;0.103, P\u0026thinsp;\u0026gt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;1.650, P\u0026thinsp;\u0026gt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;1.048, P\u0026thinsp;\u0026gt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the statistical results, both the experimental group and the control group showed significant differences in ODI scores between the preoperative and 3-month postoperative assessments (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). However, there was no significant difference in ODI scores between the two groups at both the preoperative and postoperative assessments (P\u0026thinsp;\u0026gt;\u0026thinsp;0.01)(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e4\u003c/span\u003e)..\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eODI Scores for the Experimental and Control Groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative ODI Scores\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePostoperative ODI Scores\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e统计结果\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e88.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;58.250, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExperimental Group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e88.0\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;53.637, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e统计值\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;0.641, P\u0026thinsp;=\u0026thinsp;0.530\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;0.270, P\u0026thinsp;=\u0026thinsp;0.791\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eRadiological Results\u003c/h2\u003e \u003cp\u003ePostoperative X-rays and CT scans of the 36 patients in this group showed satisfactory positions of the anterior cages and pedicle screws. Follow-up X-rays taken between 3 and 26 months postoperatively were compared with immediate postoperative X-rays to assess screw loosening and cage migration. Among the 17 patients who received PEEK cages, 3 experienced cage migration (17.6%), and 1 showed signs of posterior pedicle screw loosening (5.9%), while the remaining 2 pedicle screws were stable. In the 19 patients who received 3D-printed cages, no cage migration or pedicle screw loosening was observed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3D printed intervertebral fusion cages have excellent biocompatibility\u003c/h2\u003e \u003cp\u003eThe concept of three-dimensional printing (3DP) originated in the 1980s and has rapidly developed across various industries in recent years. It has found extensive applications particularly in military manufacturing, automotive manufacturing, and biological human tissues[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In the medical field, high-resolution imaging technologies such as CT and MRI are used to generate 3D data files, enabling 3D printing in medicine. This allows for the production of a range of 3D printed prosthetics that meet specific anatomical structures and shape requirements.\u003c/p\u003e \u003cp\u003e3D printing technology in medicine can be categorized into four types: 1. anatomical models for teaching or surgical planning; 2. tissue bioengineering; 3. external fixation devices; 4. internal fixation prostheses[\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Among these, 3D printed prostheses implanted within the body have developed rapidly in recent years, particularly in the field of spinal surgery. This technology addresses the challenges of reconstruction caused by the complex anatomical structures and the proximity of critical neural tissues.\u003c/p\u003e \u003cp\u003eDue to its excellent properties, titanium alloy is widely used in orthopedic and dental fields: 1) good biocompatibility; 2) high strength-to-weight ratio; 3) relatively low elastic modulus; and 4) excellent corrosion resistance[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The biocompatibility of Ti6Al4V has been confirmed in numerous in vivo and in vitro studies[\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In this study, the 3D printed intervertebral fusion cage was produced using electron beam melting (EBM) 3D printing technology, which forms the porous metal fusion cage with specific shapes and microporous structures by melting Ti6Al4V powder, creating a rough surface. Xue et al. demonstrated that this rough surface enhances cell adhesion and stimulates cell differentiation, with improved cell adhesion being a necessary condition for inducing bone ingrowth[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Haslauer et al. found that porous titanium alloy prostheses manufactured by EBM technology exhibit good biocompatibility and facilitate bone tissue ingrowth to achieve fusion[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Additionally, Sinclair et al. compared the host bone response to porous implants and polyether ether ketone implants in a goat cervical fusion model[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The results showed that animals implanted with porous titanium implants had a higher average mineral apposition rate of bone ingrowth compared to those with polyether ether ketone implants. Yang et al. used EBM-manufactured artificial vertebrae for vertebral reconstruction in a sheep model. X-ray, micro-CT, and histological examinations confirmed that the porous titanium artificial vertebrae manufactured using 3D printing technology possess good biocompatibility and mechanical stability, making them suitable for vertebral reconstruction post-vertebrectomy[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3D printed intervertebral fusion cages can reduce the subsidence rate of internal fixation\u003c/h2\u003e \u003cp\u003eCurrently, the elastic modulus of all metal implants is higher than that of bone, which may lead to endplate fractures or implant collapse. The compressive strength of the implant increases as porosity decreases, but the bone fusion rate decreases as porosity decreases, and the elastic modulus increases. The mismatch between the elastic modulus of the implant and that of the host bone can result in stress shielding effects, ultimately leading to implant failure.\u003c/p\u003e \u003cp\u003eIn this study, the 3D printed intervertebral fusion cage was designed to mimic the trabecular structure of human cancellous bone, with a porosity of up to 80%. Its microstructure is highly organized, with uniform pore size and shape, and it possesses mechanical properties similar to cancellous bone, reducing the stress shielding effect. Parthasarathy et al. noted that the strength of porous implants depends on their volume and porosity[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Once bone grows into the implant, it transforms into a \"reinforced concrete structure,\" significantly increasing compressive strength. Therefore, the elastic modulus of the implant is crucial, playing a key role in early bone fusion.\u003c/p\u003e \u003cp\u003eIn addition to its microporous design, the 3D printed intervertebral fusion cage is covered with melted titanium alloy particles on its surface, significantly increasing the bone-metal interface area, which is more conducive to bone tissue cell attachment. Furthermore, utilizing digital technology during the manufacturing of the fusion cage allows for full consideration of the actual dimensions and unique geometry of the implantation site, increasing the contact area between the fusion cage and the implantation site. This enhances the stability between the two, thereby reducing the incidence of endplate fractures and implant collapse.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3D printed intervertebral fusion cages can promote bone ingrowth\u003c/h2\u003e \u003cp\u003eThe porous structure of 3D printed intervertebral fusion cages facilitates bone ingrowth, achieving stability through the mechanical interlock formed by bone growth into the porous structure[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The bone ingrowth capacity of such porous implants depends mainly on parameters such as porosity, pore size, shape, and distribution. Porosity and pore size play crucial roles in bone ingrowth[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Due to cellular size and migration requirements, the minimum diameter of pores should be greater than or equal to 100 \u0026micro;m; higher porosity and larger pore size facilitate greater bone ingrowth[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. However, excessively high porosity can lead to lower mechanical strength, thus appropriate porosity and pore size are key factors for achieving effective bone ingrowth with porous implants. The 3D printed intervertebral fusion cages used in this study have a porosity of 80% and a pore size structure of 800\u0026thinsp;\u0026plusmn;\u0026thinsp;200\u0026micro;m, which is conducive to bone cell migration and proliferation. Additionally, these implants feature a three-dimensional open porous structure with interconnected pores, which plays a vital role in bone formation and growth processes, facilitating cell seeding, attachment, proliferation, differentiation, and tissue growth[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe surface of 3D printed intervertebral fusion cages appears rough due to the presence of melted titanium alloy particles covering it. Anselme et al. observed that the adhesion and differentiation levels of osteoblasts on the rough surface of metal implants were higher than those on smooth surfaces[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. A finding corroborated by other studies which showed a greater quantity of osteoblasts on rough surfaces compared to smooth ones[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Yang et al. investigated the effects of surface-treated porous titanium implants on the attachment and differentiation of mesenchymal stem cells (MSCs) in simulated body fluid cultures. The results indicated that the rough surface had greater potential to promote osteogenic differentiation of MSCs[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Subsequent studies further demonstrated the osteoinductive capabilities of rough or porous titanium alloy materials[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTherefore, the design of 3D printed intervertebral fusion cages with a three-dimensional open porous structure and a rough surface covering provides excellent osteoinductive properties and promotes bone ingrowth, thereby improving the fusion rate post-implantation and offering better biological stability.\u003c/p\u003e \u003cp\u003eA limitation of this study is the relatively small number of cases in the group, as well as the short follow-up time, due to restrictions such as patient enrollment criteria, economic conditions, and cognitive abilities. Further research is needed to investigate the long-term efficacy of this technique and to continue refining it in future studies.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIntervertebral fusion cages manufactured using 3D printing technology exhibit excellent biocompatibility and mechanical stability. Their use in posterior lumbar fusion surgery is effective, safe, and feasible, offering a new option for intervertebral fusion cages in posterior lumbar fusion procedures.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll clinical investigations had been conducted according to the principles expressed in the Declaration of Helsinki. This study was conducted with approval from the Ethics Committee of Tianjin Hospital. Informed consent to participate in the study was obtained from the participant.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication was obtained from all participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eJun Miao conceived the original ideas of this manuscript. Jingtao Ji wrote the manuscript. Jingtao Ji and Guangdong Chen performed the experiments. Jingtao Ji and Guangdong Chen were responsible for image production. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCloward RB. Spondylolisthesis: treatment by laminectomy and posterior interbody fusion. Clin Orthop Relat Res. 1981,(154):74\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMobbs RJ, Phan K, Malham G, et al. Lumbar interbody fusion:techniques, indications and comparison of interbody fusion options including PLIF, TLIF, MI-TLIF, OLIF/ATP, LLIF and ALIF. J Spine Surg. 2015;1(1):2\u0026ndash;18.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCloward RB. The treatment of ruptured lumbar intervertebral discs by vertebral body fusion. J Neurosurg, 1953,10:154\u0026ndash;168. Wetzel FT, Larcca H.The failed posterior lumbar interbody fusion. 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Biomaterials. 2006;27(13):2682\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"3D printing, interbody fusion cage, posterior lumbar fusion surgery, bone fusion","lastPublishedDoi":"10.21203/rs.3.rs-4593148/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4593148/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e: To investigate the effectiveness, safety, and usability of 3D-printed interbody fusion cages in posterior lumbar fusion surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: This randomized controlled trial included 36 patients with single-stage lumbar degenerative disease undergoing PLIF surgery. The patients were divided into two groups: the control group (17 patients) used PEEK (polyetheretherketone) cages for interbody fusion, while the experimental group (19 patients) used 3D-printed cages. The study aimed to assess the postoperative effectiveness and safety of the surgeries using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores, and to evaluate the stability and fusion effect of the cages through postoperative imaging.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: All patients were followed up for 3 to 26 months. There were statistically significant differences (P\u0026lt;0.01) in VAS and ODI scores before and three months after surgery within both the control and experimental groups. No statistically significant differences (P\u0026gt;0.01) were found between the preoperative VAS and ODI scores of the two groups. However, there were statistically significant differences (P\u0026lt;0.01) in the postoperative VAS and ODI scores between the two groups.\u003c/p\u003e\n\u003cp\u003ePostoperative X-rays and CT scans showed satisfactory placement of the anterior cages and pedicle screws in all patients. During the follow-up period, 3 out of 17 patients (17.6%) in the PEEK cage group experienced cage migration, and 1 patient (5.9%) showed signs of pedicle screw loosening, while the remaining pedicle screws were stable. In contrast, none of the 19 patients with 3D-printed cages experienced cage migration, and no signs of pedicle screw loosening were observed.\u003c/p\u003e","manuscriptTitle":"Preliminary Application of 3D-Printed Interbody Fusion Devices in the Treatment of Lumbar Degenerative Diseases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-18 15:46:22","doi":"10.21203/rs.3.rs-4593148/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a0b53084-357b-4846-a3b8-8a20451f6533","owner":[],"postedDate":"July 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-08-08T11:10:58+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-18 15:46:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4593148","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4593148","identity":"rs-4593148","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}