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Objective To evaluate biomechanical properties of the nickel-titanium (NiTi) memory alloy stent and its in vitro biomechanical properties for lumbar interbody fusion. Methods The mechanical properties of the NiTi memory alloy stent were tested on mechanical testing machine. Moreover, lumbar interbody fusion was simulated on fresh lumbar specimens, and biomechanical properties of the NiTi memory alloy stent with matching bone graft for used for lumbar interbody fusion were analyzed and compared with the traditional box-shape cage. Results The maximum compressive strength of the NiTi memory alloy stent was ( 12 964 ± 962) N. The maximum deformation within the effective range of memory characteristics was (4. 68±0. 03) mm. The recovery rate of the NiTi memory alloy stent was up to 99. 86% . Compared with the intact lumbar model, the stability of the operative segment after the simulated lumbar interbody fusion using NiTi memory alloy stent alone was increased in the direction of anterior flexion, posterior extension, lateral flexion and rotation, which was equivalent to the box shape cage group (P>0. 05). After the combined use of autogenous bone granule and absorbable bone cement the ROM of the operative segment was further reduced (P0. 05). The pull-out strength of the NiTi memory alloy stent with matching bone graft group was significantly stronger than that of the box-shape cage group (P<0. 05). Conclusions The NiTi memory alloy stent in this study was designed with a matched bone granule-absorbable bone cement graft,which provided a new idea for the further optimization and development of lumbar interbody fusion. With excellent support and deformation properties, this NiTi memory alloy stent is biomechanical equivalent to the traditional box shape cage for lumbar interbody fusion, and can greatly improve the stability of surgical segment and the pull-out strength of implants after the combined use of autogenous bone granule and absorbable bone cement.
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Spinal fusion is a standard operation for treating moderate and severe intervertebral disc diseases. In recent years, the proportion of three-dimensional printing interbody fusion cage in spinal fusion surgery has gradually increased. In this paper, the research progress of molding technology and materials used in three-dimensional printing interbody fusion cage at present is summarized. Then, according to structure layout, three-dimensional printing interbody fusion cages are classified into five types: solid-porous-solid (SPS) type, solid-porous-frame (SPF) type, frame-porous-frame (FPF) type, whole porous cage (WPC) type and others. The optimization process of three-dimensional printing interbody fusion cage and the advantages and disadvantages of each type are analyzed and summarized in depth. The clinical application of various types of 3D printed interbody fusion cage was introduced and summarized later. Lastly, combined with the latest research progress and achievements, the future research direction of three-dimensional printing interbody fusion cage in molding technology, application materials and coating materials is prospected in order to provide some reference for scholars engaged in interbody fusion cage research and application.
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Humans , Intervertebral Disc Degeneration , Intervertebral Disc Displacement , Porosity , Printing, Three-Dimensional , Spinal FusionABSTRACT
BACKGROUND: Recent clinical studies have found that during the implantation of biomaterials, the internal environment of the body will change to a certain extent, and different levels of immunity and stress responses will occur. There are also obvious differences in the immune and stress responses of different biological materials. OBJECTIVE: To investigate the effect of 3D printed interbody fusion cage on patients with cervical spondylosis of spinal cord type and its effect on serum cortisol and norepinephrine levels. METHODS: Sixty-three patients with cervical spondylotic myelopathy who were admitted to the Affiliated Hospital of Chengde Medical University from July 2015 to July 2018 were selected, including 40 males and 23 females, aged 30-78 years old. The patients were randomly divided into a research group (n=31) and a control group (n=32) according to a random number table. All patients received anterior cervical decompression and bone graft fusion and internal fixation. Patients in the research group were implanted with 3D printed intervertebral fusion cage during operation. The patients in the control group were implanted with polyetheretherketone interbody fusion cage and allogeneic bone. The operation and complications of the two groups were compared. Serum cortisol and norepinephrine levels were detected before and 1 and 3 days after operation. Cervical curvature and intervertebral height were measured before surgery, 1 week, and 6 months after surgery. Axial symptoms were counted at 6 months after surgery. The trial was approved by the Ethics Committee of the Affiliated Hospital of Chengde Medical University. RESULTS AND CONCLUSION: (1) Operation time, intraoperative blood loss and hospitalization time were not significantly different between the two groups (P > 0.05). (2) Among 31 cases, there were 1 case of screw loosening and 1 case of implant movement in the research group. Among 32 cases, there were 3 cases of screw loosening, 3 cases of immune rejection, 2 cases of implant movement, and 1 case of implant collapse in the control group. The incidence of complications was lower in the research group than that in the control group (P < 0.05). (3) At 1 and 3 days after operation, the levels of cortisol and norepinephrine were higher in both groups than those before surgery (P < 0.05), but above levels were lower in the research group than in the control group (P < 0.001). (4) The cervical curvature and intervertebral height at 1 week and 6 months after operation in both groups were higher than those before surgery (P < 0.05), and above indexes were higher in the research group than in the control group (P < 0.05). (5) The axial symptom in the research group was lighter than that in the control group at 6 months after operation (P < 0.05). (6) The results show that the application of 3D printed interbody fusion cage to cervical spondylotic myelopathy can reduce complications, promote the recovery of cervical curvature and intervertebral height, and improve the stability of cervical spine, and the body’s stress response and axial symptoms are mild.
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Objective To investigate the influence of ROI-C cervical implantation in the C5-6 segment on the C3-7 range-of-motion (ROM), biomechanical properties of the intervertebral disc and the vertebral body, and the mode of force transmission. Methods Two types of surgeries, ROI-C implantation and autograft fusion with plate fixation, were considered to establish the finite element model of cervical C5-6 segment degeneration. The ROM of C3-7 during flexion, extension, lateral bending, and axial rotation, as well as stress distributions on the adjacent discs, vertebral body, and implanted devices under two procedures, were analyzed. Results ROI-C implantation had a relatively small influence on the ROM of the adjacent segment. The stress on the vertebral discs was reduced, but the stress on the vertebral body increased significantly, with the C5 vertebral body stress increasing by 251%. In the fusion surgery model, the ROM of the surgical segment was reduced by 86%-91%, while the ROM of the adjacent segments and the stress on the vertebral disc and vertebral body increased significantly. Conclusions ROI-C implantation surgery has a relatively small influence on the cervical ROM and the intervertebral disc, and it has a greater impact on the vertebral body. The research findings provide a theoretical basis for the design of operation plans and clinical studies on ROI-C implantation and autograft fusion with plate fixation.
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Objective To analyze the clinical feasibility of unilateral transforaminal lumbar interbody fusion (TLIF) for treating lumbar degenerative diseases by finite element method. Methods Based on CT scan data, three-dimensional (3D) finite element models of the normal L3-5 segments under physiological status (intact lumbar model), L4/5 with unilateral pedicle screw fixation plus interbody fusion (unilateral TLIF model) and L4/5 with bilateral pedicle screw fixation plus interbody fusion (bilateral TLIF model) were established by using Mimics, Pro/E, ANSYS software, respectively. Preload of 500 N and load of 10 N•m torque were applied on the superior surface of the L3 segment to simulate 5 physiological activities: body upright, flexion, extension, left lateral bending and right axial rotation. The deformation and stress distributions in vertebral body, vertebral discs, pedicle screw and cage under different loads were then recorded and analyzed to compare mechanical properties of the two fixation methods. Results The deformation of L3-5 segments fixed with unilateral TLIF or bilateral TLIF decreased as compared to the intact lumbar model; the stresses in cage reached the maximum in both unilateral TLIF model and bilateral TLIF model during back extension, meanwhile peak stresses on pedicle screws in unilateral TLIF were significantly higher than those on bilateral TILF model, with the peak stress of 463.39 MPa during back extension. ConclusionsUnilateral TLIF can be selected as a method for treating lumbar degenerative diseases; however, its stability was inferior to bilateral TLIF due to the higher peak stress. Therefore, less stretch exercises may be safe for patients during rehabilitation to avoid surgery failure or pedicle screw fracture.
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BACKGROUND:There are various commonly used interbody fusion methods, such as autologous bone, al ograft bone and titanium-based posterior lumbar interbody fusion, and each method has its own advantages and disadvantages. OBJECTIVE:To observe the clinical efficacy of a bioactive nano-hydroxyapatite/polyamide 66 fusion cage in posterior lumbar interbody fusion for the treatment of lumbar disease. METHODS:A retrospective case analysis was conducted on 16 cases treated with posterior lumbar interbody fusion at the Department of Orthopedic, the First Affiliated Hospital of Gannan Medical University from July 2010 to December 2011, and al the patients were implanted with nano-hydroxyapatite/polyamide 66 biological activity fusion cage. RESULTS AND CONCLUSION:Al the patients were fol owed-up for 10-24 months, and the lumbar pain was significant improved, the lumbar visual analogue score, lumbar Japanese Orthopaedic Association score and Oswestry disability index score were significantly improved during the final fol ow-up period (Pfusion without nano-hydroxyapatite/polyamide 66 fusion cage displacement or subsidence. The results indicate that nano-hydroxyapatite/polyamide 66 fusion cage for the treatment of posterior lumbar interbody fusion can reconstruct the lumbar stability and provide immediate stability after implantation, and has good biological activity.
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[Objective]To evaluate the curative effect,indication and care for cage,the patients with lumbar vertebrae instability were treated by 1umbar interbody ecstatic fusion cage.[Method]There were 42 patients,male 31 and female 11,aged 3 5~78 years(averaged 46 years) and suffered with spondylolisthesis of isthmus non-union in 26 cases and degenerative spondylolisthsis in 1 6 cases,including spondylolisthsis of L3、4 5 cases,of L4、5 23 cases and of L5S1 14 cases.According to Meyerding classification,there were grade-I spondylolisthsis 29 cases and grade-Ⅱ 13 cases.All patients were treated with decompression of lumbar canal,resection of vertebral disc,insertion of ecstatic fusion cage.The curative effect was observed and evaluated.[Result]Patients were followed up for 6 months to 6 years,the results were good rate of JOA scores 95%,the recovery rate of inter-spinal height,reduction and bone fusion rate were up to 98%.[Conclusion]For lumbar spondylolisthesis of grade Ⅰ～Ⅱ,the ecstatic fusion cage has good effect on recovery of inter-spinal height,improvement of bone fusion rate,maintaining lumbar stability,relieving clinical symptom.It is a good curative method for lumbar vertebrae instability.
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[Objective]To observe the effect of Solis cage made of polyether ether ketone(PEEK)for the cervical interbody fusion after anterior discoidectomy of two levels cervical spondylotic myelopathy.[Method]We retrospectively analyzed the clinical outcome of 16 patients with two levels cervical spondylotic myelopathy underwent anterior discoidectomy and stabilized the operative segment using Solis cage from September 2002 to September 2004.Sequent X-ray examination was taken after operation to observe the stability and fusion of the operative segments.[Result]All of the segments were mobilized at the next day after operation.The patients were followed up from 14 months to 36 months(averaged 18 months).The operative segments were stable instantly and solid fusion was observed at 3 to 6 months after operation.15/16 of patients were satisfactory,no complication was found.[Conclusion]The immediate stability of the operative segments can be obtained by Solis cage,the Solis cage is safe and simple,complication is relatively few.It has a special advantage in the treatment of the discontinuous two levels cervical spondylotic myelopathy.
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Objective To evaluate the stability and compressive mechanical functions of the lumbar spine following insertion of a new self-made allograft interbody fusion cage.Methods Anti-bending intensity with three points test,anti-rotation intensity and compressive stiffness were measured at L4-L5 lumbar spine on five adult human fresh cadaveric specimens following insertion of a new self-made allograft interbody fusion cage and compared with that of before and after nucleus pulposus removal.Results The anti-bending intensity of flexion and extension of lumbar spine after inserting a new allograft interbody fusion cage was increased significantly(P