The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, in vitro specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using in vitro specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.
The lumbar intervertebral disc exhibits a complex physiological structure with interactions between various segments, and its components are extremely complex. The material properties of different components in the lumbar intervertebral disc, especially the water content (undergoing dynamic change as influenced by age, degeneration, mechanical loading, and proteoglycan content) - critically determine its mechanical properties. When the lumbar intervertebral disc is under continuous pressure, water seeps out, and after the pressure is removed, water re-infiltrates. This dynamic fluid exchange process directly affects the mechanical properties of the lumbar intervertebral disc, while previous isotropic modeling methods have been unable to accurately reflect such solid-liquid phase behaviors. To explore the load-bearing mechanism of the lumbar intervertebral disc and establish a more realistic mechanical model of the lumbar intervertebral disc, this study developed a solid-liquid biphasic, fiber-reinforced finite element model. This model was used to simulate the four movements of the human lumbar spine in daily life, namely flexion, extension, axial rotation, and lateral bending. The fluid pressure, effective solid stress, and liquid pressure-bearing ratio of the annulus fibrosus and nucleus pulposus of different lumbar intervertebral discs were compared and analyzed under the movements. Under all the movements, the fluid pressure distribution was closer to the nucleus pulposus, while the effective solid stress distribution was more concentrated in the outer annulus fibrosus. In terms of fluid pressure, the maximum fluid pressure of the lumbar intervertebral disc during lateral bending was 1.95 MPa, significantly higher than the maximum fluid pressure under other movements. Meanwhile, the maximum effective solid stress of the lumbar intervertebral disc during flexion was 2.43 MPa, markedly higher than the maximum effective solid stress under other movements. Overall, the liquid pressure-bearing ratio under axial rotation was smaller than that under other movements. Based on the solid-liquid biphasic modeling method, this study more accurately revealed the dominant role of the liquid phase in the daily load-bearing process of the lumbar intervertebral disc and the solid-phase mechanical mechanism of the annulus fibrosus load-bearing, and more effectively predicted the solid-liquid phase co-load-bearing mechanism of the lumbar intervertebral disc in daily life.
Objective To develop a modified short time inversion recovery (STIR) sequence grading system for lumbar intervertebral disc degeneration based on MRI STIR sequences, and to test the validity and reproducibility of this grading system. Methods A modified 8-level grading system for lumbar intervertebral disc degeneration based on routine sagittal STIR sequences and modified Pfirrmann grading system was developed. Between April 2011 and February 2012, 60 patients with different degrees of lumbar intervertebral disc degeneration were selected as objects of study, including 32 males and 28 females with an average of 50 years (range, 17-85 years). T2 weighted and STIR sequence images were obtained from the lumbar discs of L1, 2-L5, S1 of each object (total, 300 discs). All examinations were analyzed independently by 3 observers and a consensus readout was performed after all data collected. The validity and reproducibility were analyzed by calculating consistent rate and Kappa value. Results According to the grading system, there were 0 grade 1, 83 (27.7%) grade 2, 87 (29.0%) grade 3, 66 (22.0%) grade 4, 31 (10.3%) grade 5, 15 (5.0%) grade 6, 12 (4.0%) grade 7, and 6 (2.0%) grade 8. Intra-observer consistency was b (Kappa value range, 0.822-0.952), and inter-observer consistency was high to b (Kappa value range, 0.749-0.843). According to the consensus analysis, the total consistent rate was 82.7%-92.7% (mean, 85.6%). A difference of one grade occurred in 13.9% and a difference of two or more grades in 0.5% of all the cases. Conclusion Disc degeneration can be graded by using modified STIR sequence grading system, which can improve the accuracy of grading different degrees of lumbar intervertebral disc degeneration.
To detect the cell density, apoptotic incidence and the expressions of Bax and Caspase-3in human lumbar intervertebral discs, so as to further understand the mechanism of human lumbar intervertebral discdegeneration and provide a new idea for biologic treatment of it in future. Methods From May to December in 2006,30 human lumbar intervertebral discs in experimental group(L2 to S1)were surgically collected from 27 patients undergoing posterior lumbar intervertebral discoidectomy and fusion. All the cases were affirmed by MRI and they never experienced discography, collagenolysis of nucleus pulposus and percutaneous laser disc decompression. The control group consisted of 20 human lumbar intervertebral discs(L2 to S1)harvested from 5 young men without spine-related condition immediately after their accidental death. Apoptotic disc cells were detected by TUNEL and histomorphology, and immunohistochemical staining with SP method was performed to examine the expressions of Bax and Caspase-3 in all specimens. Results HE staining disclosed that the average cell density in control group (17.16 ± 1.22)/HP was higher than that in experimental group (12.41 ± 0.95)/HP (P lt; 0.01). However, TUNEL staining observed that the average TUNEL positive incidence in control group (6.97% ± 0.92%) was lower than that in experimental group (12.59% ± 0.95%), (P lt; 0.01). Immunohistochemical staining with SP method showed that the Bax and Caspase-3 positive incidence of nucleus pulposus in control group (11.02% ± 1.18%, 9.01% ± 1.00%) were lower than those in experimental group (19.29% ± 1.18%, 15.07% ± 0.97%), (P lt; 0.01). The results of the average gray scale value of nucleus pulposus in control group were 187.33 ± 7.88 and 185.68 ± 3.26, respectively, with 124.98 ±6.69 and 160.13 ± 4.37 in experimental group. There was significant difference between the two groups (P lt; 0.01). When thetotal 50 specimens in the two groups were analyzed, TUNEL positive incidence showed significant inverse correlations with their respectively corresponding cell densities (r = － 0.88, r = － 0.93, P lt; 0.01). The Bax and Caspase-3 positive incidence of nucleus pulposus showed significant positive correlation with the TUNEL positive incidence of nucleus pulposus (r = 0.83, r = 0.91, P lt; 0.01). Conclusion The decrease of cell density is involved in the development of human lumbar intervertebral disc degeneration. Bax and Caspase-3 might play a role in disc cell apoptosis in nucleus pulposus of human lumbar intervertebral disc.
Degenerative disc disease is a prevalent chronic disease that orthopaedic surgeons currently face as a difficulty. Tissue engineering represents the most promising possible therapeutic strategy for disc repair and regeneration. Surgery is the primary treatment for degenerative disc disease, but there are still inherent limits in practical practice. Electrospinning technique is a method for manufacturing nanoscale fibers with varied mechanical properties, porosity, and orientation, which can imitate the structural qualities and mechanical properties of natural intervertebral discs. Therefore, electrospinning materials can be utilized for disc regeneration and replacement. This article reviews recent advancements in disc tissue engineering and electrostatically spun nanomaterials typically utilized for the fabrication of disc scaffolds, as well as present and future techniques that may enhance the performance of electrostatically spun fibers.
ObjectiveTo summarize the research progress of hydrogels for the regeneration and repair of degenerative intervertebral disc and to investigate the potential of hydrogels in clinical application.MethodsThe related literature about the role of hydrogels in intervertebral disc degeneration especially for nucleus pulposus was reviewed and analyzed.ResultsHydrogels share similar properties with nucleus pulposus, and it plays an important role in the regeneration and repair of degenerative intervertebral disc, which can be mainly applied in nucleus pulposus prosthesis, hydrogel-based cell therapy, non-cellular therapy, and tissue engineering repair.ConclusionHydrogels are widely used in the regeneration and repair of intervertebral disc, which provides a potential treatment for intervertebral disc degeneration.
ObjectiveTo review the research progress of the role and mechanism of adipokines in intervertebral disc degeneration (IVDD) in recent years.MethodsThe domestic and foreign literature related to adipokines in the process of IVDD was extensively reviewed. The types and functions of adipokines, the role and mechanism in the process of IVDD, and the application prospects of intervertebral disc biotherapy were reviewed.ResultsAs a kind of bioactive substance secreted by adipose tissue, adipokine plays an important role in bone and joint diseases, metabolic diseases, and breast cancer. During IVDD, most adipokines can activate multiple signaling pathways by binding to autoreceptors, cause the proliferation and apoptosis of cells and proinflammatory and anti-inflammatory factors parasecretions in the intervertebral disc, and lead to imbalance of intradiscal metabolism and establishment of the initial inflammatory environment, and finally cause the IVDD.ConclusionAdipokines, as a biologically active substance with metabolic and immunomodulatory functions, play important roles in the occurrence, development, and biological treatment of IVDD.
摘要:目的:探討聯合應用激光汽化減壓(percutaneous laser disc discompression,PLDD)、射頻熱凝靶點消融、臭氧注射治療腰椎間盤突出癥的的個體化選擇。方法: 自2006年6月,在CT引導下選擇性聯合應用PLDD、射頻和臭氧治療腰椎間盤突出癥患者267例,突出椎間盤的特點個體化選擇穿刺路徑和治療方法;其中PLDD聯合臭氧治療92例(A組),射頻聯合臭氧治療67例(B組),PLDD、射頻和臭氧三者聯合治療108例(C組)。結果:所有患者均順利完成手術,于術后1周、1個月,3個月及6個月隨訪記錄VAS評分和Macanab優良率。三組患者VAS評分經方差分析,手術前、后有顯著性差異(Plt;0.05),術后1周至6個月的VAS評分統計無顯著性差異(Pgt;0.05);術后三組間VAS評分、Macanab優良率比較無顯著性差異(Pgt;0.05)。結論: 選擇性聯合應用微創技術進行個體化的立體治療,具有擴大微創手術適應癥、提高手術療效的優勢,值得推廣和利用。Abstract: Objective: To investigate the selectivity and individualization of using percutaneous laser disc discompression(PLDD) and ozone injection combined with radiofrequency thermocoagulation and target ablation curing lumbar intervertebral disc protrusion. Methods: From June 2006, 267 lumbar disc herniation cases were operated that guided by CT, the characteristic of the liable disc was confirmed by magnetic resonance imaging and CT before the procedure. 92 cases (A group) were treated by PLDD combined with ozone injection,67 case were treated by radiofrequency thermocoagulation and target ablation combined with ozone injection, 108 cases were treated by PLDD and ozone injection combined with radiofrequency thermocoagulation and target ablation. Results: All case been successfully operated, the theraptic effect was evaluated by comparing the value of VAS and excellent and good rate of therapy at preoperation and at 1 week, 1month,3 months, 6 months after operation. The value of VAS in three groups at postoperation were remarkably lower than preoperation (Plt;0.05). The excellent and good rate of therapy at 6 months was respectively 94.5％ in group A,94.0％ in group B and 95.4％ in group C,no significant difference was observed between the three groups(Pgt;0.05).Conclusion: The selectivity and individualization of using PLDD and ozone injection combined with radiofrequency thermocoagulation and target ablation curing lumbar intervertebral disc protrusion can enlarge the indication and improve the clinical curative effect, it should be spreaded in clinic.
ObjectiveTo evaluate the effectiveness of anterior lumbar interbody fusion (ALIF) with self-locked Cage in the treatment of central type lumbar intervertebral disc protrusion and recessive lumbar segmental instability. MethodsBetween March 2010 and February 2012, 31 patients with central type lumbar intervertebral disc protrusion and recessive lumbar segmental instability were treated with decompression and ALIF assisted by self-locked Cage through the mini-incision and retroperitoneal approach. There were 20 males and 11 females with the mean age of 46 years (range, 34-58 years). And the disease duration ranged from 5 to 32 months (mean, 16 months). The lesion located at the L3,4 level in 2 cases, L4,5 in 20 cases, and L5, S1 in 9 cases. The operation time, intraoperative blood loss, bedridden time, hospitalization time, and complications were recorded. The effectiveness was evaluated by Oswestry disability index (ODI) and visual analogue scale (VAS). Lumbar X-ray films and three-dimensional CT scan were taken to evaluate the fusion and the variation of the height and Cobb angle of intervertebral space. ResultsThe mean operation time was 102 minutes; the mean intraoperative blood loss was 121 mL; the mean bedridden time was 5 days; and the mean hospitalization time was 11 days. Intraoperative peritoneum tear and ascending lumbar vein tear, postoperative cerebrospinal fluid leakage, pain at donor site, and asymmetric elevated skin temperature of the lower extremity occurred in 2 cases, 1 case, 1 case, 4 cases, and 2 cases respectively, which were relieved after symptomatic treatment. All cases were followed up 12-28 months (mean, 20 months). No infection, recurrence, deep venous thrombosis, or retrograde ejaculation was observed after operation. MRI showed complete decompression at 3 months after operation. At last follow-up, the scores of ODI, VAS of lumbars and lower limbs, the intervertebral height, and Cobb angle were significantly improved when compared with preoperative ones (P<0.05); CT scan showed bone fusion in all cases. ConclusionThe clinical outcome of ALIF with self-locked Cage through mini-incision and retroperitoneal approach is satisfactory in treatment of central type lumbar intervertebral disc protrusion and recessive lumbar segmental instability. It can retain the posterior spinal construction and has the advantages of less trauma and bleeding, immediate stability, high bone fusion rate, and so on.
Objective To fabricate a novel composite scaffold with acellular demineralized bone matrix/acellular nucleus pulposus matrix and to verify the feasibility of using it as a scaffold for intervertebral disc tissue engineering through detecting physical and chemical properties. Methods Pig proximal femoral cancellous bone rings (10 mm in external diameter, 5 mm in internal diameter, and 3 mm in thickness) were fabricated, and were dealed with degreasing, decalcification, and decellularization to prepare the annulus fibrosus phase of scaffold. Nucleus pulposus was taken from pig tails, decellularized with Triton X-100 and deoxycholic acid, crushed and centrifugalized to prepare nucleus pulposus extracellular mtrtix which was injected into the center of annulus fibrosus phase. Then the composite scaffold was freeze-dryed, cross-linked with ultraviolet radiation/carbodiimide and disinfected for use. The scaffold was investigated by general observation, HE staining, and scanning electron microscopy, as well as porosity measurement, water absorption rate, and compressive elastic modulus. Adipose-derived stem cells (ADSCs) were cultured with different concentrations of scaffold extract (25%, 50%, and 100%) to assess cytotoxicity of the scaffold. The cell viability of ADSCs seeded on the scaffold was detected by Live/Dead staining. Results The scaffold was white by general observation. The HE staining revealed that there was no cell fragments on the scaffold, and the dye homogeneously distributed. The scanning electron microscopy showed that the pore of the annulus fibrosus phase interconnected and the pore size was uniform; acellular nucleus pulposus matrix microfilament interconnected forming a uniform network structure, and the junction of the scaffold was closely connected. The novel porous scaffold had a good pore interconnectivity with (343.00 ± 88.25) μm pore diameter of the annulus fibrosus phase, 82.98% ± 7.02% porosity and 621.53% ± 53.31% water absorption rate. The biomechanical test showed that the compressive modulus of elasticity was (89.07 ± 8.73) kPa. The MTT test indicated that scaffold extract had no influence on cell proliferation. Live/Dead staining showed that ADSCs had a good proliferation on the scaffold and there was no dead cell. Conclusion Novel composite scaffold made of acellular demineralized bone matrix/acellular nucleus pulposus matrix has good pore diameter and porosity, biomechanical properties close to natural intervertebral disc, non-toxicity, and good biocompatibility, so it is a suitable scaffold for intervertebral disc tissue engineering.