Interbody Fusion Cages Research Articles

Safety and efficacy of polyetheretherketone (PEEK) cages in combination with one-stage posterior debridement and instrumentation in Lumbar Brucella Spondylitis

ObjectiveThe aim of this study was to explore the efficacy and safety of surgical treatment of lumbar brucella spondylitis with PEEK cages combined with one-stage posterior debridement and instrumentation. MethodsWe performed a retrospective study for adult patients with lumbar brucella spondylitis. Medical records, imaging studies and laboratory data were collected, back pain was measured by employing the visual analog scale (VAS) and the neurological status was evaluated by using the American Spinal Injury Association (ASIA) scale. ResultsA total of 61 consecutive patients (42 males and 19 females) were enrolled with the mean age at presentation of 56.33 ± 9.16 years old. L3−4 and L4−5 were the most infected levels with the ratios of 21.31 % and 19.67 % respectively. Moreover, 12 (19.67 %) patients suffered multiple-level infection and 5 (5/12, 41.67 %) of them had non-contiguous spondylitis. In addition, epidural masses were found in 26 (42.62 %) cases and psoas abscesses were found in 14 (22.95 %) cases. The number of operative segment depended on operation indications (failure of conservative measures, instability, kyphosis, intractable pain and/or neurological impairment). VAS scores were significantly improved at 6-weeks and the last follow-up. Among the 23 (37.70 %) patients with neurological deficits, 19 (19/23, 82.61 %) obtained a full recovery and 4 (4/23, 17.39 %) had been improved incompletely during the last follow-up. All patients exhibited satisfactory bone fusion during the last follow-up. Local infection of surgical site was identified in 6 (9.84 %) cases and no other surgery-related complications were found. ConclusionUse of PEEK cages for interbody fusion is feasible and safe in patients suffering from lumbar brucella spondylitis.

Biomechanical Evaluation of two different types of Interbody Cages in Posterior Lumbar Interbody Fusion

Biomechanical Evaluation of two different types of Interbody Cages in Posterior Lumbar Interbody Fusion

Porous fusion cage design via integrated global-local topology optimization and biomechanical analysis of performance

Porous fusion cage is considered as a satisfactory substitute for solid fusion cage in transforaminal lumbar interbody fusion (TLIF) surgery due to its interconnectivity for bone ingrowth and appropriate stiffness reducing the risk of cage subsidence and stress shielding. This study presents an integrated global-local topology optimization approach to obtain porous titanium (Ti) fusion cage with desired biomechanical properties. Local topology optimizations are first conducted to obtain unit cells, and the numerical homogenization method is used to quantified the mechanical properties of unit cells. The preferred porous structure is then fabricated using selective laser melting, and its mechanical property is further verified via compression tests and numerical simulation. Afterward, global topology optimization is used for the global layout. The porous fusion cage obtained by the Boolean intersection between global structural layout and the porous structure decreases the solid volume of the cage by 9% for packing more bone grafts while achieving the same stiffness to conventional porous fusion cage. To eliminate stress concentration in the thin-wall structure, framework structures are constructed on the porous fusion cage. Although the alleviation of cage subsidence and stress shielding is decelerated, peak stress on the cage is significantly decreased, and more even stress distribution is demonstrated in the reinforced porous fusion cage. It promises long-term integrity and functions of the fusion cage. Overall, the reinforced porous fusion cage achieves a favorable mechanical performance and is a promising candidate for fusion surgery. The proposed optimization approach is promising for fusion cage design and can be extended to other orthopedic implant designs.

Lumbar disc height and vertebral Hounsfield units: association with interbody cage subsidence.

Postoperative subsidence of transforaminal lumbar interbody fusion (TLIF) cages can result in loss of lordosis and foraminal height, and potential recurrence of nerve root impingement. The objectives of this study were to determine factors associated with TLIF cage subsidence. Specifically, the authors sought to determine if preoperative disc height compared to cage height could be used to predict TLIF interbody cage subsidence, and if decreased postoperative vertebral Hounsfield units (HUs) predisposed to cage subsidence. The authors retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. The preoperative disc height was measured for the operative and adjacent-level disc on MRI. The difference between cage and disc heights was measured and compared between the subsidence and nonsubsidence groups. The average HUs of the L1 vertebral body were measured on CT scans. Eighty-nine patients were identified with complete imaging and follow-up information. Forty-five patients (50.6%) had evidence of interbody cage subsidence on follow-up CT. The average cage subsidence was 5.5 mm (range 2.2-10.8 mm). The average implant height was significantly higher in the subsidence group compared to the nonsubsidence group (12.6 vs 11.2 mm). Additionally, the difference between cage height and preoperative adjacent-level disc height was also significantly larger in the subsidence group (3.8 vs 1.2 mm). First lumbar vertebral body (L1) HUs were significantly higher in the nonsubsidence versus the subsidence group (167.8 vs 137.71 HUs, p = 0.002). Multivariate logistic regression analysis identified suprajacent disc height and L1 HUs to be independent predictors of interbody cage subsidence. Receiver operating characteristic curves identified a suprajacent to cage height difference > 1.3 mm to have a 93.3% sensitivity for cage subsidence. This study is the first of its kind to demonstrate the association between vertebral body HUs and suprajacent disc height with the development of interbody cage subsidence after TLIF. The authors found that patients with lower HUs in the L1 vertebral body were more likely to experience subsidence, regardless of surgical level. Additionally, the study demonstrated that interbody cage height > 1.3 mm above the height of the suprajacent level is an independent risk factor for cage subsidence, with 93.3% sensitivity. These findings suggest that these factors may be utilized to create a template preoperatively for intraoperative cage selection.

Technique of Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

Biportal endoscopic transforaminal lumbar interbody fusion (TLIF) may have advantages of minimally invasive fusion surgery as well as those of endoscopic surgery. The purpose of this study was to present the biportal endoscopic TLIF technique along with video presentations and a review of the literature on this technique. Basically, the biportal endoscopic TLIF technique is similar to minimally invasive TLIF with a tubular retractor. There were 2 options in the biportal endoscopic TLIF procedures. The first was the insertion of one long TLIF cage and the other was the insertion of 2 short posterior lumbar interbody fusion (PLIF) cages. After the interbody fusion procedures, percutaneous pedicles screw fixation was performed. Biportal endoscopic TLIF achieved complete neural decompression through laminectomy and facetectomy like conventional TLIF. Endplate preparation was performed completely under a clear and magnified endoscopic view. It was also feasible to insert a large TLIF cage or 2 cages for PLIF without exiting nerve root injury. Biportal endoscopic TLIF might have the advantages of endoscopic surgery as well as minimally invasive fusion surgery. Direct neural decompression, endplate preparation under endoscopic guidance, and the insertion of a large TLIF cage or 2 PLIF cages may be the merits of biportal endoscopic lumbar fusion procedures.

KUSA-A1 mesenchymal stem cells response to PEEK-Si3N4 composites

Poly-Ether-Ether-Ketone (PEEK) is a structural biopolymer with various biomedical applications, from spinal cages to dental prosthetics. Due its high chemical stability combined with good mechanical strength, PEEK is considered to be one of the most successful bio-inert polymers ever developed. In this work, a mixture of PEEK and β-Si3N4 was used to produce a composite material which combined the mechanical properties of the polymer with the bioactive effects of a reinforcing ceramic, in particular its good osteoconductivity. When tested with KUSA-A1 mesenchymal cells, the composite material resulted in a higher production of bone tissue when compared to standard PEEK or biomedical titanium alloy. On the other hand, the composite showed poor osteogenic differentiation as evaluated by ALP. Tests performed using various spectroscopic techniques showed that the bone tissue formed has a balanced mineral-to-matrix ratio, similar to that of healthy bone tissue.

Injection of Calcium Phosphate Apatitic Cement/Blood Composites in Intervertebral Fusion Cages: A Simple and Efficient Alternative to Autograft Leading to Enhanced Spine Fusion.

An animal model of anterior lumbar arthrodesis was designed to investigate whether a calcium phosphate cement (CPC) mixed with autologous whole blood might favourably compete with autograft for enhanced spine fusion. The objective of this study was to use a large animal model to investigate a new approach for spine fusion which consists in the injection of a highly resorbable CPC / blood composite to fill the interbody fusion cage, once placed in the intervertebral space. Spinal fusion via intervertebral arthrodesis is a common surgical procedure for which the gold standard consists in filling the internal hollow part of the cage with bone autograft. However, this approach suffers from some drawbacks, including a second surgical site which requires additional time spent in the surgical room, and the occurrence of additional new pain on the bone harvesting site along with risks of long-term morbidity. An animal model of anterior lumbar arthrodesis involved 14 sheep that received a fusion cage in two non-adjacent lumbar levels. For one-half of the animals, the cages were filled after impaction by injection of a CPC/blood composite in one level and the blood-free CPC reference in the other. For the other seven animals, the CPC/blood composite was compared to bone autograft. SEM and histological examination of the explants gave evidence of a good osteointegration for the three types of implanted materials. For the first group, no spine fusion was observed for the blood-free CPC reference while a highly successful spine fusion (6/7 cages) was present for the CPC/blood composite, three months after surgery. For the second group, successful arthrodesis was observed for 57% (4/7) of cages filled with iliac autograft, while the fusion rate was 71% (5/7) in the case of cages filled with the CPC/blood composite. This study reports that the observed fusion rate when filling the cage with a calcium phosphate cement mixed with autologous whole blood was at least as good as results obtained with autograft. Once placed in the intervertebral space, the cage was easily and homogeneously filled with the CPC/blood composite, and this new strategy might thus offer a less invasive option for intervertebral spine fusion. N/A.

Polyetheretherketone Versus Titanium Cages for Posterior Lumbar Interbody Fusion: Meta-Analysis and Review of the Literature.

Polyetheretherketone Versus Titanium Cages for Posterior Lumbar Interbody Fusion: Meta-Analysis and Review of the Literature.

Minimally invasive transforaminal lumbar interbody fusion

Instrumented fusion of lumbar motion segments using aminimally invasive technique. Degenerative disc disease, segmental degeneration, degenerative spondylolisthesis, isthmic spondylolisthesis, pseudarthrosis, other spinal lumbar instabilities, disc prolapse, revision for failed back surgery syndrome, unilateral neuroforaminal stenosis, facet joint arthrosis. High-grade spondylolisthesis (Meyerding gradesIII/IV, spondyloptosis), bilateral nerve root compression, vertebral fractures, tumors, high-grade spinal instabilities, primary spinal deformities, multilevel pathologies. Ipsilateral minimally invasive approach using aself-retaining tubular retractor system, partial or complete facetectomy, insertion of pedicle screws, transforaminal lumbar interbody fusion (TLIF) cage insertion preserving nerve roots, fusion, contralateral insertion of pedicle screws using aminimally invasive or percutaneous technique. Mobilization with physiotherapy, followed by standing plain x‑ray examinations, clinical and radiological follow-up at 6-12weeks and 1year postoperatively. Fusion rates >90%, comparable to open TLIF. Complication rates lower than open TLIF. Shorter radiation exposure during surgery, lower blood loss. Less surgical trauma leads to shorter hospitalization time and earlier return-to-work. Oswestry Disability index (ODI) scores and visual analog scale (VAS) scores significantly decreased.

Different interbody fustion cages and combined fixation through intermuscular approach for lumbar diseases:a case control study

To explore the clinical effect of combined fixation and interbody bone grafting through intermuscular approach with different fusion cages in the treatment of single segment lumbar diseases. From June 2014 to December 2016, the clinical data of 123 cases of single segment lumbar diseases were analyzed retrospectively, including 44 males and 79 females, aged 22 to 60 years old, with the diseases course of 6 to 84 months. The disease types involved lumbar disc degeneration in 65 cases, lumbar spinal stenosis in 30 cases, MeyerdingⅠslip in 21 cases, giant lumbar disc herniation in 7 cases. Lesions was L3, 4 in 5 cases, L4, 5 in 101 cases, L5S1 in 17 cases. According to the application of different interbody fusion cage, patients were divided into single common cage group, double common cage group and banana type cage group. The operation time, intraoperative hemorrhage, postoperative incision drainage fluid and incision length were observed in three groups; VAS score of lumbar incision and JOA score of preoperative and final follow up were recorded 72 hours after operation;the intervertebral space height, Cobb angle of lumbar coronal and sagittal plane before and after operation, and interbody fusion 12 months after operation were observed by imaging data. There was no significant difference in incision length, operation time, intraoperative bleeding volume, postoperative drainage volume and VAS score of lumbar incision 72 hours after operation among three groups (P>0.05). All cases were followed up for 12 to 36 (23.70±4.52) months. The height of intervertebral space in three groups recovered significantly (P<0.05), at the last follow-up, there were different degrees of loss, the loss degree of single common fusion cage group>banana type fusion cage group>double common fusion cage group. At the last follow-up, the Cobb angle in the coronaland sagittal planes of the three groups were significantly improved (P<0.05). During the follow-up, there were 42 cases of fusion cage subsidence, including 26 cases in the single common cage group, 5 cases in the double common cage group, 11 cases in the banana cage group, the difference was statistically significant (P<0.05). At 12 months after operation, the interbody fusion rate was 83% in the single common cage group, 95% in the double common cage group and 90% in the banana cage group, the interbody fusion rate in the two common cage group and the banana cage group was better than that in the single common cage group. No obvious degeneration was observed in the adjacent segments. At the last follow-up, the JOA scores of the three groups were statistically significant (P<0.05). The incidence of single common fusion cage group was 10%(4 / 42), that of double common fusion cage group was 9%(4 / 43), and that of banana fusion cage group was 10%(4 / 39). There was no significant difference among the three groups. Through the intermuscular approach, single pedicle screw and contralateral facet screw were used for fixation, and single common fusion cage, double common fusion cage or banana type fusion cage were used for interbody grafting to treat single segment lumbar disease. Although the application of different fusion cage could not increase the axial strength of fixed segment, the speed of fusion was accelerated by increasing the contact area, and the quality of the fusion cage reduces the settlement of the cage and the loss of the height of the intervertebral space. Therefore, two interbody fusion cages implanted in one side are of positive clinical significance for the fixation of unilateral pedicle screw combined with contralateral facet screw, without prolonging the operation time and increasing the complications.

Effects of Material Properties in Spinal Fusion Cage for Lumbar Vertebrae

Vertebral endplate subsidence failure will increase the possibility of mechanical instability in the lumbar spinal fusion. The spinal implants of cages are many type of design that can be use in spinal fusion and the type of material also been considerate. Posterior lumbar interbody fusion (PLIF) cage is believed to maintain the stability and to promote fusion between vertebrae. Different type biomaterial of cage was made by metal, ceramic and polymer, also composite. The Posterior Instrument (PI) such pedicle screw and rod was made by Titanium Alloy. The aim of this study was to examine the effects of different materials of cage in lumbar fusion. 3D vertebrae model (L3-L4) with interbody fusion using different material properties such as PEEK, PLA, Cobalt Chromium, Titanium Alloy and Stainless Steel. A fusion model with pedicle screw systems L3–L4 levels were reconstructed based on the respective surgical protocols. The stress distribution and total deformation of the cage were measured under different compressive loading conditions and motion. Results show that the titanium alloy is the best material for metal categories while PLA (Poly lactic acid) for composite category.

Polyetheretherketone Versus Titanium Cages for Posterior Lumbar Interbody Fusion: Meta-Analysis and Review of the Literature.

ObjectiveLumbar fusion with implantation of interbody cage is a common procedure for treatment of lumbar degenerative disease. This study aims to compare the fusion and subsidence rates of titanium (Ti) versus polyetheretherketone (PEEK) interbody cages after posterior lumbar interbody fusion and investigate the effect of clinical and radiological outcomes following fusion on patient-reported outcomes. MethodsA systematic search strategy of 4 electronic databases (MEDLINE, Embase, Web of Science, and Cochrane) was conducted using different MeSH (medical subject headings) terms until January 2020. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated using fixed and random-effect models based upon the heterogeneity (I2) to estimate the association between interbody cages and the measured outcomes. ResultsA total of 1,094 patients from 11 studies were reviewed. The final analysis included 421 patients (38.5%) who had lumbar surgery using a Ti and/or a Ti-coated interbody cage and 673 patient (61.5%) who had lumbar surgery using a PEEK cage. Overall, PEEK interbody devices were associated with a significantly lower fusion rate compared with Ti interbody devices (OR, 0.62; 95% CI, 0.41–0.93; p = 0.02). There was no difference in subsidence rates between Ti and PEEK groups (OR, 0.91; 95% CI, 0.54–1.52; p = 0.71). Also, there were no statistically significant differences in visual analogue scale (VAS)-low back pain (p = 0.14) and Japanese Orthopedic Association scale (p = 0.86) between the 2 groups. However, the PEEK group had lower odds of leg pain after surgery compared to the Ti group (OR [VAS-leg], 0.61; 95% CI, 0.28–0.94; p = 0.003). ConclusionTi and Ti-coated PEEK cages used for posterior lumbar interbody fusion are associated with similar rates of subsidence, but a higher rate of fusion compared to PEEK interbody cages. Randomized controlled trials are needed to better assess the effect of cage materials and potential factors that could influence the outcomes of interbody lumbar fusion.

Effects of porogen morphology on the architecture, permeability, and mechanical properties of hydroxyapatite whisker reinforced polyetheretherketone scaffolds

Porous polyetheretherketone (PEEK) and bioactive hydroxyapatite (HA) reinforced PEEK scaffolds have attracted recent interest for enabling biologic fixation of orthopaedic and spinal implants, such as interbody spinal fusion cages. Porous PEEK and HA-PEEK scaffolds have been prepared by compression molding and leaching a fugitive porogen, most commonly NaCl salt crystals which exhibit a cubic morphology. Ellipsoidal or spherical porogen particles have been suggested to improve pore interconnectivity and permeability in scaffolds through improved porogen particle contact compared with a cubic porogen, but a direct comparison without concomitant effects from other factors is lacking. Therefore, the objective of this study was to investigate the effects of the porogen morphology on the architecture, permeability, and mechanical properties of bioactive HA whisker reinforced PEEK scaffolds. HA whisker reinforced PEEK scaffolds were prepared using a cubic or ellipsoidal NaCl porogen of equivalent size at multiple, equivalent levels of porosity and a constant level of HA reinforcement. Scaffolds prepared with an ellipsoidal porogen exhibited greater pore interconnectivity, indicated by a lower specific surface area measured by micro-computed tomography, and greater permeability than scaffolds prepared with a cubic porogen at 75–85% porosity. Compressive mechanical properties were not affected by the porogen morphology. Thus, an ellipsoidal porogen facilitated improved pore interconnectivity and permeability without compromising mechanical properties, and offers a means to circumvent an otherwise inherent design tradeoff between the benefit of increased porosity on permeability and the detriment of increased porosity on mechanical properties.

Thermal localization improves the interlayer adhesion and structural integrity of 3D printed PEEK lumbar spinal cages

Additive manufacturing (AM) is a potential application for polyetheretherketone (PEEK) spinal interbody fusion cages, which were introduced as an alternative to titanium cages because of their biocompatibility, radiolucency and strength. However, AM of PEEK is challenging due to its high melting temperature and thermal gradients. Although fused filament fabrication (FFF) techniques have been shown to 3D print PEEK, layer delamination was identified in first generation FFF PEEK cages [1]. A standard cage design [2] was 3D printed with a second generation FFF PEEK printer. The effect of changing layer cooling time on the FFF cages’ mechanical strength was investigated by varying nozzle sizes (0.2 mm and 0.4 mm), print speeds (1500 and 2500 mm/min), and the number of cages printed in a single build (1, 4 and 8). To calculate the porosity percentage, FFF cages were micro-CT scanned prior to destructive testing. Mechanical tests were then conducted on the FFF cages according to ASTM F2077 [2]. Although altering the cooling time of a layer was not able to change the failure mechanism of FFF cages, it was able to improve cages’ mechanical strength. Printing a single cage per build was associated with a higher ultimate load than printing multiple cages per build. Regardless of the cage number printed per build, cages printed with bigger nozzle diameter achieved higher ultimate load compared to cages printed with smaller nozzle diameter. Printing with a bigger nozzle diameter resulted in less porosity, which might have an additional benefit on the interlayer delamination failure mechanism.

A Long-Term Follow-up, Multicenter, Comparative Study of the Radiologic, and Clinical Results Between a CaO-SiO2-P2O5-B2O3 Bioactive Glass Ceramics (BGS-7) Intervertebral Spacer and Titanium Cage in 1-Level Posterior Lumbar Interbody Fusion

This is a prospective, stratified randomized, multicenter, 4-year follow-up study. The authors aimed to evaluate the long-term clinical efficacy and safety of CaO-SiO2-P2O5-B2O3 glass ceramics (BGS-7) spacers in 1-level posterior lumbar interbody fusion (PLIF) at a 4-year follow-up. According to 1-year follow-up results, BGS-7 spacer showed similar fusion rates and clinical outcomes compared with titanium cage. A long-term follow-up study beyond 2 years is necessary to investigate the status of intervertebral bone graft volumes. Moreover, longer follow-up is mandatory to also evaluate the safety and efficacy of BGS-7 spacers, because they remain in the intervertebral space for a long time. In this prospective, randomized, multicenter, 4-year follow-up study, we evaluated 62 of the 74 patients who underwent 1-level PLIF. During 1-level PLIF, titanium cages filled with autologous local bone were inserted into the control group patients and BGS-7 spacers were inserted to the experimental group patients. Bone fusion was evaluated by plain radiography and thin-section computed tomography. Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), Short Form-36 Health Survey (SF-36), and evaluation of safety were conducted after 48 months. Computed tomography scan showed a bone fusion rate of 90.6% in the BGS-7 spacer group and 93.3% in the control group, with no significant differences between groups. The BGS-7 spacer group showed a significantly larger area directly fused to the endplate than the control group (P<0.001). The BGS-7 spacer group showed a significant increase in the fused area compared with the titanium group at 1- and 4-year follow-up. The ODI, SF-36, back pain, and lower limb pain in both groups showed significant improvement after surgery, and no significant differences were observed between the groups. Both groups showed no additional adverse events. The 4-year follow-up study showed similar fusion rates and clinical outcomes in both the BGS-7 spacer and autologous bone with a titanium cage in 1-level PLIF. However, the BGS-7 spacer implants showed a larger area of fusion with the endplates than that of autologous bone with a titanium cage. Therefore, the results demonstrated that the BGS-7 spacer can be considered as a novel intervertebral spacer to achieve successful spinal fusion without safety concerns for long-term use.

Randomized Controlled Trial of Posterior Lumbar Interbody Fusion With Ti- and CaP-Nanocoated Polyetheretherketone Cages: Comparative Study of the 1-Year Radiological and Clinical Outcome.

Polyetheretherketone (PEEK) is a popular material for posterior lumbar interbody fusion (PLIF) cages, although osseointegration remains limited. To optimize PEEK cage characteristics, titanium (Ti) and calcium phosphate (CaP) nanocoatings have been developed with proven mechanical safety. This multicenter randomized controlled trial compared the clinical and radiological outcome parameters of nanocoated and uncoated PEEK cages, up to 1 year after surgery. Standard open PLIF surgery was performed on 127 patients, randomized in 3 groups: Ti-nanocoated (n = 44), CaP-nanocoated (n = 46), and uncoated PEEK cages (n = 37). Clinical assessments up to 1 year after surgery included visual analogue scales (VASs), Oswestry Disability Index (ODI), and 36-Item Short Form Survey (SF-36). Primary radiological outcome parameters were implant stability and fusion status, assessed by x-ray and computed tomography (CT) scans. Patients, surgeons, and postsurgery analysts were blinded. PLIF surgery with all cage types resulted in significant improvements of clinical outcome parameters, exceeding the minimum clinically important differences. No significant differences in VAS, ODI, or SF-36 scores were found among the 3 groups. One year after the surgery, 65.6% of patients with uncoated PEEK cages achieved definite fusion. Significantly more patients with nanocoated PEEK cages achieved definite fusion: 93.9% for Ti nanocoating (P = .0034) and 88.0% for CaP nanocoating (P = .032). No significant differences in fusion were found between the nanocoated cage types (P = .4318). The similar clinical outcome improvements after 1 year suggest that nanocoated PEEK cages have the same safety and efficacy as the clinically accepted uncoated PEEK cages. Furthermore, nanocoated PEEK cages achieved a better fusion rate than uncoated PEEK cages at the 1-year follow-up. A 5-year follow-up study is warranted to revisit the findings. The safety, efficacy, and enhanced osseointegration of nanocoated PEEK cages were demonstrated. Osseointegration is a significant predictor of positive long-term clinical outcomes and improved implant longevity, implying a clinical added value of nanocoatings. Enhanced osseointegration becomes even more important in minimally invasive spine surgery and in patients at risk for incomplete fusion.

Population-based design and 3D finite element analysis of transforaminal thoracic interbody fusion cages

ObjectiveTo compare the biomechanical characteristics of two transforaminal thoracic interbody fusion cages based on the Chinese population thoracic anatomy. MethodComputed tomography scans of the thoracic spine of 150 patients from our institution were collected and analysed. Two cages were designed based on the anatomical parameters of these patients. Further, we used 3D finite element analysis models to compare the stability of two cages by using Mimics 17.0 and ANSYS 15.0 software. ResultTwo kinds of thoracic cages (box and kidney-shaped) were designed. Under the displacement working condition, the two new fusion cages could achieve immediate postoperative stability, but the kidney-shaped cage was better than the box-shaped cage. Under the stress working condition, no highly focused stress area was found in either cages, but the kidney-shaped cage experienced less stress than the box-shaped cage. ConclusionThe kidney-shaped cage is more stable and experiences lesser stress than the box-shaped cage after thoracic intervertebral fusion, and it is more suitable for Chinese transforaminal thoracic interbody fusion. The translational potential of this articleThis article is about thoracic fusion cage design and finite element analysis (FEA) analysis based on the thoracic anatomy parameters. For there is currently no suitable thoracic fusion cage for transforaminal thoracic interbody fusion, the results in this article may have the potential of transferring the two designed cages into clinical use.

Minimally Invasive Versus Open TLIF in the Management of Lumbar Spondylolisthesis

This study aims to assess the difference between minimal invasive TLIF surgery and conventional TLIF surgery in cases of lytic spondylolisthesis, as regards pain, disability, hospital stay and complications. Lytic Spondylolisthesis patients may require fusion of one or more spinal segments to treat their condition adequately. The chances of achieving a successful lumbar spinal fusion has increased. TLIF technique is gradually being accepted in these cases and widely used by most spine surgeons. Minimal invasive TLIF is a recent trend for spinal fusion. This is a prospective randomized comparative study conducted from March 2016 to December 2018 included forty patients with low grade lytic spondylolisthesis that underwent surgeries. Twenty patients underwent MI-TLIF through percutaneous posterior lumbar pedicular screw fixation, microscopic minimally invasive transformational discectomy and interbody cage fusion (patients group “A”) and another twenty patients underwent traditional open posterior lumbar pedicular screw fixation and TLIF (control group “B”). In our results, both surgical techniques showed improvement in pain and function within 12 months (follow up period), but group A showed statistically significant improvement in pain and function in the 1^st three months. Regarding blood loss, need for transfusion and hospital stay, group A showed statistically significant better results. As a conclusion, minimally invasive TLIF is a better option in surgical management of spondylolisthesis especially in the early postoperative period.

Comparison of fusion rate between titanium-coated PEEK cage and PEEK cage for posterior lumbar interbody fusion -80 case study with single surgeon-

Comparison of fusion rate between titanium-coated PEEK cage and PEEK cage for posterior lumbar interbody fusion -80 case study with single surgeon-

Scoliosis surgery in adulthood: what challenges for what outcome?

Adolescent idiopathic scoliosis that has progressed over time, de novo scoliosis, and degenerative scoliosis represent different types of adult spinal deformity (ASD). Functional impairment and muscular fatigue are due to sagittal and coronal imbalance of the trunk. Surgical treatment can provide a significant improvement of three-dimensional (3D) thoracolumbar alignment, function, and health-related quality of life (QoL). A patient-specific benefit-risk assessment, including clinical expectations, comorbidities, and the spinal deformity itself, has to be done preoperatively since the risk for mechanical complications is relatively high. Minimal invasive techniques combine posterior percutaneous instrumentation and lateral interbody fusion cages which enables vertebral realignment and indirect foraminal stenosis decompression. This strategy seems appropriate in mild and moderate ASD with a limited number of degenerated segments in the lumbar spine and remaining curve flexibility. Severe ASD needs to be addressed by open surgery, which combines posterior instrumentation, interbody fusion, and osteotomies in stiff deformities. Longer posterior instrumentation of the thoracolumbar spine, the sacrum, and the pelvis carries a risk for mechanical complications such as non-union and proximal junctional kyphosis (PJK). Modern surgical techniques including circumferential lumbosacral fusion and double rods might lower the risk for non-union. Accurate sagittal alignment planning, setting the lumbar sagittal apex according to pelvic incidence, and segmental lordosis distribution, are mandatory for minimizing the risk of PJK.