Factors that influence the results of indirect decompression employing oblique lumbar interbody fusion

BACKGROUND Indirect decompression is one of the potential benefits of anterior reconstruction in patients with spinal stenosis.On the other hand,the reported rate of revision surgery after indirect decompression highlights the necessity of working out prediction models for the radiographic results of indirect decompression with assessing their clinical relevance.AIM To assess factors that influence radiographic and clinical results of the indirect decompression in patients with stenosis of the lumbar spine.METHODS This study is a single-center cross-sectional evaluation of 80 consecutive patients(17 males and 63 females)with lumbar spinal stenosis combined with the instability of the lumbar spinal segment.Patients underwent single level or bisegmental spinal instrumentation employing oblique lumbar interbody fusion(OLIF)with percutaneous pedicle screw fixation.Radiographic results of the indirect decompression were assessed using computerized tomography,while MacNab scale was used to assess clinical results.RESULTS After indirect decompression employing anterior reconstruction using OLIF,the statistically significant increase in the disc space height,vertebral canal square,right and left lateral canal depth were detected(Р<0.0001).The median(M)relative vertebral canal square increase came toМ=24.5%with 25%-75%quartile border(16.3%;33.3%)if indirect decompression was achieved by restoration of the segment height.In patients with the reduction of the upper vertebrae slip,the median of the relative increase in vertebral canal square accounted for 49.5%with 25%-75%quartile border(2.35;99.75).Six out of 80 patients(7.5%)presented with unsatisfactory results because of residual nerve root compression.The critical values for lateral recess depth and vertebral canal square that were associated with indirect decompression failure were 3 mm and 80 mm2 respectively.CONCLUSION Indirect decompression employing anterior reconstruction is achieved by the increase in disc height along the posterior boarder and reduction of the slipped vertebrae in patients with degenerative spondylolisthesis.Vertebral canal square below 80 mm2 and lateral recess depth less than 3 mm are associated with indirect decompression failures that require direct microsurgical decompression.

Risk factors and care of early surgical site infection after primary posterior lumbar interbody fusion

Objectives:To explore the risk factors and nursing measures of early surgical site infection(SSI)after posterior lumbar interbody fusion(PLIF).Methods:A total of 468 patients who received PLIF in our hospital from January 2017 to June 2020 were enrolled into this study.According to the occurrence of early SSI,the patients were divided into two groups,and the general data were analyzed by univariate analysis.Multivariate logistic regression analysis was conducted with the dichotomous variable of whether early SSI occurred and other factors as independent variables to identify the risk factors of early SSI and put forward targeted prevention and nursing measures.Results:Among 468 patients with PLIF,18 patients developed early SSI(3.85%).The proportion of female,age,diabetes mellitus and urinary tract infection(UTI),operation segment,operation time,post-operative drainage volume,and drainage time were significantly higher than those in the uninfected group,with statistical significance(P<0.05),whereas the preoperative albumin and hemoglobin in the infected group were significantly lower than those in the uninfected group,with statistical significance(P<0.05).There was no significant difference between the two groups in the American Society of Anesthesiologists(ASA)grading,body mass index(BMI),complications including cardiovascular and cerebrovascular diseases or hypertension(P>0.05).Logistic regression analysis showed that preoperative diabetes mellitus(OR=2.109,P=0.012)/UTI(OR=1.526,P=0.035),prolonged drainage time(OR=1.639,P=0.029)were risk factors for early SSI.Men(OR=0.736,P=0.027)and albumin level(OR=0.526,P=0.004)were protective factors in reducing early SSI.Conclusions:Women,preoperative diabetes/UTI,hypoproteinemia,and prolonged drainage time are risk factors for early SSI after PLIF.Clinical effective preventive measures should be taken in combination with targeted nursing intervention to reduce the risk of early SSI.

Retrospective Case Series of Porous Titanium Cages in Oblique Lumbar Interbody Fusion Surgery Assessing Subsidence, Fusion and Functional Outcomes

Purpose: Implant subsidence is a possible complication of spinal interbody fusion. We aim to evaluate porous titanium cages subsidence, fusion and functional outcomes in patients subjected to oblique lumbar interbody fusion (OLIF) with these novel devices. Methods: Our institutional review board approved a single-center experience which included 60 patients who underwent OLIF from June 2018 to June 2020 utilizing the porous titanium implants. Data was collected in accordance with the Declaration of Helsinki, and written informed consent was obtained. Imaging studies including radiographs 1, 3, 6 and 12 months and computed tomography (CT) scan at 6 months obtained during routine postoperative follow-up visits, were studied for signs of implant subsidence, fusion and clinical parameters to determine the effectiveness of surgery such as Oswestry disability index (ODI). Results: Radiographic subsidence occurred in 1 out of 89 porous titanium interbody cages (1.1%). No subsidence was observed in the posterior screws and rods fixation group (N = 57). However, one case of subsidence occurred in the lateral plate fixation group (N = 3). The subsidence occurred in an osteoporotic elderly patient operated for adjacent segment disease, and she was later revised with posterior instrumentation using cemented screws and rods. She had an uneventful recovery. Fusion rates were evaluated under CT scan at 6 months with a rate of 88%. In terms of clinical outcomes, ODI decreased significantly from 20.3 preop to 10.7 postop with a P-value Conclusions: In our study, the subsidence rate was lower than previously reported in the literature. Also, we had good fusion rates at 6 months likely due to the porous titanium cages use. We had no subsidence in the posterior instrumented group and one case in the lateral fixation group with improved clinical outcomes.

Correlation study between the changes of motor evoked potential and the improvement of spinal canal volume in minimally invasive transforaminal lumbar interbody fusion

Objective:To analyze the correlation between the amplitude changes of motor evoked potential(MEP),the 3D volume changes of spinal canal measuring by postoperative CT and the improvement rate of clinical symptoms after the spinal canal decompression in minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF),and to explore the predictive value of the changes of both MEP amplitude and spinal canal volume in the assessment of long-term clinical prognosis in MIS-TLIF.Methods:A retrospective study of 68 patients with L4/5 spinal stenosis treated with MIS-TLIF was performed.The changes of both intraoperative MEP amplitude and 3D spinal canal volume during the spinal canal decompression,as well as the visual analogue scale(VAS)and Oswestry dysfunction index(ODI)scores in the long-term follow-up were all recorded.Results:The values of intraoperative MEP amplitude was 159.04%higher in 68 patients with MIS-TLIF after spinal canal decompression(P<0.01).The 3 postoperative 3D spinal canal volume(4.89±1.27)cm increased by 31.22%in comparison 3 with preoperative date(3.78±1.08)cm(P<0.01).The VAS and ODI scores were improved to 78.55%and 80.60%,respectively at the last follow-up(P<0.01).The improvement rate of MEP amplitude on the decompression side was positively correlated with the improvement rate of postoperative spinal canal volume(r=0.272,P=0.025).The improvement rate of postoperative spinal canal volume was positively correlated with the improvement rate of VAS and ODI at the last follow-up(r=0.656,r=0.490,P<0.01).Moreover,the improvement rate of MEP amplitude on the decompression side was also positively correlated with the improvement rate of VAS and ODI at the last follow-up(r=0.322 and 0.235,respectively,P<0.05).Conclusion:The increase of MEP amplitude after spinal canal decompression in patients with lumbar spinal stenosis treated by MIS-TLIF was closely correlated with both of the increase of spinal canal volume and the improvement of clinical symptoms.Therefore,MEP amplitude monitoring was not only the one of the important monitoring methods for predicting the prognosis of MIS-TLIF but also the reliably predictive value in the long-term clinical prognosis in MIS-TLIF.

Treatment of Single Level Lumbar Spondylolisthesis with Lumbar Interbody Fusion via Oblique Lateral Approach (OLIF)

Objectives: To investigate the effect of lumbar interbody fusion via the oblique lateral approach (OLIF) in the treatment of single level lumbar spondylolisthesis. Methods: Retrospective analysis was made on 32 cases of single level lumbar spondylolisthesis treated by lumbar interbody fusion via the oblique lateral approach from July 2020 to July 2021. 14 males and 18 females;the age was (66.5 ± 11.5) years (55 - 82 years). 1) The operation time, intraoperative blood loss and complications were recorded;2) the scores of visual analog scale. VAS and Oswestry disability index (ODI) of low back pain and lower limb pain were collected before operation and at the last follow-up;by observing the imaging data, the height of the intervertebral space, the anterior convex angle of the intervertebral space, the anterior convex angle of the lumbar spine, the sagittal diameter of the dural sac and the spondylolisthesis were measured. Results: All patients successfully completed the operation, the average operation time was (103.9 ± 21.1) min, the average intraoperative bleeding volume was (72.3 ± 16.4) ml. There was no vascular injury during the operation, no infection occurred in all surgical incisions, and Class I/A healing was achieved. The VAS scores of low back pain and leg pain before operation and at the last follow-up were lower than those before operation, and the difference was statistically significant (P < 0.05);the ODI at the last follow-up was lower than that before operation, and the difference was statistically significant (P < 0.05). At the last follow-up, the height of intervertebral space, the height of intervertebral foramen and the sagittal diameter of dural sac were greater than those before operation, with statistically significant differences (P < 0.05);the spondylolisthesis rate at the last follow-up was lower than that before operation, with a statistically significant difference (P < 0.05). Left thigh surface numbness occurred in 2 cases (6.3%) and disappeared after 1 week;Hip flexion weakness occurred in 1 case (0.03%), which recovered after 12 days;there were no complications such as retroperitoneal hematoma, ureteral injury, retrograde ejaculation, intestinal and lumbar plexus injury. Conclusion: The early clinical effect of OLIF in the treatment of single level lumbar spondylolisthesis is significant. This surgical method is minimally invasive, safe and effective, which can significantly reduce the amount of intraoperative bleeding and reduce the risk of postoperative complications. Its main working principle is to make the annulus fibrosus, posterior longitudinal ligament and ligamentum flavum shrink and recover the height of the intervertebral space through decompression, loosening and stretching of the intervertebral space, so as to achieve the reduction of the slipped vertebral body, increase the height of the intervertebral foramen Enlarge the spinal canal volume and eliminate dynamic compression to play an indirect decompression role, improve the symptoms of low back and leg pain, and reconstruct the stability of the spine through interbody fusion.

Two-Year Outcomes of Midline lumbar Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of L4-L5 Degenerative Disease

Objective We aimed to compare the clinical and radiological outcomes of midline lumbar fusion(MIDLF)versus minimally invasive transforaminal lumbar interbody fusion(MI-TLIF)in patients with degenerative spondylolisthesis and/or stenosis in L4-L5 two years after surgery.Methods Consecutively treated patients with lumbar pathology who underwent MIDLF(n=16)and a historical control group who underwent MI-TLIF(n=34)were included.Clinical symptoms were evaluated using Oswestry Disability Index(ODI),the 36-Item Short-Form Health Survey,and visual analog scale(VAS)scores before surgery and 3,6,12,and 24 months after surgery.Results The mean operative time and hematocrit(HCT,Day 1)were significantly shorter and lower in MIDLF cases(174 min vs.229 min,P<0.001;0.34 vs.0.36,P=0.037).The MI-TLIF group showed better improvement than the MIDLF group in ODI and VAS back and leg pain at 3 months postoperatively.VAS leg pain was higher in MIDLF than in MI-TLIF cases at 6 months.At 24 months follow-up,VAS back pain was higher in MI-TLIF than in MIDLF cases(P=0.018).Conclusion MIDLF is comparable to MI-TLIF at L4-5 in clinical outcomes and fusion rates,and the results verified the meaningful advantage of using MIDLF for the elderly with osteoporosis.

Comparison of Clinical Outcomes of Cortical Bone Trajectory and Traditional Pedicle Screw Fixation in Posterior Lumbar Interbody Fusion

Posterior lumbar interbody fusion (PLIF) is a common surgical procedure and widely used in the treatment of lumbar degenerative disc disorders. Traditionally, posterior lumbar interbody fusion is done by using the traditional pedicle screw (PS) which offers great advantages, but at the same time it has some disadvantages which include the risk of superior facet joint violation and muscle damage. Recently, an alternative method of screw insertion via cortical bone trajectory (CBT) has been invented which has less invasive process and can be placed without the drawbacks associated with the traditional pedicle screw. However, it has to remain an interest whether CBT will provide similar or greater clinical outcomes compared to PS in PLIF. So the main aim of this review is to compare the clinical outcomes of cortical bone trajectory and traditional pedicle screw fixation in posterior lumbar interbody fusion based on the articles published on this topic. Compared to the traditional pedicle screw fixation, PLIF with CBT has similar clinical outcome based on pain intensity, ODI status and JOA score, as well as similar fusion rate and radiological evaluated complication such as loosening of screw. In addition PLIF with CBT has advantages of less facet joint violation, less blood loss, less intraoperative muscle damage and perioperative pain. On the basis of this study, we can suggest that PLIF with CBT can be considered as a reasonable alternative to PS in PLIF.

Biomechanical Effects of Implant Materials on Posterior Lumbar Interbody Fusion: Comparison of Polyetheretherketone and Titanium Spacers Using Finite Element Analysis and Considering Bone Density

Few biomechanical data exist regarding whether the polyetheretherketone (PEEK) spacer or titanium spacer is better for posterior lumbar interbody fusion (PLIF). This study evaluated the biomechanical influence that these types of spacers with different levels of hardness exert on the vertebra by using finite element analysis including bone strength distribution. To evaluate the risk of spacer subsidence for PLIF, we built a finite element model of the lumbar spine using computed tomography data of osteoporosis patients. Then, we simulated PLIF in L3/4 and built models with the hardness of the interbody spacer set as PEEK and titanium. Bones around the spacer were subjected to different load conditions. Then, fracture elements and some stress states of the two modalities were compared. In both models of PLIF simulation, fracture elements and stress were concentrated in the bones around the spacer. Fracture elements and stress values of the model simulating the PEEK spacer were significantly smaller compared to those of the titanium simulation model. For PLIF of osteoporotic vertebrae, this suggested that the PEEK spacer is in a mechanical environment less susceptible to subsidence caused by microfractures of bone tissue and bone remodeling-related fusion aspects. Therefore, PEEK spacers are bio-mechanically more useful.

Successful outcomes of unilateral vs bilateral pedicle screw fixation for lumbar interbody fusion:A meta-analysis with evidence grading

BACKGROUND Whether it’s better to adopt unilateral pedicle screw(UPS)fixation or to use bilateral pedicle screw(BPS)one for lumbar degenerative diseases is still controversially undetermined.AIM To make a comparison between UPS and BPS fixation as to how they work efficaciously and safely in patients suffering from lumbar degenerative diseases.METHODS We have searched a lot in the databases through 2020 with index terms such as“unilateral pedicle screw fixation”and“bilateral pedicle screw fixation.”Only randomized controlled trials and some prospective cohort studies could be found,yielding 15 studies.The intervention was unilateral pedicle screw fixation;Primarily We’ve got outcomes of complications and fusion rates.Secondarily,we’ve achieved outcomes regarding total blood loss,operative time,as well as length of stay.Softwares were installed and utilized for subgroup analysis,analyzing forest plots,sensitivity,heterogeneity,forest plots,publication bias,and risk of bias.RESULTS Fifteen previous cases of study including 992 participants have been involved in our meta-analysis.UPS had slightly lower effects on fusion rate[relative risk(RR)=0.949,95%CI:0.910 to 0.990,P=0.015],which contributed mostly to this metaanalysis,and similar complication rates(RR=1.140,95%CI:0.792 to 1.640,P=0.481),Δvisual analog scale[standard mean difference(SMD)=0.178,95%CI:-0.021 to 0.378,P=0.080],andΔOswestry disability index(SMD=-0.254,95%CI:-0.820 to 0.329,P=0.402).In contrast,an obvious difference has been observed inΔJapanese Orthopedic Association(JOA)score(SMD=0.305,95%CI:0.046 to 0.563,P=0.021),total blood loss(SMD=-1.586,95%CI:-2.182 to-0.990,P=0.000),operation time(SMD=-2.831,95%CI:-3.753 to-1.909,P=0.000),and length of hospital stay(SMD=-0.614,95%CI:-1.050 to-0.179,P=0.006).CONCLUSION Bilateral fixation is more effective than unilateral fixation regarding fusion rate after lumbar interbody fusion.However,JOA,operation time,total blood loss,as well as length of stay were improved for unilateral fixation.

Nuances of oblique lumbar interbody fusion at L5-S1:Three case reports

BACKGROUND Oblique lumbar interbody fusion is a mini-open retroperitoneal approach that uses a wide corridor between the left psoas muscle and the aorta above L5.This approach avoids the limitations of lateral lumbar interbody fusion,is considered less invasive than anterior lumbar interbody fusion,and is similarly effective for indirect decompression and improving lordosis while maintaining a low complication profile.Including L5-S1,when required,adds to these advantages,as this allows single-position surgery.However,variations in vascular anatomy can affect the ease of access to the L5-S1 disc.The nuances of three different oblique anterolateral techniques to access L5-S1 for interbody fusion,namely,left-sided intra-bifurcation,left-sided pre-psoas,and right-sided pre-psoas approaches,are illustrated using three representative case studies.CASE SUMMARY Cases of three patients who underwent multilevel oblique lumbar interbody fusion including L5-S1,using one of the three different techniques,are described.All patients presented with symptomatic degenerative lumbar pathology and failed conservative management prior to surgery.The anatomical considerations that affected the decisions to utilize each approach are discussed.The pros and cons of each approach are also discussed.A parasagittal facet line objectively assesses the relationship between the left common iliac vein and the L5-S1 disc and assists in choosing the approach to L5-S1.CONCLUSION Oblique retroperitoneal access to L5-S1 in the lateral decubitus position is possible through three different approaches.The choice of approach to L5-S1 may be individualized based on a patient’s vascular anatomy using preoperative imaging.While most surgeons will rely on their experience and comfort level in choosing the approach,this article elucidates the nuances of each technique.

Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus. They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young＇s modulus -50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young＇s modulus -110 GPa. The results showed that the designed cages with low modulus （LMC） and high modulus （HMC） can keep identical compression load -9.8 kN and endure fatigue cycles higher than 5× 10^6 without functional or mechanical failure under 2.0 kN axial compression. The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens （T9-T10） dissected freshly from the calf with averaged age of 6 months. The results showed that the LMC has better anti-subsidence ability than the HMC （p〈0.05）. The above results suggest that the cage with low elastic modulus has great potential for clinical applications.

Strength and selection of corticocancellous allografts for anterior interbody spinal fusion

Objective: To quantify the strength of the grafts from different body sites and determine the optimalselection of corticocancellous allografts for anterior interbody fusion. Methods: Complete sets of paired freshfrozen femurs, humeri, tibias and iliac crests were obtained from 6 individual donors. One centimeter thick slicesstarting from the proximal and distal bone ends were cut from the non--diaphysial portions of the long bones usinga razor saw with a customized miter box. 2. 5 cm× 3. 0 cm × 1. 0 cm unicortical bone blocks were shaped similarlyfor clinical use as a lumbar interbody graft. Multiple 1 cm thick grafts with 1. 5 cm depth were obtained from theiliac crests, to simulate a cervical interbody graft. The left and right sides of each pair were randomized intoperpendicular and parallel cut groups in the long bones or tricortical and bicortical preparations of the iliac graft.The samples were tested on an MTS by applying a compressive load to failure. Results: The failure loads of distaltibia and femoral head grafts were significantly higher than distal femur, proximal tibia and burneral head grafts(PR0. 05). The strength of the grafts prepared by parallel cutting decreased significantly as compared with theperpendicular cutting (P <0. 05). No significant changes were seen in femoral and burneral head grafts for the 2sectioning orientations. The grafts closer to the anterior superior iliac spine had significant higher failure loads andfailure strengths than those closer to the posterior superior iliac spine. After trimming off the lateral cortex, themean strength of the bicortical grafts decreased significantly as compared with the tricortical grafts (P <0. 05).Conclusion: The grafts from femoral head and distal tibia by perpendicular cutting have higher failure load than theload bearing in lumbar spine. The grafts cut close to the anterior superior iliac spine are recommended for cervicalinterbody fusion.

Score based assessment of implant-related post fusion MRI artifacts focused on different interbody disc spacers: An <i>in vitro</i>study

Interbody disc spacers for anterior spine fusion are made of different materials, such as titanium alloys or carbon fiber reinforced polymers (CFRP). Implant-related susceptibility artifacts can decrease the quality of MRI scans. This cadaveric study aimed to demonstrate the extent that implant-related MRI artifacting affects the post fusion differentiation of the spinal canal (SC) and intervertebral disc space (IDS). In 6 cadaveric porcine spines, we evaluated the post-im- plantation MRI scans of a titanium and CFRP spacer that differed in shape and surface qualities. A spacer made of human cortical bone was used as a control. A defined evaluation unit was divided into regions of interest (ROI) to characterize the SC and IDS. Considering 15 different MRI sequences read independently by an interobserver-validated team of specialists artifact-affected image quality of the median MRI slice was rated on a modified score of 0-1-2-3. A maximum score of 15 points for the SC and 9 points for the IDS (100%) was possible. Turbo spin echo sequences produced the best scores for both spacers and the control. Only the control achieved a score of 100%. For the IDS the titanium and CFRP spacer maximally scored 0% and 74%, for the SC 80% and 99%, respectively. By using favored T1 TSE sequences the CFRP-spacer represented clear advantages in post fusion spinal imaging. Independent of artifact dimensions the used scoring system allowed us to create an implant-related ranking of MRI scan quality in reference to the bone control.

Can bone mineral density affect intra-operative blood loss of mini-invasive posterior lumbar interbody fusion?

Objective:Many factors affect intraoperative blood loss(BL)in mini-invasive posterior lumbar interbody fusion(PLIF)procedures,but only few has examined.Specifically,the impact of bone mineral density(BMD)levels on intraoperative BL.This study aims to examine the correlation between these two factors.Methods:Retrospective review of 120 patients with low back disorders who were scheduled to undergo mini-invasive PLIF from October 2018 to October 2019 was performed.Patients were divided into two groups based on BMD of the lumbar spine:normal group and abnormal group(osteoporosis and osteopenia).Comparison of age,gender,BMD,BL,BMI,prothrombin time,activated partial thromboplastin time,haemoglobin concentration,intraoperative mean arterial pressure,platelet count,and operative time(OT)between the two groups,and correlation analysis of BMD and BL were conducted.Results:The mean BL of patients in the abnormal group was remarkably higher than that in the normal group:357.22±152.55 ml and 259.37±125.90 ml respectively(p<0.001).The partial correlation coefficient between BL and BMD was0.45(p<0.001).The results of univariate regression analysis demonstrated that only BMD,gender,and OT were related to BL(BMD,r=0.427,p<0.001;gender,r=0.211,p=0.024;OT,r=0.318,p=0.001).While multivariate linear regression analysis demonstrated that patients with lower BMD and longer OT had a higher amount of intraoperative BL(p<0.001).Conclusions:BMD is an important factor influencing intraoperative BL in mini-invasive PLIF.It should be assessed routinely as a part of the preoperative examination to improve preoperative assessment and ensure patient safety.

Use of Nonlinear Finite Element Analysis of Bone Density to Investigate the Biomechanical Effect in the Bone around Intervertebral Cages in Posterior Lumbar Interbody Fusion

Preventing subsidence of intervertebral cages in posterior lumbar interbody fusion (PLIF) requires understanding its mechanism, which is yet to be done. We aimed to describe the mechanism of intervertebral cage subsidence by using finite element analysis through simulation of the osteoporotic vertebral bodies of an elderly woman. The data from computed tomography scans of L2-L5 vertebrae in a 72-year-old woman with osteoporosis were used to create 2 FE models: one not simulating implant placement (LS-INT) and one simulating L3/4 PLIF using polyetheretherketone (PEEK) cages (LS-PEEK). Loads and moments simulating the living body were applied to these models, and the following analyses were performed: 1) Drucker-Prager equivalent stress distribution at the cage contact surfaces;2) the distribution of damage elements in L2-L5 during incremental loading;and 3) the distribution of equivalent plastic strain at the cage contact surfaces. In analysis 1, the Drucker-Prager equivalent stress on the L3 and L4 vertebral endplates was greater for LS-PEEK than for LS-INT under all loading conditions and tended to be particularly concentrated at the contact surfaces. In analysis 2, compared with LS-INT, LS-PEEK showed more damage elements along the bone around the cages in the L3 vertebral body posterior to the cage contact surfaces, followed by the area of the L4 vertebral body posterior to the cage contact surfaces. In analysis 3, in the L3 inferior surface in LS-PEEK the distribution of equivalent plastic strain was visualized as gradually expanding along the cages from the area posterior to the cages to the area anterior to them with increased loading. These analyses suggested that in PLIF for osteoporotic vertebral bodies, the localized stress concentration generated by the use of PEEK cages may cause accumulation of microscopic damage in the fragile osteoporotic vertebral bodies around the cages, which may result in cage subsidence.

Delayed arterial symptomatic epidural hematoma on the 14th day after posterior lumbar interbody fusion:A case report

BACKGROUND Delayed arterial symptomatic epidural hematoma(SEH)on the 14th day after posterior lumbar interbody fusion(PLIF)is rare but it may lead to severe complications if not identified and treated in a timely manner.After diagnosis of the current case,early surgical removal of the hematoma and strict hemostasis treatment was accomplished.This case report highlights the importance of swift diagnosis and treatment in SEH patients.CASE SUMMARY A 41-year-old male patient with a single-segment lumbar disc herniation underwent left-side PLIF.On the 14th post-operative day,the patient complained of lumbar incision pain with sudden onset accompanied by left limb radiation pain and aggravated cauda equina symptoms.Magnetic resonance imaging examination and a puncture blood draw at the incision site confirmed a delayed arterial SEH.Emergency surgical removal of the hematoma and hemostasis was performed.About 70 mL of hematoma was found in the left incision.Continuous bleeding was found in the anterior branch of the transverse process of the 4th lumbar artery in the muscle area about 2 cm below the transverse process of the 4th lumbar vertebra.A blood jet of about 10 cm in height was observed and bipolar electrocoagulation was used to stop the bleeding.Post-operative lumbar incision pain and left lower limb pain were relieved immediately and gradually disappeared.There was no recurrence during the 12-mo follow-up.CONCLUSION For delayed arterial SEH on the 14th day after PLIF,preventive measures including pre-,intra-and post-operative prevention should be implemented.

Posterior Lumbar Interbody Fusion versus Posterolateral Fusion in Surgical Treatment of Lumbar Spondylolithesis

Background: The optimal surgical technique for lumbar spondylolithesis remains debated. Although posterior lumbar interbody fusion (PLIF) theoretically offers more advantages than posterolateral lumbar fusion (PLF), the evidence remains inconclusive. Aim: The aim of this study is to compare the clinical and functional outcomes of PLIF versus PLF in patients with lumbar spondylolithesis. Patients and Methods: We enrolled 38 patients with lumbar spondylolithesis (degenerative and isthmic) who underwent PLIF (N = 19) or PLF (N = 19). We collected operative data and performed follow-up for 12 months after the surgery. The collected data were analyzed using the SPSS software to detected significant differences between both groups. Results: The PLF and PLIF groups exhibited similar pre-operative characteristics between both groups in terms of age (p = 0.57), sex (p = 0.73), clinical presentation (p = 1), required levels of fixation (p = 1), pre-operative VAS score (p = 0.43) or muscle weakness (p = 1). However, the PLIF group had significantly more blood loss and longer operative time than the PLF group. Moreover, both groups had similar levels of postoperative pain (up to six months after surgery), and post-operative complications. The rates of arthrodesis were higher in PLIF group than PLF group within six months while no significant difference within 12 months of follow-up. Conclusion: In our comparative study, we achieved comparison between pedicle screw fixation with posterolateral fusion alone (PLF) in compare with pedicle screw fixation with posterior lumbar interbody fusion (PLIF). Results indicate better results of fusion rate in PLIF as regards arthrodesis with slightly more rate of complication than PLF. So we recommend PLIF in cases of lumbar spondylolithesis than PLF.

Surgical Results of Posterior Lumbar Interbody Fusion with Transpedicular Fixation in Management of Spondylolisthesis

Objective: To evaluate the surgical results of posterior lumber interbody fusion with transpedicular fixation with rod screw system in management of spondylolisthesis. Study Design: Retrospective study reviewed all patient treated by lumber interbody fusion with transpedicular fixation with rod screw system. Patients and Methods: They were 40 patients operated for lumber and lumbosacral spondylolisthesis from Feb 2014 to April 2017 in Al-Azhar university hospital. These patients followed postoperatively clinically for improved neural function and for fusion stability and hardware fixation by radiological investigation. Data about pain intensity (by Visual Analogue Scale) was collected pre- and postoperatively;and outcome was assessed by Oswetry disability index (ODI). Outcome was graded as excellent, good, fair, or poor. Pre- and Post-operative data were statistically compared. Results: The mean age was 45 years (range between 30 - 60 years) with female sex predominance (male:female = 1:3). They had lytic (n = 30) or degenerative (n = 10) spondylolisthesis;and all underwent PLIF (posterior lumbar interbody fusion). In lytic group, the level was L4/L5 in 19 patients and L5/S1 in 11 patients, while in degenerative group the level was L4/L5 in 4 patients, L5/S1 in 3 patients, L2/L3 in 2 and L3/L4 in one patient. The spondylolisthesis grade was grade I among 25 subjects, grade two among 11 subjects and retrolisthesis among 4 subjects. Sensory deficits reported in 22 subjects (19 had lytic and 3 had degenerative spondylolisthesis);while motor deficits reported among 10 subjects and reduced reflexes among 8 subjects. The outcome was excellent, good, and fair among 30, 7, and 3 subjects respectively. The return to previous levels of activity was reported among 32 patients. VAS was 3.5 ± 2.94 at the end of follow up, while ODI was 28% and 36.0% and 3 and 6 months respectively. Conclusion: PLIF associated with transpedicular rod screw fixation system for management of spondylolisthesis is considered a safe and effective surgical intervention in both lytic and degenerative types.

不同钉棒内固定方式在腰椎侧路融合中的有限元力学分析

背景:考虑到脊柱固定的稳定性,目前临床在进行侧路椎间融合时大多采用后路双边椎弓根螺钉固定的手术方式,且多数为两期手术完成。侧卧位的后路单侧、侧方椎体钉棒固定的固定方式,也有可能会提供较好的力学稳定性,所带来的手术时间缩短、风险与花费降低等获益考量值得进一步研究。目的:比较4种不同侧路椎间融合内固定方式的生物力学特性。方法:建立正常L3-5有限元模型,在验证其有效性基础上模拟4种不同内固定方式,即后路双侧椎弓根螺钉+侧路融合模型(Model A)、后路单侧椎弓根螺钉+侧路融合模型(Model B)、侧路双侧螺钉+侧路融合模型(Model C)及侧路单侧螺钉+侧路融合模型(Model D)。分别比较各模型在生理活动范围下的稳定性、螺钉内固定和椎间融合器的应力差异。结果与结论:①对所有重构模型,在融合节段(L4-5)的活动范围均显著下降,Model A的活动范围下降更明显;②在模型的屈伸、侧屈和轴向旋转运动状态,侧路置钉的峰值应力与后路置钉的峰值应力的差异分别超过67.74 MPa、80.10 MPa和43.95 MPa;③在不同重建模型内固定应力分布方面,Model A和Model B螺钉的应力分布主要集中在椎弓根螺钉的体部,而Model C和Model D的峰值应力主要集中在螺钉的尾部;④提示Model A能够获得最好的稳定性,并且能够降低cage下沉及移位的风险;而Model B亦能够提供较好的稳定性,在保证稳定和固定的前提下能成为侧路融合的替代选择;⑤此外在选择侧路置钉的内固定时,Model C能获得与Model D相似的效果,但在临床诊疗上面对腰椎后伸不稳定的患者需谨慎选择侧路的单侧内固定,亦应避免过度后伸以降低螺钉松动和疲劳断裂的发生率。

Unilateral pedicle screw fixation combined with lumbar interbody fusion for the treatment of lumbar degenerative diseases

Objective To explore the feasibility and efficiency of the treatment of lumbar degenerative diseases after transforaminal lumbar interbody fusion (TLIF) and posterolateral fusion (PLF) procedures in which unilateral pedicle screw fixation was used.