Based on the surgical model using transforaminal lumbar interbody fusion (TLIF) to treat lumbar spondylolisthesis, this paper presents the investigations of the biomechanical characteristics of cage and pedicle screw in lumbar spinal fusion implant fixed system under different combinations with finite element method. Firstly, combining the CT images with finite element pretreatment software, we established three dimensional nonlinear finite element model of human lumbar L4-L5 segmental slight slippage and implant under different fixed combinations. We then made a comparison analysis between the biomechanical characteristics of lumbar motion range, stress distribution of cage and pedicle screw under six status of each model which were flexion, extension, left lateral bending, right lateral bending, left axial rotation and right axial rotation. The results showed that the motion ranges of this model under different operations were reduced above 84% compared with those of the intact model, and the stability of the former was improved significantly. The stress values of cage and pedicle screw were relatively larger when they were fixed by single fusion device additional unilateral pedicle screw, but there was no statistically significant difference. The above research results would provide reference and confirmation for further biomechanics research of TLIF extracorporal specimens, and finally provide biomechanical basis for the feasibility of unilateral internal fixed diagonal intervertebral fusion TLIF surgery.
ObjectiveTo review the researches of in vivo kinematics in lumbar degenerative spondylol isthesis (DS).
MethodsRelated literature concerning the in vivo kinematics in patients with lumbar DS was extensively reviewed and comprehensively analyzed in 4 terms of the instabil ity of lumbar DS, vertebral motion pattern, the morphological changes of spinal canal, and intraoperative biomechanical measurement.
ResultsWhether there is lumbar segmental instabil ity in lumbar DS patients is still controversial, which should be based on degenerative stage of lumbar spine and grade of slip. The hypomobility of the lumbar spinous processes and the facet joint is seen in DS. The diameter, cross-sectional area, and volume of spinal canal in lumbar DS patients are significantly smaller than those of the normal control. Because of its invasive procedure and medical ethics, the use of the intraoperative measurement device is limited. These reported researches of in vivo kinematics in DS are almost on the sagittal plane. However, few data have been reported on the 6-degree-of-freedom (6DOF) kinematics of the diseased levels under physiological loading conditions.
ConclusionThe 6DOF kinematics data can accurately reflect the segmental motion characteristics in lumbar DS patients, recent studies have been reported, further studies are still needed.
ObjectiveTo observe the character of spino-pelvic sagittal alignment in patients with high-grade L5 isthmic spondylolisthesis, and to analyze the sagittal alignment alteration after operation.
MethodBetween January 2009 and June 2014, 25 patients with high-grade L5 isthmic spondylolisthesis underwent posterior surgery, and the clinical data were retrospectively analyzed as study group. There were 14 males and 11 females with a mean age of 42.5 years (range, 20-65 years). The mean disease duration was 6 months (range, 3-12 months). According to the Meyerding evaluating system, 15 cases were rated as degree III, and 10 cases as degree IV. Eighty healthy adult volunteers were recruited simultaneously as control group. The lumbar sacral angle (LSA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) were measured on preoperative and last follow-up standing full length lateral X-ray films. And these parameters were compared between study group (preoperative parameters) and control group. Then the patients in study group were divided into 2 subgroups according to Hresko's method:the balanced pelvis subgroup (n=14) and unbalanced pelvis subgroup (n=11) . The sagittal parameters were compared between 2 subgroups, and the alteration of sagittal parameters before surgery and at last follow-up was analyzed in each subgroup respectively.
ResultsAll patients in study group were followed up 18 months on average (range, 6-48 months). After surgery, spondylolisthesis was reduced from degree III to degree 0 in 12 cases and to degree I in 3 cases, and from degree IV to degree 0 in 6 cases and to degree I in 4 cases. Bone fusion was obtained in all patients at last follow-up. The preoperative PI, SS, PT, and SVA of study group were significantly greater than those of control group (P<0.05) , while the TK was significantly smaller than that of control group (P<0.05) . In the balanced pelvis subgroup, LSA, LL, and SVA at last follow-up significantly decreased while TK significantly increased when compared with preoperative ones (P<0.05) . In the unbalanced pelvis subgroup, LSA, PT, and SVA at last follow-up significantly decreased while SS, LL, and TK significantly increased when compared with preoperative ones (P<0.05) . The preoperative LSA and PT in the unbalanced pelvis subgroup were significantly greater, while SS, LL, and TK were significantly smaller than those of balanced pelvis subgroup (P<0.05) ; while at last follow-up, significant differentce was found only in LSA between 2 subgroups (P<0.05) .
ConclusionsThe LSA should be paid more attention in surgery to assure recovery of the sagittal balance because patients with high-grade L5 isthmic spondylolisthesis have greater PI, abnormal lumbosacral kyphosis, and sagittal imbalance.
Objective To analyze the therapeutic effect of the posterior pedicle screw system combined with interbody fusion cage on lumbarspondylolisthesis. Methods From February 2003 to March 2006, 37 lumbar spondylolisthesis patients were treated with this operation, including21 males and 16 females and aging 3969 years.The affected lumbars were L3(3cases)，L4(23 cases), and L5(11 cases). According to the Meyerdingevaluating system, 12 cases were lassified as degree Ⅰ, 20 cases as degree Ⅱ,and 5 cases as degree Ⅲ. Taillard index, Boxall index, slipping angle, lumbar lordosis angle and intervertebral height index were measured before operation, and 2 weeks and 3 months after operation. Results All patients were followed up 336 months. There were statistically significant differences in Taillard index, Boxall index, slipping angle, lumbar lordosis angle and intervertebral height index between before operation and 2 weeks after operation (P＜0.05),and no statistically significant differences between 2 weeks and 3 months afteroperation(P＞0.05). According to Dewei Zhou’s creterior for scoring, the results were excellent in 27 cases， good in 8 cases，and fair in 2 cases. Theexcellent and good rate was 94.6%. All of the embedded osseous were fused. Thefusing time was from 3 to 8 months (mean 3-9 months). There were no breakageof screw and rod. The position and configuration of the whole cages were good. Conclusion Applying the posterior pedicle screw system combined with interbody fusion cage may achieve synergism in the treatment of lumbar vertebral spondylolisthesis. Above procedure is served as solid internal fixationand offers a satisfactory reduction, and can improve the fusion rate of the spine. So it is an ideal procedure and worthily recommended method for treatment oflumbar vertebral spondylolisthesis.
Objective
To investigate the technique of reduction by posterior approach for severe spondylolisthesis, and to discuss the method to prevent nerve stretch injury.
Methods
Between July 2007 and April 2011, 17 patients with severe spondylolisthesis underwent reduction, fixation, and fusion by posterior approach. There were 2 males and 15 females with a median age of 15 years (range, 8-67 years) and a median disease duration of 18 months (range, 5 months-16 years and 4 months). The level of spondylolisthesis was at L4 in 1 case and L5 in 16 cases; the spondylolisthesis was at degree III in 12 cases and degree IV in 5 cases according to Meyerding classification. There were 16 cases of developmental spondylolisthesis (high- dysplastic and low-dysplasia spondylolisthesis in 9 and 7 cases, respectively) and 1 case of traumatic spondylolisthesis; 16 cases of developmental spondylolisthesis at L5 level included 6 cases of type 4, 9 case of type 5, and 1 case of type 6 according to Spinal Deformity Study Group (SDSG) classification. All cases underwent posterior spinal decompression, Schanz screw fixation for the slipped vertebrae, the intervertebral and posterolateral fusion and reduction of the slipped vertebrae, and correction of the lumbosacral kyphosis. The reductive degree of slipped vertebrae was modulated according to the strain of exiting spinal root. The slip degree should be reduced within Meyerding degree II. The anteroposterior and lateral radiographs of whole spine were taken in a standardized standing position to observe the correction of displacement severity and lumbosacral angle. The nerve function and pain score of lower extremity were evaluated by neurological Frankel grade and visual analogue scale (VAS). Bony fusion was assessed by followed-up CT three-dimentional reconstruction.
Results
Exiting nerve root paralysis occurred in 1 case after operation, and released at 4 weeks after operation; no aggravation of nerve damage was observed in the other patients. The incisions primarily healed. All the patients were followed up 12-48 months (mean, 25 months). The slip percentage, the lumbosacral angle, and VAS score of lower extremity were improved from 72% ± 10%, (18.2 ± 3.5)°, and 7.0 ± 1.5 at preoperation to 12% ± 6%, (
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7.3 ± 2.9)°, and 1.5 ± 1.3 at 12 months after operation respectively, all showing significant differences (P lt; 0.05). Osteosynthesis was seen at the bone grafting area by CT three-dimentional reconstruction at 12 months after operation. No breakage of screw and rod or reduction loss occurred.
Conclusion
It can obtain satisfactory clinical result to use spinal canal decompression by posterior approach, the Schanz screw fixation of the slipped vertebrae, the intervertebral and posterolateral fusion for severe spondylolisthesis. The risk of nerve stretch injury can be prevented by choosing the lowest height of intervertebral cage, modulating the reductive degree of slipped vertebrae according to the strain of exiting spinal root, and correcting lumbosacral kyphosis.
Objective To evluate the clinical outcome of autograftsof ilium and interbody fusion cage or bone morphogenetic protein(BMP)／artificial bone material／ cage in treating lumbar spondylolisthesis. Methods From January 1997 to January 2004，114 patients with lumbar spondylolisthesis were treated with posterior lumbar interbody fusion and pedicle screw fixation． There were 45 males and 69 females with an average age of 43 years ranging from 32 to 61 years. Of 114patients, 85 cases were classified as degree Ⅰ, 24 cases as degree Ⅱ and 5 cases as degree Ⅲ. The patients were divided into three groups accordingto the material used for interbody fusion: autografts of ilium (group A, n=42), interbody fusion cages(group B, n=36), and BMP／artificial bone material／ cage (group C, n=36)．The clinical and radiographic results of the patients were compared among three groups． Results All patients were followed from 13 to 30 months with an average of 15 months． There were no statistically significant differences in surgical time, blood loss, and disc space height of preoperation(P＞0.05) among three groups. No severe complication occurred in the three groups(P＞0.05). The excellent and good rates in groups A，B and C were 81.0％, 80.6％, and 83.3％ respectively, showing no statisticallysignificant difference(P＞0.05)．The fusion rate of group C(97.0%) was significantly higher than those of group A(81.0%) and group B(83.3%) (P＜0.05) after 1 year of operation．And the average loss of disc space height in groups B and C was significantly lower than that in group A(P＜0.05). Conclusion Higher fusion rate and lower loss of disc space height can beobtained in treating lumbar spondylolisthesis with BMP／artificial bone materiel.It is an effective method in the treatment of spondylolisthesis.
ObjectiveTo investigate the effectiveness of modified direction-changeable lumbar Cage in transforaminal lumbar interbody fusion (TLIF).MethodsA retrospective analysis was made of 161 patients with single segment L4 or L5 isthmic spondylolisthesis treated between January 2013 and December 2015. According to the implantation of Cage, they were divided into trial group (85 cases, modified direction-changeable lumbar Cage implanted in TLIF) and control group (76 cases, traditional nondirection-changeable Cage implanted in TLIF). There was no significant difference in the general data of gender, age, disease duration, slippage segment, and slippage grade between the two groups (P>0.05). The intraoperative implantation time of Cage, Cage position adjustments times, fluoroscopy times during implantation of Cage, fluoroscopy exposure time, and total operation time were recorded and compared between the two groups. Visual analogue scale (VAS) and Oswestry disability index (ODI) scores were used to evaluate the effectiveness of the patients before operation, and at 3, 6, and 12 months after operation, and the incidence of complications was recorded and analyzed. CT examinations were performed at 6 and 12 months after operation, and lumbar fusion was evaluated by Bridwell criteria.ResultsThe intraoperative implantation time of Cage, Cage position adjustments times, fluoroscopy times during implantation of Cage, fluoroscopy exposure time, and total operation time in trial group were significant less than those in control group (P<0.05). All the 161 patients were followed up 12-18 months (mean, 14.3 months). There was 1 case of dural sac tear in the trial group and 1 case of superficial infection in the control group; no complication such as dural tear and infection occurred in other patients. The fusion rate was 76.5% (64/85) in the trial group and 57.9% (44/76) in the control group at 6 months after operation, showing significant difference (χ2=6.44, P=0.02); at 12 months after operation, the fusion rate was 96.5% (82/85) in the trial group and 90.8% (69/76) in the control group (including 3 cases of Cage displacement and 4 cases of screw breakage), showing no significant difference in the fusion rate between the two groups (χ2=1.54, P=0.26). The VAS and ODI scores of the two groups decreased gradually at 3, 6, and 12 months after operation, and improved significantly when compared with those before operation (P<0.05). There was no significant difference in VAS and ODI scores between the two groups before and after operation (P>0.05).ConclusionBoth Cages can obtain the similar effectiveness. The modified direction-changeable lumbar Cage can significantly reduce the fluoroscopy times and radiation dose during TLIF, shorten the operation time, and effectively reduce the radiation exposure of patients and medical staff.
ObjectiveTo compare the effectiveness of robot-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and open freehand TLIF for the treatment of single-level degenerative lumbar spondylolisthesis (DSL) and analyse the influence on postoperative adjacent segmental degeneration (ASD). Methods The clinical data of 116 patients with L4、5 DLS who were admitted between November 2019 and October 2021 and met the selection criteria were retrospectively analyzed. According to the surgical methods, they were divided into the robotic group (45 cases, who underwent robot-assisted MIS-TLIF) and the open group (71 cases, who underwent open freehand TLIF). There was no significant difference in baseline data such as gender, age, body mass index, DLS Meyerding grading, and preoperative Pfirrmann grading, Weishaupt grading, L3, 4 intervertebral disc height (DH), L3, 4 intervertebral mobility, sagittal parameters [including pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT)], and Cage height (P>0.05). The grade of facet joint violation (FJV) by pedicle screws on the superior articular process was assessed postoperatively. Sagittal parameters, L3, 4 DH, L3, 4 DH loss, and L3, 4 intervertebral mobility were measured preoperatively and at last follow-up in order to determine whether ASD occurred. Based on the occurrence of postoperative ASD, logistic regression analysis was used to identify the risk factors for ASD after TLIF. Results Patients in both groups were followed up 21-47 months, with a mean of 36.1 months; there was no significant difference in the follow-up time between the two groups (P>0.05). The occurrence of postoperative FJV was significantly better in the robotic group than in the open group (P<0.05). At last follow-up, the difference in the change values of sagittal parameters PI, PT, SS, and LL was not significant when comparing the two groups of patients (P>0.05); the change values of L3, 4 DH and L3, 4 DH loss in the robotic group were smaller than those in the open group, and the change value of L3, 4 intervertebral mobility was larger than that in the open group, and the differences were significant (P<0.05). At last follow-up, ASD occurred in 8 patients (17.8%) in the robotic group and 35 patients (49.3%) in the open group, and the difference in ASD incidence between the two groups was significant (P<0.05). logistic regression analysis showed that open surgery, preoperative Pfirrmann grading Ⅳ-Ⅴ, preoperative Weishaupt grading ≥2, and postoperative FJV grading ≥1 were risk factors for the development of ASD after TLIF (P<0.05). ConclusionCompared with traditional open surgery, orthopedic robot-assisted MIS-TLIF in the treatment of single-level DLS can more accurately insert pedicle screws, reduce the loss of DH and the occurrence of FJV, and effectively reduce the incidence of mid-postoperative ASD. Preoperative disc and synovial joint degeneration in adjacent segments, nonrobotic-assisted minimally invasive therapy, and FJV are risk factors for ASD after TLIF.
ObjectiveTo compare the effectiveness of unilateral biportal endoscopic decompression and unilateral biportal endoscopic lumbar interbody fusion (ULIF) in the treatment of degreeⅠdegenerative lumbar spondylolisthesis (DLS). MethodsA clinical data of 58 patients with degreeⅠDLS who met the selection criteria between October 2021 and October 2022 was retrospectively analyzed. Among them, 28 cases were treated with unilateral biportal endoscopic decompression (decompression group) and 30 cases with ULIF (ULIF group). There was no significant difference between the two groups (P>0.05) in the gender, age, lesion segment, and preoperative visual analogue scale (VAS) score of low back pain, VAS score of leg pain, Oswestry disability index (ODI), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), disk height (DH), segmental lordosis (SL), and other baseline data. The operation time, postoperative drainage volume, postoperative ambulation time, VAS score of low back pain, VAS score of leg pain, ODI, laboratory examination indexes (CRP, ESR), and imaging parameters (DH, SL) were compared between the two groups. ResultsCompared with the ULIF group, the decompression group had shorter operation time, less postoperative drainage, and earlier ambulation (P<0.05). All incisions healed by first intention, and no complication such as nerve root injury, epidural hematoma, or infection occurred. All patients were followed up 12 months. Laboratory tests showed that ESR and CRP at 3 days after operation in decompression group were not significantly different from those before operation (P>0.05), while the above indexes in ULIF group significantly increased at 3 days after operation compared to preoperative values (P<0.05). There were significant differences in the changes of ESR and CRP before and after operation between the two groups (P<0.05). Except that the VAS score of low back pain at 3 days after operation was not significantly different from that before operation in decompression group (P>0.05), there were significant differences in VAS score of low back pain and VAS score of leg pain between the two groups at other time points (P<0.05). The VAS score of low back pain in ULIF group was significantly higher than that in decompression group at 3 days after operation (P<0.05), and there was no significant difference in VAS score of low back pain and VAS score of leg pain between the two groups at other time points (P>0.05). The ODI of the two groups significantly improved after operation (P<0.05), but there was no significant difference between 3 days and 6 months after operation (P>0.05). There was no significant difference between the two groups at the two time points after operation (P<0.05). Imaging examination showed that there was no significant difference in DH and SL between pre-operation and 12 months after operation in decompression group (P>0.05). However, the above two indexes in ULIF group were significantly higher than those before operation (P<0.05). There were significant differences in the changes of DH and SL before and after operation between the two groups (P<0.05). ConclusionUnilateral biportal endoscopic decompression can achieve good effectiveness in the treatment of degree Ⅰ DLS. Compared with ULIF, it can shorten operation time, reduce postoperative drainage volume, promote early ambulation, reduce inflammatory reaction, and accelerate postoperative recovery. ULIF has more advantages in restoring intervertebral DH and SL.
BJECTIVE: To discuss the clinical effect and the application of AF device fixation system and PROSPACE interbody fusion cage on treating lumbar spondylolisthesis. METHODS: Twenty-one cases of lumbar spondylolisthesis treated by operation from 1999 to 2002 were analyzed retrospectively (13 males and 8 females, 25-66 years old averaging 42 years). We had thorough decompression on the part of nerve compression and had replacement and fixation of the slippage vertebral body with the AF transpedicular screw/rod system so that the normal spine physiological curvature could be recovered, and then performed the posterolateral interbody fusion with implanting the PROSPACE filled with autograft bones. RESULTS: All the patients were followed up for 3 months to 3 years with an average of 15 months. The preoperation symptoms improved in 20 cases (95.2%). CONCLUSION: The combination of AF device fixation system and PROSPACE interbody fusion cage can relieve effectively nerve compression, recover the normal spinal physiological curvature, maintain the height of interbody and promote the nerve fusion. It is reliable and effective in the treatment of spondylolisthesis.
