Long-term efficacy of Waveflex semi-rigid-dynamic-internal-fixation system in delaying intervertebral disc degeneration at adjacent segments and improving spinal sagittal imbalance.

The Waveflex semi-rigid-dynamic-internal-fixation system shows good short-term effects in the treatment of lumbar degenerative diseases, but there are few long-term follow-up studies, especially for recovery of sagittal balance. Fifty patients with lumbar degenerative diseases treated from January 2016 to October 2017 were retrospectively analysed: 25 patients treated with Waveflex semi-rigid-dynamic-internal-fixation system (Waveflex group) and 25 patients treated with double-segment PLIF (PLIF group). Clinical efficacy was evaluated by Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). Imaging data before surgery and at 3 months, 1 year, and 5 years postoperatively was used for imaging indicator assessment. Local disc degeneration of the cephalic adjacent segment (including disc height index (DHI), intervertebral foramen height (IFH), and range of motion (ROM)) and overall spinal motor function (including lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and |PI-LL|) were analysed. Regarding clinical efficacy, comparison of VAS and ODI scores between the Waveflex and PLIF groups showed no significant preoperative or postoperative differences. The comparison of the objective imaging indicators showed no significant differences in the DHI, IFH, LL, |PI-LL|, and SS values between the Waveflex and PLIF groups preoperatively and 3 months postoperatively (P > 0.05). These values were significantly different at 1 and 5 years postoperatively (P < 0.05), and the Waveflex group showed better ROM values than those of the PLIF group (P < 0.05). PI values were not significantly different between the groups, but PT showed a significant improvement in the Waveflex group 5 years postoperatively (P < 0.05). The Waveflex semi-rigid dynamic fixation system can effectively reduce the probability of intervertebral disc degeneration in upper adjacent segments. Simultaneously, patients in the Waveflex group showed postoperative improvements in LL, spinal sagittal imbalance, and quality of life.

Percutaneous microchannel unilateral approach bilateral micro decompression for adjacent segmental degeneration after lumbar fusion at 10 years: a case report and review of literature.

Background: Adjacent segmental degeneration after lumbar fusion is one of the common long-term complications after lumbar fusion. With the continuous development of adjacent segmental degeneration, patients who fail conservative treatment often need reoperation to relieve symptoms. In recent years, the technique of bilateral microdecompression through unilateral approach under microchannel has been widely used in the treatment of lumbar degenerative diseases. However, the efficacy of this procedure for adjacent-segment degeneration after lumbar fusion has not been established. Here, we report a case of bilateral microscopic decompression via a unilateral approach through a microchannel in a patient with adjacent segmental degeneration after lumbar fusion. Case report: A 70-year-old male patient was admitted to hospital because of lumbago accompanied by left lower extremity pain, numbness and weakness for 2 years, which aggravated for 2 months. Ten years ago, he underwent PLIF for lumbar spinal stenosis, and recovered well after the operation. According to imaging data and physical examination, the diagnosis was adjacent segmental degeneration after lumbar fusion. Bilateral microdecompression was performed through a unilateral approach under a microchannel. Good clinical outcomes was observed through 1-year postoperative follow-up. Conclusions: This report reports the successful treatment of a patient with ASD 10 years after lumbar fusion. Bilateral microdecompression via a unilateral approach under a microchannel is a safe and effective method for the treatment of ASD after lumbar fusion with good surgical outcomes.

Comparison of safety and efficacy of posterior lumbar interbody fusion (PLIF) and modified transforaminal lumbar interbody fusion (M-TLIF) in the treatment of single-segment lumbar degenerative diseases.

OBJECTIVE: To compare modified transforaminal lumbar interbody fusion (M-TLIF) with posterior lumbar interbody fusion (PLIF) in the treatment of single-segment lumbar degenerative disorders in order to assess its safety and effectiveness. METHODS: From January 2016 to January 2021, 74 patients who received single-segment M-TLIF were examined. A total of 74 patients having single-segment PLIF during the same time period were included in a retrospective controlled study using the same inclusion and exclusion criteria. The two groups were compared in terms of the fusion rate, the Oswestry disability index (ODI), the visual analogue scale of low back pain (VAS), the perioperative condition, the postoperative complications, and the postoperative neighbouring segment degeneration. RESULTS: All patients had surgery satisfactorily and were monitored for at least a year afterwards. The baseline values for the two groups did not significantly differ. The interbody fusion rate between PLIF (98.65%) and M-TLIF (97.30%) was not significantly different. In the follow-up, the M-TLIF group's VAS score for low back and leg pain was lower than that of the PLIF group. The ODI score of the M-TLIF group was lower than that of the PLIF group at 7 days and 3 months following surgery. Both groups' post-op VAS and ODI scores for low back and leg pain were much lower than those from before the procedure. In M-TLIF group, the operation time, drainage tube extraction time, postoperative bed rest time and hospital stay time were shorter, and the amount of intraoperative blood loss was less. Compared with those before operation, the height of intervertebral space and intervertebral foramen were significantly increased in both groups during postoperative follow-up (P < 0.05). The postoperative complications and adjacent segment degeneration of M-TLIF were significantly lower than those of PLIF. CONCLUSIONS: M-TLIF is a safe and effective treatment for lumbar degenerative disorders, with a high fusion rate and no significant difference between M-TLIF and PLIF. M-TLIF's efficacy and safety are comparable to that of PLIF, particularly in terms of early relief of low back pain and improvement in quality of life following surgery. Therefore, M-TLIF technology can be popularized and applied in clinic.

Biomechanical Effect of Osteoporosis on Adjacent Segments After Anterior Cervical Corpectomy and Fusion.

BACKGROUND: Adjacent segmental degeneration (ASD) is one common long-term complication of anterior cervical corpectomy and fusion (ACCF), and osteoporosis is one basic disease in the elderly. After ACCF, patients may experience osteoporosis with age. However, the influence of osteoporosis on ASD remains unclear. The purpose of this study was to determine whether osteoporosis could affect the development of ASD following ACCF. METHODS: Three finite element models of the cervical spine, including 1 normal model, 1 ACCF model, and 1 ACCF with osteoporosis model, were constructed. ACCF was simulated at the C4-C6 level. A 73.6 N follower load and a 1 Nm moment were imposed on the normal model, and the same follower load together with an adjusted moment was applied to the ACCF model and the ACCF with osteoporosis model, to simulate movement in each direction. The range of motion, intradiscal pressure, shear stress on anulus fibrosus, and facet joint stress at C3-C4 and C6-C7 levels of the models were calculated. RESULTS: In this study, the normal model was well validated. In flexion, extension, right lateral bending, and right axial rotation, the overall range of motion was 8.92°, 19.7°, 15.37°, and 45.27° in the normal model, and the adjusted moment was 1.4 Nm, 2.7 Nm, 1.1 Nm, and 2.6 Nm in the ACCF model, and 1.3 Nm, 2.5 Nm, 1.1 Nm, and 2.4 Nm in the ACCF with osteoporosis model. Despite of a few exceptions, the maximum values of the outcome measurements were mostly found in the ACCF model, and the minimum values in the normal model. Compared with the ACCF model, most of the outcome measurements were decreased in the ACCF with osteoporosis model. CONCLUSIONS: Osteoporosis can retard the adverse influence of ACCF on adjacent segments.

[Comparison of short-term effectiveness of Prodisc-C Vivo artificial disc replacement and Zero-P fusion for treatment of single-segment cervical spondylosis].

Objective: To compare the short-term effectiveness and the impact on cervical segmental range of motion using Prodisc-C Vivo artificial disc replacement and Zero-P fusion for the treatment of single-segment cervical spondylosis. Methods: The clinical data of 56 patients with single-segment cervical spondylosis who met the selection criteria between January 2015 and December 2018 were retrospectively analyzed, and they were divided into study group (27 cases, using Prodisc-C Vivo artificial disc replacement) and control group (29 cases, using Zero-P fusion) according to different surgical methods. There was no significant difference between the two groups in terms of gender, age, type of cervical spondylosis, disease duration, involved segments and preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), surgical segments range of motion, upper and lower adjacent segments range of motion, overall cervical spine range of motion, and cervical curvature (P>0.05). The operation time, intraoperative blood loss, postoperative hospitalization stay, time of returning to work, clinical effectiveness indicators (VAS score, JOA score, NDI, and improvement rate of each score), and imaging indicators (surgical segments range of motion, upper and lower adjacent segments range of motion, overall cervical spine range of motion, and cervical curvature, prosthesis position, bone absorption, heterotopic ossification, etc.) were recorded and compared between the two groups. Results: There was no significant difference in operation time and intraoperative blood loss between the two groups (P>0.05); the postoperative hospitalization stay and time of returning to work in the study group were significantly shorter than those in the control group (P<0.05). Both groups were followed up 12-64 months, with an average of 26 months. There was no complication such as limb or organ damage, implant failure, and severe degeneration of adjacent segments requiring reoperation. The VAS score, JOA score, and NDI of the two groups at each time point after operation significantly improved when compared with those before operation (P<0.05); there was no significant difference in the above scores at each time point after operation between the two groups (P>0.05); there was no significant difference in the improvement rate of each score between the two groups at last follow-up (P>0.05). The surgical segments range of motion in the study group maintained to varying degrees after operation, while it in the control group basically disappeared after operation, showing significant differences between the two groups (P<0.05). At last follow-up, there was no significant difference in the upper and lower adjacent segments range of motion in the study group when compared with preoperative ones (P>0.05), while the upper adjacent segments range of motion in the control group increased significantly (P<0.05). The overall cervical spine range of motion and cervical curvature of the two groups decreased at 3 months after operation, and increased to varying degrees at last follow-up, but there was no significant difference between groups and within groups (P>0.05). At last follow-up, X-ray films and CT examinations showed that no prosthesis loosening, subsidence, or displacement was found in all patients; there were 2 cases (7.4%) of periprosthetic bone resorption and 3 cases (11.1%) of heterotopic ossification which did not affect the surgical segments range of motion. Conclusion: Both the Prodisc-C Vivo artificial disc replacement and Zero-P fusion have satisfactory short-term effectiveness in treatment of single-segment cervical spondylosis. Prodisc-C Vivo artificial disc replacement can also maintain the cervical spine range of motion to a certain extent, while reducing the occurrence of excessive motion of adjacent segments after fusion.

Comparative analysis of the effects of OLIF and TLIF on adjacent segments after treatment of L4 degenerative lumbar spondylolisthesis.

BACKGROUND: The fusion of the lumbar spine may lead to the degeneration of the adjacent segments. In this study, the effects of OLIF and TLIF on adjacent segments after treatment of L4 degenerative lumbar spondylolisthesis (DLS) were compared and analysed. METHODS: This was a retrospective analysis of the medical records of consecutive patients treated with OLIF or TLIF for L4DLS. They were divided into the OLIF group and TLIF group based on different treatment methods. Cage height, segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were compared between the two groups, and the postoperative biomechanical changes were analysed by establishing the disc angle (DA). The clinical outcomes were analysed by comparing the visual analogue scale (VAS), Oswestry Disability Index (ODI) and incidence of adjacent segment disease (ASDis) between the two groups. The intervertebral disc height (IDH), intervertebral foramen height (IDH), intervertebral foramen area (IFA), sliding distance (SD), and angular displacement (AD) in L3-4 and L5-S1 were compared between the two groups. The incidence of aggravated disc degeneration (ADD), the incidence of aggravated zygapophyseal joint degeneration (AJD) and the incidence of adjacent segment degeneration (ASDeg) were compared between the two groups for radiological degeneration. RESULTS: At the last follow-up, there was one case of ASDis in the OLIF group (2.78%) and two cases in the TLIF group (5.56%). At the last follow-up, compared with the preoperative values, IDH, IFH, and IFA of the adjacent segments above and below L4-5 decreased in both groups (P < 0.05); the SD and AD increased in both groups (P < 0.05). The cage height and L4-5 IDH in the OLIF group were significantly higher than those in the TLIF group (P < 0.05). SL, LL, PT, SS, and L5- S1DA were significantly improved in the OLIF group compared with the TLIF group (P < 0.05). The incidence of L3-4ASDeg in the two groups was higher than that of L5-S1. The incidence of ASDeg and the incidence of L5-S1ADD in the OLIF group were lower than those in the TLIF group, but the incidence of L5-S1AJD was higher than that in the TLIF group. CONCLUSION: L4DLS after OLIF and TLIF treatment will cause adjacent segment degeneration, and L3-4 degeneration is more obvious than L5-S1 degeneration. OLIF has more advantages in restoring lumbar sagittal balance. Compared with TLIF, OLIF can weaken the degeneration of the L5-S1 disc and increase the degeneration of the L5-S1 zygapophyseal joints.

Incidence and risk factors associated with superior-segmented facet joint violation during minimal invasive lumbar interbody fusion.

BACKGROUND CONTEXT: The trend of minimally invasive lumbar interbody fusion is increasing, and adjacent segmental degeneration (ASD) is one of the complications of the procedures in which facet joint violation (FJV) is a cause. FJVs can occur during percutaneous instrumentation. This study aimed to identify the risk factors that affect FJV during minimally invasive lumbar interbody fusion. PURPOSE: To identify the risk factors for FJVs and the factors that have a strong impact on the violation. STUDY DESIGN: Retrospective study. PATIENT SAMPLE: Patients who underwent minimally invasive lumbar interbody fusion with percutaneous screw fixation between June 2018 and December 2019. OUTCOME MEASURES: Prevalence of the FJV was reviewed by CT scans which obtained within 6 months after surgery, and the axial, coronal, and sagittal cuts of the scans were evaluated. The FJV was defined as the screw being visible in the facet joint in at least one plane of the CT scan. Radiographic parameters were measured using CT scans including diameters of the facet joints in the axial, coronal, and sagittal planes defined by the facet diameter. The facet angle (FA), the pedicle angle (PA), the screw-facet angle (SFA), the screw-endplate angle (SEA), and the superior margin of the facet joint in the sagittal plane (SD) differed from the head of the screw. At Last, the depth of back muscle was measured in the axial cut of the MRI. METHODS: This study analyzed 119 patients who underwent minimally invasive lumbar interbody fusion between June 2018 and December 2019. Facet joint violation at the uppermost level was examined using CT in all dimensions. Radiographic parameters (facet diameter, facet angle, pedicle angle, screw-facet angle, screw-endplate angle, and distance between the head of the screws and the facet) were measured. BMI, age, diagnosis, and navigation assistance were included in the study. Risk factors were analyzed to determine which factors had an effect on FJV, and the cut-off was calculated for each parameter. RESULTS: This study included 119 patients, with a mean age of 63 years. FJV occurred in 13/119 (10.9%) patients and 15/238 (6.3%) joints, respectively. No FJV occurred in 120 joints operated with navigation-assistance and 15/178 (8.4%) joints operated without navigation (p=.01). We found an increasing proportion of violations at more caudal levels: no violations occurred in eight patients with lumbar at L1 or L2, and 1/40 (2.5%), 7/158 (4.4%), and 7/32 (21.9%) of violations occurred at L3, L4, and L5, respectively (p=.01). The diameter of the facet in the axial cut, facet angle, screw facet angle, and distance between the head of the screw and facet were statistically significant in determining the increasing rate of FJV after multivariate analysis was performed (AROC=0.9486, p≤.05). The cutoff point for each radiographic parameter were diameter of facet in the axial ≥17.5 mm, diameter of facet in coronal plane ≥19.5 mm, facet angle ≥41.5o, screw-facet angle ≥39o, and distance between facet and the screw ≥-2.6 mm. The estimated probability of FJV was 96.9% when every parameter was greater than the cut-off point. CONCLUSIONS: An increase in the facet diameter in the axial plane, coronal plane, facet angle, screw facet angle, and the distance between the dome of the screw and facet are risk factors for FJV. Surgeons can avoid violations when radiographic considerations are done. Careful screw placement and good entry points for instrumentation may decrease the rate of facet violation.

Effect of Pedicle Screw Fixation on Adjacent Segments in Osteoporotic Spine Following Transforaminal Lumbar Interbody Fusion Under Whole Body Vibration.

BACKGROUND: Adjacent segmental degeneration (ASD) is the long-term complication of transforaminal lumbar interbody fusion (TLIF) combined with pedicle screw fixation. Both osteoporosis and whole-body vibration (WBV) can alter the biomechanics of adjacent segments. However, the effect of pedicle screw fixation on ASD in an osteoporotic spine after TLIF under WBV was unknown. METHODS: According to a previously validated model of L1-S1, 2 osteoporotic TLIF models with and without pedicle screw fixation were developed. In each model, a 400 N preload was applied and a 5-Hz, 40 N sinusoidal vertical load with a 40-kg mass point was imposed on the superior surface of L1. The parameters of intradiskal pressure, shear stress of annulus fibrosus, disk bulge, superior and inferior end plate stress, and facet joint contact pressure at L3-L4 and L5-S1 levels were evaluated. RESULTS: At L3-L4, the dynamic responses in intradiskal pressure, shear stress, facet joint contact pressure, superior end plate stress, and inferior end plate stress generated an increase after pedicle screw fixation, and their maximum values increased by 15.1%, 9.5%, 18.6%, 10.6%, and 9.3%, respectively. However, the parameter of disk bulge demonstrated an opposite trend. At L5-S1, the differences in maximum values of the parameters were slight and the corresponding dynamic response curves were close, overlapping, or intersecting. CONCLUSIONS: In an osteoporotic spine after TLIF, removal of pedicle screw fixation can mitigate ASD in the upper adjacent segment but has no apparent influence on the lower adjacent segment under WBV.

Effect of Osteoporosis on Adjacent Segmental Degeneration After Posterior Lumbar Interbody Fusion Under Whole Body Vibration.

BACKGROUND: Adjacent segmental degeneration (ASD) is one of the common complications after posterior lumbar interbody fusion (PLIF). Both whole body vibration (WBV) and osteoporosis are important factors associated with the biomechanics of the lumbar spine. However, to the best of our knowledge, no studies have investigated the effects of osteoporosis on ASD after PLIF under WBV. METHODS: In the present study, using one normal model, one PLIF model and one PLIF with osteoporosis model of the L1-S1 segment were developed. A 5-Hz, 40-N sinusoidal vertical load was imposed on the superior surface of L1 of each model to simulate WBV, and the dynamic responses and maximal values of intradiscal pressure, shear stress on annulus fibrosus, total deformation, and disc bulge were evaluated in the L1-L2, L2-L3, L3-L4, and L5-S1 segments. RESULTS: At the L1-L2, L2-L3, and L3-L4 levels, the differences in the dynamic responses and maximal values in intradiscal pressure, shear stress, total deformation, and disc bulge between the PLIF and PLIF with osteoporosis models were slight. However, at the L5-S1 level, the dynamic response curves and maximal intradiscal pressure, shear stress, and disc bulge values in the PLIF with osteoporosis model were significantly lower than those in the PLIF model. CONCLUSIONS: Osteoporosis can mitigate the development of ASD in the lower adjacent segment but has no obvious influence on the upper adjacent segments during WBV.

Biomechanical effects of osteoporosis on adjacent segments after posterior lumbar interbody fusion: A finite element study.

OBJECTIVE: To investigate the biomechanical effects of osteoporosis on adjacent segments after posterior lumbar interbody fusion (PLIF). METHODS: This study was designed and conducted in the Traumatology and Orthopedics Laboratory, School of Chinese Medicine, Jinan University, Guangzhou, China, between December 2019 and February 2020. A healthy finite element model of L3-S1 was developed along with one PLIF model and one PLIF with osteoporosis model. Based on a hybrid test method, the inferior surface of S1 was entirely fixed, and a preload of 400N combined with an adjusted moment was imposed on the superior surface of L3 in each model to simulate flexion, extension, lateral bending and axial rotation. The intradiscal pressure (IDP), shear stress on annulus fibrosus, and the range of motion (ROM) of L3-L4 and L5-S1 were calculated and compared. RESULTS: In each direction, the highest value of IDP and shear stress on annulus fibrosus at L3-L4 and L5-S1 was found in the PLIF model, and the lowest value in the healthy model. The largest ROM at L4-L5 appeared in the healthy model, and the smallest value in the PLIF model in each direction. At L3-L4 and L5-S1, the highest ROM in most directions was found in the PLIF model, followed by the PLIF with osteoporosis model, and the lowest value in the healthy model. CONCLUSIONS: Osteoporosis can decrease IDP, shear stress on annulus fibrosus, and ROM at adjacent levels, and slow down the development of ASD after PLIF.

Magnetic resonance imaging on disc degeneration changes after implantation of an interspinous spacer and fusion of the adjacent segment.

The aim of the study was to investigate the changes of the lumbar intervertebral disc degeneration by magnetic resonance imaging (MRI) after the implantation of interspinous device and the fusion of the adjacent segment. A total of 62 consecutive patients suffering L5/S1 lumbar disc herniation (LDH) with concomitant disc space narrowing or low-grade instability up to 5 mm translational slip in L5/S1 level were treated with lumbar interbody fusion (LIF) via posterior approach. Thirty-four of these patients (Coflex group) received an additional implantation of the interspinous spacer device (Coflex™) in the level L4/L5, while the rest of 28 patients (fusion group) underwent the fusion surgery alone. Clinical and radiographic examinations were performed at pre- and postoperative visits to compare the clinical outcomes and the changes of the L4/L5 vertebral disc degeneration on MRI in both Coflex and fusion group. Although both Coflex and fusion group showed improvements of the clinical outcomes assessed by the Oswestry Disability Index (ODI) after surgery, patients in Coflex group had more significant amelioration (P < 0.05) compared to fusion group. During follow up, the postoperative disc degeneration changes in Coflex group assessed by the relative signal intensity (RSI) differed from those in fusion group (P < 0.05). The supplemental implantation of Coflex™ after the fusion surgery could delay the disc degeneration of the adjacent segment.

Posterior interspinous fusion device for one-level fusion in degenerative lumbar spine disease : comparison with pedicle screw fixation - preliminary report of at least one year follow up.

OBJECTIVE: Transpedicular screw fixation has some disadvantages such as postoperative back pain through wide muscle dissection, long operative time, and cephalad adjacent segmental degeneration (ASD). The purposes of this study are investigation and comparison of radiological and clinical results between interspinous fusion device (IFD) and pedicle screw. METHODS: From Jan. 2008 to Aug. 2009, 40 patients underwent spinal fusion with IFD combined with posterior lumbar interbody fusion (PLIF). In same study period, 36 patients underwent spinal fusion with pedicle screw fixation as control group. Dynamic lateral radiographs, visual analogue scale (VAS), and Korean version of the Oswestry disability index (K-ODI) scores were evaluated in both groups. RESULTS: The lumbar spine diseases in the IFD group were as followings; spinal stenosis in 26, degenerative spondylolisthesis in 12, and intervertebral disc herniation in 2. The mean follow up period was 14.24 months (range; 12 to 22 months) in the IFD group and 18.3 months (range; 12 to 28 months) in pedicle screw group. The mean VAS scores was preoperatively 7.16±2.1 and 8.03±2.3 in the IFD and pedicle screw groups, respectively, and improved postoperatively to 1.3±2.9 and 1.2±3.2 in 1-year follow ups (p<0.05). The K-ODI was decreased significantly in an equal amount in both groups one year postoperatively (p<0.05). The statistics revealed a higher incidence of ASD in pedicle screw group than the IFD group (p=0.029). CONCLUSION: Posterior IFD has several advantages over the pedicle screw fixation in terms of skin incision, muscle dissection and short operative time and less intraoperative estimated blood loss. The IFD with PLIF may be a favorable technique to replace the pedicle screw fixation in selective case.