Adjacent Segment Disc Degeneration Research Articles

Long-Term Incidence of Adjacent Segmental Pathology After Minimally Invasive vs. Open Transforaminal Lumbar Interbody Fusion.

Retrospective cohort study. To compare the incidence of adjacent segmental pathology (ASP) following minimally invasive (MI) vs open transforaminal lumbar interbody fusion (TLIF) and to identify factors linked to ASP requiring reoperation. This retrospective study reviewed the outcomes of patients who underwent MI-TLIF or open TLIF. Radiographic ASP (RASP) was evaluated using X-ray imaging to distinguish between degenerative changes, spondylolisthesis, and instability in the adjacent spinal segment. Clinical ASP (CASP) was assessed with the visual analog scale score for leg and back pain and the Oswestry disability index. Patient data were collected 1, 2, 5, and 10 years postoperatively. The timing and frequency of ASP reoperation were analyzed. Five years postoperatively, the RASP rate was 35.23% and 45.95% in the MI-TLIF and open TLIF groups. The frequency of CASP differed significantly between the MI-TLIF and open TLIF groups at 1 year postoperatively. The rates of RASP, CASP, and ASP necessitating reoperation were not significantly different 10years postoperatively. Cranial facet violation significantly affected ASP in both groups. In the open TLIF group, preoperative adjacent segment disc degeneration significantly influenced ASP. The RASP rate at 5years postoperatively and the CASP rate at 1year postoperatively differed significantly between groups. There was no difference in the rate of ASP requiring reoperation. Cranial facet violation is a crucial driving factor for ASP after both surgical procedures.

Strontium ranelate retards disc degradation and improves endplate and bone micro-architecture in ovariectomized rats with lumbar fusion induced – Adjacent segment disc degeneration

ObjectivesAdjacent segment disc degeneration (ASDD) is one of the long-term sequelae of spinal fusion, which is more susceptible with osteoporosis. As an anti-osteoporosis drug, strontium ranelate (SR) has been reported to not only regulate bone metabolism but also cartilage matrix formation. However, it is not yet clear whether SR has a reversal or delaying effect on fusion-induced ASDD in a model of osteoporosis. Materials and methodsFifth three-month-old female Sprague-Dawley rats that underwent L4-L5 posterolateral lumbar fusion (PLF) with spinous-process wire fixation 4 weeks after bilateral ovariectomy (OVX) surgery. Animals were administered vehicle (V) or SR (900 mg/kg/d) orally for 12 weeks post-PLF as follows: Sham+V, OVX + V, PLF + V, OVX + PLF + V, and OVX + PLF + SR. Manual palpation and X-ray were used to evaluate the state of lumbar fusion. Adjacent-segment disc was assessed by histological (VG staining and Scoring), histomorphometry (Disc Height, MVD, Calcification rate and Vascular Bud rate), immunohistochemical (Col-II, Aggrecan, MMP-13, ADAMTS-4 and Caspase-3), and mRNA analysis (ColI, Col-II, Aggrecan, MMP-13 and ADAMTS-4). Adjacent L6 vertebrae microstructures were evaluated by microcomputed tomography. ResultsManual palpation and radiographs showed clear evidence of the fused segment's immobility. After 12 weeks of PLF surgery, a fusion-induced ASDD model was established. Low bone mass caused by ovariectomy can significantly exacerbate ASDD progression. SR exerted a protective effect on adjacent segment intervertebral disc with the underlying mechanism possibly being associated with preserving bone mass to prevent spinal instability, maintaining the functional integrity of endplate vascular microstructure, and regulating matrix metabolism in the nucleus pulposus and annulus fibrosus. DiscussionAnti-osteoporosis medication SR treatments not only maintain bone mass and prevent fractures, but early intervention could also potentially delay degenerative conditions linked to osteoporosis. Taken together, our results suggested that SR might be a promising approach for the intervention of fusion-induced ASDD with osteoporosis.

Adjacent segment disease after minimally invasive transforaminal lumbar interbody fusion for degenerative lumbar diseases: incidence and risk factors

Study designRetrospective study.ObjectivesTo explore the incidence and risk factors for symptomatic adjacent segment disease (ASD) in patients enveloped in degenerative lumbar diseases after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).MethodsData were retrospectively analyzed on 744 patients who underwent MIS-TLIF for degenerative lumbar diseases in our hospital from October 2012 to December 2018. The patients were divided into the ASD group and non-ASD (N-ASD) group on the basis of developing ASD at follow-up, and then the incidence of ASD was calculated. Clinical and radiological risk factors were assessed over time to determine their association with ASD by excluding less important factors.ResultsData were missing for 26 patients, while a total of 718 patients were successfully monitored after MIS-TLIF. Of the 718 individuals participated in the study, 34 (4.7%) patients plagued by ASD required surgical intervention. The average onset time of ASD was 62.7 ± 15.1 months. Univariate analysis results shows that age, bone mineral density (BMD), body mass index (BMI), preoperative adjacent intervertebral disc height and preoperative adjacent segment disc degeneration were significantly different between the ASD and N-ASD groups (p < 0.05). The logistic regression analysis results demonstrated that BMD (p = 0.039, OR = 0.986, 95% CI 0.899–1.115), BMI (p = 0.041, OR = 1.119, 95% CI 1.103–2.397), and preoperative adjacent intervertebral disc degeneration (p = 0.023, OR = 1.215, 95% CI 1.015–1.986) may be seen as risk factors for ASD after MIS-TLIF.ConclusionsThe incidence of ASD was about 4.7% in patients suffer from degenerative lumbar diseases after MIS-TLIF. BMD, BMI and preoperative adjacent intervertebral disc degeneration might be the risk factors for the occurrence of ASD after MIS-TLIF. Our research also suggested that patients with lower BMD, higher BMI and disc preoperative adjacent segment disc degeneration were more likely to develop ASD after MIS-TLIF.

In Vivo Evidence of Early Instability and Late Stabilization in Motion Segments Immediately Superior to Anterior Cervical Arthrodesis.

Prospective cohort study. The aim was to identify patient factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography. The etiology of adjacent segment disease (ASD) may be multifactorial. Previous studies have investigated associations between patient factors and ASD, although few attempted to link patient factors with mechanical changes in the spine that may explain ASD development. Previous studies manually measured intervertebral motion from static flexion/extension radiographs, however, manual measurements are unreliable, and those studies failed to measure intervertebral motion during rotation. Patients had continuous cervical spine flexion/extension and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific computed tomography scans were matched to the biplane radiographs using a validated tracking process. Dynamic kinematics and preoperative disc height were calculated from this tracking process. Preoperative magnetic resonance imagings were evaluated for disc bulge. Patient age, sex, body mass index, smoking status, diabetes, psychiatric history, presence of an inciting event, and length of symptoms were collected. Multivariate linear regression was performed to identify patient factors associated with 1-year postoperative changes in adjacent segment kinematics. Sixty-three patients completed preoperative and postoperative testing. Superior adjacent segment disc height and disc bulge predicted the change in superior adjacent segment range of motion after surgery. Inferior adjacent segment disc bulge, smoking history, and the use of psychiatric medications predicted the change in inferior adjacent segment flexion/extension range of motion after surgery. Preexisting adjacent segment disc degeneration, as indicated by disc height and disc bulge, was associated with reduced adjacent segment motion after ACDF, while lack of preexisting adjacent disc degeneration was associated with increased adjacent segment motion after ACDF. These findings provide in vivo evidence supporting early instability and late stabilization in the pathophysiology of disc degeneration.

Revision Surgery for Symptomatic Adjacent Segment Disc Degeneration after Initial Anterior Cervical Fusion: Is ROI-C Better than Plate-Cage Construct?

The optimal revision surgical strategy for patients who develop symptomatic adjacent segment disc degeneration (ASD) is controversial. The risks of intraoperative complications, especially the incidence of dysphagia, were relatively high for revision surgeries. This study was aimed at comparing the efficacy of revision surgery using a traditional plate-cage construct and zero-profile anchored spacer (ROI-C) device in treating symptomatic ASD after initial anterior cervical discectomy and fusion (ACDF) surgery. Forty-two patients who developed symptomatic ASD were retrospectively analyzed and classified into two groups (plate-cage group and ROI-C group). The clinical and radiological results were compared. We further evaluated the complication of dysphagia and dysphagia-related risk factors in these patients. The JOA and NDI scores, C2-7 lordotic angle, and intervertebral space height were significantly improved after revision surgery in both groups. The operative time and intraoperative blood loss both significantly decreased in the ROI-C group. The incidence of postoperative dysphagia was much lower in the ROI-C group than in the plate-cage group (18.75% vs. 57.69%; P = 0.01). The presence of dysphagia after initial surgery (P = 0.003) and revision surgery type (P = 0.01) was significantly related to the presence of dysphagia after revision surgery. These results indicated that both the plate-cage construct and ROI-C are effective in treating symptomatic ASD. However, compared with the traditional plate-cage construct, ROI-C with less operative time, less blood loss, and lower incidence of dysphagia is more suitable. Furthermore, ROI-C should preferably be used for patients who present with dysphagia after initial cervical surgery. This study will provide clinical guidance for spinal surgeons to choose the zero-profile device in treating specific and complicated cases, which will significantly improve the therapeutic efficacy of symptomatic adjacent segment degeneration.

Incidence and Risk Factors for Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion in Patients with Lumbar Degenerative Diseases.

PurposeTo explore the incidence and risk factors for adjacent segment disease (ASD) in patients with lumbar degenerative diseases after transforaminal lumbar interbody fusion (TLIF).Patients and MethodsThe clinical data of 1258 patients who underwent transforaminal lumbar interbody fusion (TLIF) for lumbar degenerative diseases in our hospital from January 2011 to December 2017 were retrospectively analyzed. Patients were divided into the ASD group and non-ASD (N-ASD) group, and the incidence of ASD was calculated. We compared age, BMI, comorbidities, surgery-related parameters, and imaging parameters before surgery between the two groups and used univariate analysis and logistic regression analysis to explore the risk factors for ASD.ResultsAmong the 1258 patients who underwent TLIF due to lumbar degenerative diseases, 65 patients developed ASD and received surgical treatment for it, for an incidence of 5.2%. The average onset time of ASD was 68.3±25.1 (20–123) months. Univariate analysis showed that BMI, hypertension, preoperative adjacent segment disc degeneration and preoperative adjacent intervertebral disc height were significantly different between the ASD and N-ASD groups (P< 0.05). Incorporating the above indicators into the logistic regression model, the results showed that BMI and preoperative adjacent intervertebral disc degeneration were risk factors for ASD after TLIF.ConclusionThe incidence of ASD after TLIF in patients with lumbar degenerative disease is approximately 5.2%. High BMI and preoperative adjacent segment disc degeneration are risk factors for ASD after TLIF.

Effect of posterior lumbar fusion on the degeneration of adjacent segments using cortical bone trajectory screw fixation

Objective: To compare the degenerative changes of adjacent segments after posterior lumbar fusion surgery using cortical bone trajectory (CBT) screws and pedicle screws (PS) in lumbar spinal degenerative disease. Methods: According to certain inclusion and exclusion criteria, prospective non-randomized study on cases of the single-segment lumbar spinal fusion surgery using cortical bone trajectory screws fixation and pedicle screws fixation in Beijing Chao-Yang Hospital from January 2015 to February 2016 was performed. The intervertebral space height (ISH), foramen height (FH), foramen width (FW), cephalad adjacent segment (CAS) and intervertebral disc degeneration grades at MRI scans were measured before surgery and during follow-up. Clinical symptoms were evaluated by Oswestry Dysfunction Index (ODI) score and pain visual analogue scale (VAS) before and during the follow-up. Radiologic adjacent segment degeneration (R-ASD) and symptomatic adjacent segment disease (S-ASD) patients were diagnosed during the follow-up. Paired sample t test was performed when data were compared before surgery and during follow-up. Results: A total of 69 patients were included in the study, 33 in the CBT group (male/female, 15/18), with an average age of (65±11) years, and 36 in the PS group (male/female, 17/19), with an average age of (64±10) years. The follow-up time was no less than 36 months. At the last follow-up, the ISH of the adjacent segments in the CBT group were not statistically different from that before surgery; the ISH of the adjacent segments in the PS group were significantly reduced compared with that before surgery (t=6.78, P<0.05). The loss of ISH, FH, and FW in the adjacent segments in the CBT group were smaller than those in the PS group, and the differences were statistically significant. During follow-up, 4 cases (12.1%) of R-ASD and no S-ASD were found in the CBT group, while 12 cases (33.3%) of R-ASD appeared in the PS group, which was significantly higher than that in the CBT group (χ(2)=4.35, P=0.04). According to MRI, the adjacent discs of PS group had significantly more severe degeneration at the last follow-up than the CBT group (Z=-2.14, P=0.03). Conclusions: Compared with the PS fixation fusion, the CBT screw fixation can effectively reduce the occurrence of adjacent segment degeneration.

Percutaneous transforaminal full endoscopic decompression for the treatment of lumbar spinal stenosis

BackgroundOne advantage of an endoscopic approach to treating lumbar spinal stenosis is preservation of spine stability and the adjacent anatomy, and there is a decrease in adjacent segment disc degeneration. The purpose of this study was to discuss the clinical efficacy of percutaneous transforaminal endoscopic decompression for the treatment of lumbar spinal stenosis (LSS).MethodsThis is a retrospective study. From September 2012 to June 2017, 45 patients who were diagnosed with LSS underwent the treatment of percutaneous transforaminal endoscopic decompression (PTED) and were followed up at 1 week, 3 months and 1 year postoperatively. Low back pain and leg pain were measured by Visual Analogue Scale scoring methods (VAS-back and VAS-leg), while functional outcomes were assessed by using the Oswestry Disability Index (ODI). All patients had one-level lumbar spinal stenosis.ResultsThe most common type of stenosis was lateral recess stenosis (n = 22; 48.9%), followed by central stenosis (n = 13; 28.9%) and foraminal stenosis (n = 10: 22.2%). Regarding comparisons of VAS-back, VAS-leg, and ODI scores before and after operation, VAS and ODI scores significantly improved. The average leg VAS score improved from 7.01 ± 0.84 to 2.28 ± 1.43 (P < 0.001). The average ODI improved from 46.18 ± 10.11 to 14.40 ± 9.59 (P < 0.001). We also examined changes in ODI and VAS scores from baseline according to types of spinal stenosis, stenosis grade, spinal instability, and revision surgery in the same segment. The improvement percentage of leg VAS score was significantly less in patients with severe stenosis at both 3 months and 1 year postoperatively. The improvement percentages of ODI and leg VAS scores were significantly less in patients who had spinal instability and patients who had undergone revision surgery.ConclusionThe PTED approach seems to give good results for the treatment of LSS. However, this approach may be less effective for LSS patients who have lumbar instability or require revision surgery in the same segment.

Incidence and risk factors of adjacent segment disease following posterior decompression and instrumented fusion for degenerative lumbar disorders.

The purpose of this study was to explore incidence and risk factors of adjacent segment disease (ASD) following posterior decompression and instrumented fusion for degenerative lumbar disorders, and hope to provide references in decision making and surgical planning for both spinal surgeon and surgically treated patients.By retrieving the medical records from January 2011 to December 2013 in our hospital, 237 patients were retrospectively reviewed. According to the occurrence of ASD at follow up, patients were divided into 2 groups: ASD and N-ASD group. To investigate risk values for the occurrence of ASD, 3 categorized factors were analyzed statistically: Patient characteristics: age, sex, body mass index (BMI), bone mineral density (BMD), duration. Surgical variables: surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, intraoperative superior facet joint violation. Radiographic parameters: preoperative lumbar lordosis, preoperative angular motion at adjacent segment, preoperative adjacent segment disc degeneration, preoperative paraspinal muscle degeneration.Postoperative ASD was developed in 15 of 237 patients (6.3%) at final follow up. There was no statistically significant difference between the 2 groups in patient characteristics of age, sex composition, BMD, duration, while the BMI was higher in ASD group than that in N-ASD group. There was no difference in surgical variables of surgical strategy, number of fusion level, surgery segment, surgery time, blood loss, while intraoperative superior facet joint violation was more common in ASD group than that in N-ASD group. There was no difference in radiographic parameters of preoperative lumbar lordosis, preoperative paraspinal muscle degeneration, while preoperative adjacent segment disc degeneration were more severe in ASD group than that in N-ASD group. The Logistic regression analysis revealed that, BMI >25 kg/m2, preoperative disc degeneration, and superior facet joint violation were independently associated with ASD.In conclusion, higher BMI, preoperative disc degeneration at adjacent segment and intraoperative superior facet joint violation are risk factors for ASD. Patients who are overweight or obesity and with preoperative disc degeneration at adjacent segment should be fully informed the risk of ASD. For surgeons, it is essential to prevent superior facet joint violation in pedicle screw insertion procedure.

Prognosis and adjacent segment disease after lumbar spinal fusion surgery for destructive spondyloarthropathy in long-term hemodialysis patients.

Lumbar destructive spondyloarthropathy (DSA) is a serious complication in long-term hemodialysis patients. There have not been many reports regarding the surgical management for lumbar DSA. In addition, the adjacent segment pathology after lumbar fusion surgery for DSA is unclear. The objective of this study was to assess the clinical outcome and occurrence of adjacent segmental disease (ASD) after lumbar instrumented fusion surgery for DSA in long-term hemodialysis patients. A consecutive series of 36 long-term hemodialysis patients who underwent lumbar instrumented fusion surgery for DSA were included in this study. The mean age at surgery was 65 years. The mean follow-up period was 4 years. Symptomatic ASD was defined as symptomatic spinal stenosis or back pain with radiographic ASD. The Japanese Orthopedic Association score (JOA score), recovery rate (Hirabayashi method), complications, and reoperation were reviewed. The mean JOA score significantly increased from 13.5 before surgery to 21.3 at the final follow-up. The mean recovery rate was 51.4%. Six of the 36 patients died within 1 year after index surgery. One patient died due to perioperative complication. Symptomatic ASD occurred in 43% (13 of 30) of the cases. Of these 13 cases, 5 had adjacent segment disc degeneration and 8 had adjacent segment spinal stenosis. Three cases (10%) required reoperation due to proximal ASD. Multi-level fusion surgery increased the risk of ASD compared with single-level fusion surgery (59% vs. 23%). The recovery rate was significantly lower in the ASD group than the non-ASD group (38% vs. 61%). This study demonstrated that symptomatic ASD occurred in 43% of patients after surgery for lumbar DSA. A high mortality rate and complication rate were observed in long-term hemodialysis patients. Therefore, care should be taken for preoperative planning for surgical management of DSA.

Changes of proteoglycan and collagen II of the adjacent intervertebral disc in the cervical instability models.

Post-operation of cervical decompression fusion and internal fixation (CDF) accelerated adjacent segment disc degeneration (ASD). It is not clear that whether instability of one single segmental accelerates the degeneration of adjacent segment disc. This study aims to explore the effect of cervical instability on the change of morphology and biochemistry in adjective segment (above) in the L5/6 cervical instability rabbit models. Thirty-two mature New Zealand white rabbits (3000±250g) were randomly divided into two groups, control group (n=8) and model group (n=24). The animal models were established by destruction of partly annulus fibrosus and suction of nucleus pulposus. ASD was detected by X-ray after 4, 8 or 12 weeks surgery (8 model rabbits of each time). Animals were then euthanatized for cervical intervertebral disc tissue samples separation. Histomorphology, proteoglycan and collagen II of samples were detected. Histomorphology data showed that notochord cells were decreased in C4/5 cervical nucleus pulposus and were replaced by fibroblast-like cells; a small amount cartilage cells were emerged; intervertebral disc anulus fibrosus becomes rough, disorganized, hyaline degeneration and pigmentation, in which contained fibrocartilage cells and cracks between the inner and outer layers. Proteoglycan content of nucleus pulposus was significantly decreased. Meanwhile, type II collagen of nucleus pulposus and annulus was also apparently reduced. Cervical instability can alter morphology and reduce the content of proteoglycan and collagen II in adjacent intervertebral disc, thereby contributes adjacent intervertebral disc degeneration.

Paraspinal muscle, facet joint, and disc problems: risk factors for adjacent segment degeneration after lumbar fusion

Background ContextAdjacent segment degeneration (ASD) is one of the major complications after lumbar fusion. Several studies have evaluated the risk factors of ASD. Although the paraspinal muscles play an important role in spine stability, no study has assessed the relationship between paraspinal muscle atrophy and the incidence of ASD after lumbar fusion. PurposeIn the present study, we aimed to verify the known risk factors of ASD, such as body mass index (BMI), preoperative adjacent facet joint degeneration, and disc degeneration, and to assess the relationship between paraspinal muscle atrophy and ASD. Study DesignThis is a retrospective 1:1 pair analysis matched by age, sex, fusion level, and follow-up period. Patient SampleTo calculate the appropriate sample size for the study, we performed a pre-study analysis of the paraspinal muscle cross-sectional area (CSA), and estimated that at least 35 cases would be needed for each group. Among the 510 patients who underwent posterior lumbar fusion for degenerative lumbar disease between January 2009 and October 2009, a total of 50 patients with ASD after surgery were selected. Another group of 50 matched patients with degenerative lumbar disease without ASD after spinal fusion were selected as the control group. Each patient in the ASD group was matched with a control patient according to age, sex, fusion level, and follow-up period. Outcome MeasuresRadiographic measurements and demographic data were reviewed. MethodsThe risk factors considered were higher BMI, preoperative adjacent segment disc and facet degeneration, and preoperative paraspinal muscle atrophy and fatty degeneration. The radiographic data were compared between the ASD and control groups to determine the predictive factors of ASD after posterior lumbar fusion by using logistic regression analysis. The study was not externally funded. The authors have no conflict of interest to declare. ResultsMultivariate logistic regression analysis indicated that higher BMI (odds ratio [OR]: 1.353, p=.008), preoperative facet degeneration on computed tomography examination (OR: 3.075, p=.011), disc degeneration on magnetic resonance imaging (MRI) (OR: 2.783, p=.003), fatty degeneration (OR: 1.080, p=.044), and a smaller relative CSA of the paraspinal muscle preoperatively (OR: 0.083, p=.003) were significant factors for predicting the development of ASD. ConclusionsThe occurrence of radiological ASD is most likely multifactorial, and is associated with a higher BMI, preexisting facet and disc degeneration on preoperative examination, and a smaller preoperative relative CSA of the paraspinal muscle on MRI.

Protective effect of calcitonin on lumbar fusion-induced adjacent-segment disc degeneration in ovariectomized rat.

BackgroundIntervertebral disc (IVD) degeneration and pathological changes in the spinal cord are major causes of back pain. In addition to its well-established anti-resorptive effect on bone, calcitonin (CT) potentially exerts protective effects on IVD degeneration in ovariectomized rats. However, possible therapeutic effects of CT on lumbar fusion-induced adjacent-segment disc degeneration (ASDD) have not been investigated yet. In this study, we examined the effects of CT on IVD degeneration adjacent to a lumbar fusion in ovariectomized rats.MethodsPosterolateral lumbar fusion (PLF) at L4–5 was performed 4 weeks after ovariectomy (OVX) or sham surgery in female Sprague–Dawley rats. Following PLF + OVX, rats received either salmon CT (OVX + PLF + sCT, 16 IU/Kg/2d) or vehicle (OVX + PLF + V) treatment for 12 weeks; the remaining rats were divided into Sham + V, OVX + V, and PLF + V groups. Fusion status was analyzed by manual palpation and radiography. Adjacent segment disc was assessed by histological, histomorphometric, immunohistochemical analysis. L6 vertebrae microstructures were evaluated by micro-computed tomography.ResultsHistological analysis showed more severe ASDD occurred in OVX + PLF + V rats compared with the OVX + V or PLF + V groups. CT treatment suppressed the score for ASDD, increased disc height, and decreased the area of endplate calcification. Immunohistochemical staining demonstrated that CT decreased the expression of collagen type-I, matrix metalloproteinase-13, and a disintegrin and metalloproteinase with thrombospondin motifs-4, whereas it increased the expression of collagen type-II and aggrecan in the disc. Micro-computed tomography indicated that CT increased bone mass and improved the microstructure of the L6 vertebrae.ConclusionsThese results suggest that CT can prevent ASDD, induce beneficial changes in IVD metabolism, and inhibit deterioration of the trabecular microarchitecture of vertebrae in osteoporotic rats with lumbar fusion.

Enhancement of Lumbar Fusion and Alleviation of Adjacent Segment Disc Degeneration by Intermittent PTH(1-34) in Ovariectomized Rats.

Osteoporosis, which is prevalent in postmenopausal or aged populations, is thought to be a contributing factor to adjacent segment disc degeneration (ASDD), and the incidence and extent of ASDD may be augmented by osteopenia. Parathyroid hormone (PTH) (1-34) has already been shown to be beneficial in osteoporosis, lumbar fusion and matrix homeostasis of intervertebral discs. However, whether PTH(1-34) has a reversing or retarding effect on ASDD in osteopenia has not been confirmed. In the present study, we evaluated the effects of intermittent PTH(1-34) on ASDD in an ovariectomized (OVX) rat model. One hundred 3-month-old female Sprague-Dawley rats underwent L4 -L5 posterolateral lumbar fusion (PLF) with spinous-process wire fixation 4 weeks after OVX surgery. Control groups were established accordingly. PTH(1-34) was intermittently administered immediately after PLF surgery and lasted for 8 weeks using the following groups (n = 20) (V = vehicle): Sham+V, OVX+V, Sham+PLF+V, OVX+PLF+V, OVX+PLF+PTH. The fused segments showed clear evidence of eliminated motion on the fusion-segment based on manual palpation. Greater new bone formation in histology was observed in PTH-treated animals compared to the control group. The extent of ASDD was significantly increased by ovariotomy. Intermittent PTH(1-34) significantly alleviated ASDD by preserving disc height, microvessel density, relative area of vascular buds, endplate thickness and the relative area of endplate calcification. Moreover, protein expression results showed that PTH(1-34) not only inhibited matrix degradation by decreasing MMP-13, ADAMTS-4 and Col-I, but also promote matrix synthesis by increasing Col-II and Aggrecan. In conclusion, PTH(1-34), which effectively improves lumbar fusion and alleviates ASDD in ovariectomized rats, may be a potential candidate to ameliorate the prognosis of lumbar fusion in osteopenia.

Alendronate Prevents Intervertebral Disc Degeneration Adjacent to a Lumbar Fusion in Ovariectomized Rats

A model of disc degeneration adjacent to a lumbar fusion in osteoporotic rats. We determined the effect of alendronate (ALN) on the disc degeneration adjacent to a lumbar fusion in ovariectomized rats. Adjacent-segment disc degeneration (ASDD) is one of the negative sequelae of spinal fusion. Previous studies have shown that ALN can alleviate disc degeneration. However, no data have been documented regarding the effect of ALN on ASDD after posterolateral lumbar fusion (PLF) in osteoporosis. 50 female Sprague-Dawley rats underwent either a sham operation (sham) (n = 20) or bilateral ovariectomy (OVX) (n = 30). 4 weeks later, all but 10 rats from each group underwent PLF consisting of an intertransverse process spinal fusion using autologous-iliac-bone grafts with spinous-process wire fixation at the L4-L5 segment. Animals were subcutaneously administered vehicle (V) or ALN (70 μg/kg/wk) for 12 weeks post-PLF as follows: Sham+V, OVX+V, PLF+V, OVX+PLF+V, and OVX+PLF+ALN. Fusion status was analyzed by manual palpation and radiography. Adjacent-segment disc was assessed by histological, histomorphometric, immunohistochemical, and mRNA analysis. L6 vertebrae microstructures were evaluated by microcomputed tomography. The fused segments showed clear evidence of fusion based on manual palpation and radiographs. The OVX+PLF+V group showed more severe degenerative alterations and higher histological scores in the disc than the Sham+V, OVX+V, and PLF+V groups (P < 0.05). Compared with the OVX+PLF+V group, the OVX+PLF+ALN group exhibited significantly improved bone mass and vertebrae microstructures (P < 0.05), an increased disc height, and a decreased endplate calcification area (P < 0.05). ALN also significantly decreased Col-I, MMP-13, and ADAMTS-4 expression and increased Col-II and Aggrecan expression in the disc matrix (P < 0.05). ALN effectively alleviated ASDD post-PLF in ovariectomized rats. These data indicate that ALN can be used as a potential therapeutic agent to attenuate ASDD progression in osteoporosis.

Biomechanical Analysis of Cervical Disc Replacement and Fusion Using Single Level, Two Level, and Hybrid Constructs.

A biomechanical study comparing arthroplasty with fusion using human cadaveric C2-T1 spines. To compare the kinematics of the cervical spine after arthroplasty and fusion using single level, 2 level and hybrid constructs. Previous studies have shown that spinal levels adjacent to a fusion experience increased motion and higher stress which may lead to adjacent segment disc degeneration. Cervical arthroplasty achieves similar decompression but preserves the motion at the operated level, potentially decreasing the occurrence of adjacent segment disc degeneration. 11 specimens (C2-T1) were divided into 2 groups (BRYAN and PRESTIGE LP). The specimens were tested in the following order; intact, single level total disc replacement (TDR) at C5-C6, 2-level TDR at C5-C6-C7, fusion at C5-C6 and TDR at C6-C7 (Hybrid construct), and lastly a 2-level fusion. The intact specimens were tested up to a moment of 2.0 Nm. After each surgical intervention, the specimens were loaded until the primary motion (C2-T1) matched the motion of the respective intact state (hybrid control). An arthroplasty preserved motion at the implanted level and maintained normal motion at the nonoperative levels. Arthrodesis resulted in a significant decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR adjacent to fusion preserved motion at the arthroplasty level, thereby reducing the demand on the other levels. Cervical disc arthroplasty with both the BRYAN and PRESTIGE LP discs not only preserved the motion at the operated level, but also maintained the normal motion at the adjacent levels. Under simulated physiologic loading, the motion patterns of the spine with the BRYAN or PRESTIGE LP disc were very similar and were closer than fusion to the intact motion pattern. An adjacent segment disc replacement is biomechanically favorable to a fusion in the presence of a pre-existing fusion.

Age and pro-inflammatory gene polymorphisms influence adjacent segment disc degeneration more than fusion does in patients treated for chronic low back pain.

Does lumbar fusion lead to accelerated adjacent segment disc degeneration (ASDD) or is it explained by genetics and aging? The influence of genetics on ASDD remains to be explored. This study assesses whether the disc space height adjacent to a fused segment is associated with candidate gene single nucleotide polymorphisms (SNPs). Patients with low back pain from four RCTs (N = 208 fusion; 77 non-operative treatment) underwent standing plain radiography and genetic analyses at 13 ± 4 years follow-up. Disc space height was measured using a validated computer-assisted distortion-compensated roentgen analysis technique and reported in standard deviations from normal values. Genetic association analyses included 34 SNPs in 25 structural, inflammatory, matrix degrading, apoptotic, vitamin D receptor and OA-related genes relevant to disc degeneration. These were analysed for their association with disc space height (after adjusting for age, gender, smoking, duration of follow-up and treatment group) first, separately, and then together in a stepwise multivariable model. Two SNPs from the IL18RAP gene (rs1420106 and rs917997) were each associated with a lower disc space height at the adjacent level (B = -0.34, p = 0.04 and B = -0.35, p = 0.04, respectively) and the MMP-9 gene SNP rs20544 was associated with a greater disc space height (B = 0.35, p = 0.04). Age (p < 0.001) and fusion (p < 0.008) were also significant variables in each analysis. The total explained variance in disc space height was for each SNP model 13-14 %, with 11-12 % of this being accounted for by the given SNP, 64-67 % by age and 19-22 % by fusion. In the multivariable regression analysis (with nine SNPs selected for entry, along with the covariates) the total explained variance in disc space height was 23 %, with the nine SNPs, age and fusion accounting for 45, 45 and 7 % of this, respectively. Age was the most significant determinant of adjacent segment disc space height followed by genetic factors, specifically inflammatory genes. Fusion explained a statistically significant but small proportion of the total variance. Much of the variance remained to be explained.

ISSLS Prize winner: Long-term follow-up suggests spinal fusion is associated with increased adjacent segment disc degeneration but without influence on clinical outcome: results of a combined follow-up from 4 randomized controlled trials.

Cross-sectional analysis of long-term follow-up (LTFU) data from 4 randomized controlled trials of operative versus nonoperative treatment for chronic low back pain. To examine the influence of spinal fusion on adjacent segment disc space height as an indicator of disc degeneration at LTFU. There is ongoing debate as to whether adjacent segment disc degeneration results from the increased mechanical stress of fusion. Plain standing lateral radiographs were obtained at LTFU (mean, 13 ± 4 yr postrandomization) in 229 of 464 (49%) patients randomized to surgery and 140 of 303 (46%), to nonoperative care. Disc space height and posteroanterior displacement were measured for each lumbar segment using a validated computer-assisted distortion compensated roentgen analysis technique. Values were reported in units of standard deviations above or below age and sex-adjusted normal values. Patient-rated outcomes included the Oswestry Disability Index and pain scales. Radiographs were usable in 355 of 369 (96%) patients (259 fusion and 96 nonoperative treatment). Both treatment groups showed significantly lower values for disc space height of the adjacent segment than norm values. There was a significant difference between treatment groups for the disc space height of the cranial adjacent segment (in both as-treated and intention-to-treat analyses). The mean treatment effect of fusion on adjacent segment disc space height was -0.44 SDs (95% CI, -0.77 to -0.11; P = 0.01; as-treated analysis); there was no group difference for posteroanterior displacement (0.18 SDs, 95% confidence interval, -0.28 to 0.64, P = 0.45). Adjacent level disc space height and posteroanterior displacement were not correlated with Oswestry Disability Index or pain scores at LTFU (r = 0.010-0.05; P > 0.33). Fusion was associated with lower disc space height at the adjacent segment after an average of 13 years of FU. The reduced disc space height had no influence on patient self-rated outcomes (pain or disability). 2.

Prevalence of adjacent segment disc degeneration in patients undergoing anterior cervical discectomy and fusion based on pre-operative MRI findings

Anterior cervical discectomy and fusion (ACDF) is a widely accepted surgical treatment for symptomatic cervical spondylosis. Some patients develop symptomatic adjacent segment degeneration, occasionally requiring further treatment. The cause and prevalence of adjacent segment degeneration and disease is unclear at present. Proponents for motion preserving surgery such as disc arthroplasty argue that this technique may decrease the “strain” on adjacent discs and thus decrease the incidence of symptomatic adjacent segment degeneration. The purpose of this study was to assess the pre-operative prevalence of adjacent segment degeneration in patients undergoing ACDF. A database review of three surgeons’ practice was carried out to identify patients who had undergone a one- or two-level ACDF for degenerative disc disease. Patients were excluded if they were operated on for recent trauma, had an inflammatory arthropathy (for example, rheumatoid arthritis), or had previous spine surgery. The pre-operative MRI of each patient was reviewed and graded using a standardised methodology. One hundred and six patient MRI studies were reviewed. All patients showed some evidence of intervertebral disc degeneration adjacent to the planned operative segment(s). Increased severity of disc degeneration was associated with increased age and operative level, but was not associated with sagittal alignment. Disc degeneration was more common at levels adjacent to the surgical level than at non-adjacent segments, and was more severe at the superior adjacent level compared with the inferior adjacent level. These findings support the theory that adjacent segment degeneration following ACDF is due in part to the natural history of cervical spondylosis.

Canadian Spine Society abstracts1.1.01 Supraspinal modulation of gait abnormalities associated with noncompressive radiculopathy may be mediated by altered neurotransmitter sensitivity1.1.02 Neuroprotective effects of the sodium-glutamate blocker riluzole in the setting of experimental chronic spondylotic myelopathy1.1.03 The effect of timing to decompression in cauda equina syndrome using a rat model1.2.04 Intraoperative waste in spine surgery: incidence, cost and effectiveness of an

# 1.1.01 Supraspinal modulation of gait abnormalities associated with noncompressive radiculopathy may be mediated by altered neurotransmitter sensitivity {#article-title-2} Radiculopathy resulting from intervertebral disc herniation involves mechanical compression and biochemical inflammation of