Segment Degeneration Research Articles

An upper bound computational model for investigation of fusion effects on adjacent segment biomechanics of the lumbar spine

Prediction of the biomechanical effects of fusion surgery on adjacent segments is a challenge in computational biomechanics of the spine. In this study, a two-segment L3-L4-L5 computational model was developed to simulate the effects of spinal fusion on adjacent segment biomechanical responses under a follower load condition. The interaction between the degenerative segment (L4-5) and the adjacent segment (L3-4) was simulated using an equivalent follower spring. The spring stiffness was calibrated using a rigid fusion of a completely degenerated disc model at the L4-5 level, resulting in an upper bound response at the adjacent (L3-4) segment. The obtained upper bound equivalent follower spring was used to simulate the upper bound biomechanical responses of fusion of the disc with different degeneration grades. It was predicted that as the disc degeneration grade at the degenerative segment decreased, the effect on the adjacent segment responses decreased accordingly after fusion. The data indicated that the upper bound computational model can be a useful computational tool for evaluation of the interaction between segments and for investigation of the biomechanical mechanisms of adjacent segment degeneration after fusion.

Biomechanical study of proximal adjacent segment degeneration after posterior lumbar interbody fusion and fixation: a finite element analysis

PurposeTo investigate the biomechanical changes in the proximal adjacent segment with different grades of degeneration after posterior lumbar interbody fusion (PLIF).MethodsWe created three finite element models of the L3–5 with different grades of degeneration (healthy, mild, and moderate) at the L3–4 that were developed by changing the disc height and material properties of the nucleus pulposus. The L4–5 were operated by interbody fusion cages and pedicle screws. All models were loaded with a compressive pre-load of 400 N and a bending moment of 10 N a in three planes to recreate flexion, extension, lateral bending, and axial rotation. The range of motion (ROM), nucleus pressure, and annulus fibrosus pressure of the L3–4 were evaluated.ResultsThe ROM, nucleus pressure, and annulus fibrosus pressure increased at the L3–4 after PLIF. As the degeneration progressed in the L3–4, the ROM of the L3–4 decreased while the nucleus pressure and annulus fibrosus pressure increased.ConclusionsAdjacent segment degeneration (ASD) may be related to the ROM and intradiscal pressure after PLIF. However, as the degeneration of the proximal adjacent segment increases, the ROM in the proximal adjacent segment gradually decreases, but the pressure on the nucleus pulposus and annulus fibrosus gradually increases. Degeneration of the proximal adjacent segment before operation is a risk factor for the ASD after PLIF.

TOTAL ARTHROPLASTY AND ANTERIOR CERVICAL DISCECTOMY WITH FIXATION: LONG-TERM RESULTS OF A RANDOMIZED CLINICAL TRIAL

Objective.To perform comparative analysis of the long-term results of using the methods of total cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) in the surgical treatment of patients with single-level degenerative diseases of cervical intervertebral discs.Material and Methods.The study included 186 patients aged 21–60 years. Independent sequential randomization (1:1) of 173 patients was performed using software. The following parameters were used to evaluate patients: the VAS score of pain syndrome severity in the cervical spine and upper extremities, the Neck Disability Index (NDI) score of the quality of life, the amplitude of movements of the operated segment, the frequency of adjacent discs degeneration and of repeated surgical interventions and adverse events.Results.In the long-term follow-up, the best clinical outcomes according to VAS and NDI data were recorded in patients from the CDA group. Their amplitude of movements in the segment remained in the physiological volume. In the ACDF group, a complete fusion was verified in 83 (93.3 %) cases. A significantly higher degree of degenerative disease of superjacent intervertebral discs was revealed in ACDF group (p < 0.01), while no significant degenerative changes were recorded in the subjacent discs (p > 0.05). The number of intraoperative and early postoperative complications did not have a statistically significant intergroup difference (p > 0.05). Symptomatic degeneration of adjacent segments was verified in 2 (2.4 %) respondents from the CDA group and in 8 (9.0 %) from the ACDF group (p < 0.001). Symptomatic adverse effects were found in 3 (3.6 %) CDA patients in the form of heterotopic ossification and in 6 (6.7 %) ACDF patients in the form of pseudoarthrosis.Conclusions.The operations of total disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) are safe and effective methods of surgical treatment of patients with single-level degenerative diseases of cervical intervertebral discs. In CDA patients, significantly better clinical results were noted, as compared with the ACDF group. The CDA method allowed preserving the normal biomechanics of the cervical spine and preventing the development of degenerative disease of adjacent segments.

COLD PLASMA NUCLEOPLASTY VERSUS RADIOFREQUENCY ANNULOPLASTY FOR DISCOGENIC PAIN SYNDROME: COMPARATIVE ANALYSIS OF EFFICACY

Introduction. The intervertebral disc is considered the main source of pain syndrome in degenerative diseases of the spine. The methods of laser, mechanical and cold plasma nucleotomy are widely used in Russia and are included into the system of high-tech medical care. The most promising annuloplasty methods are less known and have only recently been introduced into the national surgical practice. patients’ selection criteria and surgical procedure choice are not clearly defined and the information about annuloplasty in the national literature is practically not presented.Purpose — to conduct the comparative analysis for efficiency of paracentetic nucleoplasty and radiofrequency annuloplasty for discogenic pain and to identify the factors determining the surgery outcomes.Materials and Methods. The authors performed a retrospective cohort study. patients were divided into two groups: 107 patients underwent cold plasma nucleoplasty (Np), 72 patients received radiofrequency annuloplasty (RFap) at one or several levels. evaluation of outcomes was based on the dynamics of the NRS-11 digital pain scale and the Oswestry index (OdI). Positive results were recognized with decrease of NRS-11 index by 50% (or NRc-11 4) and OdI by 20% from the original (or OdI 20%) when the outcome was preserved for 6 or more months postoperatively. To identify the factors influencing the outcome the authors assessed the following criteria prior to surgery: clinical findings (acute, chronic or recurrent pain syndrome), severity and prevalence of disc degeneration at the level of intervention and in adjacent segments, the use of other interventional diagnostic methods for excluding other sources of pain. Results. In results of the procedures the authors reported a decrease of indices in both groups (p0.001) in the absence of significant differences between the groups (p = 0.672). However, but the number of positive outcomes in the RFap group was higher than in the Np group — 49 (68.1%) and 55 (51.4%) respectively. Significant prognostic factors in the Np group were acute character of the pain syndrome (Spearman ρ = 0.252, p = 0.014), fewer operated levels (ρ = -0.304, p0.001); in both groups such factors were failure of other procedures (Np ρ = 0.413, p0.001; RFap ρ = 0.464, p0.001) and the degree of disc degeneration of adjacent segments (Np ρ = -0.387, p0.001; RFap ρ = -0.297, p0.001). With regression analysis the best results were observed under the criteria “failure of other procedures”, for Np (OR 0.77 at 95% cI (0.682-0.857) and for RFap (OR 0.81, 95% cI (0.701-0.924)). Conclusion. Both methods of cold plasma nucleoplasty and radiofrequency annuloplasty demonstrate positive and similar outcomes provided the discogenic character of the pain syndrome has been defined correctly. The most significant is the exclusion of other sources of pain by diagnostic blockades, especially for patients with chronic pain syndrome and advanced multi-level lesion of the spine segments.

Clinical Relationship of Degenerative Changes between the Cervical and Lumbar Spine.

Study DesignRetrospective, observational, case series.PurposeTo elucidate the prevalence of degenerative changes in the cervical and lumbar spine and estimate the degenerative changes in the cervical spine based on the degeneration of lumbar disc through a retrospective review of magnetic resonance (MR) images.Overview of LiteratureOver 50% of middle-aged adults show evidence of spinal degeneration. However, the relationship between degenerative changes in the cervical and lumbar spine has yet to be elucidated.MethodsA retrospective review of positional MR images of 152 patients with symptoms related to cervical and lumbar spondylosis with or without a neurogenic component was conducted. The degree of intervertebral disc degeneration (IDD) was assessed on a grade of 1–5 for each segment of the cervical and lumbar spine using MR T2-weighted sagittal images. The grades across all segments were summed to produce the degenerative disc score (DDS) for the cervical and lumbar spine. The patients were divided into two groups based on the IDD grade for each lumbar segment: normal (grades 1 and 2) and degenerative (grades 3–5).ResultsDDSs for the cervical and lumbar spine were positively correlated. Significant differences in cervical DDSs between the groups were observed in all lumbar segments. Although there were no significant differences in cervical DDSs among the degenerative lumbar segment, cervical DDSs at the L1–2 and L2–3 segments tended to be higher than those at the L3–4, L4–5, and L5–S degenerative segments.ConclusionsOur study shows that participants with degenerative changes in the upper lumbar segments are more likely to have a certain amount of cervical spondylosis. This information could be used to lower the incidence of a missed diagnosis of cervical spine disorders in patients presenting with lumbar spine symptomology.

Is the Interspinous Device (Coflex) Outdated in the Treatment of Lumbar Spinal Stenosis? A Seven-Year Follow-up

Background: Coflex, a kind of dynamic interspinous spacer, has been widely used for the treatment of lumbar spinal stenosis in the past a few years. However, controversy remains as to whether dynamic interspinous spacer use is superior to traditional decompression and fusion surgery. High complication, reoperation rate, and costs with poor outcomes were also mentioned in the literature. The aim of the present study is to evaluate whether Coflex implantation following spinal decompression provided better clinical outcomes compared with traditional decompression and fusion for symptomatic lumbar spinal stenosis through midterm follow-up. Methods and findings: A total of 100 patients who were confirmed L4/5 lumbar spinal stenosis was surveyed from June 2007 to June 2010. They were randomly and equally divided into two groups: 50 cases underwent spinal decompression with Coflex implantation, and 50 cases were treated with spinal decompression with fixation and fusion. The operation time, intraoperative blood loss, ambulation time, and hospitalization days, Japanese Orthopedic Association scores, visual analogue scale scores, Oswestry disability index and SF-36 scores were compared between the two groups. The ranges of motion and the height loss at adjacent segments (L3/4 and L5/S1) were measured preoperative and postoperative, respectively. Adjacent segment degeneration at L3/4 and L5/Sl was assessed by Pfirrmann classification. Complications were also recorded. The average age was 57.6 ± 5.9 years old in Coflex implantation group and 59.0 ± 6.7 years old in fusion group, respectively. The average follow-up period was 7.12 ± 1.1 year in Coflex implantation group and 7.31 ± 1.6 year in fusion group, respectively. JOA, ODI, VAS and SF-36 scores were improved at the last follow-up in all the two groups with significant differences (P 0.05). The intervertebral heights of adjacent segments were decreased at the last follow-up and the ranges of intervertebral motions were increased in both groups. The height loss and the range of motion increase of adjacent segments were greater in fusion group than those in Coflex group with statistical significant difference (P<0.01). At the last follow-up, adjacent segment disc Pfirrmann grade progressed more obviously in fusion group compared with that in Coflex group, and there was significant difference (P<0.05) between the two groups. Conclusion: Based on the present study, it showed that Coflex implantation and fusion after spinal decompression had the same clinical outcomes and satisfaction in treatment of symptomatic lumbar spinal stenosis after 7 years follow-up. Nevertheless, Coflex implantation had the advantages of less bleeding loss, less trauma and quick recovery. Compared with fusion surgery, Coflex implantation had also advantages in maintaining intervertebral height and delaying intervertebral disc degeneration of adjacent segments.

Does stabilization of the degenerative lumbar spine itself produce multifidus atrophy?

The effect of stabilization of the degenerative segment on changes in the pattern of paraspinal muscle activity was investigated using a previously developed musculoskeletal model. Muscle activity change depending on L4-L5 segment stabilization with and without taking into account the presence of multifidus atrophy according to direct invasion of the back muscle during surgery (MADIBM) was analysed in erect standing and 20° flexed postures. For the stabilization of the degenerative segment, a fusion or non-fusion stabilization with a pedicle-based dynamic stabilization system (PBDS) was applied. During erect standing, fusion generated a 12% reduction in the total multifidus muscle force, while its reduction was 6.6% with PBDS application. The presence of MADIBM produced 23.0% and 22.5% reductions in fusion and with PBDS application, respectively. During 20° flexion, 10.5% and 9.3% reductions were produced for fusion and PBDS application, respectively, and the corresponding values were 23.4% and 23.0%, respectively, in the presence of MADIBM. Increased facet joint contact forces were produced at the non-stabilized levels after stabilization while in erect standing posture. Alterations in muscle activity, which could be regarded as adaptions to altered spinal stability, may generate unexpected secondary problems in the spine.

Micro-computed tomography, scanning electron microscopy and energy X-ray spectroscopy studies of facet joint degeneration: A comparison to clinical imaging

Segmental degeneration in the human lumbar spine affects both the intervertebral discs and facet joints. Facet joint degeneration not only affects the cartilage surface, but also alters the cellular properties of the cartilage tissue and the structure of the subchondral bone. The primary focus of this study is the investigation of these microstructural changes that are caused by facet joint degeneration. Microstructural analyses of degenerated facet joint samples, obtained from patients following operative lumbar interbody fusion, have not previously been extensively investigated. This study analyzes human facet joint samples from the inferior articular process using scanning electron microscopy, micro-computed tomography, and energy dispersive X-ray spectroscopy to evaluate parameters of interest in facet joint degeneration such as elemental composition, cartilage layer thickness and cell density, calcification zone thickness, subchondral bone portion, and trabecular bone porosity. These microstructural analyses demonstrate fragmentation, cracking, and destruction of the cartilage layer, a thickened calcification zone, localized calcification areas, and cell cluster formation as pathological manifestations of facet joint degeneration. The detailed description of these microstructural changes is critical for a comprehensive understanding of the pathology of facet joint degeneration, as well as the subsequent development and efficacy analysis of regenerative treatment strategies.

Classification of Degenerative Segment Disease in Adults with Deformity of the Lumbar or Thoracolumbar Spine

Introduction Lumbar and thoracolumbar deformity in the adult is a condition with impairment of health status that can need surgical treatment. In contrast with adolescent deformity, where magnitude of the curve plays a significant role in surgical indication, the aspects relevant in adult deformity are pain and dysfunction that correlate with segment degeneration and imbalance. Previous classifications of adult deformity have been of little use for surgical planning. Materials and Methods Chart review and classification of radiographic and clinical findings. A classification of degenerative disc disease based on distribution of diseased segments and balance status of the spine is presented. Results Four main categories are presented: Type I (limited nonapical segment disease), Type II (limited apical segment disease), Type III (extended segment disease: apical and nonapical), and Type IV (imbalanced spine: IVa, sagittally imbalanced; IVb, sagittally and coronally imbalanced). Conclusion Types I and II can be treated by fusion of a selective area of the curve. Type III needs fusion of all the extension of the coronal curve. Type IV usually needs aggressive corrective procedures, frequently including posterior tricolumnar osteotomies. This classification permits interpreting the extension and magnitude of the disease and can help establish a surgical plan regarding selective fusion and methods of sagittal correction. Future research is needed to validate the classification.

Effect of intervertebral disc degeneration on spinal flexibility in patients with degenerative lumbar scoliosis

To investigate degenerative changes of the intervertebral disc and their impact on spinal flexibility in patients with degenerative lumbar scoliosis (DLS). Retrospective analysis of 66 patients (average age 58.4 years, 10 males and 56 females) with DLS was conducted from May 2008 to February 2014. For all patients, pre-operative standing X-ray film, Bending X-ray films and thoracolumbar MRI were taken. Cobb's angle was measured in each X-ray film and intervertebral angle was measured in both standing and Bending X-ray films. All discs were graded according to Pfirrmann degeneration grades on T2 weighted saggital MRI imaging. Statistical analyses were performed to determine the correlation between intervertebral disc degeneration with the whole spine flexibility and segmental flexibility. For all 66 subjects, the average Cobb's angle of pre-operative and bending X-ray film was 36° ± 13°, 21° ± 11°, respectively. The average flexibility was 45% ± 15% in our study. Totally 268 discs were graded, including gradeI8, II 68, III 83, IV 91, V 18. In the main curve, there was significant correlation between the average degree of disc degeneration and the whole spine flexibility(r = -0.727, P < 0.01). There was significant correlation between the grade of segmental disc degeneration and segmental flexibility (P < 0.01) . The apical intervertebral disc had the most degeneration (P < 0.01) and worst flexibility (P < 0.01) , compared with other discs in the main curve. The degree of intervertebral disc degeneration is closely correlated with spinal flexibility in DLS. The more the disc degeneration is, the worse the spinal flexibility becomes.

The effect of gamma irradiation on the biological properties of intervertebral disc allografts: in vitro and in vivo studies in a beagle model.

Study DesignAn animal experiment about intervertebral disc allograft.ObjectiveTo explore the feasibility to decellularize disc allografts treated by 6°Co Gamma Irradiation, and simultaneously, to assess the possibility to make use of the decellularized natural disc scaffold for disc degeneration biotherapy.Summary of Background DataStudies of both animal and human disc allograft transplantation indicated that the disc allograft may serve as a scaffold to undertake the physiological responsibility of the segment.Methods Experiment in vitro: 48 discs of beagles were harvested and divided randomly into four groups including a control group and three irradiated groups. Immediate cell viability and biomechanical properties of the discs were checked and comparisons were made among these groups. Experiment in vivo: 24 beagles accepted single-level allografted disc treated with different doses of gamma irradiation. Plain X-rays and MRIs were taken before and after surgery. Then, the spinal columns were harvested en bloc from the sacrificed beagles and were examined morphologically.ResultsThere were significant differences of both the annulus fibrosus and nucleus pulposus immediate cell viabilities among the various groups. There were no obvious differences of the biomechanical properties among the four groups. The disc height and range of motion decreased significantly in all groups as time went on. The observed indexes in irradiated groups were much smaller than those in the control group, but the indexes in 18-kGy group were larger than those in 25-kGy and 50-kGy groups. Both MRI and macroscopic findings showed that the segmental degeneration in the control and 18-kGy group was less severe than that in 25-kGy and 50-kGy groups.ConclusionGamma Irradiation can decellularize disc allograft successfully to provide natural scaffold for the study of degenerative disc disease therapy, and also can be used as an effective method to produce adjustable animal models.

Adjacent Intervertebral Disc Changes in Patients with Isobar Semirigid Dynamic Stabilization System

Introduction The reported incidence of adjacent segment degeneration (ASD) after lumbar fusion ranges from 8 to &gt; 100%, average 27%. Another literature review reported that 5.2 to 18.5% of patients required surgery for adjacent segment disease after lumbar fusion surgery. Posterior dynamic stabilization systems may prevent the development and progression of ASD after surgery. Hybrid dynamic stabilization with posterior spinal fusion, or “Topping-off surgery,” is applied in patients with preoperative adjacent segment degeneration. The objective of this approach is to protect the degenerative adjacent segment from progressing. Efficacy of this procedure is debated. The objective of this study was to evaluate intervertebral disk changes of the dynamically stabilized spine segment in patients receiving single-level intervertebral fusion and adjacent segment dynamic stabilization using the Isobar (Alphatec Spine, Inc.) semirigid dynamic stabilization system. Materials and Methods Twenty-seven patients with confirmed degenerative disk disease were enrolled in a retrospective study. Patients received single level intervertebral fusion and dynamic stabilization of the adjacent level using the Isobar semi-rigid dynamic stabilization system. Patient outcomes were evaluated by visual analogue scale for pain (VAS) and Chinese version of Oswestry Disability Index (ODI). Intervertebral space ratio (IVS) and range of motion (ROM) were measured on plain radiographs. MRI relative gray-scale values of the central bright area of discs were analyzed by Image J software. Results Of the 27 patients, 16 were male and 11 were female. Ages ranged from 31 to 65 years (average 47 years). Average duration of surgery was 213 (SD = 52) minutes and average blood loss was 225 mL (SD = 105). The average follow-up time was 27 months, ranging from 24 to 40 months. There was no significant change in relative gray-scale value of adjacent disc between preoperative and two year follow-up (23.98 ± 8.86 and 22.22 ± 6.25, respectively, p = 0.46). Relative gray-scale values of first cephalic adjacent disc were reduced at 2 years follow-up compared with baseline (28.63 ± 8.35 and 32.54 ± 10.75, respectively, p = 0.06). Significant difference was found in relative gray-scale value of second cephalic adjacent disc between baseline and 2-year follow-up (35.51 ± 8.15 and 29.29 ± 7.56, respectively, p &lt; 0.01). The inter-vertebral space (IVS) of index level was maintained after the surgery (Table 1). There was no statistical difference between the IVS before the surgery and final follow-up ( p = 0.33). The range of motion (ROM) of the adjacent level was reduced from 6.91 ± 3.14 preoperatively to 2.46 ± 1.03 degrees at the final follow-up ( p &lt; 0.05). There were no significant differences in the index level ROM among any of the follow-up times. VAS and ODI scores significantly improved preoperatively to final follow-up (VAS: 6.12 ± 0.80 and 1.65 ± 0.69, respectively, p = &lt; 0.01; ODI: 54.91 ± 10.96 and 14.61 ± 3.88, respectively, p = &lt;0.01). One patient received a debridement due to wound infection after operation, but the fixation system and interbody cage were not removed. This patient recovered well after the debridement. At the 2-year follow-up, one patient had two screw fractures at S1 level and another patient had two screws loosen. Conclusion Dynamic stabilization of the level adjacent to the fused level using the Isobar TTL Semi-rigid Spinal System seems to prevent progression of degenerative changes in the stabilized spine segment and is associated with favorable patient outcomes. Disclosure of Interest Q. Zhou: Conflict with Third Military Medical University, AO International R. Shi: None declared B. Kopjar: Conflict with AO Foundation, Smith &amp; Nephew, Cerapedics H. Wang: None declared D. Chen: None declared H. Li: None declared N. Di: None declared F. Luo: None declared F. Dai: None declared J. Xu: None declared

Histopathology assessment of incisional wound-healing behaviour of peritoneum-sutured and not-sutured techniques following laparotomy and omentopexy in West African dwarf (WAD) goats

Muscle tissue sections harvested on post-surgery days (psd) 3, 7, 14 and 42 from sutured sites following peritoneum-sutured and peritoneum-not-sutured techniques of laparotomy and omentopexy in WAD goats were subjected to histopathology examinations for various stages of wound healing. On psd 3, samples from the peritoneum-sutured techniques without omentopexy (group A) showed intense eosinophilia and myoglobin deposition. The group with peritoneum-sutured techniques with omentopexy (group C) was characterised by polymorphonuclear leucocytes and hyperaemia. Samples from the groups with peritoneum-not-sutured techniques without omentopexy (group B) and with the peritoneum-not-sutured techniques with omentopexy (group D) showed wide area of fibrosis and segmental degeneration. On psd 7, sections from group A had intense infiltration of phagocytic cells and proliferating myoblast while myoblast and fibroblast were predominant in group C sections. Groups B and D sections showed large area of necrosis and lysis of necrotic muscles. On psd 14, there was evidence of new blood vessels, fibrous connective tissues and collagen deposition in tissues from groups A and C. On psd 42, collagen deposition and myocyte proliferation were conspicuous in group A sections. Group C sections showed myofibre formation and thin connective tissues between muscle bundles. There was evidence of mild myocyte proliferation and fibrosis in group B sections while in group D sections, no evidence of myocyte proliferation was seen, there were fibrosis and the stroma were only oedematous. It was concluded that peritoneum-sutured techniques facilitate wound healing while peritoneum-not-sutured techniques delay wound healing.

Classification of degenerative segment disease in adults with deformity of the lumbar or thoracolumbar spine

Lumbar and thoracolumbar deformity in the adult is a condition with impairment of health status that can need surgical treatment. In contrast with adolescent deformity, where magnitude of the curve plays a significant role in surgical indication, the aspects relevant in adult deformity are pain and dysfunction that correlate with segment degeneration and imbalance. Previous classifications of adult deformity have been of little use for surgical planning. Chart review and classification of radiographic and clinical findings. A classification of degenerative disc disease based on distribution of diseased segments and balance status of the spine is presented. Four main categories are presented: Type I (limited nonapical segment disease), Type II (limited apical segment disease), Type III (extended segment disease--apical and nonapical), Type IV (imbalanced spine: IVa, sagittally imbalanced; IVb, sagittally and coronally imbalanced). Types I and II can be treated by fusion of a selective area of the curve. Type III needs fusion of all the extension of the coronal curve. Type IV usually needs aggressive corrective procedures, frequently including posterior tricolumnar osteotomies. This classification permits interpreting the extension and magnitude of the disease and can help establish a surgical plan regarding selective fusion and methods of sagittal correction. Future research is needed to validate the classification.

Clinical efficacy analysis of hybrid spinal fusion surgery in the treatment of cervical spondylotic myelopathy

Objective To investigate the clinical efficacy,operative essentials and indications of hybrid spinal fusion surgery for cervical spondylotic myelopathy.Methods From August 2008 to December 2011,thirty-eight patients with cervical spondylotic myelopathy underwent hybrid spinal fusion surgery in our hospital.There were 27 males and 11 females,aged from 33 to 70 years (average,51 years).A total of 86 segments were treated (fusion 48 vs.non-fusion 38).Twenty-eight patients underwent a two-level surgery,and ten patients received a three-level surgery.The Japanese Orthopaedic Association (JOA) score and Visual analogue scale (VAS) were used to evaluate pre-and post-operative neurological function and pain,respectively.The pre-and post-operative range of motion of the cervical spine was measured according to Xrays.Moreover,the surgical complications were recorded and analyzed.Results Thirty-seven patients were followed up for 15 to 55 months (average,29.1 months).The improvement of neurological function was obtained in 36 patients.The JOA score was improved from preoperative 10.5±1.57 to 14.3±1.97 at final follow-up,with an improvement rate of 58.46％,and the results were excellent in 16 cases,fair in 20 cases and poor in 1 case.The VAS was improved from preoperative 7.3±1.04 to 3.2±1.41 at final follow-up.The Cobb angle changed from preoperative 25°±3.21°to 20°±2.56°at final follow-up.After operation,the neurological function was not restored in 1 case; hoarseness and bucking occurred in 2 cases; sore throat occurred in 22 cases; anterior displacement of prosthesis (PCM) occurred in 3 cases.Other patients had no complications,such as displacement,loosening and heterotopic ossification.Conclusion In hybrid spinal fusion surgery,the lesions segments are decompressed fully,the severely degenerative segments are fused,and the motion of the non-fusion segments is reserved.As a result,not only the stability of the cervical spine is achieved,but also an obvious improvement of symptoms and a satisfactory short-term efficacy can be obtained.Therefore,this method is an alternative procedure for cervical spondylosis myelopathy. Key words: Cervical vertebrae; Spinal cord compression; Spinal fusion; Intervertebral disk

Finite element analysis of long-time aging and sudden accidental degeneration of lumbar spine segments in compression

Finite element analysis of long-time aging and sudden accidental degeneration of lumbar spine segments in compression

Measurement of intervertebral cervical motion by means of dynamic x-ray image processing and data interpolation.

Accurate measurement of intervertebral kinematics of the cervical spine can support the diagnosis of widespread diseases related to neck pain, such as chronic whiplash dysfunction, arthritis, and segmental degeneration. The natural inaccessibility of the spine, its complex anatomy, and the small range of motion only permit concise measurement in vivo. Low dose X-ray fluoroscopy allows time-continuous screening of cervical spine during patient's spontaneous motion. To obtain accurate motion measurements, each vertebra was tracked by means of image processing along a sequence of radiographic images. To obtain a time-continuous representation of motion and to reduce noise in the experimental data, smoothing spline interpolation was used. Estimation of intervertebral motion for cervical segments was obtained by processing patient's fluoroscopic sequence; intervertebral angle and displacement and the instantaneous centre of rotation were computed. The RMS value of fitting errors resulted in about 0.2 degree for rotation and 0.2 mm for displacements.

Continuous clinical observation of the Dynesys dynamic neutralization system for degenerative lumbar spine diseases

Objective To evaluate the clinical indications and outcomes of dynesys neutralization system in the treatment of degenerative lumbar diseases.Methods From January 2007 to December 2011,102 consecutive patients with degenerative lumbar spine diseases underwent posterior decompression and internal fixation with the Dynesys dynamic neutralization system.Among them,69 patients were followed up,including 39 males and 30 females,aged from 30 to 62 years (average,44 years).The series of cases were composed of 24 cases of lumber disc herniation,35 cases of degenerative spinal stenosis,10 cases of degenerative changes of lumbar discs.Results The mean follow-up period was 35 months (range,6-44 months).The visual analogue scale (VAS) score decreased from preoperative 8.6 (range,6-9) to postoperative 2.8 (range,0-5),and the Oswestry disability index (ODI) improved from preoperative 73％ (range,30％-91％) to postoperative 30％ (range,0-61％).There were no implant failure or infection.According to the evaluation criteria of surgical treatment for low back pain,which was established by the Chinese Orthopaedic Association,the result was excellent in 53 patients,good in 12 patients,fair in 4 patients and poor in 1 patient.Conclusion The Dynesys dynamic neutralization system is effective in the treatment of degenerative lumbar spine disease,which can reserve the range of motion of stabilized segments,prevent degeneration of adjacent segments and improve clinical outcomes. Key words: Lumbar vertebrae; Internal fixators; Treatment outcome

A Comparison of Adjacent Segment Diseases Above One Versus Above Two Vertebral Segment after Spinal Fusion of the Degenerative Lumbar Disease

Study Design: Retrospective study. Objective: To compare patients who underwent spinal revision surgery of adjacent segment degeneration with above one and above two vertebral segment preceded by initial spinal fusion surgery. Summary of Literature Review: The adjacent segment disease(ASD) occurs more frequently at the more proximal segment of the spinal fusion. Also, the preexisting degenerative segments (with discs or facet joints) not included in the fusion procedure, fusion segmental sagittal angle, fixed appliances method, gender, and age, have been accepted as the causes. Materials and Methods: The patients were watched over a year after the spinal revision operation followed by initial spinal fusion of single or multiple segments; the subjects were limited to 41 patients. The average age, entity of diseases, average duration between the initial spinal fusion and the revision surgery, multiple clinical and radiographic parameters were evaluated and compared. Results: Using the UCLA grade of intervertebral disc degeneration, the average grade of 1 level upper segment was 2.2 in group A and 1.9 in group B without statistical significance(p=0.426). However, the average grade of 2-level upper segment was 1.8 in group A and 2.4 in group B with significant difference(p=0.021). There was no statistical difference in other factors between the two groups. Conclusions: Patients with ASD of above two-vertebral segment after spinal fusion were more severe in disc degeneration than those with ASD of above one vertebral segment before initial spinal fusions.

Orientation and Osteoarthritis of Lumbar Facet Joints: Association with Degenerative Disk Disease

Introduction Several studies have shown relationship between sagittal orientation of lumbar facet joint and degenerative spondylolisthesis1,2,3; however, there is no current information on how much the facet orientation and osteoarthritis associate with different grades and morphologies of lumbar disk degeneration on MRI. We hypothesize that sagittally oriented facet joints promote a degenerated intervertebral disk (IVD) to develop spondylolisthesis rather than a collapsed disk. Aim of this study is to evaluate the association between lumbar facet joint orientation, facet osteoarthritis, IVD herniation, and different grades of disk degeneration. Materials and Methods A total of 550 patients who underwent lumbar spine MRI for low back pain or radicular leg pain were reviewed. Patients with previous back surgery, congenital anomalies, spondylolysis, infection, tumor, or fracture were excluded. Total 153 patients were included and assessed for IVD degeneration according to Modified Pfirrmann (MP) grading4 at L3-S1 lumbar segments. Facet joint angles on axial scan and Fujiwara osteoarthritic grading5 were assessed at spinal segments of the following six groups: “Bright disk” (MP grade 1 or 2), “Black disk” (MP grade 4 or 5), “Collapse disk” (MP grade 6 to 8), “Herniated disk” (bulging or prolpase), spondylolisthesis and “nonslip level” of spondylolisthesis. The mean facet angles and the percentages of the mild (Fujiwara grade 1 or 2) and advanced (Fujiwara grade 3 or 4) facet osteoarthritis were compared between six groups using independent sample t test and Pearson Chi Square test, respectively. The association of facet joint orientation and osteoarthritis was also examined by linear regression analysis. Results The mean facet angles relative to the coronal plane in patients who had “Black disk” (right L3/4: 55.70, L4/5: 47.50, L5/S1: 39.70), “Collapse disk” (right L3/4: 54.10, L4/5: 470, L5/S1: 380) and “Herniated disk” (right L3/4: 560, L4/5: 46.10, L5/S1: 38.10) were significantly more sagittal at all levels (p0, L4/5: 41.10, L5/S1: 35.80). There was no statistical difference of mean facet angles at all levels between “Black disk”, “Collapse disk,” and “Herniated disk” (Table 1). Facet joint osteoarthritis were more advanced in “Black disk”, “Collapse disk”, “Herniated disk” than “Bright disk”, but there was no difference in percentage of mild and advanced facet osteoarthritis among three groups. Degenerative spondylolisthesis segments demonstrated significantly more sagittal mean facet angle (right L3/4: 72.60, L4/5: 67.20, L5/S1: 490, p0, L4/5: 540, L5/S1: 420, p0, which is the mean facet angle of patient without spondylolisthesis + SD, was 25 times more likely to have degenerative spondylolisthesis. Advanced degenerative “Collapse disk” had no significant difference in mean facet angle from that of early degenerative “Black disk.” A positive association between sagittal orientation and osteoarthritis of facet joints was demonstrated. Only degenerative spondylolisthesis demonstrated the significant correlation between facet joint osteoarthritis and disk degeneration (Fig. 1). Conclusion Sagittal facet orientation relates to facet joint osteoarthritis and IVD degeneration. Degenerative spondylolisthesis had more advanced facet osteoarthrosis and disk degeneration. The increase in facet angles at “nonslip” levels other than that of the spondylolisthesis suggests that increased facet angles represent variations in developmental anatomy and contribute to instability of a functional spine unit when degenerative disk loses its anterior vertebral column support. I confirm having declared any potential conflict of interest for all authors listed on this abstract No Disclosure of Interest None declared Kalichman, et al. Facet orientation and tropism associations with facet joint osteoarthritis and degeneratives. Spine 2009; 34(16):E579-E585 Boden, et al. Orientation of the lumbar facet joints: association with degenerative disc disease. Journal of Joint and Bone surgery 1996;78A(3):403–411 Fujiwara, et al. Orientation and osteoarthritis of the lumbar facet joint. CORR 2001;385:88–94 Griffith, et al. Modified Pfirrmann grading system for lumbar intervertebral disc degeneration. Spine 2007; 32(24):708–712 Fujiwara, et al. The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study. European Spine Journal 1999; 8:396–401