Changes In Disc Height Research Articles

Long-Term Outcome of Dynesys Dynamic Stabilization for Lumbar Spinal Stenosis.

Background:Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization.Methods:Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration (ASD).Results:There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODI scores were significantly improved at the final follow-up evaluation, as compared to the baseline values (16.1 ± 5.7 vs. 57. 2 ± 14.2, t = 61.41, P < 0.01). The VAS scores for back and leg pain were significantly improved from 4.82 ± 0.89 and 4.04 ± 0.82 preoperatively to 0.93 ± 0.61 and 0.54 ± 0.51 postoperatively (t = 6.59, P < 0.01, and t = 5.91, P < 0.01, respectively). There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8° ± 2.4° to 4.5° ± 1.5° (t = 7.18, P < 0.05), while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° (t = 2.87, P = 0.01). The change in disc height of stabilized segments was not significant (11.9 ± 2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15), whereas the decrease in disc height of the upper adjacent segments was significant (12.5 ± 2.0 preoperatively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01). The occurrence of radiographic and symptomatic ASD was 16% (6/38) and 3% (1/38), respectively.Conclusions:Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients <60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.

Wednesday, September 26, 2018 3:35 PM – 5:05 PM Preserving Spinal Motion: 91. Interlaminar stabilization versus PLF in the ≤ 65 year-old patient: five-year follow-up

BACKGROUND CONTEXT After conservative treatment has failed, surgical intervention for symptomatic lumbar spinal stenosis (LSS) is common. However, LSS is rarely a discreet issue and often presents with spondylolisthesis, deformity, or other degenerative changes. Although decompression surgery is considered the standard treatment, trends indicate spine fusion surgery has disproportionately increased despite it being the more invasive approach. Interlaminar stabilization (ILS) is a less invasive alternative to fusion that is non-terminal and motion preserving. PURPOSE The purpose of this study was to compare the efficacy of decompression plus ILS (D+ILS) to decompression plus posterolateral fusion (D+PLF) in patients aged ≤ 65 years with LSS with or without grade 1 spondylolisthesis. STUDY DESIGN/SETTING Cohort analysis of a large, prospective, multi-centered, and randomized controlled Investigational Device Exemption (IDE) trial comparing ILS and decompression to posterolateral fusion with bilateral pedicle screw instrumentation. PATIENT SAMPLE A total of 181 patients from 21 US sites who underwent decompression with ILS or decompression with posterolateral spinal fusion. OUTCOME MEASURES The primary outcome was overall composite clinical success (CCS) as determined by: Oswestry Disability Index (ODI) scores, incidence of postoperative epidural injections and/or reoperations, incidence of device-related complications, and persistent or progressive neurological deficit. Secondary outcomes included patient satisfaction as measured by Visual Analog Scale (VAS) for back and worse leg pain, and Zurich Claudication Questionnaire (ZCQ) scores. Narcotic usage data and radiographic assessment of changes in postoperative posterior disc height and foraminal height were also evaluated. METHODS A cohort from the original multi-center, randomized controlled IDE clinical trial was examined with 5-year follow-up. The cohort was randomized in a 2:1 fashion with 181 patients in total, 131 in the D+ILS (coflex, Paradigm Spine, New York, NY, USA) group and 50 in the D+PLF group. Data including the length of hospital stay (LOS), estimated blood loss (EBL), and operative time were recorded. Pain management surveys and patient-reported outcomes including Oswestry Disability Index (ODI), Short Form Surveys (SF-12), Zurich Claudication Questionnaire (ZCQ), and Visual Analog Scale (VAS) for back and leg pain were completed preoperatively and out to 60 months postoperatively. Composite clinical success (CCS) was defined as a ≥15 point improvement of ODI plus the absence of reoperations, neurological deficits, and major device-related complications. RESULTS Patient follow-up at 60 months for the D+ILS group and D+PLF groups were 88.2% and 86.7% respectively. Mean length of hospital stay was 1.79 days in the D+ILS group and 3.06 days in the D+PLF group (p CONCLUSIONS At 5-year follow-up, D+ILS has been shown to be a durable and efficacious treatment option in a younger spinal stenosis population with or without grade 1 spondylolisthesis. Decompression + ILS surgery is significantly less invasive for the patient as measured by shorter operative times, decreased blood loss, and shorter length of stay. As hospital costs are of growing concern, these substantial differences should be strongly considered. As a cohort of a non-inferiority study design, patient-reported outcomes showed no differences between the groups. However, in this younger and more physically active patient population, a safe and effective non-terminal surgery should be considered before more invasive fusion surgery. FDA DEVICE/DRUG STATUS Coflex, Paradigm Spine, New York, NY (Approved for this indication)

Finite element analysis of the influence of three-joint spinal complex on the change of the intervertebral disc bulge and height.

This study evaluated the changes of height and bulging occurring in individual layers of the annulus fibrosus of the intervertebral disc for 3 load scenarios (axial compression, flexion, and extension). The numerical model of a single motion segment of the thoracic spine was analysed for 2 different configurations, ie, for the model of a physiological segment and a segment with the posterior column removed. In the physiological segment, all annulus fibrosus layers decrease in height regardless of the applied load, bulging outside the intervertebral disc. Removal of the posterior column increases mobility and disrupts the load transfer system, with the lamellae bulging into the intervertebral disc.

Experimental study of polylactic acid-glycolic acid/tricalcium phosphate scaffold repairing the degenerative intervertebral disc

Objective To investigate the effect of collagen modified polylactic acid-glycolic acid/tricalcium phosphate (PLGA/TCP) scaffold combined with human umbilical cord mesenchymal stem cells (hUC-MSCs) to repair the rabbit intervertebral disc degeneration in vivo. Methods The rabbit model of degenerative intervertebral disc was built. Using collagen modified PLGA/TCP scaffold combined with hUC-MSCs implantation for the experimental group, scaffold implantation alone for the control group, and no repairs for the blank group. Rabbit lumbar disc imaging examination was performed 2, 4, 8 and 12 weeks after operation, and histological examination was implemented 12 weeks after surgery. Results Measurement of intervertebral disc height and intervertebral space changes found that vertebral degeneration were significantly lower in the experimental group (Brander disc index BDI 0.063±0.011, disc height index DHI 87.6±10.4) when compared to the control group (BDI 0.039±0.006, P=0.014) (DHI 66.8±9.2, P=0.028) and the blank group (BDI 0.033±0.006, P=0.010) (DHI 46.7±7.3, P=0.001). The MRI results showed that the change of T2 value of experimental group (0.760±0.078) was significantly smaller that of the control group (0.600±0.071, P=0.033) and the blank group (0.540±0.093, P=0.015). Immunohistochemistry results showed that type II collagen of intervertebral disc tissue in the experimental group (151.7±10.3) was more than the control group (125.8±9.6, P=0.023) and the blank group (118.2±6.1, P=0.017), and the difference is of significance. Conclusion Collagen modified PLGA/TCP scaffold combined with hUC-MSCs can significantly promote degenerative disc repair, which can be used as a biological method to repair disc degeneration in the future. Key words: Collagen modification; Polylactic acid glycolic acid/tricalcium phosphate; Umbilical cord mesenchymal stem cells; Intervertebral disc degeneration

Five-year follow-up of clinical and radiological outcomes of LP-ESP elastomeric lumbar total disc replacement in active patients

Background contextThe surgical treatment of degenerative disc disease at the lumbar spine may involve fusion. Total disc replacement (TDR) is an alternative treatment to avoid fusion-related adverse events, specifically adjacent segment disease. New generation of elastomeric non-articulating devices has been developed to more effectively replicate the shock absorption and flexural stiffness of native disc. PurposeTo report 5 years clinical and radiographic outcomes, range of motion (ROM), and position of the center of rotation after a viscoelastic lumbar TDR. Study DesignProspective observational cohort study Patient sampleSixty-one patients Outcome MeasuresThe clinical evaluation was based on visual analog scale (VAS) for pain, Oswestry disability index (ODI) score, short form-36 (SF-36) including the physical component summary (PCS) and the mental component summary (MCS), and general health questionnaire-28 (GHQ28). The radiological outcomes were ROM and position of the center of rotation at the index and the adjacent levels and the adjacent disc height changes. MethodsOur study group included 61 consecutive patients with monosegmental disc replacement. We selected patients who could provide a global lumbar spine mobility analysis (intermediate functional activity according to the Baecke score). Hybrid constructs had been excluded. Only the cases with complete clinical and radiological follow-up at 3, 6, 12, 24, and 60 months were included. ResultsThere was a significant improvement in VAS (3.3±2.5 vs. 6.6±1.7, p<.001), in ODI (20±17.9 vs. 51.2±14.6, p<.001), GHQ28 (52.6±15.5 vs. 64.2±15.6, p<.001), SF-36 PCS (58.8±4.8 vs. 32.4±3.4, p<.001), and SF-36 MCS (60.7±6 vs. 42.3±3.4, p<.001). The mean location centers of the index level and adjacent discs were comparable to those previously published in asymptomatic patients. According to the definition of Zigler and Delamarter, all of our cases remained grade 0 for adjacent level disc height (within 25% of normal). ConclusionsThis series reports significant improvement in midterm follow-up after TDR, which is consistent with previously published studies but with a lower rate of revision surgery and no adjacent level disease pathologies. The radiographic assessment of the patients demonstrated the quality of functional reconstruction of the lumbar spine after LP-ESP viscoelastic disc replacement.

The Barrow Biomimetic Spine: Comparative Testing of a 3D-Printed L4-L5 Schwab Grade 2 Osteotomy Model to a Cadaveric Model.

IntroductionThe Barrow Biomimetic Spine project is an ongoing effort to develop a three-dimensional (3D)-printed synthetic spine model with high anatomical and biomechanical fidelity to human tissue. The purpose of this study was to evaluate the biomechanical performance of an L4-L5 3D-printed synthetic spine model in a lordotic correction test after Schwab grade 2 osteotomies as compared to human cadaveric spines that have undergone the same osteotomies and lordotic correction.MethodsTen different L4-L5 synthetic spine models were 3D printed. Each print varied in either the material used for the soft tissue components, the infill density of the bony and soft tissue structures, the pre-correction disc height, or the model orientation on the print bed. Each print was instrumented with pedicle screws and underwent a Schwab grade 2 osteotomy. Changes in disc height measurements and end-plate angle were compared against cadaveric data acquired using the same study method.ResultsA simple linear correlation analysis demonstrated that for horizontally printed models using PolyFlex (Polymaker, New York, NY, USA)(models 1-3, 8, 10), the pre-correction posterior disc height and lordotic correction were moderately correlated (r = 0.56), but this correlation did not achieve statistical significance (P = 0.12). Regression analysis demonstrated a very strong correlation between lordotic correction and change in posterior disc height (r = 0.92, P < 0.001). Models printed either vertically (models 4-6) or with low bone density and high soft tissue density (model 10) appeared to perform the most similarly to the cadaveric tissue.DiscussionThe 3D-printed synthetic spine models demonstrated predictable and reliable performance in a lordotic correction test based on their respective material qualities and print densities. The print variables tested further demonstrated that this model is capable of achieving high biomechanical fidelity to cadaveric tissue when subjected to the same lordotic correction test after Schwab grade 2 osteotomies.

Clinical and Radiographic Results of a Minimally Invasive Lateral Transpsoas Approach for Treatment of Septic Spondylodiscitis of the Thoracolumbar and Lumbar Spine

The minimally invasive lateral transpsoas approach allows retroperitoneal access for discectomy and graft placement. However, the procedure has rarely been used for the treatment of septic spondylodiscitis. The purposes of this study were to evaluate the clinical and radiographic outcomes from this minimally invasive procedure for septic spondylodiscitis. Thirty-one consecutive patients (17 males and 14 females) were included in this study from July 2013 to January 2016. Clinical outcomes were assessed by Oswestry Disability Index, visual analog scale, modified Macnab criteria, and inflammatory parameters. Radiographic results were analyzed by studying the changes in diseased disc height, lordosis, and fusion status. The Oswestry Disability Index and visual analog scale score improved by 58% and 69% at the last follow-up. The modified Macnab criteria were found to be excellent in 21 patients (68%) and good in 10 (32%). Inflammatory parameters normalized over the average 24 months follow-up. There were no major complications that might have influenced the outcomes in this cohort. A complete fusion after 12 months was achieved in 87% of patients. A mean 7.5 mm restoration in disc height and 6.4° restoration in lumbar lordosis were observed in all patients, whereas an average 4.5 mm loss in restored height resulting from graft subsidence was observed in 24 patients during the follow-up. However, graft subsidence did not influence clinical outcomes significantly. A minimally invasive lateral transpsoas approach in combination with instrumentation provides a novel treatment for patients with septic spondylodiscitis without severe kyphosis and neurologic impairment.

Outcomes of oblique lateral interbody fusion for degenerative lumbar disease in patients under or over 65\xa0years of age

BackgroundOblique lateral interbody fusion (OLIF) offers the solution to problems of anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF). However, OLIF technique for degenerative spinal diseases of elderly patients has been rarely reported. The objective of this study was to determine the clinical and radiological results of OLIF technique for degenerative spinal diseases in patients under or over 65 years of age.MethodsSixty-three patients who underwent OLIF procedure were enrolled, including 29 patients who were less than 65 years of age and 34 patients who were over 65 years of age. Fusion rate, change of disc height and lumbar lordotic angle, Numeric Rating Scale (NRS), return to daily activity, patient’s satisfaction rate (PSR), and Oswestry disability index (ODI) were used to assess clinical and functional outcomes.ResultsThe mean NRS scores for back and leg pain decreased, respectively, from 4.6 and 5.9 to 2.3 and 1.8 in the group A (less than 65 years) and from 4.5 and 6.8 to 2.6 and 2.2 in the group B (over 65 years) at the final follow-up period. The mean ODI scores improved from 48.4 to 24.0% in the group A and from 46.5 to 25.2% in the group B at the final follow-up period. In both groups, the NRS and ODI scores significantly changed preoperatively to postoperatively (p < 0.001). However, statistical analysis yielded no significant difference in postoperative NRS/ODI scores between two groups. In both groups, the changes in the disc height, segmental lordosis, and fusion rate between the preoperative and postoperative periods were significant. The amount of change between preoperative and postoperative disc height, segmental lordosis, and whole lumbar lordosis demonstrated significant intergroup differences (p < 0.05). Overall perioperative complications occurred in 8 of 29 (27.6%) patients in the group A and in 10 of 34 (29.4%) patients in the group B. In both groups, the major complication incidence was 0 and 3%, respectively.ConclusionAlthough there was the slightly high incidence of complication associated with high rate of co-morbidities in elderly patients, OLIF for degenerative lumbar diseases in elderly patients showed favorable clinical and radiological outcomes.

The evaluation of lumbar paraspinal muscle quantity and quality using the Goutallier classification and lumbar indentation value.

The cross-sectional area and fat infiltration are accepted as standard parameters for quantitative and qualitative evaluation of muscle degeneration. However, they are time-consuming, which prevents them from being used in a clinical setting. The aim of this study was to analyze the relationship between lumbar muscle degeneration and spinal degenerative disorders, using lumbar indentation value (LIV) as quantitative and Goutallier classification as qualitative measures. This is a retrospective analysis of kinematic magnetic resonance images (kMRI). Two-hundred and thirty patients with kMRIs taken in weight-bearing positions were selected randomly. The LIV and Goutallier classification were evaluated at L4-5. The correlation of these two parameters with patients' age, gender, lumbar lordosis (LL), range of motion, disc degeneration, disc height, and Modic change were analyzed. There was no significant trend of LIV among the different grades of Goutallier classification (p=0.943). There was a significant increase in age with higher grades of Goutallier classification (p<0.001). In contrast, there was no correlation between LIV and age (p=0.799). The Goutallier classification positively correlated with LL (r=0.377) and severe disc degeneration (r=0.249). The LIV positively correlated with LL (r=0.476) and degenerative spondylolisthesis (r=0.184). Multinomial logistic regression analysis showed that age (p=0.026), gender (p=0.003), and LIV (p<0.001) were significant predictors for patients with low LL (<10°). Lumbar muscle quantity and quality showed specific correlation with age and spine disorders. Additionally, LL can be predicted by the muscle quantity, but not the quality. These time-saving evaluation tools potentially accelerate the study of lumbar muscles. These slides can be retrieved under Electronic Supplementary Material.

Double-level isthmic spondylolisthesis treated with posterior lumbar interbody fusion with cage

Objective: Double-level isthmic spondylolisthesis in the lumbar spine is rare. The authors report on 21 cases of double-level isthmic spondylolisthesis treated by posterior lumbar interbody fusion (PLIF) with cage.Patients and methods: Between 2005 and 2015, twenty-one patients with double-level isthmic spondylolisthesis who underwent posterior lumbar interbody fusion (PLIF) with cage were reviewed retrospectively. The VAS (Visual Analogue Scale) and JOA (Japanese Orthopedic Association) score were used to evaluate preoperative and postoperative clinical outcomes.Results: The back pain and sciatica decreased from 6.53 and 4.24 points preoperatively to 1.80 and 1.18 points on the VAS at final follow-up, respectively. The average JOA score improved from 13.4 ± 3.2 preoperative to 25.4 ± 1.5 (range, 17–28) points postoperative. The average recovery rate was 76.9%. The good and excellent rate was 85.7% (18/21). The fusion rate was 95.2% (20/21). Changes in disc height, degree of listhesis, whole lumbar lordosis, and sacral inclination following surgery were also observed.Conclusions: Our results suggest that PLIF with cage appears to be an appropriate technique for the treatment of double-level isthmic spondylolisthesis.

Transforaminal lumbar interbody fusion with expandable cages: Radiological and clinical results of banana-shaped and straight implants.

Purpose:Expandable titanium transforaminal lumbar interbody fusion (TLIF) devices are a relatively new group of implants allowing restoration of lumbar lordosis (LL) and thus improvement of sagittal alignment. The purpose of our study is to compare clinical and radiological results of two different expandable TLIF devices.Materials and Methods:In a retrospective study, patients who underwent TLIF surgery with a banana-shaped or straight TLIF cage in our spine center were analyzed. Primary outcome was change of disc height (DH), segmental lordosis angle (SLA), and lumbar lordotic angle (LLA). Moreover, basic patients parameters and cage subsidence were evaluated.Results:Sixty-one patients were studied (33 banana-shaped and 28 straight cages). DH changed in the banana group from 4.8 mm (standard deviation SD 2.5) to 10.4 (SD 2.4) and in the straight cage group from 6.2 mm (SD 2.5) to 9.6 mm (SD 1.7). The difference was statistically significant (P = 0.03). In addition, SLA correction was higher in the banana group with 5.8° (SD 5.0)–3.7° (SD 3.6), but not significant. LLA improved in the straight group with 5.2 (SD 6.4) compared to 3.7° (SD 5.8) in the banana group. We found subsidence in four patients (6.6%) in the banana-shaped group and nine cases (14.8%) in the other group.Conclusions:Expandable titanium implants show similar improvements in restoring segmental and global lordosis. Banana-shaped expandable cages offer higher potency restoring the intervertebral DH and show less rates of subsidence compared to straight expandable cages.

Preflight, In-Flight, and Postflight Imaging of the Cervical and Lumbar Spine in Astronauts

Back pain is a common complaint during spaceflight that is commonly attributed to intervertebral disc swelling in microgravity. Ultrasound (US) represents the only imaging modality on the International Space Station (ISS) to assess its etiology. The present study investigated: 1) The agreement and correlation of spinal US assessments as compared to results of pre- and postflight MRI studies; and 2) the trend in intervertebral disc characteristics over the course of spaceflight to ISS. Seven ISS astronauts underwent pre- and postflight US examinations that included anterior disc height and anterior intervertebral angles with comparison to pre- and postflight MRI results. In-flight US images were analyzed for changes in disc height and angle. Statistical analysis included repeated measures ANOVA with Bonferroni post hoc analysis, Bland-Altman plots, and Pearson correlation. Bland-Altman plots revealed significant disagreement between disc heights and angles for MRI and US measurements while significant Pearson correlations were found in MRI and US measurements for lumbar disc height (r2 = 0.83) and angle (r2 = 0.89), but not for cervical disc height (r2 = 0.26) or angle (r2 = 0.02). Changes in anterior intervertebral disc angle-initially increases followed by decreases-were observed in the lumbar and cervical spine over the course of the long-duration mission. The cervical spine demonstrated a loss of total disc height during in-flight assessments (∼0.5 cm). Significant disagreement but significant correlation was noted between US and MRI measurements of disc height and angle. Consistency in imaging modality is important for trending measurements and more research related to US technique is required.Harrison MF, Garcia KM, Sargsyan AE, Ebert D, Riascos-Castaneda RF, Dulchavsky SA. Preflight, in-flight, and postflight imaging of the cervical and lumbar spine in astronauts. Aerosp Med Hum Perform. 2018; 89(1):32-40.

Does Resection of the Posterior Longitudinal Ligament Affect the Stability of Cervical Disc Arthroplasty?

The need for posterior longitudinal ligament (PLL) resection during cervical total disc arthroplasty (TDA) has been debated. The purpose of this laboratory study was to investigate the effect of PLL resection on cervical kinematics after TDA. Eight cadaveric cervical spine specimens were tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) to moments of ±1.5 Nm. After testing the intact condition, anterior C5-C6 cervical discectomy was performed followed by PLL resection and implantation of a compressible, 6-degrees-of-freedom disc prosthesis (M6-C, Spinal Kinetics Inc, Sunnyvale, California). Next, a second prosthesis was implanted at C6-C7 with PLL intact. Finally, the C6-C7 PLL was resected while the disc prosthesis remained in place. Segmental range of motion (ROM) and stiffness in the high flexibility zone around the neutral posture were analyzed using repeated measures ANOVA. At C5-C6, following TDA and PLL resection, FE, LB, and AR ROMs decreased significantly. Anterior and posterior disc height, segmental lordosis, and flexion stiffness increased significantly. At C6-C7, TDA with the PLL intact resulted in a significant increase in anterior disc height and segmental lordosis with no change in posterior disc height. FE, LB, and AR ROMs all decreased significantly, while flexion stiffness increased significantly compared to intact. PLL resection at C6-C7 did not result in a notable change compared to TDA with PLL intact. At the same level, flexion stiffness decreased following PLL resection compared to TDA with a value closer to intact. Two-level TDA (C5-C7) with PLL resection did not result in a loss of segmental stability. PLL resection did not significantly affect motion segment kinematics following cervical TDA using a prosthesis with inherent stiffness. Motion segment stiffness loss after PLL resection can be compensated for by a TDA design that can provide resistance to angular motion.

Is L5-S1 motion segment different from the rest? A radiographic kinematic assessment of 72 patients with chronic low back pain.

The relationship between biomechanical instability and degenerative changes in the lumbar spine in chronic low back pain (CLBP) patients remains controversial. The main objective of this retrospective radiographical study was to evaluate changes in kinematics at different lumbar levels (in particular the L5-S1 level) with progressive grades of disc degeneration and facet joint osteoarthritis in CLBP patients. Using standing neutral and dynamic flexion/extension (Fx/Ex) radiographs of the lumbar spine, in vivo segmental kinematics at L1-L2 through L5-S1 were evaluated in 72 consecutive CLBP patients. Disc degeneration was quantified using changes in signal intensity and central disc height on mid-sagittal T2-weighted magnetic resonance (MR) scans. Additionally, the presence or absence of facet joint osteoarthritis was noted on T2-weighted axial MR scans. Disc degeneration and facet joint osteoarthritis occurred independent of each other at the L5-S1 level (p=0.188), but an association was observed between the two at L4-L5 (p<0.001) and L3-L4 (p<0.05) levels. In the absence of facet joint osteoarthritis, the L5-S1 segment showed a greater range of motion (ROM) in Ex (3.3°±3.6°) and a smaller ROM in Fx (0.6°±4.2°) compared with the upper lumbar levels (p<0.05), but the differences diminished in the presence of it. In the absence of facet joint osteoarthritis, no change in L5-S1 kinematics was observed with progressive disc degeneration, but in its presence, restabilisation of the L5-S1 segment was observed between mild and severe disc degeneration states. The L5-S1 motion segment exhibited unique degenerative and kinematic characteristics compared with the upper lumbar motion segments. Disc degeneration and facet joint osteoarthritis occurred independent of each other at the L5-S1 level, but not at the other lumbar levels. Severe disc degeneration in the presence of facet joint osteoarthritis biomechanically restabilised the L5-S1 motion segment.

Real-time Ultrasound Assessment of Astronaut Spinal Anatomy and Disorders on the International Space Station.

Back pain is one of the most common conditions of astronauts during spaceflight and is hypothesized to be attributed to pathologic anatomic changes. Ultrasound (US) represents the only available imaging modality on the International Space Station, but a formal US protocol for imaging the structures of the spinal column does not exist. This investigation developed a method of acquiring diagnostic-quality images of the anterior lumbar and cervical regions of the spine during long-duration spaceflight. Comprehensive spinal US examinations were conducted on 7 long-duration spaceflight astronauts before flight, in flight, and after flight and compared to preflight and postflight magnetic resonance imaging data. In-flight scans were conducted after just-in-time training assisted by remote expert tele-US guidance. Novice users were able to obtain diagnostic-quality spinal images with a 92.5% success rate. Thirty-three anomalous or pathologic findings were identified during the preflight US analysis, and at least 14 new findings or progressions were identified during the postflight US analysis. Common findings included disk desiccation, osteophytes, and qualitative changes in the intervertebral disk height and angle. Ultrasound has proven efficacy as a portable and versatile diagnostic imaging modality under austere conditions. We demonstrated a potential role for US to evaluate spinal integrity and alterations in the extreme environment of space on the International Space Station. Further investigations should be performed to corroborate this imaging technique and to create a larger database related to in-flight spinal conditions during long-duration spaceflight.

Double-level isthmic spondylolisthesis treated with posterior lumbar interbody fusion: A review of 32 cases

ObjectiveThe incidence of double-level isthmic spondylolisthesis is rare. The aim of this study is to evaluate the short-term functional and radiological outcomes of surgical treatment for double-level isthmic spondylolisthesis. Patients and methodsBetween 2004 and 2014, thirty-two patients with double-level isthmic spondylolisthesis who underwent posterior lumbar interbody fusion (PLIF) with autogenous bone chips were reviewed retrospectively. The clinical outcomes were measured by VAS (Visual analog scale) and JOA(Japanese Orthopedic Association) score. ResultsAt an average follow-up of 2.8 years, the mean score on the VAS of back pain and sciatica decreased from 6.48 and 4.26 points preoperatively to 1.82 and 1.10 points at final follow-up, respectively. The average JOA score improved from 13.8±3.1 preoperative to 25.6±1.3 (range, 17–28) points postoperative. The average recovery rate was 77.6%. The good and excellent rate was 84.3% (27/32). The fusion rate was 87.5% (28/32). Changes in disc height, degree of listhesis, whole lumbar lordosis, and sacral inclination between the pre- and postoperative periods were significant. ConclusionsOur findings suggest that PLIF with autogenous bone chips for double-level isthmic spondylolisthesis could yield good functional short-term results. It seems to be a viable approach in the treatment of double-level isthmic spondylolisthesis.

The Quantitative Structural and Compositional Analyses of Degenerating Intervertebral Discs Using Magnetic Resonance Imaging and Contrast-Enhanced Micro-Computed Tomography.

The intervertebral disc (IVD) is susceptible to degenerative changes that are associated with low back pain. Murine models are often used to investigate the mechanistic changes in the development, aging, and diseased states of the IVD, yet the detection of early degenerative changes in structure is challenging because of the minute size of the murine IVDs. Histology is the gold standard for examining the IVD structure, but it is susceptible to sectioning artifacts, spatial biases, and requires the destructive preparation of the sample. We have previously demonstrated the feasibility of using Ioversol for the contrast-enhanced micro-computed tomography (microCT) to visualize and quantitate the intact healthy murine IVD. In this work, we demonstrate utility of this approach to monitor the longitudinal changes of in vitro nucleolytic- and mechanical injury- degeneration models of the murine discs and introduce novel quantitative metrics to characterize the structure and composition of the IVD. Moreover, we compared the imaging quality and quantitation of these in vitro models to magnetic resonance imaging (MRI) and histology. Stab puncture, trypsin injection, and collagenase injection all induced detectable and significant changes in structure and composition of the discs overtime. Compared to MRI and histology, contrast-enhanced microCT produced superior images that capture the degenerative progression in these models. Contrast-enhanced microCT was also capable of monitoring the structural deteriorations via the changes in disc height and volume, and novelthe nucleus pulposus intensity/disc intensity (NI/DI) parameter provides a surrogate measure of proteoglycan composition (R=0.96). Overall, this approach allows for the nondestructive monitoring of the structure and composition of the IVD at very high resolutions.

Effect of collagen fibre orientation on intervertebral disc torsion mechanics.

The intervertebral disc is a complex fibro-cartilaginous material, consisting of a pressurized nucleus pulposus surrounded by the annulus fibrosus, which has an angle-ply structure. Disc injury and degeneration are noted by significant changes in tissue structure and function, which significantly alters stress distribution and disc joint stiffness. Differences in fibre orientation are thought to contribute to changes in disc torsion mechanics. Therefore, the objective of this study was to evaluate the effect of collagen fibre orientation on internal disc mechanics under compression combined with axial rotation. We developed and validated a finite element model (FEM) to delineate changes in disc mechanics due to fibre orientation from differences in material properties. FEM simulations were performed with fibres oriented at [Formula: see text] throughout the disc (uniform by region and fibre layer). The initial model was validated by published experimental results for two load conditions, including [Formula: see text] axial compression and [Formula: see text] axial rotation. Once validated, fibre orientation was rotated by [Formula: see text] or [Formula: see text] towards the horizontal plane, resulting in a decrease in disc joint torsional stiffness. Furthermore, we observed that axial rotation caused a sinusoidal change in disc height and radial bulge, which may be beneficial for nutrient transport. In conclusion, including anatomically relevant fibre angles in disc joint FEMs is important for understanding stress distribution throughout the disc and will be important for understanding potential causes for disc injury. Future models will include regional differences in fibre orientation to better represent the fibre architecture of the native disc.

The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion.

ObjectivesMany studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens.MethodsFirst, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images.ResultsAll the vertebral motion segments (L3/4, L4/5 and L5/S1) had greater changes in disc height and DASEP from neutral to flexion than from neutral to extension. The change in anterior disc height gradually increased from upper to lower levels, from neutral to flexion. The changes in anterior and posterior disc heights were similar at the L4/5 level from neutral to extension, but the changes in anterior disc height were significantly greater than those in posterior disc height at the L3/4 and L5/S1 levels, from neutral to extension.ConclusionsThe lumbar motion segment showed level-specific changes in disc height and DASEP. The data may be helpful in understanding the physiologic dynamic characteristics of the lumbar spine and in optimising the parameters of lumbar surgical instruments.Cite this article: M. Fu, Q. Ye, C. Jiang, L. Qian, D. Xu, Y. Wang, P. Sun, J. Ouyang. The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion. Bone Joint Res 2017;6:245–252. DOI: 10.1302/2046-3758.64.BJR-2016-0245.R1.

Mechanical effects of traction on lumbar intervertebral discs: A magnetic resonance imaging study

BackgroundAlthough traction has long been used for treating patients with low back pain (LBP), its effects are still inconclusive mainly because of limited high-quality evidence. ObjectiveTo provide evidence of the mechanism of traction on lumbar intervertebral discs. DesignA quantitative approach with a repeated measurement protocol. MethodNine participants (mean age = 22.1 ± 0.8 years) without any LBP history were recruited. Magnetic Resonance Images of the lumbar spine of each participant were recorded before and after 30 min of horizontal lying and directly after 30 min of horizontal traction of 42% body weight. The average, anterior, central, and posterior disc height and tilt angle of each lumbar disc and lumbar lordosis were measured. ResultsA significant increase in the average disc height for all lumbar discs, a significant reduction of lumbar lordosis and changes in tilt angle were observed after the application of 30 min of resting followed by 30 min of traction. A significant increase in the average disc height was observed only in lower lumbar discs after 30 min of traction. The increase in the posterior disc height was more apparent than that in the anterior disc height. ConclusionsHorizontal traction was evidently effective in increasing the disc height of lower lumbar levels, particularly in the posterior regions of the discs. Further evidence of the effects of traction of different modes, magnitudes, and durations on the change in disc height is required for proper control of traction applied to specific disc levels.