Average Disc Height Research Articles

Zero-profile implant system versus novel plate systems after ACDF for comparison of sagittal balance parameters and clinical efficacy analysis

BackgroundThe zero-profile implant system (Zero-P) and conventional plates have been widely used in anterior cervical discectomy and fusion (ACDF) to treat cervical spondylosis. The purpose of this study was to compare the effects of the application of Zero-P and new conventional plates (ZEVO, Skyline) in ACDF on the sagittal imaging parameters of cervical spondylosis patients and to analyze their clinical efficacy.MethodsWe conducted a retrospective study on 119 cervical spondylosis patients from January 2018 to December 2021, comparing outcomes between those receiving the Zero-P device (n = 63) and those receiving a novel conventional plate (n = 56, including 46 ZEVO and 10 Skyline plates) through ACDF. Cervical sagittal alignment was assessed pre- and postoperatively via lateral radiographs. The Japanese Orthopedic Association (JOA), Neck Disability Index (NDI), and visual analog scale (VAS) scores were recorded at baseline, after surgery, and at the 2-year follow-up to evaluate patient recovery and intervention success.ResultsThere were significant differences in the postoperative C0-C2 Cobb angle and postoperative sagittal segmental angle (SSA) between patients in the novel conventional plate group and those in the Zero-P group (P < 0.05). Postoperatively, there were significant changes in the C2‒C7 Cobb angle, C0‒C2 Cobb angle, SSA, and average surgical disc height (ASDH) compared to the preoperative values in both patient groups (P < 0.05). Dysphagia in the immediate postoperative period was lower in the Zero-P group than in the new conventional plate group (0% in the Zero-P group, 7.14% in the novel conventional plate group, P = 0.046), and the symptoms disappeared within 2 years in both groups. There was no statistically significant difference between the two groups in terms of complications of adjacent spondylolisthesis (ASD) at 2 years postoperatively (3.17% in the Zero-P group, 8.93% in the novel conventional plate group; P = 0.252). According to the subgroup analysis, there were significant differences in the postoperative C2‒C7 Cobb angle, C0‒C2 Cobb angle, T1 slope, and ASDH between the ZEVO group and the Skyline group (P < 0.05). Compared with the preoperative scores, the JOA, NDI, and VAS scores of all groups significantly improved at the 2-year follow-up (P < 0.01). According to the subgroup analysis, the immediate postoperative NDI and VAS scores of the ZEVO group were significantly better than those of the Skyline group (P < 0.05).ConclusionIn ACDF, both novel conventional plates and Zero-P can improve sagittal parameters and related scale scores. Compared to the Zero-P plate, the novel conventional plate has a greater advantage in correcting the curvature of the surgical segment, but the Zero-P plate is less likely to produce postoperative dysphagia.

The Relationship Between Endplate Defect Scores and Lumbar Sagittal Translation Stability in Lumbar Spondylolisthesis Patients

BackgroundLumbar instability and endplate defects are commonly seen in patients with spondylolisthesis. However, little is known about associations between segmental stability and endplate defects. The present study explored associations between stability-related radiographic parameters and endplate defect scores and assessed whether endplate defect scores can predict lumbar stability in lumbar spondylolisthesis. MethodsNeutral, flexion and extension radiographs of 159 patients with monosegmental lumbar spondylolisthesis were analyzed. Radiographic parameters included average intervertebral disc height (IDH), slip distance, sagittal translation (ST) and sagittal angulation (SA). Correlation analysis and linear regression analysis were used to explore associations between endplate defect scores and radiographic parameters. Logistic regression analysis was used to assess associations between endplate defect scores and ST stability. Receiver-operating characteristic curve (ROC) analysis was used to evaluate the value of the endplate defect score in predicting ST stability. ResultsA total of 11.9% of patients had ST≥4 mm, and 30% of patients had SA≥10 degrees. Endplate defect scores were negatively correlated with ST and IDH and positively correlated with slip distance in isthmic spondylolisthesis but not in degenerative spondylolisthesis. In multiple regression analysis, endplate defect scores were significantly associated with ST, slip distance, IDH, and disc degeneration. ST instability was associated with endplate defect scores in isthmic spondylolisthesis (OR=0.460, P=0.010). The AUCs for using the endplate defect score to evaluate ST stability in overall patients and isthmic spondylolisthesis patients were 0.672 and 0.774, respectively. The optimal threshold of the endplate defect score constructed by the Youden index was 7.5 for predicting ST stability. ConclusionsEndplate defect scores increase with a reduction in IDH, progression of slippage and a decrease in ST in isthmic spondylolisthesis but not in degenerative spondylolisthesis. ST instability was associated with endplate defect scores in isthmic spondylolisthesis, and endplate defect scores could be used to reflect lumbar stability at the slippage segment.

Transforaminal lumbar interbody fusion with an expandable interbody device: Two-year clinical and radiographic outcomes

BackgroundThe use of interbody cages as an adjunct to lumbar spinal fusion remains an important technique to enhance segmental stability, promote solid arthrodesis, maintain neuroforaminal decompression, and preserve/improve segmental lordosis. Appropriate segmental lumbar lordosis and sagittal balance is well-known to be critical for long-term patient outcomes. This study sought to evaluate the radiographic and clinical results of TLIF in patients using an articulating, expandable cage. Primary endpoint was clinical and radiographic outcomes, including complications, at 12 and 24 months. MethodsA total of 37 patients underwent open single-level or 2-level TLIF by a single surgeon using an expandable cage with concomitant bilateral pedicle screws and posterolateral arthrodesis. Clinical outcomes included ODI and VAS for back and legs. Radiographic outcomes included pelvic incidence and tilt, lumbar and segmental lordoses, and disc height at the operative level(s). All outcomes were collected at baseline, 2-weeks, 6-weeks, 3-months, 6-months, 12-months, and 24-months postop. ResultsA total of 28 patients were available for analysis. Nine patients failed to follow-up at 24 months. Mean ODI scores showed significant improvement, from pre-to-postoperative at 24 months (55%; p<.0001). VAS for back and legs was significantly lower at 24 months on average by 72 and 79%, respectively (p<.0001 for both). Both segmental and lumbar lordoses significantly improved by 5.3° and 4.2° (p<.0001 and p=.049), respectively. Average disc height improved by 49% or 6.1 mm (p<.001). No device-related complications nor instances of measured subsidence. One patient had a superficial infection, and another had an intraoperatively repaired incidental durotomy. ConclusionsThe use of an expandable cage contributed to improvement in both segmental and lumbar lordosis with no reported complications at 24-month follow-up. All clinical measures significantly improved as well. The expandable cage design represents an effective and safe option to increase cage size and allow significant segmental lordosis correction.

Increased cage angle effects on radiographic outcomes after stand-alone anterior lumbar interbody fusion.

Anterior lumbar interbody fusion (ALIF) is a well-accepted surgical technique used to treat various lumbar degenerative pathologies. Recently, hyperlordotic cages have been introduced to create higher degrees of lordosis to the lumbar spine. There are little data currently available to define the radiographic benefits that these cages provide with stand-alone ALIF. The goal of the present study was to assess the effect of increasing cage angles on postoperative subsidence, sagittal alignment, and foraminal and disc height in patients who underwent single-level stand-alone ALIF surgery. A retrospective cohort study was performed of consecutive patients who underwent single-level ALIF by a single spine surgeon. Radiographic analysis included global lordosis, operative level of segmental lordosis, cage subsidence, sacral slope, pelvic tilt, pelvic incidence, pelvic incidence-lumbar lordosis mismatch, edge loading, foraminal height, posterior disc height, anterior disc height, and adjacent-level lordosis. Multivariate linear and logistic regressions were performed to analyze the relationship between cage angle and radiographic outcomes. Seventy-two patients were included in the study and divided into three groups based on cage angle: < 10° (n = 17), 10°-15° (n = 36), and > 15° (n = 19). Within the entire study cohort, there were significant improvements in disc and foraminal height, as well as segmental and global lordosis, at the final follow-up after single-level ALIF. However, when stratified by cage angle groups, patients with > 15° cages did not have any additional significant changes in global or segmental lordosis compared with those patients with smaller cage angles, but patients with > 15° cages showed greater risk of subsidence while also having significantly less improvements in foraminal height, posterior disc height, and average disc height compared with the other groups. Patients with < 15° stand-alone ALIF cages showed improved average foraminal and disc (posterior, anterior, and average) height without sacrificing improvements in sagittal parameters or increasing risk of subsidence when compared to patients with hyperlordotic cages. The use of hyperlordotic cages > 15° did not provide spinal lordosis commensurate with the lordotic angle of the cage and had a greater risk of subsidence. Although this study was limited by a lack of patient-reported outcomes to correlate with radiographic results, these findings support the judicious use of hyperlordotic cages in stand-alone ALIF.

DEEP LEARNING-BASED HIGH-ACCURACY QUANTITATION FOR LUMBAR INTERVERTEBRAL DISC DEGENERATION FROM MRI

Using deep learning and image processing technology, a standardized automatic quantitative analysis systerm of lumbar disc degeneration based on T2MRI is proposed to help doctors evaluate the prognosis of intervertebral disc (IVD) degeneration.A semantic segmentation network BianqueNet with self-attention mechanism skip connection module and deep feature extraction module is proposed to achieve high-precision segmentation of intervertebral disc related areas. A quantitative method is proposed to calculate the signal intensity difference (SI) in IVD, average disc height (DH), disc height index (DHI), and disc height-to-diameter ratio (DHR). According to the correlation analysis results of the degeneration characteristic parameters of IVDs, 1051 MRI images from four hospitals were collected to establish the quantitative ranges for these IVD parameters in larger population around China.The average dice coefficients of the proposed segmentation network for vertebral bodies and intervertebral discs are 97.04% and 94.76%, respectively. The designed parameters of intervertebral disc degeneration have a significant negative correlation with the Modified Pfirrmann Grade. This procedure is suitable for different MRI centers and different resolution of lumbar spine T2MRI (ICC=.874~.958). Among them, the standard of intervertebral disc signal intensity degeneration has excellent reliability according to the modified Pfirrmann Grade (macroF1=90.63%~92.02%).we developed a fully automated deep learning-based lumbar spine segmentation network, which demonstrated strong versatility and high reliability to assist residents on IVD degeneration grading by means of IVD degeneration quantitation.

Do lumbar intervertebral disc parameters in patients with chronic low back pain differ quantitatively from healthy individuals? A comparative study

Objectives: Studies in the past were not able to find any definitive correlation between disc parameters and LBP. The objectives of the current study were to evaluate the association of the lumbar disc parameters with LBP and to find the quantitative differences between the discs in LBP patients and healthy individuals. Methodology: Fifty patients with chronic LBP (group A) and 25 healthy individuals (group B) were subjected to magnetic resonance imaging of lumbar spine. Disc parameters of orientation and size were estimated. Results: There was a statistically significant difference in disc angle at L1-L2 ( p = 0.01), L2-L3 ( p = 0.05), and L3-L4 ( p = 0.001), and skin angle at L2-L3 ( p = 0.03) and L4-L5 ( p = 0.05) level. Length and cross-sectional area (CSA) of anterior intervertebral height, posterior intervertebral height, intervertebral disc, anterior disc material, posterior disc material; and volume of anterior disc material and volume of posterior disc material were statistically significantly more at various disc levels in group A. Antero-posterior dural sac length and CSA of the sac were statistically significantly smaller at L4-L5 and L5-S1 levels. There was a significant association between average disc height and dural sac area at L1-L2 ( p-value = 0.0393) and L5-S1 ( p-value = 0.0022) and CSA of the disc and dural sac area at L5-S1 ( p-value = 0.049) in group A. Conclusions: There was a significant difference in the lumbar disc orientation and dimensions between LBP patients and healthy individuals. Larger disc parameters (height, volume, CSA, and length) and altered orientation may affect the biomechanics of the spine, thus predisposing to LBP.

Measurement of Intervertebral Disc Heights in the Lumbar Spine. Comparison of X-Ray and Magnetic Resonance Imaging, Method of Measurement and Determination of Inter-observer Reliability.

Retrospective radiological examination (X-ray and MRI) aims to investigate the diagnostic value of various methods of measurement with regard to the determination of the intervertebral disc heights of the lumbar spine. Of 130 patients without detectable damage to the intervertebral discs, the X-ray and MRI images of the lumbar spine were evaluated. The measurements were made either in the center line (Hurxthal) or in the 2-point method according to Dabbs or in the 3-point method according to Fyllos. The average intervertebral disc height for all measured segments was 8.8mm (SD 1.4mm). In the Hurxthal measurement, the significantly (p<0.001) highest values were measured with an average of 9.1mm (SD 1.3mm). The average readings for the Fyllos method were 7.5mm (SD 1.2mm) and according to Dabbs 6.7mm (SD 1.2mm). The measured values of Observer I were on average 1.2mm (SD 0.3mm) smaller than those of Observer II (p<0.001). The highest interobserver correlation was found in the measurements in projection radiography in the AP method according to Dabbs and Fyllos. The measured values in men were 0.5mm (SD 0.01mm) larger than in women (p<0.001), regardless of the method. The height of the intervertebral discs increases significantly until the age of 40, but beyond the age of 40, the height of the intervertebral discs either remains constant or falls off slightly, but not significantly. The lordosis angle of the lumbar spine and the concavity index of the vertebral bodies showed no correlation with the measured disc heights. The radiological measurements to determine the intervertebral disc height have only moderate reliability. The results of X-rays are superior to those of MRI examination. The most accurate results are provided by measurements based on exact landmarks of the vertebral bodies. The method according to Dabbs seems to be the most accurate at the moment. There is no clear age-atypical chondrosis in patients without intervertebral disc damage.

P122. Comparing long term deformity correction and other outcomes between single level circumferential XLIF and MI-TLIF: a retrospective review with 5-year minimum follow up

<h3>BACKGROUND CONTEXT</h3> XLIF with percutaneous pedicle screw fixation (circumferential XLIF) and MI-TLIF are two commonly used minimally invasive approaches to the lumbar spine. Because of its lateral approach, traditional XLIF is blocked to the L5-S1 disc space by the iliac crest. Studies that have compared these two techniques typically do not account for this limitation and, furthermore, tend to not restrict their analysis by number of levels operated on. Additionally, studies evaluating long term (>5-year) outcomes of these techniques are less numerous. Therefore, this study aims to compare the clinical and radiological outcomes of single level circumferential XLIF and MI-TLIF exclusively at the L4-L5 disc space. <h3>PURPOSE</h3> To compare the clinical and radiological outcomes of single level XLIF and MI-TLIF at L4-L5. <h3>STUDY DESIGN/SETTING</h3> Retrospective comparative study. <h3>PATIENT SAMPLE</h3> A total of 108 total patients (75 MI-TLIF and 33 circumferential XLIF) that underwent single level surgery at L4-L5 at a single institution from 2008 to 2015 with a minimum of 5-year follow up. <h3>OUTCOME MEASURES</h3> 1) Patient demographics: age, sex, BMI, length of follow up; 2) rate of complications requiring a return to the OR (RTO); 3) Radiographic outcomes: graft subsidence, final anterior and posterior disc height (ADH and PDH); 4) Patient outcome scores: Oswestry Disability Index (ODI), Visual Analogue Scale (VAS). <h3>METHODS</h3> A retrospective review was performed to identify all patients between 2008-2015 who underwent circumferential XLIF or MI-TLIF with a minimum followup of 5 years. Demographic data, complication-related data, radiographic outcomes and patient outcome scores were recorded and compared between cohorts. Standard binominal and categorical comparative analyses were performed. <h3>RESULTS</h3> A total of 108 patients were included for analysis (75 MI-TLIF and 33 circumferential XLIF). Mean age (53.5 MI-TLIF and 53.9 XLIF), BMI (32.3 MI-TLIF and 31.4 XLIF), and length of follow up (90 months MI-TLIF and 103 months XLIF) were similar between cohorts. Overall RTO rate was found to be statistically similar between groups at 16.0% (95% CI, 9.24-26.07) in the MI-TLIF group and 6.1% (95% CI, 0.68-20.60) in the XLIF group. Final ADH was 9.03±1.10 mm in the MI-TLIF group and 12.3±2.60 mm in the XLIF group (p < 0.0001). Final PDH was 9.97±1.96 mm for MI-TLIF and 7.12±2.2 mm for XLIF (p < 0.0001). Average DH was 9.50±1.59 mm and 9.71±2.41 mm for the MI-TLIF and XLIF groups, respectively (p=0.593). Change in ODI and VAS scores at final follow up were similar between MI-TLIF and XLIF groups (p=0.629 for ODI and p=0.322 for VAS). <h3>CONCLUSIONS</h3> This long-term comparative study demonstrates similar clinical and radiological outcomes between single level MI-TLIF and circumferential XLIF at the L4-L5 level. As expected, MI-TLIF had significantly greater long-term improvement in posterior disc height and XLIF had significantly greater improvement in anterior disc height. However, average disc height was found to be similar between groups. This suggests that although MI-TLIF and circumferential XLIF lead to equivalent long-term improvement at the L4-L5 level, choosing one's approach based on the anterior versus posterior disc anatomy of the patient may enhance patient outcome. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

212. ALIF as a salvage procedure for TLIF pseudarthrosis: a clinical outcome study

<h3>BACKGROUND CONTEXT</h3> Lumbar fusion procedures are at risk for pseudarthrosis as a complication. Despite its relative prevalence, few studies have characterized the clinical efficacy of salvage procedures. <h3>PURPOSE</h3> To characterize clinical outcomes following anterior lumbar interbody fusion (ALIF) as a salvage procedure for pseudarthrosis of transforaminal lumbar interbody fusion (TLIF). <h3>STUDY DESIGN/SETTING</h3> Retrospective. <h3>PATIENT SAMPLE</h3> Thirty-four ALIF patients. <h3>OUTCOME MEASURES</h3> VAS back and leg, ODI, SF-12 PCS, VR-12 PCS. <h3>METHODS</h3> A retrospective review of a surgical database of eligible procedures between November 2010 and June 2020 was performed. Inclusion criteria were as follows: single-level revision ALIF procedures performed at the index level for pseudarthrosis of TLIF. Patients were excluded if procedures were primary or performed for infectious, malignant or traumatic etiologies. Demographic and perioperative characteristics were collected. Additionally, time to revision, rates of 1-year arthrodesis, 6-month pseudarthrosis and postoperative complications were calculated. Radiographic measurements were performed to evaluate sagittal alignment and disc height at the preoperative, immediate postoperative and final postoperative timepoint. Differences between preoperative and final postoperative radiographic measurements were evaluated using a Student's t-test. Visual analog scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), 12-Item Short Form physical composite score (SF-12 PCS and VR-12 PCS) were collected preoperatively and postoperatively. Overall achievement of a minimum clinically important difference (MCID) was calculated using the following established values: 1.2 (VAS Back), 1.6 (VAS leg), 12.8 (ODI), 4.0 (SF-12 PCS). <h3>RESULTS</h3> A total of 34 patients who underwent an ALIF revision procedure at the index level were identified. Mean age was 46.7 years with 81.1% being male and 64.9% obese (body mass index: 30 kg/m²). A total of 83.8% had an ASA < 2 and 75.5% carried a CCI > 1. Mean time from index TLIF to salvage ALIF procedure was 21.3 months. Mean operative time was 135.3 minutes with an average blood loss of 75.0mL and hospital length of stay of 49.5 hours. The majority of procedures were performed at the L5-S1 level (73.5%). Patients demonstrated a one-year arthrodesis rate of 100.0% with 2/34 patients requiring an additional revision procedure at the index level for neuroforaminal bone growth. A total of six postoperative complications were observed with one patient suffering from a mild urinary tract infection, one with acute renal failure, one with a venous thromboembolism, one with altered mental status, and two with fever of unknown origin. Following ALIF salvage, there was a significant increase in segmental lordosis, mean anterior and posterior disc height, as well as average disc height (p≤0.037, all). Mean preoperative outcome scores were 7.2 ± 1.9 for VAS back, 6.8 ± 2.8 for VAS leg, 56.7 ± 16.5 for ODI, and 28.1 ± 10.9 for SF-12 PCS. Clinically relevant improvement of PROMs as measured by MCID achievement rates by one-year were 67.1% for VAS back, 57.1% for VAS leg, 40.0% for ODI and 37.5% for SF-12 PCS. <h3>CONCLUSIONS</h3> Use of ALIF as a salvage procedure at either the L4-5 or L5-S1 level for TLIF pseudoarthrosis demonstrated a high arthrodesis rate at one-year. Patients demonstrated high rates of MCID achievement for back and leg pain, as well as ODI. These results support the use of ALIF as a salvage procedure for failed TLIFs at the L4-5 and L5-S1 levels. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Minimally Invasive Deformity Correction Technique: Initial Case Series of Anterior Lumbar Interbody Fusion at L5–S1 for Multilevel Lumbar Interbody Fusion in a Lateral Decubitus Position

Many surgical options exist for multilevel lumbar interbody fusion, including anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF). While current technique of repositioning patients between supine ALIF and lateral decubitus LLIF offers many benefits, intraoperative repositioning can be cumbersome. We present a novel approach that accomplishes both multilevel LLIF and L5-S1 ALIF in a lateral decubitus position. This case series retrospectively enrolled 12 consecutive patients who underwent L5-S1 ALIF in the lateral decubitus position and anterior-to-psoas LLIF at more cranial levels as part of a multilevel lumbar interbody fusion surgery between September 2020 and December 2021. All surgeries were performed by a single spine-focused neurosurgeon at an urban academic hospital. Radiographic imaging analysis demonstrated significant changes in coronal Cobb angle (-5.43°±3.81°; P=0.0029), global lumbar lordosis (6.77°±12.04°; P=0.0049), segmental lumbar lordosis (8.91°±10.21°; P=0.0005), spinopelvic mismatch (-7.93°±7.91°; P=0.0010), average disc height (5.30±1.64mm; P=0.0005), and L5-S1 disc height (6.68±2.10mm; P=0.0005). Two patients developed postoperative complications including wound dehiscence and grade I graft subsidence at L4-L5. This case series demonstrated that a combined lateral decubitus L5-S1 ALIF and LLIF at more cranial levels is a safe, efficient approach to multilevel lumbar interbody fusions. This technique significantly restored spinopelvic alignments with a low complication rate and no patient repositioning. Efficacy of this minimally invasive deformity correction technique should be further investigated through a multicenter trial.

Radiographic and clinical evaluation of single-level lateral interbody fusion in patients with severe stenosis analyzed using cluster analysis.

This study was a retrospective review of patients treated in a single institution. We performed a cluster analysis of the degree of preoperative stenosis to investigate the effect of indirect neural decompression in single-level lateral lumbar interbody fusion (LLIF). Surgery is generally indicated for patients with severe stenosis. On the other hand, severe lumbar spinal stenosis is a relative contraindication to LLIF and is excluded in most studies. If LLIF, which is less invasive to treatment, can be applied to severe stenosis patients, it may help treatment. Cluster analysis classified 80 patients into 3 groups based on preoperative central canal area (CCA), preoperative canal diameter (CD), and preoperative Schizas grade: group 1 with severe stenosis (n = 43); group 2 with moderate stenosis (n = 27); and group 3 with mild stenosis (n = 10). Preoperative and immediately postoperative CCA and CD in magnetic resonance imaging were compared between groups. Disc angle (DA) and anterior, posterior, and average disc heights (AvDH) (anterior disc height, posterior disc height, average disc height AvDH) were measured using standing lateral plain radiographs. For clinical analysis, a numeric rating scale was used to evaluate clinical outcomes. DA, anterior disc height, posterior disc height, and AvDH increased significantly after the operation in all groups, but the average changes in these factors did not differ. Mean midsagittal CD and axial CCA on MRI magnetic resonance imaging increased significantly in all groups, but as with DA and DH, the changes in axial CCA and midsagittal CD did not differ between groups. The numeric rating scale score did not differ between groups at any time. The cluster analysis results suggested that postoperative changes in indirect neural decompression for severe stenosis after LLIF similar for moderate and mild stenosis and that pain did not differ according to the severity of stenosis after surgery.

Lumbar intervertebral disks: morphometric parameters and indices

An important element of evidence-based medicine is to take into account the individual variability of the indicators of the norm of intervertebral discs, which is undoubtedly the basis for early preclinical detection of their pathology. Mathematical modeling and comprehensive assessment of the parameters of the intervertebral discs can not only predict and determine the early manifestations of pathological changes, but also help to correct them in advance. The aim of the study was to calculate and evaluate the variability of absolute, calculated and relative metric parameters of intervertebral discs in the norm with the subsequent possibility of modeling standards based on individual linear dimensions of intervertebral discs of the lumbar spine and general anthropometric characteristics (body length and weight) in young men and men of the first period of adulthood (17-28 years), both in separate age groups and in the combined group. The series of MRI scans obtained on a Phillips Achieva 1.5T scanner measured the anterior, middle and posterior vertical dimensions, maximum sagittal and frontal dimensions of the intervertebral discs L1-L2, L2-L3, L3-L4, L4-L5 segments of the spine (IVDL1-L2, IVDL2-L3, IVDL3-L4, IVDL4- L5). We calculated the average height of the intervertebral discs, cross-sectional area and volume of intervertebral discs, as well as relative indicators - the ratio of the sum of sagittal and transverse dimensions, the sum of three dimensions, cross-sectional area and volume of intervertebral discs to the average intervertebral disc height. Statistical analysis of the obtained morphometric parameters was performed in the license package “STATISTICA 6.1”. The distribution of variation series indicators, their average values and standard errors, coefficients of variation and asymmetry were evaluated. It was determined that the sums of the transverse and sagittal sizes and the sums of the three sizes increase proportionally in the caudal direction, have a distribution of indicators as close as possible to normal, and their coefficients of variation are many times smaller than for cross-sectional areas and volumes. Indicators of the ratio of the sum of the sagittal and transverse size and the sum of the three sizes to the average height of the intervertebral discs have a variability of less than 10% and correspond to the characteristics of the general population. Body weight and length have significantly higher correlation coefficients with the sums of sagittal and transverse dimensions, the sums of three dimensions and cross-sectional areas than with the partial dimensions of the intervertebral discs.

Sensitivity of Intervertebral Disc Finite Element Models to Internal Geometric and Non-geometric Parameters.

Finite element models are useful for investigating internal intervertebral disc (IVD) behaviours without using disruptive experimental techniques. Simplified geometries are commonly used to reduce computational time or because internal geometries cannot be acquired from CT scans. This study aimed to (1) investigate the effect of altered geometries both at endplates and the nucleus-anulus boundary on model response, and (2) to investigate model sensitivity to material and geometric inputs, and different modelling approaches (graduated or consistent fibre bundle angles and glued or cohesive inter-lamellar contact). Six models were developed from 9.4 T MRIs of bovine IVDs. Models had two variations of endplate geometry (a simple curved profile from the centre of the disc to the periphery, and precise geometry segmented from MRIs), and three variations of NP-AF boundary (linear, curved, and segmented). Models were subjected to axial compressive loading (to 0.86 mm at a strain rate of 0.1/s) and the effect on stiffness and strain distributions, and the sensitivity to modelling approaches was investigated. The model with the most complex geometry (segmented endplates, curved NP-AF boundary) was 3.1 times stiffer than the model with the simplest geometry (curved endplates, linear NP-AF boundary), although this difference may be exaggerated since segmenting the endplates in the complex geometry models resulted in a shorter average disc height. Peak strains were close to the endplates at locations of high curvature in the segmented endplate models which were not captured in the curved endplate models. Differences were also seen in sensitivity to material properties, graduated fibre angles, cohesive rather than glued inter-lamellar contact, and NP:AF ratios. These results show that FE modellers must take care to ensure geometries are realistic so that load is distributed and passes through IVDs accurately.

Normative Magnetic Resonance Imaging Data of Age-Related Degenerative Changes in Cervical Disc Morphology

Few studies have examined a possible correlation between cervical disc degeneration and disc height. The aim of this study was to establish age-related changes and sex-specific differences of cervical disc height using magnetic resonance imaging (MRI) and to evaluate the relationship between degree of cervical disc degeneration and disc height in asymptomatic subjects. We measured the intervertebral disc anteroposterior diameter and disc height in each disc level using MRI in 1211 relatively healthy volunteers (606 men and 605 women, mean age 49.5 years). We included at least 100 males and 100 females in each decade of life between the 20s and the 70s. Cervical disc degeneration was defined according to the modified Pfirrmann classification system, and disc index and intervertebral disc height narrowing ratio were evaluated on sagittal plane MRI. Intervertebral disc height decreased gradually with increasing age in both sexes. The grade of disc degeneration significantly increased with age in both sexes at every level. Mild disc degeneration was observed even in subjects their 20s. Disc degeneration occurred around the C5-C6 level. The average disc height decreased with aging after the 40s. Disc index and intervertebral disc height narrowing ratio decreased with a progression in the disc degeneration grade in both sexes. This large-scale cross-sectional analysis of cervical spine MRI data in healthy subjects demonstrated that cervical disc height narrowing progresses with age. Cervical disc height narrowing is highly correlated with the progression of disc degeneration.

Analysis of lumbosacral sagittal balance parameter variation in minimally invasive transforaminal lumbar interbody fusion with real-time 3D navigation techniques

To explore the dynamic changes of lumbosacral sagittal parameters after real-time three-dimensional navigation assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and traditional open TLIF for treatment of lumbar degenerative disease. The clinical data of 61 patients with lumbar degenerative disease underwent single-segment surgery from September 2017 to September 2019 were retrospectively analyzed. Among them, 31 cases underwent MIS-TLIF with 3D navigation techniques (MIS-TLIF group) and another 30 cases underwent conventional open TLIF (traditional open TLIF group). The basic information, operative time and intraoperative blood loss were collected. The sagittal radiologic parameters were measured before surgery and 3 months after surgery, including lumbar lordosis (LL), segmental lordosis (SL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), anterior disc height (ADH), posterior disc height(PDH).And the average disc height(DH) and pelvic incidence to lumbar lordosis mismatch (PI-LL) were calculated. Operative time and intraoperative blood loss in MIS-TLIF group were significantly less than in traditional open TLIF group(P<0.05). In MIS-TLIF group, LL, SL, PI-LL, and DH were significantly improved at 3 months after surgery (P<0.05), while PI, PT, and SS were not statistically different from those before surgery (P>0.05). LL, PI-LL, and DH of patients in the traditional open TLIF group were significantly improved at 3 months after surgery (P<0.05), while the PI, PT, SS, and SL were not statistically different from those before surgery (P>0.05). LL change showed a significant correlation with SL change (r= 0.433, P<0.001). Change in SL closely correlated to change in ADH (r=0.621, P<0.05) and PDH(r=0.527, P<0.05). Real-time navigation-assisted MIS-TLIF and traditional open TLIF can recover DH in a short term for lumbar degenerative diseases, improve LL and PI-LL, and make the arrangement of the sagittal plane of the lumbosacral region more coordinated after surgery. But only the navigation assisted MIS -TLIF can significantly improve SL. Compared with traditional open TLIF, real-time navigation assisted MIS-TLIF in the treatment of degenerative lumbar diseases has the advantages of short operation time and less intraoperative bleeding.

Lumbar degenerative spondylolisthesis: factors associated with the decision to fuse

BACKGROUND CONTEXTThe indication to perform a fusion and decompression surgery as opposed to decompression alone for lumbar degenerative spondylolisthesis (LDS) remains controversial. A variety of factors are considered when deciding on whether to fuse, including patient demographics, radiographic parameters, and symptom presentation. Likely surgeon preference has an important influence as well. PURPOSEThe aim of this study was to assess factors associated with the decision of a Canadian academic spine surgeon to perform a fusion for LDS. STUDY DESIGN/SETTINGThis study is a retrospective analysis of patients prospectively enrolled in a multicenter Canadian study that was designed to evaluate the assessment and surgical management of LDS. PATIENT SAMPLEInclusion criteria were patients with: radiographic evidence of LDS and neurogenic claudication or radicular pain, undergoing posterior decompression alone or posterior decompression and fusion, performed in one of seven, participating academic centers from 2015 to 2019. OUTCOME MEASURESPatient demographics, patient-rated outcome measures (Oswestry Disability Index [ODI], numberical rating scale back pain and leg pain, SF-12), and imaging parameters were recorded in the Canadian Spine Outcomes Research Network (CSORN) database. Surgeon factors were retrieved by survey of each participating surgeon and then linked to their specific patients within the database. METHODSUnivariate analysis was used to compare patient characteristics, imaging measures, and surgeon variables between those that had a fusion and those that had decompression alone. Multivariate backward logistic regression was used to identify the best combination of factors associated with the decision to perform a fusion. RESULTSThis study includes 241 consecutively enrolled patients receiving surgery from 11 surgeons at 7 sites. Patients that had a fusion were younger (65.3±8.3 vs. 68.6±9.7 years, p=.012), had worse ODI scores (45.9±14.7 vs. 40.2±13.5, p=.007), a smaller average disc height (6.1±2.7 vs. 8.0±7.3 mm, p=.005), were more likely to have grade II spondylolisthesis (31% vs. 14%, p=.008), facet distraction (34% vs. 60%, p=.034), and a nonlordotic disc angle (26% vs. 17%, p=.038). The rate of fusion varied by individual surgeon and practice location (p<.001, respectively). Surgeons that were fellowship trained in Canada more frequently fused than those who fellowship trained outside of Canada (76% vs. 57%, p=.027). Surgeons on salary fused more frequently than surgeons remunerated by fee-for-service (80% vs. 64%, p=.004). In the multivariate analysis the clinical factors associated with an increased odds of fusion were decreasing age, decreasing disc height, and increasing ODI score; the radiographic factors were grade II spondylolisthesis and neutral or kyphotic standing disc type; and the surgeon factors were fellowship location, renumeration type and practice region. The odds of having a fusion surgery was more than two times greater for patients with a grade II spondylolisthesis or neutral and/or kyphotic standing disc type (opposed to lordotic standing disc type). Patients whose surgeon completed their fellowship in Canada, or whose surgeon was salaried (opposed to fee-for-service), or whose surgeon practiced in western Canada had twice the odds of having fusion surgery. CONCLUSIONSThe decision to perform a fusion in addition to decompression for LDS is multifactorial. Although patient and radiographic parameters are important in the decision-making process, multiple surgeon factors are associated with the preference of a Canadian spine surgeon to perform a fusion for LDS. Future work is necessary to decrease treatment variability between surgeons and help facilitate the implementation of evidence-based decision making.

Cluster analysis to predict factors associated with sufficient indirect decompression immediately after single-level lateral lumbar interbody fusion

ObjectiveChanges in indirect decompression using lateral lumbar interbody fusion (LLIF) were classified into three clusters based on cluster analysis. We investigated cage variables and position to assess the effects of single-level LLIF on indirect decompression. MethodsCluster analysis was used to classify patients into three groups based on the change in the axial cross-sectional spinal canal area (ΔCSA): group 1 with slight postoperative indirect decompression (n = 35); group 2 with average indirect decompression (n = 19); and group 3 with marked indirect decompression (n = 13). Preoperative and immediately postoperative imaging data were compared between groups. ResultsPostoperative segmental lordosis, anterior, posterior, and average disc height increased significantly in each group, but the differences between groups were not significant. Cage length (p = 0.251) and cage height (p = 0.709) did not differ, but cage position differed significantly between groups (p < 0.05). ΔCSA correlated significantly with cage position for all 67 levels (r = 0.411, p < 0.01), but this association was not significant in group 2 (r = − 0.367, p = 0.122) or group 3 (r = − 0.005, p = 0.986). ΔCSA correlated with cage height in group 2 (r = 0.645, p < 0.01) and with cage width in group 3 (r = 0.644, p < 0.05). ConclusionsThe cluster analysis results suggest that placing the cage in the posterior position might be effective for expanding the CSA, but other factors, such as cage height or width, may also influence the sufficiency of LLIF.

Two-year Clinical and Radiographic Results with a Multidimensional, Expandable Interbody Implant in Minimally Invasive Lumbar Spine Surgery.

IntroductionMinimally invasive spine surgery has become more prevalent in recent years, but the delivery of interbody devices with small footprints may insufficiently restore the disc space, which may lead to instability and non-union. Vertically expandable interbody implants have partially addressed this limitation, but lateral fusion support remains a concern. The purpose of this study was to evaluate two-year safety and effectiveness outcomes with a multidimensional, expandable interbody fusion device (Luna 3D Interbody Fusion System, Benvenue Medical, Inc., Santa Clara, CA) that is delivered through a minimally invasive approach (6-8 mm) that expands in situ to approximate an anterior lumbar interbody fusion footprint of 25 mm diameter.Material and methodsThis was a retrospective, single-center study that evaluated the clinical utility of a multi-expandable interbody cage in patients undergoing posterior or transforaminal lumbar interbody fusion. Key patient-reported outcomes included back pain severity, leg pain severity, and the Oswestry Disability Index (ODI). Radiographic assessments included disc height (anterior, posterior, and average), foraminal height, segmental lordosis, subsidence, implant migration, and pseudarthrosis. Patients were followed at regular intervals over two years postprocedure.ResultsA total of 50 consecutive patients were treated with transforaminal lumbar interbody fusion (TLIF) using the multidimensional expandable implant. Procedural blood loss was minimal (median 200 ml) and the mean hospital stay was 2.1 days. Perioperative complications were reported in three patients and included a dural tear, postoperative ileus, and end-plate violation. All complications were successfully managed conservatively. There were no nerve root injuries or perioperative infections. Over the two-year follow-up period, one case of subsidence and one case of implant migration were noted on radiographic imaging but required no treatment. Comparing the values reported at baseline and two years, the mean ODI score decreased by 61%, back pain severity decreased by 67%, and leg pain severity decreased by 80% (all p<0.001). Comparing radiographic measures from baseline to two years, anterior disc height increased from 7.6 mm to 15.5 mm, posterior disc height increased from 2.9 mm to 10.1 mm, average disc height increased from 5.6 mm to 13.3 mm, foraminal height increased from 12.2 mm to 20.2 mm, and segmental lordosis increased from 6.2 degrees to 14.0 degrees (all changes p<0.001). One case of non-union was observed and the corresponding two-year fusion rate was 98%.ConclusionsThe utilization of a minimally invasive, multidimensional, expandable interbody implant was safe and effective over two years of clinical follow-up. The implant allows the surgeon to re-establish sagittal balance and to provide a larger surface area for fusion as compared to traditional minimally invasive interbody devices.

Needle-Guided Suture Technique for Lumbar Annular Fiber Closure in Microendoscopic Discectomy: A Technical Note and Case Series.

BackgroundAnnular fiber closure techniques have been proven effective in reducing short-term recurrence after discectomy. However, annular fiber closure devices are expensive and still fail at a low rate. We present a novel suture method, needle-guided annular closure suture (NGACS) that does not require a special device and can be performed for annular fiber closure following microendoscopic discectomy.Material/MethodsTwenty-five patients who underwent treatment with NGACS were reviewed by analysis of the medical records. The clinical outcomes were assessed and compared preoperatively and immediately, 1, 6, and 12 months postoperatively. The parameters included the Visual Analog Scale (VAS)-back and VAS-leg scores and the Oswestry Disability Index (ODI). Midsagittal T2WI images were obtained to evaluate lumbar disc degeneration using the Pfirrmann grade. Additional adverse events were also recorded and tracked.ResultsThe VAS-back and VAS-leg scores and the ODI were significantly different at each follow-up time point (P<0.001), and improvements in pain and disability were maintained well during the follow-up period. Lumbar disc reherniation or other serious adverse events were not observed in this series. There was no significant difference between the initial and final Pfirrmann grades (Z=−1.414, P=0.157). The preoperative average disc height was 9.94±1.97 mm, and the disc height at 12 months after surgery was 9.14±1.88 mm. The average decrease in disc height was 8.11±3.36%.ConclusionsThis study demonstrates the feasibility and superior clinical outcomes of the NGACS technique. This method can be a good substitution when annular fiber closure devices are not available. Moreover, this technique can be easily popularized due to its low cost and few restrictions.

Radiographic and clinical outcomes of huge lumbar disc herniations treated by transforaminal endoscopic discectomy

ObjectivesLarge Central disc herniations (occupying more than 50% of canal area) are notorious as they are generally associated with worse outcomes and are technically difficult to manage. Transforaminal endoscopy (TELD) has evolved to become an interesting alternative for lumbar disc herniations. The aim of the paper is to review our technique of transforaminal endoscopy in large central disc herniations and describe the clinical and radiographic results. We also describe an innovative technique of intraoperative epidurography to assess the adequacy of decompression in some cases with severe canal compromise. Patients and methodsWe performed a retrospective analysis of all the patients undergoing TELD from December 2012 to October 2018 for huge central lumbar disc herniations. The procedure was done under local anaesthesia and required a more horizontal approach angle, undercutting of superior articular process and posterior annular release to reach the herniated fragment in the epidural space. In severe cases, a radiopaque dye was introduced via trans-sacral catheter to check the adequacy of decompression. The disc height, lumbar lordosis, segmental lordotic angle on standing radiographs and Canal cross sectional area(CSA) on MRI were evaluated preoperatively and compared with postoperative images at the end of 1 year/final follow-up. The Visual analogue scale(VAS) for Back and Leg pain and Oswestry disability index (ODI), MacNab criteria, return to daily activities, return to work, patient satisfaction rate and recommendation to others were the clinical outcomes evaluated. The percentage of patients achieving the Minimal clinically important difference (MCID) of 3 points for VAS and 12 points for ODI was calculated. ResultsA total of 18 patients, with an average age of 35.1years (range 20–61), were operated. The mean VAS back improved from 5.7(±1.77) to 1(±0.77) and VAS leg improved from 7.3(±1.37) to 1.1(±1.09). The ODI improved from 49.88(±11.42) to 13.88(±7.28) at final follow-up. According to MacNab criteria, 17 patients had excellent and 1 had good outcome at final follow-up. The patient satisfaction rate was 90.5%, with 94% patient recommendation rate. All the patients returned to daily activities and work/modified work within a median of 5 weeks. There was 1 patient who required conversion to open surgery due to incidental dural tear, 1 patient who had a remnant disc required a revision tubular discectomy and 1 patient who had recurrence at 6 weeks and again at 2 years which was treated by repeat TELD. Five patients had impending cauda equina. All the patients achieved the MCID for VAS and ODI within a median period of 6 weeks and 3 months, respectively. The recovery rate was 90.1%. Five patients had grade 4 weakness of great toe/ankle dorsiflexion, one also had ankle flexion weakness preoperatively which improved after surgery. The CSA improved from a preoperative mean of 62.26(±30.3)mm2 to 122.16(±56.5)mm2 postoperatively. The CSA improved to 141.05(±63.86)mm2 at 1 year followup. The average disc height which was 9.71 mm(±2.4) was maintained at follow-up of one year which was 9.21 mm(±2.4). The lumbar lordosis and segmental lordotic angle changed from 27.08°(±15.9) and 2.82°(±5.7) to 35.8°(±8.56) and 4.85°(±4.39) respectively. ConclusionTELD may be considered as an alternative to microdiscectomy or fusion procedures for huge central disc herniations with favourable outcomes. However, sufficient expertise with the procedure is necessary. Intraoperative decompression may be confirmed with intraoperative epidurography. The patient acceptability of the procedure is good and causes minimal disruption of the normal anatomy.