Interbody cages versus structural bone grafts in lumbar arthrodesis: a systematic review and meta-analysis.

OBJECTIVE: The role of interbodies in lumbar arthrodesis has been insufficiently supported by evidence, impacting clinical decision-making and occasionally insurance coverage. This study aimed to compare clinical and radiological outcomes between lumbar arthrodesis with a synthetic interbody spacer (cage) versus structural bone graft alone (autograft or allograft) in patients with degenerative spine disease. METHODS: A systematic review of the literature was performed to identify studies directly comparing outcomes of lumbar interbody arthrodesis with and without interbody cage use. The outcomes of individual studies were synthesized in meta-analyses using random-effects models. RESULTS: Twenty studies with 1508 patients (769 with an interbody cage and 739 without an interbody cage) were included. Interbody cage placement was associated with a significantly greater increase in disc height after surgery (4.0 mm vs 3.4 mm, p < 0.01). There was a significantly greater reduction of back pain (visual analog scale [VAS] score) in cases in which an interbody cage was used (5.4 vs 4.7, p = 0.03). Fusion rates were 5.5% higher in the cage group (96.3% vs 90.8%) and reached statistical significance (p = 0.03). No statistically significant differences were identified between the two groups regarding all-cause reoperation rates, complication rates, or improvement in Oswestry Disability Index score or leg pain (VAS score). CONCLUSIONS: These results suggest that implantation of an interbody cage is associated with higher rates of fusion, more effective maintenance of disc height, and greater improvement of back pain. This study underlines the clinical value of interbody cages in lumbar arthrodesis for patients with degenerative spine disease.

Relationship between intervertebral disc height and post operative dysphagia secondary to single-level anterior cervical discectomy and fusion- a retrospective study.

BACKGROUND: One goal of Anterior Cervical Discectomy and Fusion (ACDF) is to restore the loss of intervertebral disc height (IDH) results from the degenerative process. However, the effects of IDH on postoperative dysphagia after ACDF remain unclear. METHODS: Based on the results of a one-year telephone follow-up, A total of 217 consecutive patients after single-level ACDF were enrolled. They were divided into dysphagia and non-dysphagia groups. The age, BMI, operation time and blood loss of all patients were collected from the medical record system and compared between patients with and without dysphagia. Radiologically, IDH, spinous process distance (SP) of the operated segment, and C2-7 angle (C2-7 A) were measured preoperatively and postoperatively. The relationship between changes in these radiological parameters and the development of dysphagia was analyzed. RESULTS: Sixty-three (29%) cases exhibited postoperative dysphagia. The mean changes in IDH, SP, and C2-7 A were 2.84 mm, -1.54 mm, and 4.82 degrees, respectively. Changes in IDH (P = 0.001) and changes in C2-7 A (P = 0.000) showed significant differences between dysphagia and non-dysphagia patients. Increased IDH and increased C2-7 A (P = 0.037 and 0.003, respectively) significantly and independently influenced the incidence of postoperative dysphagia. When the change in IDH was ≥ 3 mm, the chance of developing postoperative dysphagia for this patient was significantly greater. No significant relationship was observed between the change in spinous process distance (SP) and the incidence of dysphagia. The age, BMI, operation time and blood loss did not significantly influence the incidence of postoperative dysphagia. CONCLUSION: The change in IDH could be regarded as a predictive factor for postoperative dysphagia after single-level ACDF.

Caudad Insertion of Pedicle Screws Facilitates Interbody Distraction During Spondylolisthetic Vertebrae Restoration: A Retrospective Study.

INTRODUCTION: Based on the results of long-term clinical and radiological follow-up studies of decompression and fusion with internal fixation for degenerative lumbar spondylolisthesis (DLS), we recognized that the direction of the pedicle screw affects the stability of the fixation. However, few studies have analyzed the role of pedicle screw insertion trajectory in disc height recovery after fusion. We therefore analyzed patients' general information, clinical efficacy and sagittal, coronal and implant parameters to determine whether there is a correlation between the insertion trajectory of screws and the recovery of intervertebral space height, with the ultimate aim to provide a basis for improving the clinical efficacy and radiological outcomes of patients with DLS and to identify an optimal technique for spine surgeons that would benefit patients with spondylolisthesis. METHODS: From May 2015 to October 2019, patients who underwent single-segment decompression and fusion with internal fixation for DLS at our department were screened for enrollment in the study. The clinical history, pre- and post-operative lumbar sagittal parameters, intervertebral height, rate of recovery from spondylolisthesis and pedicle screw angle of inpatients were recorded and followed up for at least 6 months. Clinical assessments included the Oswestry Disability Index (ODI) and the Visual Analogue Scale (VAS) for lower back and leg pain. Data on screw angle, fusion segment intervertebral space height and clinical outcome were the primary outputs. Pearson correlation and multivariate regression analyses were performed to investigate the relationship between the pedicle screw angle, the sagittal parameters of the fusion segment and clinical efficacy. RESULTS: A total of 50 patients were initially enrolled, two patients were lost to follow-up after 6 months, 48 patients (17 men, 31 women) were eventually enrolled, and the follow-up rate was 96%. At least 6 months after the operation, vertebral spondylolisthesis improved to varying degrees [> 80% in 17 cases (35.4%) and > 20% in 43 cases (87.5%), respectively]. Changes in disc height (DH) were significantly associated with lower pedicle screw angle, while lumbar lordosis and segment lordosis remained the same. Multivariate regression analysis showed a significant negative correlation between the upper and lower pedicle screw angles and the change in DH (P < 0.05). At 2 weeks post-operation, the VAS score for low back pain and the ODI had improved significantly compared to pre-operation (P < 0.05). CONCLUSIONS: These results suggest that the Caudad insertion trajectory technique of pedicle screws may be an ideal alternative for the treatment of DLS. TRIAL REGISTRATION NUMBER: Chinese Clinical Trial Registry (ChiCTR): ChiCTR1800020368.

Evaluation of a rabbit model of adjacent intervertebral disc degeneration after fixation and fusion and maintenance in an upright feeding cage.

Purpose: To establish an animal model of adjacent intervertebral disc degeneration by performing spinal fixation and fusion after percutaneous needle puncture and removal of the intervertebral disc or percutaneous needling of the vertebral body without removal of the intervertebral disc. Methods: We established a model of adjacent intervertebral disc degeneration after spinal fixation and fusion of rabbits maintained in upright feeding cages. Twenty-five healthy New Zealand rabbits were used. In the experimental group, the L3-4 intervertebral disc was percutaneously punctured with an 18-G needle under fluoroscopic guidance. Once degeneration occurred, the L3-4 disc was excised, and interbody fusion was performed. The changes in the adjacent intervertebral discs were observed periodically via X-ray and MRI. In the control group, the L3 vertebral body was percutaneously needled with an 18-G needle under fluoroscopic guidance. The changes in the adjacent intervertebral discs were observed on X-ray and MRI at 4, 8, and 12 weeks after puncture in both groups. At 12 weeks postoperatively, the animals were euthanized, and the histopathologic changes of the adjacent intervertebral discs were assessed using hematoxylin-eosin and TdT-mediated dUTP nick end labeling (TUNEL) staining. The mRNA and protein expressions of aggrecanase-1 were measured by real-time quantitative PCR and Western blot analysis. The product of aggrecan degradation, Aggrecan ARGxx, was measured by Western blot analysis. Results: The degeneration of the intervertebral discs in the adjacent segments in the experimental group increased over time. The mRNA and protein expressions of aggrecanase-1 and the expression of Aggrecan ARGxx in the experimental group were significantly increased after puncture, fixation, and fusion (P<0.05). The adjacent intervertebral disc sections had a significantly lower cell density and significantly higher TUNEL-positive cell rate in the experimental group than the control group (P<0.05). Conclusion: The results suggest that the occurrence of intervertebral disc degeneration in adjacent segments may begin with the degeneration of the punctured intervertebral disc.

Effect of Disc Height and Degree of Distraction on Heterotopic Ossification After Cervical Disc Replacement.

BACKGROUND: Heterotopic ossification (HO) is a potential and severe complication of cervical disc replacement (CDR). However, the underlying mechanism of CDR and its association with preoperative disc height loss (DHL) and postoperative degree of distraction remain unclear. We hypothesized that DHL and postoperative degree of distraction could predict HO after CDR. METHODS: Data were obtained from 127 patients who underwent single-level CDR with a minimum follow-up of 2 years. DHL and adjusted degree of distraction (ADD) were obtained from lateral radiographs, and HO was evaluated at the last follow-up appointment. Receiver operating characteristic curves were calculated to verify the diagnostic value of DHL and ADD in predicting HO. RESULTS: Both DHL and ADD were significantly larger in the HO group than in the non-HO group (P < 0.05). DHL ≥24.97% increased the risk of HO by 5 times (P = 0.003, 95% confidence interval 1.62-15.49), and ADD ≥36.67% increased the risk of HO by 3.87 times (P < 0.001, 95% confidence interval 1.81-8.27). A combined DHL and ADD (combined parameter) cutoff of 60.36 had a sensitivity of 87.18%, specificity of 67.35%, and area under the curve of 0.77 for predicting HO. CONCLUSIONS: DHL and ADD are associated with the development of HO after CDR. The cutoff value of DHL may narrow the criteria for CDR with the aim of reducing HO formation. The combined parameter may help surgeons to select the most suitable implant height to reduce the prevalence of HO.

Image-Based Markers Predict Dynamic Instability in Lumbar Degenerative Spondylolisthesis.

OBJECTIVE: To identify possible radiographic predictors markers of dynamic instability including disc height (DH), disc degeneration, and spondylosis in the setting of degenerative spondylolisthesis (DS). METHODS: A retrospective review with prospectively collected data was performed on 125 patients with L4-5 DS who underwent decompression and fusion. Patients were divided into groups with dynamic instability and those without. Radiographs of the lumbar spine in neutral, flexion, and extension were used to determine degree of slip, DH, translational motion, angular motion, spondylotic changes, and lumbar lordosis. Magnetic resonance imaging (MRI) scans were reviewed to assess disc degeneration. RESULTS: Thirty-one percent of the patients met criteria for dynamic instability. Significant correlations (p < 0.05) were found between preserved DH and dynamic instability; increased spondylotic changes and decreased translational motion; as well as advanced MRI-based disc degeneration scores with decreased angular motion, respectively. Six radiographic parameters were utilized to create a predictive model for dynamic instability, and a receiver operating characteristic curve was able to validate the predictive model (area = 0.891, standard error = 0.034, p < 0.001). CONCLUSION: In DS patients, preserved DH was significantly related to dynamic instability. This finding may represent a greater potential for slip progression over time in these patients. In contrast, disc degeneration on MRI, and spondylotic changes were inversely related to dynamic instability and may represent restabilization mechanisms that decrease the chance of future slip progression in DS.

Evaluation criteria for the assessment of occupational diseases of the lumbar spine - how reliable are they?

BACKGROUND: In 2005, the German Association of Occupational Accident Insurance Funds (DGUV) defined radiological evaluation criteria for the assessment of degenerative occupational diseases of the lumbar spine. These include the measurement of intervertebral osteochondrosis and classification of vertebral osteosclerosis, antero-lateral and posterior spondylosis, and spondyloarthritis via plain radiography. The measures currently remain in daily use for determining worker compensation among those with occupational diseases. Here, we aimed to evaluate the inter- and intra-observer reliability of these evaluation criteria. METHODS: We enrolled 100 patients with occupational degenerative diseases of the lumbar spine. Native antero-posterior and lateral radiographs of these patients were evaluated according to DGUV recommendations by 4 observers with different levels of clinical training. Evaluations were again conducted after 2 months to assess the intra-observer reliability. RESULTS: The measurement of intervertebral osteochondrosis showed good inter-observer reliability (ICC: 0.755) and excellent intra-observer reliability (ICC: 0.827). The classification of vertebral osteosclerosis exhibited moderate kappa values for inter-observer reliability (К: 0.426) and intra-observer reliability (К: 0.441); the remaining 3 criteria showed poor inter- and intra-observer reliabilities. CONCLUSION: The measurement of intervertebral osteochondrosis and classification of vertebral osteosclerosis showed adequate inter- and intra-observer reliability in the assessment of occupational diseases of the lumbar spine, whereas the classification of antero-lateral and posterior spondylosis and spondyloarthritis stage exhibited insufficient reliability. Hence, we recommend the revision of the DGUV recommendations for the evaluation of occupational diseases of the lumbar spine.

Radiological exploration on adjacent segments after total cervical disc replacement with Prodisc-C prosthesis.

PURPOSE: The relationship between upper or lower adjacent segments (UAS/LAS) and the cervical spine parameters was not clear yet. So, the purpose was to analyze range of motion (ROM), lordosis (LOR), and intervertebral disc height (IDH) of UAS and LAS before and after total cervical disc replacement (TDR) and to explore the influencing factors of cervical spine radiological parameters on adjacent segments. METHODS: A single-center retrospective study was performed on patients completing 10-year follow-up undergone TDR. As the primary outcomes, radiological parameters included UAS-ROM/LAS-ROM, UAS-LOR/LAS-LOR, and UAS-IDH/LAS-IDH. The secondary outcomes were ROM and LOR of C2-C7 and surgical levels, IDH of surgical segments, prosthesis migration, subsidence, heterotopic ossification (HO), and adjacent segment degeneration (ASD), which were measured on X-ray. RESULTS: UAS-ROM and LAS-ROM remained stable in follow-up periods. There was no significance on UAS-LOR or LAS-LOR between pre- and post- operation, so was UAS-IDH or LAS-IDH. UAS-ROM was larger in the segments with ASD (P < 0.001), the same to LAS-ROM (P < 0.001), and UAS-LOR was larger in segments with ASD (P = 0.02). UAS-ROM was positively correlated with C2-C7 ROM and LOR (both P < 0.001). UAS-LOR was correlated with operated-segmental LOR while LAS-LOR were in correlation with surgical segment ROM. The influencing factors of UAS-ROM were the surgical segment ROM and C2-C7 LOR. The influencing factors of UAS-LOR and LAS-LOR were LAS-ROM and UAS-ROM, respectively. The influencing factors of UAS-IDH were LAS-IDH, surgical segment IDH, and HO while that of LAS-IDH were UAS-IDH and surgical segment IDH. CONCLUSIONS: TDR has only a little effect on the adjacent segments. There is an interaction between UAS and LAS. The maintenance on surgical segments ROM and reconstruction of IDH will benefit to adjacent segments.

Reliability and validity of lumbar disc height quantification methods using magnetic resonance images.

Disc height has been a focus of research on disc degeneration and low back pain (LBP). However, choosing an appropriate method to quantify disc height remains controversial. The aim of the present study was to determine the reliability and construct validity of disc height quantification methods. Repeated semi-automatic measurements of L4-5 and L5-S1 discs were obtained from 43 T2-weighted mid-sagittal 3T magnetic resonance (MR) images of 22 subjects with LBP (43±13 years), blinded to prior measurements. Heights were calculated with area-based methods (using 60%, 80% and 100% of the disc width), and point-based methods (Hurxthal's, Dabbs' and combining the two). Intra-class correlation coefficients (ICC) and standard error of measurement (SEM) were estimated. Construct validity was assessed using correlation coefficients. Intra-rater ICC(3,1) of the area-based disc height measurements ranged from 0.84 to 0.99 with an inter-rater ICC(2,1) of 0.99. Measurements with point-based methods had lower intra- and inter-rater reliability ranging between 0.76 and 0.96 and between 0.84 and 0.98, respectively. Inter-rater SEM varied between 0.2 and 0.3 mm for area-based methods and between 0.3 and 0.7 mm for point-based methods. Excluding Dabbs', high correlations (r>0.9) were observed between methods. Area-based height measurements using partial disc width demonstrated excellent reliability and construct validity and outperformed point-based methods.

Morphometric Analysis of Lumbar Intervertebral Disc Height: An Imaging Study.

BACKGROUND: Little published data exist regarding normal values of disc height. Current literature relies on plain radiographs making accurate measurements of individual lumbar disc height difficult. OBJECTIVE: We seek to establish normal values for lumbar intervertebral discs in different age groups using computed tomography scans in healthy individuals. METHODS: Two hundred forty anonymized abdominal computed tomography scans (131 women) were prospectively collected once institutional review board approval was obtained. Individuals with spinal pathologies were excluded. Disc height measurements were obtained at the anterior edge, center, and posterior edge of each vertebra in the midsagittal plane, averaged, and compared against age and sex. RESULTS: Average age was 45 (14-83) years for women and 48 (14-89) years for men. Average lumbar disc height was 5.6 ± 1.1 mm for men and 4.8 ± 0.8 mm for women at T12/L1, 6.9 ± 1.3 mm for men and 5.8 ± 0.9 mm for women at L1/2, 8.1 ± 1.4 mm for men and 6.9 ± 1.1 mm for women at L2/3, 8.7 ± 1.5 mm for men and 7.6 ± 1.2 mm for women at L3/4, 9.2 ± 1.6 mm for men and 8.5 ± 1.6 mm for women at L4/5, and 8.8 ± 1.6 mm for men and 8.6 ± 1.8 mm for women at L5/S1. Disc height was significantly smaller for women than men (P < 0.001), except at L5/S1. CONCLUSIONS: Variation in disc height is determined much more by sex than age. The maximum height of the interbody space in the adult lumbar spine was at the L4/5 level (8.9 ± 1.7 mm [men], 8.6 ± 1.8 mm [women]). Based on our findings, >10 mm cage height will result in supraphysiologic interbody space restoration and potentially predispose to complications.

Correlation between lumbar intervertebral disc height and lumbar spine sagittal alignment among asymptomatic Asian young adults.

BACKGROUND: To investigate the distribution and characteristics of the lumbar intervertebral disc height (IDH) in asymptomatic Asian population and to determine whether the lumbar IDH is related to the lumbar spine sagittal alignment. METHODS: A cohort of 169 cases of asymptomatic volunteers was enrolled from January 2014 to July 2016. All participants underwent magnetic resonance imaging of the lumbar spine and panoramic radiography of the spine. Panoramic radiographs of the spine were taken to evaluate pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) using Surgimap® software. Roussouly classification was utilized to categorize all subjects according to the four subtypes of sagittal alignment. The IDH was measured on the MRI mid-saggital section of the vertebral body. The relationships between lumbar IDH and spine-pelvic parameters were also assessed using the Spearman correlation analysis. RESULTS: The reference value ranges of IDH in asymptomatic Asian volunteers between L1/2, L2/3, L3/4, L4/5, and L5/S1 were (6.25, 10.99), (6.97, 12.08), (7.42, 13.3), (7.76, 14.57),and (7.11, 13.12) mm, respectively. Based on the above reference value, the high lumbar intervertebral space is defined as more than 14 mm. According to the Roussouly Classification, there are 33 cases in type I, 48 in type II, 66 in type III, and 22 in type IV. According to the definition of the high IDH, there are two cases in type I, three in type II, nine in type III, and eight in type IV. The results indicated that people in the Roussouly III and IV subtypes had greater values for IDH compared to those of Roussouly I and II subtypes, and the spinopelvic parameters were partly correlated with IDH in different subtypes. In addition, levels L4-L5 showed the highest IDH for all four groups followed by the L3-L4 and L5-S1 levels, and the value of L3-L4 is equivalent to that of L5-S1. All type groups showed moderate and positive correlations between the PI and IDH except the level of L1-L2 in type IV. CONCLUSIONS: The IDH may influence the lumbar spine sagittal alignment in asymptomatic Asian adults. Moreover, pre-operative evaluation of IDH is useful for selection of optimal cage size and reconstruction of spinal alignment.

Micro-CT evaluation of asymmetrical ovine intervertebral disc height loss from surgical approach.

PURPOSE: The primary goal of this study is to clearly define and evaluate new intervertebral disc height parameters in analysing the morphological pathology of disc degeneration for application in damage model and regeneration therapy development, as well as applying traditional variables to 3-D characterization methods. METHODS: A posterolateral surgical approach was used to induce disc degeneration in an ovine model. At 12-months post-operation, sheep vertebral segments were removed and characterized using micro-CT to evaluate disc height parameters in regard to injury localization. RESULTS: Statistically significant differences between the disc height loss of the left and right side of the disc, consistent with the lateral surgical approach used were seen using the modified average disc height method by Dabbs et al. However, convexity index and the newly proposed Cross Tilt Index did not conclusively demonstrate a difference. CONCLUSION: Two-dimensional morphological evaluations can be applied in 3-D to provide a more complete picture of disc height loss for injury models. New 3-D parameters that are tailored to the type of surgical approach used should be investigated, with the 9-point system described herein providing a useful basis for derived values. Additionally, the surgical approach chosen when artificially injuring the disc can result in asymmetrical degeneration, as indicated by uneven disc height loss.

Bone mineral density and intervertebral disc height in type 2 diabetes.

BACKGROUND: Studies of the effect of type 2 diabetes (T2D) on bone mineral density (BMD have produced conflicting results, possibly due to failure to adjust for potential confounding factors. Nonetheless, T2D has consistently been associated with increased fracture risk, suggesting that other factors might play a role. OBJECTIVE: This study assesses the relationship between T2D and BMD at the femoral neck and spine in diabetic and non-diabetic subjects, after adjusting for multiple covariates which may affect BMD. Intervertebral disc height was also investigated in view of its possible relation to fracture risk. METHODS: A cross-sectional study of 100 patients with T2DM of at least 5 years duration and 86 non-diabetic subjects was carried out. RESULTS: There were no significant differences in T scores in either the spine or femoral neck after adjustment for potential confounding variables between T2D subjects and controls. Diabetic patients had a statistically lower intervertebral disc height between the 2nd and 3rd lumbar vertebrae (D3) after adjustment for potential confounders (p=0.004). Urinary albumin:creatinine ratio, total cholesterol, LDL-cholesterol and cigarette smoking were independently associated with lower height of D3 in diabetic subjects. CONCLUSIONS: There is no significant independent association between T2D and BMD. However we found a novel association of significantly lower disc height in patients with T2D. This may contribute to the increased vertebral fracture risk in subjects with T2D. Further studies are needed to investigate the relationship of disc height, T2D and fracture risk.