The relationship between disc degeneration and flexibility of the lumbar spine.

BACKGROUND CONTEXT: A relationship between degenerative changes of the intervertebral disc and biomechanical functions of the lumbar spine has been suggested. However, the exact relationship between the grade of disc degeneration and the flexibility of the motion segment is not known. PURPOSE: To investigate the relationship between degenerative grades of the intervertebral disc and three-dimensional (3-D) biomechanical characteristics of the motion segment under multidirectional loading conditions. STUDY DESIGN/SETTING: A biomechanical and imaging study of human cadaveric spinal motion segments. METHODS: One hundred fourteen lumbar motion segments from T12-L1 to L5-S1 taken from 47 fresh cadaver spines (average age at death, 68 years; range, 39 to 87 years) were used in this study. The severity of degeneration (grades I to V according to Thomson's system) was determined using magnetic resonance (MR) images and cryomicrotome sections. Pure unconstrained moments with dead weights were applied to the motion segments in six load steps. The directions of loading included flexion, extension, right and left axial rotation, and right and left lateral bending. RESULTS: When the MR images were graded, 2 segments had grade I disc degeneration; 45, grade II; 20, grade III; 26, grade IV; and 21, grade V. When the cryomicrotome sections were graded, 14 segments had grade I disc degeneration; 31, grade II; 22, grade III; 26, grade IV; and 21, grade V. Segments from the upper lumbar levels (T12-L1 to L3-4) tended to have greater rotational movement in flexion, extension, and axial rotation with disc degeneration up to grade IV, whereas the motion decreased when the disc degenerated to grade V. In the lower lumbar spine at L4-5 and L5-S1, motion in axial rotation and lateral bending was increased in grade III. CONCLUSIONS: These results suggest that kinematic properties of the lumbar spine are related to disc degeneration. Greater motion generally was found with disc degeneration, particularly in grades III and IV, in which radial tears of the annulus fibrosus are found. Disc space collapse and osteophyte formation as found in grade V resulted in stabilization of the motion segments.     

The effect of disc degeneration on anterior shear translation in the lumbar spine

Many pathologies involving disc degeneration are treated with surgery and spinal implants. It is important to understand how the spine behaves mechanically as a function of disc degeneration. Shear loading is especially relevant in the natural and surgically stabilized lumbar spine. The objective of our study was to determine the effect of disc degeneration on anterior translation of the lumbar spine under shear loading. We tested 30 human cadaveric functional spinal units (L3–4 and L4–5) in anterior shear loading. First, the specimens were imaged in a 1.5 T magnetic resonance scanner. The discs were graded according to the Pfirrmann classification. The specimens were then loaded up to 250 N in anterior shear with an axial compression force of 300 N. Motion of the vertebrae was captured with an optoelectronic camera system. Inter‐ and intra‐observer reliability for disc grading was determined (Cohen's and Fleiss' Kappa), and a non‐parametric test was performed on the translation data to characterize the effect of disc degeneration on this parameter. We found fair to moderate agreement between and within observers for the disc grading. We found no significant effect of disc degeneration on anterior shear translation (Kruskal‐Wallis ANOVA). Our results indicate that disc degeneration, as classified with the Pfirrmann scale, does not predict lumbar spinal motion in shear. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:450–457, 2015.     

Hybrid construct for two levels disc disease in lumbar spine

Prospective study. To study the validity of Hybrid construction (Anterior Lumbar Interbody Fusion) ALIF at one level and total disc arthroplasty (TDA) at adjacent, for two levels disc disease in lumbar spine as surgical strategy. With growing evidence that fusion constructs in the treatment of degenerative disc disease (DDD) may alter sagittal balance and contribute to undesirable complications in the long-term, total disc arthroplasty (TDA) slowly becomes an accepted treatment option for a selected group of patients. Despite encouraging early and intermediate term results of single-level total disc arthroplasty reported in the literature, there is growing evidence that two-level arthroplasty does not fare as well. Hybrid fusion is an attempt to address two-level DDD by combining the advantages of a single-level ALIF with those of a single-level arthroplasty. 42 patients (25 females and 17 males) underwent Hybrid fusion and had a median follow-up of 26.3 months. The primary functional outcomes were assessed before and after surgery with Oswestry Disability Index and the visual analogue score of the back and legs. Patients were divided into four groups according to the percentage improvement between preop and postop ODI scores. A total of 42 patients underwent a hybrid fusion as follows: 35 L5-S1 ALIF/L4-5 prosthesis, 3 L4-5 ALIF/L3-4 prosthesis, 2 L5-S1 ALIF/L4-5 prosthesis/L3-4 prosthesis, 1 L5-S1 prosthesis/L4-5 ALIF, and 1 L5-S1 ALIF/L4-5 ALIF/L3-4 prosthesis. At 2-years clinical outcomes, mean reduction in ODI is 24.9 points (53.0% improvement compared to preop ODI). The visual analogue score for the back is 64.6% improvement. At 2-year clinical outcomes, Hybrid fusion is a viable surgical alternative for the treatment of two-level DDD in comparison with two-level TDA and with two-level fusion.     

Grade three disc degeneration is a critical stage for anterior spondylolisthesis in lumbar spine

Introduction

Little is known about when and how progressive spondylolisthesis occurs. In this report segmental motion related to age and disc degeneration at L4/5 disc was investigated.

Materials and methods

637 patients with low back and/or leg pain underwent radiologic and MRI examinations simultaneously. Because 190 patients with conditions which might impede accurate measurement were excluded, 447 patients, comprising 268 men and 179 women, were included; age range, was 10–86 (mean: 53) years. Three radiologic parameters slip in neutral position (mm), sagittal translation (mm), and segmental angulation (degrees) were examined at the L4/5 segment. On T2-weighted MRI, severity of disc degeneration at L4/5 was classified by Pfirrmann’s criteria, grade 1-5.

Results

Results showed stage of disc degeneration that progressed according to aging with significant differences except for between grades 4 and 5. Amount of anterior slip was small among grades 1 to 3; however, it greatly increased between grades 3 and 4 and between grades 4 and 5, suggesting that grade 3 disc degeneration has a potential risk of future progression of anterior slip. This finding may also suggest that once significant slip occurs, it will progress to the final grade. Furthermore, the grade 3 degeneration group exhibited large amounts of motion in both angulation and translation, suggesting it was the most unstable group.

Conclusion

Our results with radiography and MRI indicate that grade 3 disc degeneration is a critical stage for the progression of lumbar spondylolisthesis at L4/5 segment.     

Dynesys fixation for lumbar spine degeneration

The dynamic fixation system Dynesys is utilized in the last 10 years for treatment of degenerative segmental disease of the lumbar spine. Dynesys is a semi-rigid fixation system that allows minimal lengthening and shortening between two segmental pedicle screws as opposed to a rigid metal bar. Thus, the system is regarded to maintain stability and near physiological motion patterns of the lumbar spine. The theoretical advantage of this system is to stabilize the treated segment and to prevent adjacent segment degeneration. The goal of this prospective trial was to evaluate clinical, radiographic, and computed tomography (CT) scan outcomes in 54 consecutive cases. Postoperative complications are discussed in detail. Forty cases were recruited with a mean follow-up of 16 months (range, 12 to 37). Postoperative pain scores (Hannover Activities of Daily Living Questionnaire and VAS for back and leg pain) improved in 29 cases (73%) and was best when dynamic fusion was combined with nerve root decompression. Outcome data were not superior to conventional rigid fusion systems and had a considerable number of complications requiring revision surgery in 27.5% of cases.     

Adjacent segment degeneration in the lumbar spine

BACKGROUND: A primary concern after posterior lumbar spine arthrodesis is the potential for adjacent segment degeneration cephalad or caudad to the fusion segment. There is controversy regarding the subsequent degeneration of adjacent segments, and we are aware of no long-term studies that have analyzed both cephalad and caudad degeneration following posterior arthrodesis. A retrospective investigation was performed to determine the rates of degeneration and survival of the motion segments adjacent to the site of a posterior lumbar fusion. METHODS: Two hundred and fifteen patients who had undergone posterior lumbar arthrodesis were included in this study. The study group included 126 female patients and eighty-nine male patients. The average duration of follow-up was 6.7 years. Radiographs were analyzed with regard to arthritic degeneration at the adjacent levels both preoperatively and at the time of the last follow-up visit. Disc spaces were graded on a 4-point arthritic degeneration scale. Correlation analysis was used to determine the contribution of independent variables to the rate of degeneration. Survivorship analysis was performed to describe the degeneration of the adjacent motion segments. RESULTS: Fifty-nine (27.4%) of the 215 patients had evidence of degeneration at the adjacent levels and elected to have an additional decompression (fifteen patients) or arthrodesis (forty-four patients). Kaplan-Meier analysis predicted a disease-free survival rate of 83.5% (95% confidence interval, 77.5% to 89.5%) at five years and of 63.9% (95% confidence interval, 54.0% to 73.8%) at ten years after the index operation. Although there was a trend toward progression of the arthritic grade at the adjacent disc levels, there was no significant correlation, with the numbers available, between the preoperative arthritic grade and the need for additional surgery. CONCLUSIONS: The rate of symptomatic degeneration at an adjacent segment warranting either decompression or arthrodesis was predicted to be 16.5% at five years and 36.1% at ten years. There appeared to be no correlation with the length of fusion or the preoperative arthritic degeneration of the adjacent segment.     

腰椎间盘髓核退变研究进展

腰椎间盘作为一个完整的结构单元,由纤维环、髓核和软骨终板三部分组成。由于生理性及病理性因素的影响,腰椎间盘容易发生退行性变。腰椎间盘的退变被认为是腰椎间盘突出症等疾病的病理基础。其中髓核的退变较纤维环和软骨终板更明显,主要表现为水份含量的降低、蛋白多糖浓度的下降和成分的改变。其生物力学特性也随之发生改变,正常的载荷传递和吸收功能减弱,从而引起了一系列的临床症状。同时影像学上也有相应的表现。如何正确地评价髓核的退变,关系到临床的诊断、治疗以及预后估计。1　髓核退变的病理形态学特点正常髓核位于椎间盘中央偏…     

The relationship between vertebral body deformity and disc degeneration in lumbar spine of the senile

This study provides an investigation of the relationship between vertebral deformities and disc degeneration in patients with senile osteoporosis using biomechanical and medical imaging methods. The finite element analysis showed that stress concentration in the central area of the vertebral body is much decreased with disc degeneration, indicating that load transmission has been altered. Radiography and MRI suggested that vertebral deformities are related to the height and degeneration of the disc just below this vertebral body. When a disc has decreased height or degeneration, the vertebral body just above it is less likely to be deformed for patients with spinal osteoporosis. Received: 22 February 1997 Revised: 26 July 1997 Accepted: 1 August 1997     

骨质疏松与腰段脊柱退行性变

骨质疏松是一种以低骨量和骨组织微结构破坏为特征、导致骨脆性增加的全身性疾病,可分为绝经后骨质疏松与老年性骨质疏松两型〔１〕。据１９９０年统计,我国老年性（＞６０岁）骨质疏松的发生率男性为６０－７２％,女性为９０－８４％〔２〕。这种低骨量和微结构破坏在外周主要表现在桡骨远端和股骨颈,而在脊柱的表现较在外周骨更早,更为广泛,常可导致椎体形态、脊柱曲度和力学性质的改变〔３〕,其中以下腰段脊柱的改变较为明显,其引发１９９９０２０１收稿,１９９９０６１５修回作者单位：第四军医大学西京医院骨科,陕西…     

腰椎间盘退行性改变研究进展

随着人口老龄化加速,腰背痛患者数量增多,严重威胁中老年人群健康。作为腰背痛的常见原因之一,腰椎间盘退行性改变不仅是腰椎间盘突出症的病理基础,而且是腰椎疾病发生发展的根本原因。腰椎间盘退行性改变是由多因素引起的复杂慢性退行性疾病,发病率很高,可能给患者带来长期的身心痛苦,甚至导致双下肢瘫痪。为避免腰椎间盘退行性改变发生和延缓其发展,全面了解腰椎间盘解剖及腰椎间盘退行性改变的病因、诊断和防治方法尤为重要,有利于早期诊断和早期治疗。椎间盘生长因子注射治疗、转基因治疗和细胞注射治疗等生物治疗方法是目前研究的重点,有望恢复椎间盘的高度和结构。椎间盘间充质干细胞移植是一种很有前途的治疗方法,但仍需大量临床试验验证。该文就腰椎间盘退行性改变研究进展作一综述。     

Determinants of evolution of endplate and disc degeneration in the lumbar spine: a multifactorial perspective

Purpose

Evolution and progression of disc and endplate bone marrow degeneration of the lumbar spine are thought to be multifactorial, yet, their influence and interactions are not understood. The aim of this study was to find association of potential predictors of evolution of degeneration of the lumbar spine.

Methods

Patients (n = 90) who underwent two lumbar magnetic resonance imaging (MRI) exams with an interval of at least 4 years and without any spinal surgery were included into the longitudinal cohort study with nested case–control analysis. Disc degeneration (DD) was scored according to the Pfirrmann classification and endplate bone marrow changes (EC) according to Modic in 450 levels on both MRIs. Potential variables for degeneration such as age, gender, BMI, scoliosis and sagittal parameters were compared between patients with and without evolution or progression of degenerative changes in their lumbar spine. A multivariate analysis aimed to identify the most important variables for progression of disc and endplate degeneration, respectively.

Results

While neither age, gender, BMI, sacral slope or the presence of scoliosis could be identified as progression factor for DD, a higher lordosis was observed in subjects with no progression (49° ± 11° vs 43° ± 12°; p = 0.017). Progression or evolution of EC was only associated with a slightly higher degree of scoliosis (10° ± 10° vs 6° ± 9°; p = 0.04) and not to any of the other variables.

Conclusion

While a coronal deformity of the lumbar spine seems associated with evolution or progression of EC, a higher lumbar lordosis is protective for radiographic progression of DD. This implies that scoliotic deformity and lesser lumbar lordosis are associated with higher overall degeneration of the lumbar spine.     

Myxomatous degeneration of the lumbar intervertebral disc

Sixteen patients were operated on for lumbar pain and pain radiating into the sciatic nerve distribution. In all 16, when the anulus fibrosus was incised, soft, gray disc material extruded under pressure like toothpaste being squeezed from a tube. This syndrome of myxomatous degeneration is a distinct entity, different from classical fibrotic disc degeneration or herniated nucleus pulposus. Surgical removal associated with partial facetectomy produced excellent results. The concept of incompetence of the anulus fibrosis is discussed.     

Bone architecture and disc degeneration in the lumbar spine of mice lacking GDF-8 (myostatin).

GDF-8, also known as myostatin, is a member of the transforming growth factor-beta superfamily of secreted growth and differentiation factors that is expressed in vertebrate skeletal muscle. Myostatin functions as a negative regulator of skeletal muscle growth and myostatin null mice show a doubling of muscle mass compared to normal mice. We describe here morphology of the lumbar spine in myostatin knockout (Mstn(-/-)) mice using histological and densitometric techniques. The Mstn(-/-) mice examined in this study weigh approximately 10% more than controls (p<0.001) but the iliopsoas muscle is over 50% larger in the knockout mice than in wild-type mice (p<0.001). Peripheral quantitative computed tomography (pQCT) data from the fifth lumbar vertebra show that mice lacking myostatin have approximately 50% greater trabecular bone mineral density (p=0.001) and significantly greater cortical bone mineral content than normal mice. Toluidine blue staining of the intervertebral disc between L4-L5 reveals loss of proteoglycan staining in the hyaline end plates and inner annulus fibrosus of the knockout mice. Loss of cartilage staining in the caudal end plate of L4 is due to ossification of the end plate in the myostatin-deficient animals. Results from this study suggest that increased muscle mass in mice lacking myostatin is associated with increased bone mass as well as degenerative changes in the intervertebral disc.     

Annular tears and disc degeneration in the lumbar spine. A post-mortem study of 135 discs.

We studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally distributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogenic pain.