How much intervertebral disk tissue is in reality removed in percutaneous nucleotomy?]

In an experimental study with standardized conditions nuclear material of 40 human lumbar discs was excised. In 20 the non-automated discectomy method was used (NAPLD-method). In the other 20 the automated discectomy method (APLD-method). The excised material was weighted. After the removal, the material of the NAPLD-method was wet with isotonic saline over 45 minutes and again weighted. Afterwards the wet material of both methods was freeze dried and again weighted. The weight of the wet material of the NAPLD-method in relation to that of the freeze dried material was a factor 11 (average value: 7.7 g in relation to 0.7 g) and in the APLD-method a factor 15 (average value: 4.5 g in relation to 0.3 g). This means, that the uptake and distribution of the saline is different in both methods and for this reason it is not allowed to compare the wet weight of the two methods. This has to be considered in clinical comparative studies. Because the biomechanical changes after a discectomy are dependent of the amount of the excised nuclear material, the NAPLD- and APLD-method can only be compared when the amount of the excised material is changed in a freeze dried weight.     

Thoracic intervertebral disk herniation]

The history of thoracic intervertebral disc herniation recognition as a distinct condition is presented on the ground of the literature. Pathogenesis, pathology, clinical signs and symptoms, diagnostics and differentiation is discussed. Evolution of surgical methods from laminectomy, through thoracotomy to lateral approach is presented. Comparison of results achieved by different methods proved disadvantageous for laminectomy. Increasing over recent decades contribution of orthopedic surgeons in treatment of thoracic intervertebral disc herniation is underlined. The issue is rarely present in Polish literature, thus the need to introduce it to orthopedic surgeons.     

Effect of artificial disk nucleus implant on mobility and intervertebral disk high of an L4/5 segment after nucleotomy

This study investigated whether after a nucleotomy and implantation of a prosthetic disk nucleus (PDN) the original height and mobility of an L4/L5 disk can be restored. Compared to the intact state (100%), nucleotomy increased the median values of the normalized range of motion (ROM) in flexion/extension to 118%, lateral bending to 112%, and axial rotation to 121%. PDN implantation reduced ROM to 102%, 88%, and 90%. These differences were even more distinct when comparing the neutral zone (NZ) with 210%, 173%, and 107% after nucleotomy and 146%, 149%, and 44% after PDN implantation. With an axial preload of 200 N, disk height after nucleotomy was reduced by about 1.3 mm and could be restored with PDN implantation. PDN implantation can restore disk height and ROM after nucleotomy to normal values and reduce the strong NZ increase. Further biomechanical characterization of this therapy with PDN is necessary.     

The effect of uniform heating on the biomechanical properties of the intervertebral disc in a porcine model.

BACKGROUND CONTEXT: The use of minimally invasive lumbar intradiscal heating techniques, including intradiscal electro-thermal therapy (IDET), endoscopic radio-frequency annuloplasty, nucleoplasty and laser discectomy, for chronic lumbar discogenic pain and contained disc herniation has recently gained popularity. The purported therapeutic mechanisms of these interventions include subtotal nuclectomy, annular nociceptor ablation, and stabilization of the annular fibers. Basic science data elucidating the biomechanical and histomorphologic alterations of heat treatments on disc remain sparse. PURPOSE: The purpose of this study is to examine the effects of uniform heating on biomechanical properties and histomorphology of intervertebral disc tissues using a porcine model. STUDY DESIGN/SETTING: In a laboratory setting, porcine functional spinal units consisting of vertebra-nucleus pulposus-vertebra core and porcine hamstring tendons were harvested. Studies were performed on these tissue samples by uniformly heating the specimens in a constant temperature water bath. Ten porcine lumbar disc core and twenty-five porcine hamstring tendons were utilized as the subjects for this study. The effects of uniform heat treatments on disc core and hamstring tendon were measured for shrinkage, stiffness, and load to failure strength. Histomorphological study was also carried on the same specimen. METHODS: The porcine vertebra-nucleus pulposus-vertebra segments were cored to a uniform 1-cm diameter. The hamstring tendons were cut to uniform 1.2-inch lengths. The tendon specimens were divided into groups of five each and heated in constant temperature water baths of 60 degrees C, 65 degrees C, 70 degrees C, or 75 degrees C for 10 min. Unheated specimens served as controls. The disc core specimens were divided in two group of five each, and tested at room temperature or after immersion in a 70 degrees C bath. The shrinkage was monitored during immersion in the water bath. Biomechanical testing to failure was carried out using mechanical loading on an MTS servohydraulic testing machine operating under stroke control. Strength and stiffness of the tissue was determined. Histomorphology was studied by staining the specimen with hematoxylin and eosin (H&E), and examined under 200 times magnification. Non-heated controls were used for comparisons. RESULTS: The porcine hamstring tendons had no measurable shrinkage in specimens heated up to 65 degrees C. At temperatures above 65 degrees C, the shrinkage was concluded within 2 min of immersion and 70 degrees C appeared to be the optimal temperature, as temperatures higher than this did not demonstrate incremental effects. The disc core samples were heated to 70 degrees C (optimum temperature), and there appeared to be gross contraction of the disc core circumference to visual inspection, but no measurable lengthwise shrinkage could be appreciated. Histologically, the specimens demonstrated progressive loss of individual collagen fiber outline as the temperature increased. In the tendons, at 75 degrees C all of the fibers appear to be fused together, and the voids between individual collagen fibers were no longer present. Biomechanical testing revealed that the tendons undergo a substantial reduction in stiffness after heating. The mean tendon stiffness for the unheated specimens was 19,356 psi, while the corresponding value for the heated tendons was 1023 psi. These were significantly different using the paired t-test at p=0.0043. For the disc core samples, there was no significant difference in either stiffness (p=0.182) or failure strength (p=0.998) after heating. All failures occurred in mid-substance of the specimen. CONCLUSIONS: The application of uniform heating to nucleus pulposus disc core caused visible contraction of its circumference but not lengthwise shrinkage. The same heating shrinks the hamstring tendon and reduces its stiffness. Ultimate failure strength of the disc core specimen remains unchanged. The failure data was not obtainable for the tendon due to premature slippage from the fixation apparatus before failure. The results of this study fail to support a biomechanical justification for the application of uniform heat treatment to the whole intervertebral disc. Heating annulus fibrosus and nucleus pulposus separately to specific temperatures may have potential clinical benefits.     

Minimally invasive techniques for the treatment of intervertebral disk herniation

Hemilaminectomy with diskectomy, the original surgical option to address intervertebral disk herniation, was superseded by open microdiskectomy, a less invasive technique recognized as the surgical benchmark with which minimally invasive spine surgery techniques have been compared as they have been developed. These minimally invasive surgical techniques for patients with herniated nucleus pulposus and radiculopathy include laser disk decompression, arthroscopic microdiskectomy, laparoscopic techniques, foraminal endoscopy, and microendoscopic diskectomy. Each has its own complications and requires a long learning curve to develop familiarity with the technique. Patient selection, and especially disk morphology, are the most important factors in choice of technique. The optimal candidate has a previously untreated single-level herniation with limited migration or sequestration of free fragments.     

The effects of freezing or freeze-drying on the biomechanical properties of the canine intervertebral disc

The transplantation of spinal allografts to correct defects that include disc, body, or segments of both is currently under experimental investigation. A method of graft preservation that will least compromise the biomechanical integrity of the bodies or discs is required. Using a five-mode biomechanical analysis, the authors compared the change in stiffness of ten preserved canine spines. The freeze-dried specimens lost a significantly greater amount of stiffness in compression, flexion, extension, and torsion than did the frozen specimens. Therefore, from a biomechanical viewpoint, deep-freezing is superior to freeze-drying for spinal allograft preservation.     

Biomechanical properties of synthetic lumbar intervertebral disk implants

AIM: The aim of this study was to determine the influence of two different artificial nucleus implants for lumbar discs on the biomechanical properties of the spinal motion segment. METHODS: From 7 calf spines, the lumbar segments L2/3 and L4/5 were harvested, the lamina and the muscles were removed with care to preserve the anterior and posterior longitudinal ligament. The segments were fixed on a special testing device mounted in an universal testing machine (Zwick, Ulm, Germany). Physiological load with a maximum of 7 Nm was applied in flexion/extension, right and left side bending, and right torsion. Three cycles of measurement were performed in all specimen: a) the intact segment, b) segment after nucleotomy, c) 6 segment with 2 PDN devices (Ray Medica) and 8 segments with an autopolymerized polymer. RESULTS: There was a statistically significant (p = 0.0078/p = 0.0313) increase in segmental mobility in all directions after nucleotomy. After introduction of two PDN implants as well as the polymer implant, there was a restoration of segmental mobility for all movement directions with no statistically significant difference (p > 0.05) compared to the intact situation before nucleotomy.     

Characteristics of an intervertebral disk herniation in spondylolisthesis]

Treatment of intervertebral disc herniation associated with spondylolisthesis is not different from common procedures concerning indication for surgery and surgical technique as far as sciatica is not related to retrolisthetic soft tissue or the posterior edge of the vertebral body. In a case of a disc herniation L5/S1 and an olisthesis grade I with radicular pain L5 a microdiscectomy of the prolapse and parts of the retrolisthetic soft tissue was performed. An immediate reintervention was necessary due to postoperative symptoms of paralysis. Derangement of the retrolisthetic soft tissue was found to cause the increased L5-symptoms.     

经皮内窥镜下射频消融术治疗腰椎间盘突出症

目的:探讨经皮内窥镜下射频消融术治疗腰椎间盘突出症的安全性和疗效。方法:58例确诊为单纯性腰椎间盘突出症患者(其中L4/5突出44例,L5/S1突出13例,L3/4突出1例),在C型臂X光机透视监视下,采用经皮穿刺技术将同轴椎间盘内窥镜置入椎间盘内,摘除部分髓核后,在直视下采用ELLMAN射频机的双极可弯曲电极行髓核组织消融,完全去除镜下所见髓核组织。结果:采用MacNab标准评定,58例患者随访1~8个月,显效36例(62%),有效16例(28%),无效6例(10%),有效率为90%。所有病例均无严重并发症发生。结论:经皮内窥镜下射频消融术治疗单纯性腰椎间盘突出症安全、有效。     

颈椎内固定对相邻节段椎间盘及椎间关节应力影响的生物力学研究

目的探讨颈椎间植骨内固定相邻节段退变的生物力学机制。方法 5具成人尸体颈椎（C2～T1）标本用于试验。固定T1,施加作用力于C2,实验按顺序分为A、B1、C1、D1、B2、C2、D2 7组,测试各组在前屈、后伸两种状态下相邻节段C3～4椎间盘、椎间关节应力。结果各组相邻节段椎间盘、椎间关节应力随固定强度和节段增加而增加,即D2组〉C2组〉B2组〉A组、D2组〉D1组、C2组〉C1组、B2组〉B1组,其中C2、D2两组与A组、C2组与B2组、D2组与C2组、D2组与D1组、C2组与C1组比较差异均有统计学意义（P〈0.05）。结论颈椎间植骨内固定后相邻节段椎间盘、椎间关节应力增加;固定强度及节段越大影响越大。     

The effect of various sterilization procedures on the osteoinductive properties of demineralized bone matrix]

To minimize potential infection following the transplantation of allogeneic bone, extremely rigorous selection of donors and careful processing and storage of samples are required. Other major problems related to allogeneic transplants, such as reduced osteogenic properties and immunological reactions, led to the development of demineralized bone matrix (DBM). This osteoinductive bone extract is largely free of antigens and is easy to produce. However, to eliminate the potential risk of infection, DBM should be sterilized prior to implantation. The purpose of this study was to investigate the influence of different sterilization techniques on the osteoinductive properties of DBM. A series of 76 cortical defects (drill holes) 0.6 cm in diameter in the tibiae of 11 Merino sheep were filled with DBM in addition to autogeneic and allogeneic cancellous bone. Prior to implantation DBM was sterilized by autoclaving, gamma irradiation, or application of ethylene oxide or ethyl alcohol. A further 12 drill holes were left empty as controls. The formation of new bone was examined 3 and 6 weeks postoperatively, using histological, fluorescent-optical and microradiographical techniques. The amount of newly formed bone was also quantified. Apart from autoclaved DBM all matrix grafts showed excellent new bone formation following sterilization, by far exceeding the formation with allogeneic cancellous bone.     

Is epidural injection treatment with hypertonic saline solution in intervertebral disk displacement useful? (The effect of NaCl solution on intervertebral disk tissue)

The effect of sodium chloride solution on disc tissue was investigated in vitro. Tissue material was obtained from 19 discectomies. The specimens were incubated in aqua ad injectionem and in different sodium chloride solutions and weighted regularly during a maximum of 24 hours. Following the incubation periods the specimens were examined histologically. After one hour the surgical specimens showed a weight increase of 290% for aqua bidest., 170% for 0.9% NaCl and 100% for 5.85% NaCl and 10% NaCl. Disc tissue obtained from six autopsies was also examined under the same conditions. The weight increase in nucleus pulposus and anulus fibrosus tissue was less than in the disc tissue obtained from surgery. The weight increase in anulus fibrosus tissue was less than in nucleus pulposus tissue. In vitro incubation of disc tissue in a hypermolar sodium chloride solution always resulted in a weight increase. Successful therapy could not be explained by shrinkage of disc tissue treated with hypermolar sodium chloride.     

Shaving of the lumbar disk space--a new technique in lumbar nucleotomy

A complete curettage of the intervertebral space using the common surgical instruments (forceps, sharp spoons) is not possible during nucleotomy because of the anatomic site and the shape of the instruments. An alternative technique--called "shaving"--is described, which enables a faster, more effective, and less traumatizing removal of free-floating, pulpy residue in the intervertebral space.