Intradiscal pressure after intradiscal injection of hypertonic saline: an experimental study

Although chemonucleolysis with chymopapain is a long-established treatment for lumbar intervertebral disc herniation, serious complications have been reported. Accordingly, alternative substances for chemonucleolysis have been sought. The main beneficial effect of chemonucleolysis derives from the decrease in intradiscal pressure. Several previous studies have investigated the relationship between physiological saline injection and disc mechanics in cadaveric specimens [2, 5, 16]. However, no previous study has assessed the intradiscal pressure after intradiscal injection of “hypertonic saline” in living animals. The present study compared the changes in intradiscal pressure after intradiscal injection of hypertonic saline with those after chymopapain injection. The lumbar intervertebral discs of 26 living rabbits were examined: 10% hypertonic saline was injected in ten rabbits, and chymopapain (10 pikokatal units) was injected intradiscally in another ten, with the remaining six being used as controls. The intradiscal pressure was measured at 1, 4, and 12 weeks after injection. The intradiscal pressure of the hypertonic saline-injected group at 4 weeks was significantly lower than that of the control group, but by 12 weeks it had recovered. On the other hand, that of the chymopapain-injected group remained significantly lower than that of the control group at 12 weeks. The results of this study found that hypertonic saline injected into the intervertebral discs temporarily decreased the intradiscal pressure. Received: 26 July 1999 Revised: 26 November 1999 Accepted: 22 December     

In vitro measurement of pressure in intervertebral discs and annulus fibrosus with and without annular tears during discography

BACKGROUND CONTEXT: Discogram studies have shown that pain reproduction correlates with the extent of annular disruption. However, it has not been assessed if pressure changes in the annulus fibrosus vary incrementally with intradiscal pressure. PURPOSE: To determine the relationship between intradiscal pressure and outer annular pressure during discography in intervertebral discs with and without annular tears. STUDY DESIGN: Intradiscal and periannular pressures were measured simultaneously in vitro during intradiscal injection in porcine cadaver spines. METHODS: Twenty fresh porcine cadaver lumbar spines with intervening discs were tested. Intradiscal and periannular pressures were measured simultaneously using two pressure sensors during intradiscal contrast injection. The tip of a 25-gauge needle connected with a pressure manometer was placed in the center of the nucleus pulposus. A second pressure transducer was located at the outer third of the annulus fibrosus. Needle and transducer locations were confirmed by fluoroscopy. To compare the intact and torn annulus fibrosus, annular disruptions were created with a 20-gauge needle and confirmed by fluoroscopy. RESULTS: During intradiscal injections of discs with an intact annulus, annulus fibrosus pressure remained low and a sharp increase in intradiscal pressure was observed. Significantly higher pressures were noted in the outer annulus in discs with annular tears (p<.01). Mean pressures at the central nucleus pulposus, the outer third of intact annuli and torn annuli were 93.4+/-40.9 psi, 14.8+/-1.9 psi and 85.7+/-24.8 psi, respectively. CONCLUSIONS: Volumetric injection of intervertebral discs with a torn annulus fibrosis during discography may increase intra-annular pressure similar to the increase in pressure that may occur during spinal loading activities. This effect may not occur in discs with an intact annulus fibrosus.     

腰椎间盘纤维环切口不同修复方法的生物力学研究

【摘要】 目的：通过生物力学测试研究腰椎间盘纤维环切口不同修复方法的生物力学强度。方法：选取小牛腰椎标本制成50个脊柱功能节段,每个节段均在纤维环上作一10mm横切口。按照不同修复方法随机平均分为5组：粘合剂组（A组,选用DermaBond粘合切口）、简单缝合组（B组,采用常规U型缝合法处理切口）、MPSS组（C组,采用改良荷包缝合法处理切口）、粘合剂+简单缝合组（D组）及粘合剂+MPSS组（E组）,然后进行纤维环抗静水压强度测试及疲劳测试,根据各组的泄露压力和极限转数来评价其修复效果。结果：A～E组的泄露压力分别为（0.76±0.11）MPa、（1.66±0.11）MPa、（1.84±0.15）MPa、（1.88±0.13）MPa、（2.16±0.24）MPa。E组泄露压力明显高于其他组,差异有显著性（P＜0.05）。在疲劳测试中,从A～E组各组最后的极限转数分别为（4.42±0.59）万次、（8.06±0.75）万次、（8.44±1.01）万次、（9.76±0.23）万次、（9.88±0.21）万次。E组与D组比较差异无显著性（P＞0.05）,与其他各组比较差异均有统计学意义（P＜0.05）。结论：应用粘合剂+改良荷包缝合法处理纤维环切口,具有较高的生物力学强度。     

Intradiscal pressure after repeat intradiscal injection of hypertonic saline: an experimental study

Chemonucleolysis with chymopapain is an effective alternative to an operation for the treatment of some patients who have a lumbar intervertebral disc herniation. However, chymopapain is associated with rare but serious complications. Accordingly, alternative substances for chemonucleolysis have been sought. The main beneficial effect of chemonucleolysis derives from the decrease in the intradiscal pressure. We have previously reported that hypertonic saline injected into the intervertebral discs decreased the intradiscal pressure, but only temporarily. The present experimental study investigated changes in the intradiscal pressure after a repeat intradiscal injection of hypertonic saline. The lumbar intervertebral discs of 18 living rabbits were examined: 10% hypertonic saline was injected intradiscally just once in 12 rabbits, and the same dosage was injected again, 4 weeks later, in the same animals. The intradiscal pressure was measured at 1, 4, 8, and 12 weeks after the second injection. The remaining six rabbits were used as controls, without puncture and without injection. The intradiscal pressure of the group with repeat hypertonic saline injection at 4 weeks was significantly lower than that of the control group. The decreased pressure showed a tendency to increase at 8 weeks, and it had recovered at 12 weeks. The results of this study suggest that repeat hypertonic saline injections may be clinically useful.     

Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure

In recent years, non-fusion implants to stabilise the lumbar spine have become more and more popular. However, little is known on the load bearing of such dynamic stabilisation systems. In order to investigate the load bearing of discs bridged with rigid and dynamic stabilisation systems, six lumbar cadaver spines were mounted in a spine tester and loaded with pure moments in the three main motion planes. Four different states of the specimens were studied: intact, destabilised, stabilisation with a Dynesys^® and stabilisation with an internal fixator. Intradiscal pressure (IDP) measurements were used to assess the load bearing of the bridged disc. In the neutral unloaded position, there were small but not significant differences in disc pressure for the four states of the treated disc (P>0.05). Concerning the disc pressure during the course of loading, both the Dynesys^® and internal fixator did significantly reduce the pressure change from neutral to extension in comparison to the intact state (−0.05, −0.04 and +0.24 MPa, respectively) (P<0.05). Compared to the intact state, there was no significant pressure change from neutral to flexion (0.14, 0.15 and 0.18 MPa, respectively) (P>0.05). The devices apparently eliminated the pressure change from neutral to lateral bending (Dynesys 0.01 MPa, Fixator 0.01 MPa and intact 0.24 MPa), but due to large variations in the intact and defect states the differences were not significant (P>0.05). In axial rotation, the pressure change for the internal fixator was reduced compared to the intact state; however, the change was only significant in left axial rotation (P<0.05). The Dynesys^® showed no significant differences (P>0.05) in axial rotation. No changes in IDP were seen in the adjacent discs for either the Dynesys or the internal fixator. Our results showed that the IDPs for both devices were similar, but altered compared to the intact disc.     

Spinal loads after osteoporotic vertebral fractures treated by vertebroplasty or kyphoplasty

Vertebroplasty and kyphoplasty are routine treatments for compression fractures of vertebral bodies. A wedge-shaped compression fracture shifts the centre of gravity of the upper body anteriorly and generally, this shift can be compensated in the spine and in the hips. However, it is still unclear how a wedge-shaped compression fracture of a vertebra increases forces in the trunk muscle and the intradiscal pressure in the adjacent discs. A nonlinear finite element model of the lumbar spine was used to estimate the force in the trunk muscle, the intradiscal pressure and the stresses in the endplates in the intact spine, and after vertebroplasty and kyphoplasty treatment. In this study, kyphoplasty represents a treatment with nearly full fracture reduction and vertebroplasty one without restoration of kyphotic angle although in reality kyphoplasty does not guarantee fracture reduction. If no compensation of upper body shift is assumed, the force in the erector spine increases by about 200% for the vertebroplasty but by only 55% for the kyphoplasty compared to the intact spine. Intradiscal pressure increases by about 60 and 20% for the vertebroplasty and kyphoplasty, respectively. In contrast, with shift compensation of the upper body, the increase in muscle force is much lower and increase in intradiscal pressure is only about 20 and 7.5% for the vertebroplasty and kyphoplasty, respectively. Augmentation of the vertebral body with bone cement has a much smaller effect on intradiscal pressure. The increase in that case is only about 2.4% for the intact as well as for the fractured vertebra. Moreover, the effect of upper body shift after a wedge-shaped vertebral body fracture on intradiscal pressure and thus on spinal load is much more pronounced than that of stiffness increase due to cement infiltration. Maximum von Mises stress in the endplates of all lumbar vertebrae is also higher after kyphoplasty and vertebroplasty. Cement augmentation has only a minor effect on endplate stresses in the unfractured vertebrae. The advantages of kyphoplasty found in this study will be apparent only if nearly full fracture reduction is achieved. Otherwise, differences between kyphoplasty and vertebroplasty become small or vanish. Our results suggest that vertebral body fractures in the adjacent vertebrae after vertebroplasty or kyphoplasty are not induced by the elevated stiffness of the treated vertebra, but instead the anterior shift of the upper body is the dominating factor.     

Epidural abscess and cauda equina syndrome after percutaneous intradiscal therapy in degenerative lumbar disc disease

Background context

Percutaneous intradiscal therapies are gaining popularity as a regenerative treatment option for spinal disc degeneration. The risks, benefits, and possible complications associated with such procedures have been poorly defined. As these procedures are performed with increasing frequency, the likelihood that clinicians will be faced with significant complications also increases.

Purpose

The purpose of this study is to describe a significant complication of a percutaneous intradiscal bone marrow and adipose tissue transplantation for symptomatic lumbar disc degeneration.

Study design

The study design is a case report.

Methods

Two weeks after an injection of adipose cells, bone marrow aspirate and plasma into his L3–L4 and L5–S1 lumbar discs, a 64-year-old patient presented to the emergency room with cauda equina syndrome, fever, and back pain. Magnetic resonance imaging diagnosed L3–L4 disc extrusion, discitis with osteomyelitis, and epidural abscess, resulting in emergency decompressive surgery. An epidural abscess was drained, extruded disc material was removed, and cultures obtained. Five days later, once afebrile on antibiotics, he underwent a definitive interbody arthrodesis and stabilization.

Results

Cauda equina syndrome resolved, osteomyelitis (methicillin-resistant Staphylococcus epidermidis) was treated, and instrumented arthrodesis stabilized the involved segment.

Conclusions

Complications associated with the intradiscal injection of agents, such as stem cells, fibrin glue, adipose tissue, or bone marrow, have been poorly defined. Given the nature of the degenerating disc, serious adverse events, including discitis, osteomyelitis, and extrusion of disc contents, may occur.     

The effect of design parameters of interspinous implants on kinematics and load bearing: an in vitro study

Introduction

A number of concepts with controversy approaches are currently discussed for interspinous stabilization (IPS). However, comparative biomechanical studies among the different systems are rare. Nevertheless, it remains unclear which biomechanical characteristics are influenced by different design features of these implants, such as implant stiffness or an additional tension band. Therefore, the aim of the present study was to compare different interspinous implants to investigate the biomechanical impact of IPS implant design on intersegmental kinematics, such as range of motion, neutral zone, center of rotation (COR), as well as load transfer like intradiscal pressure (IDP), to gain additional experience for clinical indications and limitations.

Material and method

Twelve human lumbar spine specimens were tested in a spine loading apparatus. In vitro flexibility testing was performed by applying pure bending moments of 7.5 Nm without and with additional preload of 400 N in the three principal motion planes. Four interspinous implants, Coflex “COF” (Paradigm Spine, Germany), Wallis “WAL” (Abbott Laboratories, France), DIAM “DIA” (Sofamor Danek, France) and InterActiv (Aesculap AG, Germany) with two treatment options (without dorsal tensioning “IAO” and with dorsal tensioning “IAM”) were consecutively tested in comparison to the native situation “NAT” and to a defect situation “DEF” of the functional spinal unit. The tested IPS devices are comprised of a compression stiffness range of 133 to 1,674 N/mm and a tensile stiffness range of 0–39 N/mm. Range of motion, neutral zone, center of rotation and intradiscal pressure were analyzed for all instrumentation steps and load cases.

Conclusion

For the IPS, we found a correlation between compression stiffness and stabilization in extension. Here, the system with the lowest stiffness, DIA, displayed nearly no stabilization of the treated segment, whereas the system with the highest stiffness, WAL and COF, was most pronounced. This applies also for the correlation between device stiffness and IDP. In flexion only the degree of stabilization is in correlation with the tensile stiffness, whereas the IDP stays constant and is not affected by the different tensile stiffness. IPS is not able to stabilize in the frontal and transversal plane. Furthermore IPS does not substantially alter the location of the COR.     

Changes on MRI in lumbar disc protrusions in two patients after intradiscal electrothermal therapy

We examined changes to the protruded lumbar disc after intradiscal electrothermal therapy (IDET) using magnetic resonance imaging (MRI) in two patients with chronic discogenic low back pain who underwent IDET. MRI was performed before and 6 months after the treatments. In the follow-up MRI studies, the protrusions were almost abolished and normalized in both patients. We thus confirmed shrinkage of the protruded disc by IDET on MRI images in two patients.     

The effect of design parameters of dynamic pedicle screw systems on kinematics and load bearing: an in vitro study

As an alternative treatment for chronic back pain due to disc degeneration motion preserving techniques such as posterior dynamic stabilization (PDS) has been clinically introduced, with the intention to alter the load transfer and the kinematics at the affected level to delay degeneration. However, up to the present, it remains unclear when a PDS is clinically indicated and how the ideal PDS mechanism should be designed to achieve this goal. Therefore, the objective of this study was to compare different PDS devices against rigid fixation to investigate the biomechanical impact of PDS design on stabilization and load transfer in the treated and adjacent cranial segment. Six human lumbar spine specimens (L3–L5) were tested in a spine loading apparatus. In vitro flexibility testing was performed by applying pure bending moments of 7.5 Nm without and with additional preload of 400 N in the three principal motion planes. Four PDS devices, “DYN” (Dynesys^®, Zimmer GmbH, Switzerland), “DSS™” (Paradigm Spine, Wurmlingen, Germany), and two prototypes of dynamic rods, “LSC” with a leaf spring, and “STC” with a spring tube (Aesculap AG, Tuttlingen, Germany), were tested in comparison to a rigid fixation device S⁴ (Aesculap AG, Tuttlingen, Germany) “RIG”, to the native situation “NAT” and to a defect situation “DEF” of the specimens. The instrumented level was L4–L5. The tested PDS devices comprising a stiffness range for axial stiffness of 10 N/mm to 230 N/mm and for bending stiffness of 3 N/mm to 15 N/mm. Range of motion (ROM), neutral zone (NZ), and intradiscal pressure (IDP) were analyzed for all instrumentation steps and load cases of the instrumented and non-instrumented level. In flexion, extension, and lateral bending, all systems, except STC, showed a significant reduction of ROM and NZ compared to the native situation (p < 0.05). Furthermore, we found no significant difference between DYN and RIG (p > 0.1). In axial rotation, only DSS and STC reduced the ROM significantly (p < 0.005) compared to the native situation, whereas DYN and LSC stayed at the level of the native intersegmental rotation (p > 0.05). A correlation was found between axial stiffness and intersegmental stabilization in the sagittal and frontal plane, but not in the transversal plane where intersegmental stabilization is mainly governed by the systems’ ability to withstand shear loads. Furthermore, we observed the systems’ capacity to reduce IDP in the treated segment. The adjacent segment does not seem to be affected by the stiffness of the fixation device under the described loading conditions.     

腰部椎间盘造影及椎间盘内加压注射疗法

目的:探讨椎间盘内加压注射疗法对脱出型腰椎间盘突出症的治疗效果.方法:突出的椎间盘内加压注射3～20ml生理盐水,要避免用力过大,加压注射的压力低于3kg/cm^2.结果:脱出的椎间盘组织进入硬膜外腔后接触血液系统,逐渐被血液系统中的T细胞及单核细胞清除吸收.加压注射疗法能够促进这一吸收过程.结论:L1～5椎间盘和L5～S1椎间盘的穿刺体位和穿刺方向虽然有一定的差异,但是椎间盘内加压注射疗法是一种有效的治疗腰椎椎间盘突出症的微创疗法.     

Intradiskales Druckverhalten zervikaler Bandscheiben unter physiologischen und pathologischen Bedingungen In-vitro-Untersuchung

Zusammenfassung Sowohl klinische als auch experimentelle Arbeiten zur intradiskalen Druckmessung beschränken sich weitgehend auf Untersuchungen an der Lendenwirbelsäule. So konnte z.B. eine Abhängigkeit des intradiskalen Druckverhaltens vom Degenerationszustand der Bandscheibe v.a. aber von äußeren Lasteinwirkungen nachgewiesen werden. Um zu überprüfen, ob diese Befunde auch auf die Halswirbelsäule zutreffen, führten wir eine In-vitro-Studie mit humanen Präparaten durch. Diese wurden unter verschiedenen Bedingungen biomechanisch gesestet und simultan der intradiskale Druck in 2 Bandscheiben registriert. Wir konnten hierbei bei der Literatur in vivo erhobene Werte für den intradiskalen Druck in Neutralstellung experimentell bestätigen. Die Simulation von Muskelkräften führte zu einer eindrucksvollen Erhöhung des intradiskalen Drucks. Zudem konnte gezeigt werden, daß die Fusion eines zervikalen Bewegungssegments erheblichen Einfluß auf den intradiskalen Druck in den-beiden Nachbarsegmenten hat. Die Ergebnisse insgesamt erweitern unseren Kenntnisstand über das Verhalten intradiskaler Drücke in zervikalen Bandscheiben. Die Befunde an fusionierten Präparaten könnten dazu beitragen, ein lang bekanntes Phänomen zu erklären, und zwar die Beobachtung, daß die an ein blockiertes Segment unmittelbar angrenzenden Etagen langfristig einer vermehrten Degeneration unterliegen.

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In vitro measurements of cervical intra-discal pressure in different situations

Clinical and experimental studies concerning intradiscal pressure have mainly been carried out using the lumbar spine. It has been shown that degenerative changes in the intervertebral disc and external loads can significantly influence intradiscal pressure. To see if these findings are also relevant for cervical discs, we carried out an in vitro study using human cervial spine specimens. The specimens were tested biomechanically under various conditions with simultaneous recording of intradiscal pressure in two cervical discs. We were able to confirm in vivo measurements of intradiscal pressure reported in the literature. Simulation of muscle force led to a marked increase in intradiscal pressure. Moreover, it was demonstrated that ventral cervical fusion has a significant influence on intradiscal pressure in both adjacent segments. In general, the results improve our understanding of the basic biomechanics of the cervical spine. The experiments with fused specimens could help to explain why degeneration is accelerated in adjacent motion segments after ventral cervical fusion.

     

Biomechanical effect of different lumbar interspinous implants on flexibility and intradiscal pressure

Interspinous implants are used to treat lumbar spinal stenosis or facet joint arthritis. The aims of implanting interspinous devices are to unload the facet joints, restore foraminal height and provide stability especially in extension but still allow motion. The aim of this in vitro study was to compare four different interspinous implants––Colfex, Wallis, Diam and X-Stop––in terms of their three-dimensional flexibility and the intradiscal pressure. Twenty-four human lumbar spine specimens were divided into four equal groups and tested with pure moments in flexion/extension, lateral bending and axial rotation: (1) intact, (2) defect, (3) after implantation. Range of motion and the intradiscal pressure were determined.In each implant-group the defect caused an increase in range of motion by about 8% in lateral bending to 18% in axial rotation. Implantation had similar effects with all four implants. In extension, Coflex, Wallis, Diam, and X-Stop all overcompensated the instability caused by the defect and allowed about 50% of the range of motion of the intact state. In contrast, in flexion, lateral bending and axial rotation the values of the range of motion stayed about the values of the defect state. Similarly the intradiscal pressure after implantation was similar to that of the intact specimens in flexion, lateral bending and axial rotation but much smaller during extension. All tested interspinous implants had a similar effect on the flexibility: they strongly stabilized and reduced the intradiscal pressure in extension, but had almost no effect in flexion, lateral bending and axial rotation.     

不同后枕颈角对枕颈融合时下颈椎运动范围和椎间压力的影响

【摘要】 目的：分析以不同后枕颈角（posterior occipitocervical angle,POCA）行枕颈固定时下颈椎的运动范围（range of motion,ROM）和椎间压力（intradiscal pressure,IDP）,探讨枕颈融合（occipitocervical fusion,OCF）术中POCA的选择策略。方法：选取8具新鲜冰冻人体枕颈部标本（C0~T1,头端包括枕骨粗隆以下的颅底骨性结构）,年龄为25～45岁,男4具,女4具,X线透视排除骨性异常及破坏。剔除附着的肌肉、脂肪组织,完整保留各种韧带、关节囊及椎间盘,作为正常组。将标本置于2N·m 载荷下,运用伺服液压材料测试系统、光电运动分析系统及微型压力传感器测量C3/4、C4/5、C5/6、C6/7运动节段在前屈、后伸、左旋及左侧弯4个方向上的ROM以及IDP。后将标本以不同POCA行枕颈固定作为实验组,5组分别为：中立位组（POCA=111°）、中立位-标准差（standard deviation,SD）组（POCA=101°）、中立位+SD组（POCA=121°）、中立位-2SD组（POCA=91°）及中立位+2SD组（POCA=131°）。固定节段为C0、C2及C3。各实验组均采用位移控制模式进行实验,测量4个运动节段在4个方向上的ROM及IDP。结果：枕颈固定以后,C0~C3 4个方向上的ROM较正常组均显著减小（P<0.001）。POCA的变化对4个运动节段前屈和后伸方向上的ROM及IDP的影响呈现一定的规律性：前屈方向上,随着POCA的增大,各节段的ROM及IDP呈递减趋势;后伸方向上,随着POCA的增大,各节段的ROM呈递增趋势,而IDP呈减小趋势。POCA固定于中立位时,各运动节段前屈、后伸方向上的ROM虽明显大于正常组,但未出现POCA过小时前屈方向上或过大时后伸方向上极度增大的ROM,且IDP与正常组之间无显著差异（P>0.05）。而在左旋及左侧弯方向上,随POCA变化4个运动节段的ROM较正常组显著增加,但其对ROM及IDP的影响无规律性。结论：OCF术中,POCA于中立位固定时,下颈椎的ROM、IDP最接近正常状态。     

Effects of unisegmental disc compression on adjacent segments: an in vivo animal model

It is controversial whether fusion of discs in the spine leads to increased degeneration on the remaining discs or whether the degenerative changes are merely a part of the inevitable natural history process. To determine the effects of unisegmental compression and subsequent recovery on adjacent segments, we studied histology, radiology and intradiscal pressure using an in vivo rabbit model. Fifteen New Zealand rabbits were divided in to three groups of five. In the first group, the intervertebral disc L4–L5 of the lumbar spine was axially loaded for 28 days with an external loading device. In the second group, the intervertebral disc was compressed for 28 days and allowed to recover for an equal amount of time, with the loading device removed. Five animals underwent a sham operation, in which the external loading device was situated, but their discs remained unloaded for 28 days. The intradiscal pressure was determined in the loaded discs as well as in the cranial and caudal adjacent discs. Lateral radiographs were taken from each subjected intervertebral disc with adjacent vertebral bodies and the cranial and caudal adjacent segments. The compressed discs showed lower intradiscal pressure in comparison with the control group, which remained unloaded. In the cranial and caudal discs adjacent to the loaded discs the average intradiscal pressure was similar to the unloaded controls. The loaded discs demonstrated a significant decrease in disc space. No discs adjacent to the loaded discs changed in height. The lamellar architecture of the inner, middle, and outer annulus became more disorganized in the loaded discs. The nucleus pulposus showed increase of mucoid degeneration and increased cell death. Intervertebral discs from the control group and the adjacent discs to the compressed discs maintained their normal morphology. This study shows that mechanical loading of discs in the spine can cause rapid degeneration. Adjacent discs, however, did not change in terms of radiology, intradiscal pressure, or histology.     

Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: an experimental study on the rabbit lumbar spine model

Intervertebral disc (IVD) pressure measurement is an appropriate method for characterizing spinal loading conditions. However, there is no human or animal model that provides sufficient IVD pressure data. The aim of our study was to establish physiological pressure values in the rabbit lumbar spine and to determine whether temporary external disc compression and distraction were associated with pressure changes. Measurements were done using a microstructure-based fibreoptic sensor. Data were collected in five control rabbits (N, measurement lying prone at segment L3/4 at day 28), five rabbits with 28 days of axial compression (C, measurement at day 28) and three rabbits with 28 days of axial compression and following 28 days of axial distraction (D, measurement at day 56). Disc compression and distraction was verified by disc height in lateral radiographs. The controls (N) showed a level-related range between 0.25 MPa–0.45 MPa. The IVD pressure was highest at level L3/4 (0.42 MPa; range 0.38–0.45) with a decrease in both cranial and caudal adjacent segments. The result for C was a significant decrease in IVD pressure (0.31 MPa) when compared with controls (P=0.009). D showed slightly higher median IVD pressure (0.32 MPa) compared to C, but significantly lower levels when compared with N (P=0.037). Our results indicate a high range of physiological IVD pressure at different levels of the lumbar rabbit spine. Temporary disc compression reduces pressure when compared with controls. These data support the hypothesis that temporary external compression leads to moderate disc degeneration as a result of degradation of water-binding disc matrix or affected active pumping mechanisms of nutrients into the disc. A stabilization of IVD pressure in discs treated with temporary distraction was observed.     

椎间盘内电热疗法治疗盘源性腰痛的疗效

目的探讨经皮椎间盘内电热治疗(IDET)对盘源性腰痛(DLBP)的临床疗效。方法对49例(49个病变椎间盘)DLBP患者行CT联合"C臂"X线机引导下IDET的治疗,其中Pfirrmann分级Ⅱ级26例,Ⅲ级23例。采用WHO疼痛缓解标准,将疼痛缓解程度分为无缓解、轻微缓解、部分缓解和完全缓解。结果对49个椎间盘均穿刺成功并行IDET治疗。术后1周及1、3和6个月随访,Ⅱ级、Ⅲ级两组患者疼痛缓解均随着术后时间的延长而逐渐明显,术后6个月时Ⅱ级患者有效率[88.46%(23/26)]高于Ⅲ级患者[60.87%(14/23),P0.05]。术中、术后均未出现严重并发症。结论IDET治疗DLBP近期疗效较好,术后6个月时Pfirrmann分级为Ⅱ级的患者疗效优于Ⅲ级。