Disc degeneration of cervical spine on MRI in patients with lumbar disc herniation: comparison study with asymptomatic volunteers

An association between progression of cervical disc degeneration and that of lumbar disc degeneration has been considered to exist. To date, however, this association has not yet been adequately studied. Age-related changes in the cervical intervertebral discs were evaluated by magnetic resonance imaging (MRI) in patients with lumbar disc herniation, and compared with the MRI findings of healthy volunteers without lower back pain. The purpose of this study was to clarify whether the prevalence of asymptomatic cervical disc degeneration is higher in patients with lumbar disc herniation than in healthy volunteers. The study was conducted on 51 patients who were diagnosed as having lumbar disc herniation and underwent cervical spine MRI. The patients consisted of 34 males and 17 females ranging in age from 21–83 years (mean 46.9 ± 14.5 years) at the time of the study. The control group was composed of 113 healthy volunteers (70 males and 43 females) aged 24–77 years (mean 48.9 ± 14.7 years), without neck pain or low back pain. The percentage of subjects with degenerative changes in the cervical discs was 98.0% in the lumbar disc herniation group and 88.5% in the control group (p = 0.034). The presence of lumbar disc herniation was associated significantly with decrease in signal intensity of intervertebral disc and posterior disc protrusion in the cervical spine. None of the MRI findings was significantly associated with the gender, smoking, sports activities, or BMI. As compared to healthy volunteers, patients with lumbar disc herniation showed a higher prevalence of decrease in signal intensity of intervertebral disc and posterior disc protrusion on MRI of the cervical spine. The result of this study suggests that disc degeneration appears to be a systemic phenomenon.     

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     

An observation of ruptured annulus fibrosus in lumbar discs.

To observe anatomical or pathological changes in lumbar intervertebral discs, discography and computed tomography-discography (CTD) were performed on fresh human cadavers. The results of discograms and CTD were compared with histological findings of cross sections of discs. Preoperative CTD of lumbar disc herniation was investigated based on these results. Ruptures of the annulus fibrosus were divided into two categories: circumferential rupture and radial rupture. In CTD images of fresh human cadavers, most images of rupture of the annulus fibrosus showed anterior to lateral circumferential rupture. As disc degeneration progressed, circumferential rupture tended to coexist with radial rupture in many cases. In CTD cases of lumbar disc herniation, most images of ruptures of the annulus fibrosus showed a posterior radial rupture, which was the route for herniated nucleus. The greater the degree of degeneration, the more the images tended to show radial ruptures coexisting with circumferential ruptures.     

The translaminar approach to canalicular and cranio-dorsolateral lumbar disc herniations

Summary. Summary.   Introduction: The interlaminar approach is the standard procedure for most disc herniations in lumbar spine surgery. However, in cranially extruded disc herniations including canalicular herniations, partial or complete facetectomy is necessary with increased risk of postoperative spinal instability. We present the translaminar technique which allows a more direct and less destructive operative approach.   Methods: 30 patients using the translaminar fenestration were analysed by a postoperative follow-up of 6 weeks and one year. The mean-age was 57.2 years. For resection of the disc herniation, a small round or oval fenestration (6–8 mm) in the hemilamina, craniomedially to the facet joint, was performed. No patient received a partial or total facetectomy.   Results: The majority of affected discs were at the L4-L5 level (53%). An extruded fragment was found in 28 patients (93%). In 5 patients bleeding from epidural veins complicated the intra-operative course. In 50% the nerve root was visually exposed. 15 patients (50%) had an intervertebral discectomy additional to the fragment excision.  One patient was re-operated on after 10 days because of persisting radicular pain by using the same translaminar approach. 28 patients showed complete or nearly complete relief of radicular pain. Using this approach we have seen no major complication or clinical instability during a follow-up of at least one year.   Conclusions: The translaminar approach is an effective and minimally invasive technique in both canalicular and cranio-dorsolateral disc herniations. It gives an additional possibility to avoid partial removal of the facet joints, can be performed in all lumbar segments and preserves structures important for segmental spinal stability. The approach allows access to the extruded disc fragment and intervertebral disc space comparable to classical approaches and is a frequently used operative technique in our department.     

Peak stresses observed in the posterior lateral anulus

STUDY DESIGN: The stress distributions within cadaveric lumbar intervertebral discs were measured for a range of loading conditions. OBJECTIVES: To examine the distribution of stress across the area of the intervertebral disc and to compare regional variations in peak stress during compression loading with various flexion angles. SUMMARY OF BACKGROUND DATA: The rate of disc degeneration and the occurrence of low back disorders increase with higher mechanical loading of the spine. The largest peak stresses occur in the anulus. METHODS: Human lumbar L2--L3 and L4--L5 cadaver functional spinal units were obtained and tested. The distribution of disc stress was measured using a pressure probe with loads applied, pure compression and compression with 5 degrees of either flexion or extension. RESULTS: Stress profiles were recorded across the intervertebral disc at a compressive force of 1000 N and each of the three flexion-extension angles. The highest values (2.99 +/- 1.31 MPa) were measured during extension-compression lateral to the midline of the disc in the posterior anulus. The pressure in the nucleus was relatively unchanged by flexion angle remaining about 1.00 MPa for a 1000-N compression. CONCLUSIONS: Pressure measurements of the cadaveric nucleus have been used to validate models of lumbar spine loading and to evaluate the risk of low back injury and disc herniation. Previous observations limited to midsagittal measurements of the nucleus did not identify the regions of highest stress. The highest values observed here within the posterolateral anulus correspond to common sites of disc degeneration and herniation.     

Qualitative and quantitative assessment of degeneration of cervical intervertebral discs and facet joints

Degeneration of intervertebral discs and facet joints is one of the most frequently encountered spinal disorders. In order to describe and quantify degeneration and evaluate a possible relationship between degeneration and biomechanical parameters, e.g., the intervertebral range of motion and intradiscal pressure, a scoring system for degeneration is mandatory. However, few scoring systems for the assessment of degeneration of the cervical spine exist. Therefore, two separate objective scoring systems to qualitatively and quantitatively assess the degree of cervical intervertebral disc and facet joint degeneration were developed and validated. The scoring system for cervical disc degeneration consists of three variables which are individually scored on neutral lateral radiographs: “height loss” (0–4 points), “anterior osteophytes” (0–3 points) and “endplate sclerosis” (0–2 points). The scoring system for facet joint degeneration consists of four variables which are individually scored on neutral computed tomography scans: “hypertrophy” (0–2 points), “osteophytes” (0–1 point), “irregularity” on the articular surface (0–1 point) and “joint space narrowing” (0–1 point). Each variable contributes with varying importance to the overall degeneration score (max 9 points for the scoring system of cervical disc degeneration and max 5 points for facet joint degeneration). Degeneration of 20 discs and facet joints of 20 patients was blindly assessed by four raters: two neurosurgeons (one senior and one junior) and two radiologists (one senior and one junior), firstly based on first subjective impression and secondly using the scoring systems. Measurement errors and inter- and intra-rater agreement were determined. The measurement error of the scoring system for cervical disc degeneration was 11.1 versus 17.9% of the subjective impression results. This scoring system showed excellent intra-rater agreement (ICC = 0.86, 0.75–0.93) and excellent inter-rater agreement (ICC = 0.78, 0.64–0.88). Surgeons as well as radiologists and seniors as well as juniors obtained excellent inter- and intra-rater agreement. The measurement error of the scoring system for cervical facet joint degeneration was 20.1 versus 24.2% of the subjective impression results. This scoring system showed good intra-rater agreement (ICC = 0.71, 0.42–0.89) and fair inter-rater agreement (ICC = 0.49, 0.26–0.74). Both scoring systems fulfilled the criteria for recommendation proposed by Kettler and Wilke. Our scoring systems can be reliable and objective tools for assessing cervical disc and facet joint degeneration. Moreover, the scoring system of cervical disc degeneration was shown to be experience- and discipline-independent. An erratum to this article can be found at     

The influence of torsion on disc herniation when combined with flexion

The role of torsion in the mechanical derangement of intervertebral discs remains largely undefined. The current study sought to investigate if torsion, when applied in combination with flexion, affects the internal failure mechanics of the disc wall when exposed to high nuclear pressure. Thirty ovine lumbar motion segments were each positioned in 2° axial rotation plus 7° flexion. Whilst maintained in this posture, the nucleus of each segment was gradually injected with a viscous radio-opaque gel, via an injection screw placed longitudinally within the inferior vertebra, until failure occurred. Segments were then inspected using micro-CT and optical microscopy in tandem. Five motion segments failed to pressurize correctly. Of the remaining 25 successfully tested motion segments, 17 suffered vertebral endplate rupture and 8 suffered disc failure. Disc failure occurred in mature motion segments significantly more often than immature segments. The most common mode of disc failure was a central posterior radial tear involving a systematic annulus–endplate–annulus failure pattern. The endplate portion of these radial tears often propagated contralateral to the direction of applied axial rotation, and, at the lateral margin, only those fibres inclined in the direction of the applied torque were affected. Apart from the 2° of applied axial rotation, the methods employed in this study replicated those used in a previously published study. Consequently, the different outcome obtained in this study can be directly attributed to the applied axial rotation. These inter-study differences show that when combined with flexion, torsion markedly reduces the nuclear pressure required to form clinically relevant radial tears that involve cartilaginous endplate failure. Conversely, torsion appears to increase the disc wall’s resistance to radial tears that do not involve cartilaginous endplate failure, effectively halving the disc wall’s overall risk of rupture.     

Lumbar facet joint and intervertebral disc loading during simulated pelvic obliquity

Background contextIntervertebral disc and facet joints are the two primary load-bearing structures of the lumbar spine, and altered loading to these structures may be associated with frontal plane spinal deviations.PurposeTo determine the load on the lumbar facet joint and intervertebral disc under simulated frontal plane pelvic obliquity combined loading, an in vitro biomechanical study was conducted.Study design/settingAn in vitro biomechanical study using a repeated-measures design was used to compare L4–L5 facet joint and intervertebral disc loading across pure moment and combined loading conditions.MethodsEight fresh-frozen lumbosacral specimens were tested under five loading conditions: flexion/extension, lateral bending, axial rotation using pure moment bending (±10 Nm), and two additional tests investigating frontal plane pelvic obliquity and axial rotation (sacrum tilted left 5° and at 10° followed by a ±10-Nm rotation moment). Three-dimensional kinematics, facet load, and intradiscal pressures were recorded from the L4–L5 functional spinal unit.ResultsSagittal and frontal plane loading resulted in significantly smaller facet joint forces compared with conditions implementing a rotation moment (p<.05). The facet joint had the highest peak load during the 10° combined loading condition (124.0±30.2 N) and the lowest peak load in flexion (26.8±16.1 N). Intradiscal pressure was high in lateral flexion (495.6±280.9 kPa) and flexion (429.0±212.9 kPa), whereas intradiscal pressures measured in rotation (253.2±135.0 kPa) and 5° and 10° combined loading conditions were low (255.5±132.7 and 267.1±127.1 kPa, respectively).ConclusionsFacet loading increased during simulated pelvic obliquity in frontal and transverse planes, whereas intradiscal pressures were decreased compared with sagittal and frontal plane motions alone. Altered spinopelvic alignment may increase the loads experienced by spinal tissue, especially the facet joints.     

Central Lumbar Disc Herniation

Summary  A follow-up study which describes the experience of the Department of Neurosurgery in Berne in the treatment of patients with central lumbar disc herniation (CLDH).  Background Data. The anatomical position of lumbar disc herniation, in general, does not seem to affect postoperative outcome. However, according to other studies a subgroup of patients with central lumbar disc herniations appears to have poorer results.  Objectives. The aim of the present study was to assess clinical outcome in a recent cohort of patients, to investigate whether there is a difference in outcome with regard to the surgical approach (unilateral vs bilateral) and to compare the postoperative results between the subcategories of CLDH: central massprolaps (CMP) and central contained disc herniation (CCDH).  Methods. Between 1990 and 1997, 40 out of 3150 patients operated on for lumbar disc herniation were diagnosed with CLDH (1.2%). The patients were operated on through unilateral or bilateral fenestrations with microdiscectomy. Recent follow-up studies were obtained by standardized questionnaires. The retrospective investigation was performed by an unbiased observer.  Results. Long-term follow-up was available for 34 of the 40 patients (85%) at a mean of 3.3 years. Eight patients had an excellent result (24%), 15 patients a good result (44%), 8 patients a fair (24%) and 3 patients had a poor result (9%). Overall, the operation was considered successful in 68% of patients. There was no statistically significant difference in outcome in patients with CMP as compared with those with CCDH (75% versus 64%). There was also no significant difference for better outcome between bilateral as compared with unilateral approaches.  Conclusions. Postoperative outcome of central lumbar disc herniation (CLDH) is poorer as compared with other types of lumbar disc herniation. The reason seems to be the anatomical position of the disc herniation with a peculiar derangement of the disc architecture. The surgical approach itself or the subcategories of CLDH appear to have only minor impact on postoperative outcome. Interlaminar fenestrations, in general, are appropriate for removal of the disc fragments.     

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.     

Eight year outcome after surgery for lumbar disc herniation: a comparison of reoperated and not reoperated patients

Summary  A retrospective study of 211 patients with unilateral sciatica operated on for lumbar disc herniation during 1988 and 1989 was performed in order to compare the results of reoperated patients with the results of patients operated on only once. The patients completed a standardized questionnaire in 1997 which included questions about reoperations, back and leg pain, functional status and disability pension. Outcome scores were calculated, giving values from 0 (no pain/normal function) to 100 (totally disabled).  A follow-up status of 80.1% was obtained; 163 patients answered the questionnaire while six patients had died. 23.9% of the patients (n=39) had been reoperated on. A recurrent disc herniation at the same level was suspected before the reoperation in 18.4%, but a recurrence was found in only 8.6%. 3.7% were reoperated on more than once. Outcome score was worse among “reoperated” patients (median 45.0, range 0–94) than among patients who only had the primary operation (median 10.5, range 0–81) (P<0.001). In addition, 34,3% of the “reoperated” patients received a disability pension compared to 9,9% of the patients not reoperated on (P<0.01). Patients reoperated upon at the same level without peroperative signs of recurrent disc herniation, had an outcome score of 53.0 (range 0–82) compared to a score of 30.0 (range 0–66) in patients with a confirmed recurrence (P<0.05). The percentage of disability pension was 53.8% versus 9.1%, respectively, for those two groups (P<0.05).  Eight years after operation for lumbar disc herniation, the outcome was significantly worse in “reoperated” patients than in patients operated on once. In addition, reoperated patients with peroperatively confirmed recurrence of the same disc, seemed to have a better outcome than patients without peroperative signs of a recurrence.     

MRI在腰椎间盘突出症中的应用与临床价值

本文对122例腰椎间盘突出症的MRI成像,结合临床进行了分析。通过手术摘除的45个椎间盘证实,结果突出符合率为96.9％,纤维破裂及髓核脱出符合率为92.3％;讨论了MRI成像在腰椎间盘突出症应用中具有定位,定性的准确性及鉴别诊断的价值。对于手术后症状复发的病例,可指导再手术及准确地避免了再手术,有着目前所不可取代的优越性。同时,提出MRI在对伴有神经通道狭窄方面的诊断,往往结果不尽人意,以及临床弥补的方法。     

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.     

CT value analysis and clinical significance before and after percutaneous lumbar discectomy

OBJECTIVE: To provide theoretical basis for effect and mechanism of percutaneous lumbar discectomy in clinic. METHODS: A total of 180 patients with lumbar intervertebral disc herniation were evaluated by CT on the fifth day before and after operation. Meanwhile, CT value was measured in the determined level and region. RESULTS: After operation, CT value of the central and posterior determined point of herniated intervertebral disc was lower significantly than that before operation (P<0.01), but CT value of the anterior determined point was different insignificantly. The excellent and good results of the patients together were 83% postoperatively. CONCLUSIONS: The curative effect of percutaneous lumbar discectomy is achieved through reduction of lumbar intradiscal pressure.     

Effectiveness of posterior tension band fixation in the thoracolumbar seat-belt type injuries of the young population

The effects of different parameters on the mechanical behaviour of the lumbar spine were in most cases determined deterministically with only one uncertain parameter varied at a time while the others were kept fixed. Thus most parameter combinations were disregarded. The aim of the study was to determine in a probabilistic finite element study how intervertebral rotation, intradiscal pressure, and contact force in the facet joints are affected by the input parameters implant position, implant ball radius, presence of scar tissue, and gap size in the facet joints. An osseoligamentous finite element model of the lumbar spine ranging from L3 vertebra to L5/S1 intervertebral disc was used. An artificial disc with a fixed center of rotation was inserted at level L4/L5. The model was loaded with pure moments of 7.5 Nm to simulate flexion, extension, lateral bending, and axial torsion. In a probabilistic study the implant position in anterior–posterior (ap) and in lateral direction, the radius of the implant ball, and the gap size of the facet joint were varied. After implanting an artificial disc, scar tissue may develop, replacing the anterior longitudinal ligament. Thus presence and absence of scar tissue were also simulated. For each loading case studied, intervertebral rotations, intradiscal pressures and contact forces in the facet joints were calculated for 1,000 randomized input parameter combinations in order to determine the probable range of these output parameters. Intervertebral rotation at implant level varies strongly for different combinations of the input parameters. It is mainly affected by gap size, ap-position and implant ball radius for flexion, by scar tissue and implant ball radius for extension and lateral bending, and by gap size and implant ball radius for axial torsion. For extension, intervertebral rotation at implant level varied between 1.4° and 7.5°. Intradiscal pressure in the adjacent discs is only slightly affected by all input parameters. Contact forces in the facet joints at implant level vary strongly for the different combinations of the input parameters. For flexion, forces are 0 in 63% of the cases, but for small gap sizes and large implant ball radii they reach values of up to 533 N. Similar results are found for extension with a maximum predicted force of 560 N. Here the forces are mainly influenced by gap size, implant ball radius and scar tissue. The forces vary between 0 and 300 N for lateral bending and between 0 and 200 N for axial torsion. The parameters that have the greatest effect in both loading cases are the same as those for extension. Intervertebral rotation and contact force in the facet joints depend strongly on the input parameters studied. The probabilistic study shows a large variation of the results and likelihood of certain values. Clinical studies will be required to show whether or not there is a strong correlation of parameter combinations that cause high facet joint forces and low back pain after total disc replacement.     

K-ROD系统治疗腰椎间盘突出伴相邻节段退变的疗效

目的探讨K-ROD系统治疗腰椎间盘突出伴相邻节段退变的临床疗效。方法将20例腰椎间盘突出伴相邻节段退变的患者按照手术方式的不同分为观察组(采用K-ROD系统治疗,11例)和对照组(采用单节段后路椎体间融合治疗,9例)。观察两组手术情况、临床疗效(腰、腿部疼痛VAS评分和功能障碍指数)和影像学指标(椎间隙高度和椎间活动度)。结果患者均获得随访,观察组随访时间34~53(44.55±6.52)个月,对照组随访时间31~54(40.22±9.26)个月。①手术时间、术中出血量观察组明显长(多)于对照组(P<0.05)。②临床疗效:术后1年、末次随访时两组均较术前明显改善(P<0.05);末次随访时观察组各项指标均明显优于对照组(P<0.05)。③影像学指标:术后1年椎间隙高度两组比较差异无统计学意义(P>0.05),末次随访时观察组椎间隙高度明显高于对照组(P<0.05);术后1年、末次随访时与术前比较,观察组退变椎间盘节段椎间活动度(ROM 1)均降低(P<0.05),退变椎间盘上位相邻节段椎间活动度(ROM 2)均增高(P<0.05),对照组ROM 1、ROM 2均增高(P<0.05),ROM 1两组间比较差异均有统计学意义(P<0.05)。末次随访时出现邻椎退变观察组1例、对照组7例,两组比较差异有统计学意义(P<0.05)。结论K-ROD系统用于治疗腰椎间盘突出伴相邻节段退变临床疗效较好,可延缓手术相邻节段椎间盘的退变。     

臭氧联合复方倍他米松注射治疗腰椎间盘突出症

目的比较臭氧椎间盘内注射联合复方倍他米松椎间孔注射治疗腰椎间盘突出症的临床疗效。方法经CT或MRI诊断为腰椎间盘突出症的患者64例,按入院前后顺序随机入组。对照组31例单纯椎间盘内注射臭氧。试验组33例采用椎间盘内注射臭氧,联合复方倍他米松椎间孔注射。临床疗效采用MacNab评分及VAS评分,分别评价术后1d、5d,电话随访3个月疗效。结果术后1d、5d的有效率分别为：试验组：96.97%,93.94%,对照组：77.19%、74.19%。组间比较差异有显著性（P〈0.05）。术后3个月的有效率为试验组87.88%,对照组80.65%,组间比较差异无显著性（P〉0.05）。结论臭氧盘内联合复方倍他米松椎间孔注射可以加速腰腿疼痛症状的改善,提高腰椎间盘突出症的近期疗效。     

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.     

Correlation between bone mineral density and intervertebral disk degeneration in pre- and postmenopausal women

 The purpose of this study was to investigate the relationship between intervertebral disk degeneration and bone mass. Magnetic resonance imaging was performed to evaluate lumbar disk degeneration according to Thompson's classification (grades 1 and 2, normal disk; grades 3, 4, and 5, degenerated disk), and bone mineral density (BMD) in the lumbar vertebrae, radius, and calcaneus was measured by dual-energy X-ray absorptiometry for 90 women (22–74 years old). The relationship between the grade of intervertebral disk degeneration and the BMD (Z score) was analyzed in pre- and postmenopausal women. In premenopausal women, BMD was significantly higher at all measured sites in the degenerated disk group judged at the L5–S1 level than in the normal disk group (P < 0.05). In postmenopausal women, BMD was significantly higher at the anteroposterior L2–L4, lateral L3, and calcaneus in the degenerated disk group judged at the L2–L3 level than in the normal disk group (P < 0.05). BMD at the anteroposterior L2–L4 and calcaneus was significantly higher in the degenerated disk group judged at the L3–L4 level than in the normal disk group (P < 0.05). In conclusion, the BMD of not only the lumbar vertebrae but also the calcaneus and radius was mutually related to lumbar intervertebral disk degeneration from an early stage of degeneration. Received: May 16, 2002 / Accepted: July 31, 2002 Offprint requests to: Y. Nanjo     

T1–2 disc herniation following an en bloc cervical laminoplasty

 We report a rare case of T1–2 disc herniation following cervical laminoplasty. A 56-year-old male patient presented with left foot-drop and gait disturbance of abrupt onset 11 years after a successful laminoplasty from C3–7. Magnetic resonance imaging revealed spinal stenosis at T1–2 due to intervertebral disc herniation and ligamentum flavum hypertrophy. Three days later, laminectomy with disc fragment excision was performed at that level. Two weeks after surgery, he was able to walk without assistance. Mechanical stresses may have directly affected the T1–2 intervertebral disc following laminoplasty and may have caused disc herniation. Received: October 17, 2001 / Accepted: February 1, 2002