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Purpose: To determine the safety and efficacy of percutaneous lumbar discectomy (PLD) and percutaneous disc cementoplasty (PDCP) for painful lumbar disc herniation (LDH) in patients >60 years of age., Materials and Methods: Sixteen older patients (mean age, 71.00 ± 6.24 years) with painful LDH were treated with PLD and PDCP. The outcome data (the Macnab criteria, visual analog scale score, and Oswestry disability index) were collected preoperatively; at 1 week postoperatively; at posttreatment months 1, 3, and 6; and every 6 months thereafter. In addition, treatment duration, injection volume of bone cement, length of hospital stay, and complications were assessed., Results: Treatment was successful in all patients. The pain relief rate at the last follow-up was 87.5%. Six, 8, and 2 patients showed excellent, good, and fair results, respectively; no patient showed a poor result. The average visual analog scale for back and leg pain decreased from 6.75 ± 1.06 and 7.00 ± 0.89 before the procedure to 2.81 ± 1.60 and 2.87 ± 1.75 at 1 month, 2.79 ± 1.58 and 2.71 ± 1.64 at 6 months, and 2.90 ± 1.73 and 3.00 ± 1.76 at 1 year, respectively. The scores were 2.44 ± 1.63 and 2.44 ± 1.71, respectively, at the last follow-up. The Oswestry disability index also changed after the procedure, with significant differences between baseline scores and those at each follow-up (P < .001). The mean procedure duration, injection volume of bone cement, and length of hospital stay were 55.69 ± 5.86 minutes, 2.50 ± 0.63 mL, and 7.06 ± 2.41 days, respectively. There were no complications., Conclusions: The combination of PLD and PDCP is feasible, safe, and effective for older patients with painful LDH., (Copyright © 2018 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the safety and efficacy of oxygen-ozone treatment delivered via a novel, handheld ozone-generating device for improving pain and function in herniated disc patients., Materials and Methods: A total of 39 patients with contained herniated lumbar discs received oxygen-ozone treatment at 1 of 3 centers. Treatment consisted of injection of 2% ozone (10 mL): 3 mL delivered into the nucleus pulposus and 7 mL delivered into the adjacent paravertebral tissues. The first 8 patients received only ozone injections, whereas subsequent patients also received periganglionic methylprednisolone (40 mg) and 0.5% bupivacaine (1 mL) injections. Patients were evaluated at baseline and at 1 month, 6 months, and 12 months after treatment using the Oswestry Disability Index (ODI) and the Visual Analogue Scale (VAS) for leg pain and for back pain. Analgesic medication use was also assessed at each timepoint., Results: Overall, 91% (32/35) of the per-protocol patients (those who completed follow-up and did not have significant protocol deviations) showed detectable improvement in ODI at 1-month follow-up; this increased to 93% (26/28) of patients at 12-months follow-up. At 1 month after treatment, 60% (21/35) of patients showed significant improvement in ODI scores (P = .01); 54% (19/35) showed significant improvement in VAS scores for leg pain (P = .05); and 49% (17/35) showed significant improvement in VAS scores for back pain (P = .12). At 6 months after treatment, 67% (22/33) of patients showed significant improvement in ODI scores (P = .02); 64% (21/33) showed significant improvement in VAS scores for leg pain (P = .01); and 52% (17/33) showed significant improvement in VAS scores for back pain (P = .12). At 12 months after treatment, 68% (19/28) of patients showed significant improvement in ODI scores (P < .01); 64% (18/28) showed significant improvement in VAS scores for leg pain (P < .01); and 61% (17/28) showed significant improvement in VAS scores for back pain (P = .09). Leg pain typically subsided more quickly than back pain. Use of analgesic medications also significantly decreased at all follow-up timepoints compared to baseline (P < .01). There were no adverse events or device-related issues., Conclusions: At 1, 6, and 12 months after treatment, patients experienced significant improvements in pain and function as well as significantly decreased use of analgesic medication. Taken together with the absence of adverse events at 1-year follow-up, these data suggest that oxygen-ozone treatment is a safe and effective therapy for contained herniated discs., (Copyright © 2018 SIR. Published by Elsevier Inc. All rights reserved.)

Background: Pain of spinal origin contributes significantly to cervical, thoracic, and lower back pain presentations. Such pain originates in the nerve fibers supplying the joints or the surrounding ligaments and intervertebral discs. Although there has been little detailed discussion of spinal bony innervation patterns in the literature, the clinical implications of these patterns are anatomically and medically significant., Methods: The present review provides a detailed analysis of the innervation of the spine, identifying the unique features of each part via online search engines., Conclusions: The clinical implications of these various studies lie in the importance of the innervation patterns for the mechanism of spinal pain. Immunohistochemical studies have provided further evidence regarding the nature of the innervation of the spine.

Background: Although lumbar discectomy for treatment of lumbar disc herniation in the general population generally improves patients' pain, function, and validated outcomes scores, results of treatment in elite athletes may differ because of the unique performance demands required of competitive athletes., Questions/purposes: We performed a systematic review to answer the following questions: (1) What proportion of athletes return to play after lumbar discectomy, and what is the effect of sport? (2) What is the expected recovery time after lumbar discectomy in elite athletes? (3) What is the expected career length and performance of elite athletes after lumbar discectomy?, Methods: We performed a systematic literature review of articles of lumbar discectomy in the elite athlete population through the MEDLINE and EMBASE databases from 1947 to 2013. Elite athletes were defined as professional, Olympic, or National Collegiate Athletic Association Division I collegiate level. A hand search of the references of all key articles was performed to ensure inclusion of all relevant studies. Information regarding study design, types of athletes, level of sport, recovery time, return to sport, length of career after surgery, and career performance after surgery was extracted. Ten articles met the inclusion and exclusion criteria for this review. These articles consisted of levels III and IV data and were graded based on the Methodological Index for Non-Randomized Studies (MINORS) scale., Results: Overall, the studies included in this review found that 75% to 100% of athletes were able to return to elite competition after operative treatment. In general, a higher proportion of baseball players returned to elite competition compared with other athletes. The reported recovery period after lumbar discectomy ranged from 2.8 to 8.7 months. The average career length after lumbar discectomy ranged from 2.6 to 4.8 years. Elite athletes reached an average of 64.4% to 103.6% of baseline preoperative statistics after lumbar discectomy with variable performance based on sport., Conclusions: A high proportion of elite athletes undergoing lumbar discectomy return to play with variable performance scores on return. Future prospective studies are needed to compare the recovery time, career longevity, and performance for athletes undergoing lumbar discectomy versus nonoperative treatment for lumbar disc herniation.

Background: Lumbar disc herniation (LDH) is a common indication for lumbar spine surgery. The proportion of patients having a second surgery within 2 years varies in the literature between 0.5% and 24%, with recurrent herniation being the most common cause. Several studies have not found any relevant outcome differences between patients undergoing surgery for primary LDH and patients undergoing reoperation for a recurrent LDH, but these studies have limitations, including small sample size and retrospective design., Questions/purposes: We (1) compared patient-reported outcomes between patients operated on for primary LDH and patients reoperated on for recurrent LDH within 1 year after index surgery and (2) determined risk factors for worse outcomes., Methods: We obtained data from the Swedish National Spine Register, Swespine, where patient-reported outcomes are collected using mailed protocols at 1, 2, 5, and 10 years after surgery. Of the 13,562 patients identified who underwent LDH between January 2000 and May 2011, 13,305 (98%) underwent primary surgery for LDH and 257 (2%) underwent reoperation for a recurrent LDH within the first year. Patient-reported outcomes at 1 to 2 years were available for 8497 patients (63%), 8350 of 13,305 (63%) in the primary LDH group and 147 of 257 (57%) in the recurrent LDH group (p = 0.068). We compared leg and back pain (VAS: 0-100), function (Oswestry Disability Index [ODI]: 0-100), quality of life (EQ-5D: -0.59 to 1.0), patient satisfaction, and global assessment of leg pain between groups. We also analyzed rsik factors for worse global assessment and satisfaction., Results: Mean (95% CI) differences in improvement between groups favoring patients with primary LDH were VAS leg pain 9 (4-14), ODI 6 (3-9), and EQ-5D 0.09 (0.04-0.15). While statistically significant, these effect sizes may be lower than the minimal clinically important differences often referred to. Percentage of satisfied patients was 79% and 58% in the primary and recurrent LDH groups, respectively (p < 0.001), and percentage of patients with no or better leg pain (global assessment) was 74% and 65%, respectively (p = 0.008). Reoperation for recurrent LDH represented the largest independent risk for dissatisfaction; this factor and smoking represented similar risks for less improvement in leg pain., Conclusions: Repeat surgery for a recurrent LDH was performed with good probability for improvement, although not as good as for primary LDH surgery, and patients undergoing repeated surgery were less satisfied. Studies on risk factors for recurrence are warranted., Level of Evidence: Level II, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Background: The Spine Patient Outcomes Research Trial (SPORT) evaluated the effects of surgery versus nonoperative treatment for lumbar intervertebral disc herniation (IDH), among other pathologies. Multiple subgroup analyses have been completed since the initial publications, which have further defined which patient factors lead to better or worse patient-reported outcomes; however, the degree to which these factors influence patient-reported outcomes has not been explored., Questions/purposes: We reviewed the subgroup analyses of the SPORT IDH studies to answer the following questions: (1) What factors predicted improvement in patient-reported outcomes after operative or nonoperative treatment of lumbar IDH? (2) What factors predicted worse patient-reported outcomes compared to baseline after operative or nonoperative treatment of lumbar IDH? And (3) what factors influenced patient-reported outcomes of surgery in patients with lumbar IDH?, Methods: We conducted a MEDLINE(®) search to identify the subgroup analyses of the SPORT IDH data that were responsive to our study questions. Eleven articles were identified that met our search criteria., Results: The patient factors associated with larger improvements in Oswestry Disability Index at 4 years with either surgical or nonoperative treatment included a higher baseline Oswestry Disability Index, BMI of less than 30, not being depressed, being insured, having no litigation pending, not having workers compensation, and having symptoms for less than 6 weeks, though there were others. Factors leading to improvement with surgical treatment were mostly related to anatomic characteristics of the disc herniation such as posterolateral and sequestered herniations. There were no patient or clinical factors identified that were associated with worse patient-reported outcomes compared to baseline after either operative or nonoperative treatment. At 2-year followup, the treatment effects were greater for those patients with upper-level herniations, patients not receiving workers compensation, and nondiabetic patients. In a 4-year multivariate analysis, being married, without joint problems, and having worse symptoms at baseline resulted in greater treatment effect with surgery., Conclusions: While most patients with IDH will likely see improvement with either surgical or nonoperative treatment, there are patient-related factors that can help predict which subgroups will demonstrate a greater improvement with surgery, such as not having joint problems, being married, having worsening symptoms at baseline, and not having diabetes. These results can help providers and patients when discussing treatment options., Level of Evidence: Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Background: Long-term postdiscectomy degenerative disc disease and low back pain is a well-recognized disorder; however, its patient-centered characterization and quantification are lacking., Questions/purposes: We performed a systematic literature review and prospective longitudinal study to determine the frequency of recurrent back pain after discectomy and quantify its effect on patient-reported outcomes (PROs)., Methods: A MEDLINE search was performed to identify studies reporting on the frequency of recurrent back pain, same-level recurrent disc herniation, and reoperation after primary lumbar discectomy. After excluding studies that did not report the percentage of patients with persistent back or leg pain more than 6 months after discectomy or did not report the rate of same level recurrent herniation, 90 studies, which in aggregate had evaluated 21,180 patients, were included in the systematic review portion of this study. For the longitudinal study, all patients undergoing primary lumbar discectomy between October 2010 and March 2013 were enrolled into our prospective spine registry. One hundred fifteen patients were more than 12 months out from surgery, 103 (90%) of whom were available for 1-year outcomes assessment. PROs were prospectively assessed at baseline, 3 months, 1 year, and 2 years. The threshold of deterioration used to classify recurrent back pain was the minimum clinically important difference in back pain (Numeric Rating Scale Back Pain [NRS-BP]) or Disability (Oswestry Disability Index [ODI]), which were 2.5 of 10 points and 20 of 100 points, respectively., Results Systematic Review: The proportion of patients reporting short-term (6-24 months) and long-term (> 24 months) recurrent back pain ranged from 3% to 34% and 5% to 36%, respectively. The 2-year incidence of recurrent disc herniation ranged from 0% to 23% and the frequency of reoperation ranged from 0% to 13%., Prospective Study: At 1-year and 2-year followup, 22% and 26% patients reported worsening of low back pain (NRS: 5.3 ± 2.5 versus 2.7 ± 2.8, p < 0.001) or disability (ODI%: 32 ± 18 versus 21 ± 18, p < 0.001) compared with 3 months., Conclusions: In a systematic literature review and prospective outcomes study, the frequency of same-level disc herniation requiring reoperation was 6%. Two-year recurrent low back pain may occur in 15% to 25% of patients depending on the level of recurrent pain considered clinically important, and this leads to worse PROs at 1 and 2 years postoperatively.

Degeneration of the intervertebral discs (IVDs) is a major contributor to back, neck and radicular pain. IVD degeneration is characterized by increases in levels of the proinflammatory cytokines TNF, IL-1α, IL-1β, IL-6 and IL-17 secreted by the IVD cells; these cytokines promote extracellular matrix degradation, chemokine production and changes in IVD cell phenotype. The resulting imbalance in catabolic and anabolic responses leads to the degeneration of IVD tissues, as well as disc herniation and radicular pain. The release of chemokines from degenerating discs promotes the infiltration and activation of immune cells, further amplifying the inflammatory cascade. Leukocyte migration into the IVD is accompanied by the appearance of microvasculature tissue and nerve fibres. Furthermore, neurogenic factors, generated by both disc and immune cells, induce expression of pain-associated cation channels in the dorsal root ganglion. Depolarization of these ion channels is likely to promote discogenic and radicular pain, and reinforce the cytokine-mediated degenerative cascade. Taken together, an enhanced understanding of the contribution of cytokines and immune cells to these catabolic, angiogenic and nociceptive processes could provide new targets for the treatment of symptomatic disc disease. In this Review, the role of key inflammatory cytokines during each of the individual phases of degenerative disc disease, as well as the outcomes of major clinical studies aimed at blocking cytokine function, are discussed.

Study Design: A retrospective case-control analysis of prospectively collected data., Objective: First, to evaluate spinal intervertebral mobility in patients with joint hypermobility (JHM) and matched controls without JHM, and second, to investigate the influence of JHM on back pain, disability, and general health status in young males., Summary of Background Data: Despite the significance of benign JHM in the musculoskeletal feature, there have been no studies regarding low back pain and segmental motion in subjects with JHM. Furthermore, the clinical significance of the excessive segmental motion in young males with JHM remains unknown., Methods: The JHM group included 32 subjects who had Beighton scale score of 4 or more according to 9° Beighton scale. The age-matched 32 young males without JHM were selectively included in the control group. In both groups, Oswestry Disability Index (ODI), visual analogue pain scale (VAS) for back pain, and Short-Form 36 was assessed. Radiological sagittal plane motions for each segment and whole lumbar spine were calculated as the difference between the Cobb angle measurements in the flexion and extension plain radiographs. In the lateral radiograph with neutral standing position, the intervertebral disc heights were also measured at each segment., Results: The JHM group showed significantly larger range of motion and higher intervertebral disc height at each matched segment than the control group. The JHM group had significant increased VAS for back pain and ODI score, compared with control group. The Short-Form 36 physical function, role physical, role emotional, and physical component summary in the JHM group were significantly lower than in the control group., Conclusion: This study shows that young males with JHM were found to have excessive lumbar segmental motion that was associated with increased low back pain, disability, and limited physical activity.

Study Design: Prospective, multicenter, single-blind, randomized, controlled clinical study., Objective: To investigate outcomes associated with repairing the anulus fibrosus after lumbar discectomy for the surgical management of herniated nucleus pulposus., Summary of Background Data: In patients undergoing discectomy, the incidence of reherniation ranges from 10% to 15%. Repair of the anulus fibrosus defect after lumbar discectomy may decrease the incidence of recurrent herniation for these patients., Methods: A total of 750 patients were treated for herniated lumbar discs and randomly assigned in a 2:1 ratio to discectomy with the Xclose Tissue Repair System (Anulex Technologies, Minnetonka, MN) for anular repair (n = 500) or discectomy without anular repair (n = 250). Patient self-reported measures included visual analogue scales for leg and back pain, Oswestry Disability Index, and Short Form-12 Health Survey. Adverse events and subsequent reherniation surgical procedures were documented. Preoperative outcome measures were compared with follow-up visits at 2 weeks, 6 months, 1 year, and 2 years., Results: Patient symptoms were improved after surgery in an equivalent manner in both study groups. In the overall study analysis, the rate of reherniation surgery was lower for Xclose patients at all follow-up time points, but these differences were not statistically significant. In patients with predominant leg pain, there was a significant reduction in reherniation risk at 3 and 6 months postoperation for patients receiving Xclose. A positive reduction was maintained through 2 years, with a clinically relevant risk reduction of 45%, although not statistically significant. Safety was demonstrated with similar improvements in patient outcomes and no difference in reported adverse events., Conclusion: Without a safe and effective method for closing the anulus fibrosus after discectomy, current practice has been to leave the anulus in a compromised state. This multicenter randomized study demonstrated that, while not statistically significant, anular repair reduced the need for subsequent reherniation surgery while retaining the benefits of discectomy with no increased risk for patients., Level of Evidence: 1.

Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved., (Copyright © 2012 Sociedad Española de Neurocirugía. Published by Elsevier España. All rights reserved.)

Object: Patients with radiculopathy, with or without back pain, often do not respond to conservative care and may be considered for epidural steroid injection therapy or a disc decompression procedure. Plasma disc decompression (PDD) using the Coblation SpineWand device is a percutaneous, minimally invasive interventional procedure. The purpose of this study was to evaluate clinical outcomes with PDD as compared with standard care using fluoroscopy-guided transforaminal epidural steroid injection (TFESI) over the course of 2 years., Methods: This was a multicenter randomized controlled clinical study. Ninety patients (18-66 years old) who had sciatica (visual analog scale score > or = 50) associated with a single-level lumbar contained disc herniation were enrolled. In all cases, their condition was refractory to initial conservative care and 1 epidural steroid injection had failed. Participants were randomly assigned to receive either PDD (46 patients) or TFESI (44 patients, up to 2 injections)., Results: The patients in the PDD Group had significantly greater reduction in leg pain scores and significantly improved Oswestry Disability Index and 36-Item Short Form Health Survey ([SF-36], physical function, bodily pain, social function, and physical components summary) scores than those in the TFESI Group. During the 2-year follow-up, 25 (56%) of the patients in the PDD Group and 11 (28%) of those in the TFESI Group remained free from having a secondary procedure following the study procedure (log-rank p = 0.02). A significantly higher percentage of patients in the PDD Group showed minimum clinically important change in scores for leg and back pain and SF-36 scores that exceeded literature-based minimum clinically important changes. Procedure-related adverse events, including injection site pain, increased leg or back pain, weakness, and lightheadedness, were observed in 5 patients in the PDD Group (7 events) and 7 in the TFESI Group (14 events)., Conclusions: In study patients who had radicular pain associated with a contained lumbar disc herniation, those patients treated with PDD had significantly reduced pain and better quality of life scores than those treated using repeated TFESI. In addition, significantly more PDD patients than TFESI patients avoided having to undergo a secondary procedure during the 2-year study follow-up.

Background: Nucleoplasty is a minimally invasive procedure for treating pain caused by symptomatic disc herniation that is refractory to conservative therapy. Observational studies have reported differing outcomes for this procedure and thus its effectiveness is yet to be determined., Study Design: A systematic review of the efficacy of the nucleoplasty procedure., Objectives: To assess the clinical efficacy of the nucleoplasty procedure for treating back pain from symptomatic, contained disc herniation and to evaluate the methodological quality of the included studies., Methods: The relevant literature for nucleoplasty was identified through a search of the following databases: Pubmed, Ovid Medline, and the Cochrane library, and by a review of the bibliographies of the included studies. A review of the literature of the effectiveness of the nucleoplasty procedure for managing discogenic pain was performed according to the criteria for observational studies using a "Quality Index" scale to determine the methodological quality of the literature. The level of evidence was classified as Level I, II, or III based on the quality of evidence developed by the United States Preventive Services Task Force (USPSTF) for therapeutic interventions. Recommendations were based on the criteria developed by Guyatt et al., Outcome Measures: The main outcome measures evaluated were the percentage of pain relief based on visual analogue scale (VAS) or numeric rating scale (NRS), percentage of patients with more than 50% reduction in pain, percentage of patients meeting one or more success criteria after nucleoplasty, and improvement in patient function. Secondary measures noted were reports of complications and the Quality Index scores of each study that was evaluated., Results: The quality of evidence for improvement in pain or function after a nucleoplasty procedure is Level II-3. The recommendation is 1C/strong for the nucleoplasty procedure based on the quality of evidence available. The median Quality Index score was 16 (range 12 - 19), indicating adequate methodological quality of the available literature. None of the studies reported major complications related to nucleoplasty., Conclusions: Observational studies suggest that nucleoplasty is a potentially effective minimally invasive treatment for patients with symptomatic disc herniations who are refractory to conservative therapy. The recommendation is a level 1C, strongly supporting the therapeutic efficacy of this procedure. However, prospective randomized controlled trials with higher quality of evidence are necessary to confirm efficacy and risks, and to determine ideal patient selection for this procedure.

Study Design: A retrospective study assessing new adjacent vertebral compression fracture (VCF) after percutaneous vertebroplasty (PV)., Objective: To evaluate the relationship between cement leakage into the disk during initial PV and development of subsequent new adjacent VCF., Summary of Background Data: Cement leakage outside the vertebral body during PV has been reported and usually responds to conservative treatment. Sometimes bone cement may leak into the intervertebral disk and result in painful new adjacent VCF that usually requires another PV for pain relief., Methods: From January 2002 to December 2002, a total of 106 consecutive patients underwent PVs for osteoporotic VCFs. The risk of new fractures of adjacent vertebral bodies, the amount of cement injection, and the duration of development of new adjacent fractures in relation to cement leakage into the disk were retrospectively assessed and statistically compared., Results: New adjacent VCFs occurred in 20 (18.9%) of 106 patients at 22 adjacent vertebral bodies after PVs during at least 24 months of follow-up. The difference in number of new adjacent fractures between both patients and vertebral bodies with cement leakage and those without leakage into the disk were statistically significant (P<0.001 and P<0.001). Amounts of cement injected and duration to development of new adjacent fractures differed between patients with or without cement leakage (P<0.001 and P=0.005, respectively)., Conclusions: PV is a simple and effective, but not risk-free or complication-free procedure for the treatment of osteoporotic VCF. Patients undergoing PV should be informed of the possibility of new adjacent fractures and the higher risk if cement leaks into the disk.

The homeostasis of intervertebral disc (IVD) tissues is accomplished through a complex and precise coordination of a variety of substances, including cytokines, growth factors, enzymes and enzyme inhibitors. Recent biological therapeutic strategies for disc degeneration have included attempts to up-regulate the production of key matrix proteins or to down-regulate the catabolic events induced by pro-inflammatory cytokines. Several approaches to deliver these therapeutic biologic agents have been proposed and tested in a preclinical setting. One of the most advanced biological therapeutic approaches to regenerate or repair a degenerated disc is the injection of a recombinant growth factor. Abundant evidence for the efficacy of growth factor injection therapy for the treatment of IVD degeneration can be found in preclinical animal studies. Recent data obtained from animal studies on changes in cytokine expression following growth factor injection illustrate the great potential for patients with chronic discogenic low back pain. The first clinical trial for growth factor injection has been initiated and the results of that study may prove the usefulness of growth factor injection for treating the symptoms of patients with degenerative disc diseases. The focus of this review article is the effects of an in vivo injection of growth factors on the biological repair of the degenerated intervertebral disc in animal models. The effects of growth factor injection on the symptoms of patients with low back pain, the therapeutic target of growth factor injection and the limitations of the efficacy of growth factor therapy are also reviewed. Further quantitative studies on the effect of growth factor injection on pain generation and the long term effects on the endplate and cell survival after an injection using large animals are needed. An international academic-industrial consortium addressing these aims, such as was achieved for osteoarthritis (The Osteoarthritis Initiative), may further the development of biological therapies for degenerative disc diseases.

Recent basic science studies on discogenic low back pain have provided new knowledge about this condition. This paper reviews some of these results and presents an overview of the following findings. The rat lumbar intervertebral disk may be innervated non-segmentally through the paravertebral sympathetic nerve and segmentally through the sinuvertebral nerves, and also by dichotomizing sensory fibers. The exposure of the nucleus pulposus (NP) to the outer annulus fibrosus (AF) may induce nerve injury and ingrowth into the disk. Nerve growth factor (NGF)-sensitive neurons are predominant in the rat intervertebral disk, which indicates that hyperalgesic responses can be induced by inflammation. NGF in the NP may promote axonal growth. Lumbar fusion may inhibit nerve ingrowth into the degenerated disk and reduce the percentage of calcitonin gene related peptide (CGRP)-positive neurons.

Spinal range of motion is evaluated in assessing patients with back problems and monitoring outcomes, as well as in general fitness assessments. Yet, determinants of the substantial interindividual variation in spinal range of motion are not well understood. Substantial genetic effects on global measures of range of motion and hypermobility have been suggested from earlier studies, but genetic influences specifically on spinal range of motion have not been previously studied. The objectives of the present study were to investigate the relative role of genetic and environmental influences on lumbar range of motion in adult men and the pathways through which genes may influence range of motion. Thus we conducted a classic twin study of 300 monozygotic and dizygotic male twin pairs with consideration of covariates, using standard statistical methods. All subjects underwent a clinical examination, including general anthropometrics, lumbar range of motion, and lumbar MRI to assess disc degeneration, as well as an extensive interview on environmental and behavioral exposures and back pain history. We found the proportion of variance in lumbar range of motion attributable to genetic influences (heritability estimate) to be 47%. The extent of lumbar range of motion in flexion was predominantly determined by genetic influences (64%), while extension was influenced to a somewhat greater degree by environmental and behavioral factors. Statistically significant age-adjusted genetic correlations were found between lumbar extension and disc degeneration variables (r(a) = -0.38 to -0.43) and between flexion and body weight (r(a) = -0.33), suggesting two pathways through which genes influence lumbar range of motion.

This review article describes anatomy, physiology, pathophysiology and treatment of intervertebral disc. The intervertebral discs lie between the vertebral bodies, linking them together. The components of the disc are nucleus pulposus, annulus fibrosus and cartilagenous end-plates. The blood supply to the disc is only to the cartilagenous end-plates. The nerve supply is basically through the sinovertebral nerve. Biochemically, the important constituents of the disc are collagen fibers, elastin fibers and aggrecan. As the disc ages, degeneration occurs, osmotic pressure is lost in the nucleus, dehydration occurs, and the disc loses its height. During these changes, nociceptive nuclear material tracks and leaks through the outer rim of the annulus. This is the main source of discogenic pain. While this is occurring, the degenerative disc, having lost its height, effects the structures close by, such as ligamentum flavum, facet joints, and the shape of the neural foramina. This is the main cause of spinal stenosis and radicular pain due to the disc degeneration in the aged populations. Diagnosis is done by a strict protocol and treatment options are described in this review. The rationale for new therapies are to substitute the biochemical constituents, or augment nucleus pulposus or regenerate cartilaginous end-plate or finally artificial disc implantation..

A significant number of patients who have had surgery for lumbosacral radicular syndrome still have a reduced work capacity several months later. In a prospective cohort study of 182 people who underwent lumbar disc surgery, we determined the predictive value of preoperatively measured cognitive-behavioral and work-related factors on work capacity 6 months after surgery. Logistic regression analyses indicated that these factors independently predicted work capacity 6 months after surgery. Specifically, fear of movement/(re)injury, more passive pain coping, and higher physical work-load predicted reduced work capacity in multiple logistic regression analyses, taking into account the role of a wide range of control variables including demographic variables, preoperative disability and pain intensity, neurological deficits, intake of analgesics, duration of complaints, and pain intensity 3 days postoperatively. The study supports the need to develop and evaluate preoperative risk screening measures that include both cognitive-behavioral and work-related factors and to evaluate the effectiveness of cognitive-behavioral and work-related interventions in patients at risk of reduced work capacity after surgery for LRS.

Smith and Nephew (Endoscopy division, Andover, MA, USA) have estimated that 60,000 Intra-Discal Electrothermal Therapy (IDET) procedures have been performed world wide up to June 2005. Despite the large number of procedures performed, a critical appraisal of the evidence of efficacy of IDET has not appeared in the literature. This paper reviews the current evidence of clinical efficacy for IDET obtained via a systematic review of the literature. Studies were included if they used at least one of four specified primary outcome measures; pain intensity as assessed by a visual analogue score (VAS), global measurement of overall improvement, back specific functional status such as Oswestry disability Index (ODI) and return to work. Levels of evidence were assigned according to the hierarchy described by the Oxford Centre for Evidence-Based Medicine (www.cebm.net). Papers addressing possible mechanisms of action of IDET were not considered as the focus of the literature review was clinical effectiveness. Eleven prospective cohort studies (level II evidence) were reported on a total of 256 patients with a mean follow-up of 17.1 months (range 12-28 months). The mean improvement in the VAS for back pain was 3.4 points (range 1.4-6.5) and the mean improvement in ODI was 5.2 points (range 4.0-6.4). A total of 379 patients were reported in five retrospective studies (level III evidence). Between 13 and 23% of patients subsequently underwent surgery for low back pain within the study period. Two randomised controlled trials of IDET have been reported in the literature. The first randomised 64 patients (37 to IDET, 27 to Sham). The advantage for IDET patients amounted to 1.3 points on the VAS and seven points on the ODI. The second study randomised 57 subjects (38 to IDET, 19 to Sham) and showed no benefit from IDET over placebo. The evidence for efficacy of IDET remains weak and has not passed the standard of scientific proof.

The vertebral endplates are critical for maintaining disc function yet like other components of the disc are vulnerable to degeneration. This paper provides an overview of the development and normal function of the endplates as well as an impression of what happens when they undergo progressive degeneration. Recent research suggests that the degenerative process can be retarded or reversed.

Study Design: A retrospective, long-term follow-up study., Objectives: To find out whether incidental durotomy in lumbar disc surgery is associated with long-term sequelae., Summary of Background Data: Incidental durotomy is a frequent complication during spinal surgery. Little is known about the clinical long-term outcome., Methods: The study population comprised 1,280 patients who underwent standard discectomy of a lumbar disc herniation. A total of 41 patients with incidental durotomies (Group A) were compared with a control group (n = 41) (Group B) matched for age, sex, spinal level, and duration of follow-up. After a mean follow-up period of 10.2 years (Group A) or 10.3 years (Group B), the patients reported complaints, headache, and low back or leg pain. The patients' activity was assessed by means of a questionnaire concerning hindrance in daily activities, the Tegner score for general activities in daily life, and the Hannover Functional Ability Questionnaire for Measuring Back Pain-Related Functional Limitations (FFbH-R). The frequency of reoperation and the intake of analgesics were included. Furthermore, the patients' inability to work, change of profession, and retirement were registered., Results: Patients with incidental durotomy had a poorer outcome after surgery. The Tegner score was significantly decreased for the group with dural tears. Furthermore, significant more patients with incidental durotomy complained about headaches after surgery. A strong tendency for worse outcome in Group A was shown in regard to reported complaints and daily activity. The patients with incidental durotomy had a tendency to more reoperations, a longer duration of inability to work, more back-pain, and functional limitations related to back-pain (FFbH-R)., Conclusion: Our study revealed that incidental durotomy in lumbar disc surgery was associated with long-term clinical sequelae. We therefore conclude that dural tears bring about poor clinical outcome at the long-term follow-up.

This is the first report of clinical and radiologic outcomes for the CHARITE artificial disc with a minimum follow-up of 10 years. A total of 107 patients indicated for total lumbar disc replacement were implanted with the CHARITE prosthesis. Of these 107, 100 were followed for a minimum of 10 years (range 10-13.4 years). A total of 147 prostheses were implanted with 54 one-level and 45 two-level procedures and 1 three-level procedure. The prostheses were placed through a standard anterior retroperitoneal approach. Clinically, 62% had an excellent outcome, 28% had a good outcome, and 10% had a poor outcome. Of the 95 eligible to return to work, 88 (91.5%) either returned to the same job as prior to surgery or a different job. These included 63.2% (12) of those working in heavy labor employment returning to the same job. Mean flexion/extension motion was 10.3 degrees for all levels (12.0 degrees at L3-L4, 9.6 degrees at L4-L5, 9.2 degrees at L5-S1). Mean lateral motion was 5.4 degrees . In the sagittal plane, 9 (6.1%) were anterior of geometric center, 50 (34.0%) were centered, and 88 (59.9%) were posterior of center. In the frontal plane, 110 (75%) were centered, and 37 (25%) were noted to be lateral to center. Slight subsidence was observed in two patients, but they did not require further surgery. No subluxation of the prostheses and no cases of spontaneous arthrodesis were identified. There was one case of disc height loss of 1 mm. Five patients required a secondary posterior arthrodesis. A good or excellent clinical outcome rate of 90% and a return to work rate of 91.5% compare favorably with results described in the literature for fusion for the treatment of lumbar degenerative disc disease. With a minimum follow-up of 10 years, the CHARITE artificial disc demonstrated excellent flexion/extension and lateral range of motion with no significant complications.

Factors such as driving motor vehicles, sedentary occupations, vibration, smoking, previous full-term pregnancies, physical inactivity, increased body mass index (BMI), and a tall stature are associated with symptomatic disc herniations. Fitness and strength is postulated to protect an individual from disc rupture. The objective of our study was to determine the pain levels and differences of functional and economic situations of patients who had undergone one or more than one operation due to lumbar disc herniation and to put forward the effect of risk factors that may be potential, especially from the aspect of undergoing reoperation. Patients who had undergone one (n=46) or more than one operation (n=34) due to lumbar disc herniation were included in the study. It was a prospective study with evaluation on the day the patients were discharged and at second and sixth months after lumbar disc operation. The Oswestry Disability Index (ODI) was used in determining the functional disability associated with back pain; the Prolo Functional Economic Rating Scale (Prolo scale) was used in determining the effect of back pain on functional and economic situations. In the ODI measurements made in the postoperative second and sixth months, significant differences appeared in favor of patients who had undergone one operation (p<0.05). According to the Prolo scale, it was found that the economic situation was better in the sixth month and the functional situation was better in the second and sixth months in patients having undergone one operation (p<0.05). The logistic regression analysis demonstrated that the lack of regular physical exercise was a significant predictor for reoperation (OR, 4.595; CI, 1.38-15.28), whereas gender, age, BMI, occupation, or smoking did not indicate so much significance as regular exercise.

A local inflammatory and potentially painful response, of which the ultimate cause is unknown, has been described in nervous tissues in contact with degenerated disc material in patients with low back and leg pain. With the rationale that a possible cause of such inflammation could be bacterial infection, we utilized PCR (polymerase chain reaction) amplification of the 16S rRNA (ribosomal RNA) gene followed by gene sequencing, to investigate whether bacterial DNA might be detected in the degenerative discs of 10 patients operated for disc herniation or post-discectomy syndrome. One patient with disc hernia harbored DNA homologous to Bacillus cereus, and in one patient suffering from post-discectomy syndrome, Citrobacter braaki/freundii DNA was detected. The finding demonstrates that 16S rRNA PCR can be a useful tool in search of bacterial DNA in degenerated discs, which in turn may be indicative of low-grade infection, manifesting itself only as pain rather than as clinical infection.

Study Design: The author reviewed literature and reports on spine imaging, selected key articles in which novel imaging strategies were described, and prepared a review of currently developing imaging strategies in intervertebral disc degeneration., Objectives: To provide a review of imaging in intervertebral disc degeneration that covers the current methodology briefly and describes developing techniques in detail., Summary of Background Data: Computed tomography and magnetic resonance imaging provide excellent anatomic images of the spine. However, anatomic imaging of the spine does not reliably identify the source of pain in patients with intervertebral disc degeneration. Many functional imaging techniques are suited to the study of the spine. Some of these techniques will improve our understanding of intervertebral disc degeneration and clinical symptomatology., Methods: The author selected reports in the current literature for further review and attempted to describe succinctly the material in the reports that are most relevant to spine imaging., Results: New and potentially useful imaging strategies for spine imaging include dynamic computed tomography, dynamic magnetic resonance imaging, functional magnetic resonance imaging, diffusion imaging, and magnetic resonance spectroscopy., Conclusions: Technological advances in magnetic resonance imaging and computed tomography imaging continue to offer more opportunities to investigate and diagnose back pain and intervertebral disc degeneration.

Background: Previous studies have shown Graf ligament stabilisation procedure to give mixed results in the short to medium term. The aim of this study was to correlate the pre-operative state of the disc, multifidus muscles, age of the patient, levels operated and the clinical outcome after a mean follow-up of 47 months., Methods: Graf ligament stabilisation procedure was carried out in 38 patients between 1996 and 1999. Their post-operative status was assessed using MacNab criteria. The post-operative follow-up was by postal questionnaires and review of the clinical notes. Disc morphology and multifidus muscle wasting was graded blindly and independently. The intra- and interobserver reliability was measured with kappa score and classified using the kappa classification of Landis and Koch. Correlation was measured with the help of Spearman correlation coefficient., Results: Thirty-eight patients (100%) returned the questionnaires. Mean follow-up time was 47.55 months. Fifty-nine levels were operated on. Mean age was 39.68 years. The overall re-operation rate was 15.8%. The intra- and interobserver reliability was graded as good to substantial. Twenty-two patients (57.89%) were satisfied with the procedure. There was no statistically significant correlation between disc morphology, multifidus muscle wasting, sex, age, number of levels operated, the levels operated, and the satisfaction rate., Conclusions: The indications of Graf ligament stabilisation procedure are not clear. Further work is necessary to clearly identify the indication for the procedure.

Aims: The aim of this study is to give a short overview about the innervation of the intervertebral disc and the nerve connections between the somatosensible and autonomous nervous systems in the paravertebral region., Methods: A short review of the clinical and experimental literature including gross-anatomical, histochemical and immunohistochemical studies as well as functional studies after application of tracer substances has been made. We also present our own experimental immunohistochemical and molecular biological investigations on paravertebral muscle biopsies of a patient with post-discotomy syndrome., Results: The annulus fibrosus of the intervertebral disc is innervated by myelinated nerve fibres. Neuronal markers for pain-leading fibres were found to be positive in the dorsal region of the annulus, and especially in the posterior longitudinal ligament. Nerve ingrowth into the diseased intervertebral disc was found in chronic back pain. The main innervation of the intervertebral disc is formed by the sinuvertebral nerves. The sinuvertebral nerves are recurrent branches of the ventral rami that re-enter the intervertebral foramina to be distributed within the vertebral canal. They are mixed polysegmental nerves and nerve plexuses, each being formed by a somatic root from a ventral ramus and an autonomic root from a grey ramus communicans. The number of nerve bundles was reduced by resection of sympathetic trunks. The expression of neuronal markers in the sarcolemma of the paravertebral muscles is reduced after discotomy., Conclusions: The neuroanatomical basis of discogenic pain can be summarised as follows: 1. The intervertebral disc receives an extensive innervation, especially the annulus fibrosus. 2. Nerve extension was found into the nucleus pulposus of the degenerated disc. 3. The sinuvertebral nerve plexuses facilitate a polysegmental signal and pain spreading. 4. The innervation of the intervertebral disc is very high connected with the paravertebral muscles. 5. A local denervation of the paravertebral muscles was found in post-discotomy syndrome.

A newly designed technique for a minimally invasive approach to the laterally herniated disc is presented. Fifteen patients suffering from far lateral disc herniation (extraforaminal) were operated according to this technique. Through a small skin incision (1.5 cm), the paraspinal muscles are spread by dilators, until a working channel of 9 mm inner diameter and 11 mm outer diameter can be placed. The next steps are done through this channel using the surgical microscope. No bone resections are necessary and the facet joints are left untouched. However, partial resection of the intertransverse ligament may be necessary. The mean follow-up period for these 15 patients was 11.5 months, and they were evaluated by using the visual analogue scale (VAS) and the Oswestry Disability Index (ODI). The average surgical time was 43 min. The ODI improved from 30.6 (preoperative) to 14.3 (postoperative). The VAS of leg pain improved from 7 (preoperative) to 3.6 (postoperative), which represented a statistically significant improvement at the significance level of (P<0.01). No intra-operative or early postoperative complications occurred. However, one recurrence did occur, which was treated by the same technique. This technique combines the advantages of three-dimensional visual control (operating microscope) with the minimal surgical trauma of endoscopic techniques, while avoiding some of the shortcomings of both the microsurgical and endoscopic techniques.

The oncoproteins c-Fos and c-Jun create a transcriptional site early response activating protein (AP-1) mediating the regulation of gene expression in response to extracellular signalling by, for example, cytokines. These proteins are important in the signalling pathway from the cell membrane to the nucleus. Previously, oncoproteins have been located in articular synovium and in chondrocytes, participating in transcription. There is, however, no such study of intervertebral disc tissue. In disc degeneration and after herniation, cell proliferation markers have been demonstrated. In the present study we visualize the AP-1 transcriptional site factors c-Fos and c-Jun in 38 human herniated intervertebral disc tissue samples by immunohistochemical staining with monoclonal antibodies. No immunoreactivity could be observed in control disc tissue, indicating that after herniation, disc cells are entering from the resting stage to the cell cycle. Furthermore, c-Jun immunoreactivity was also observed in disc cell clusters, thus demonstrating them to be active transcriptional sites in disc tissue. c-Fos immunoreactivity was seen in 15/38 and c-Jun in 28/38 herniated discs (39% and 74% respectively). Immunopositive groups of disc cells were noted in 7/28 (25%) of the oncoprotein-immunopositive samples. We did not see any difference in immunoreactivity between female and male patients. Furthermore, we did not notice any statistical difference regarding the immunoreaction for proto-oncogenes c-Fos and c-Jun in extrusions, sequesters and protrusions. Nor did immunostaining show any significant relationship with preoperative pain duration. We concluded that, in herniated disc tissue, the oncoproteins c-Fos and c-Jun are activated in disc cells and cell clusters. In the future, learning more about this transcriptional signal pathway may result in new specific treatments for intervertebral disc pathology.

After a review of disk structure, the pivotal role of disk cells in producing and renewing the extracellular disk matrix is emphasized. Disk cells rely on nutrients that diffuse through the vertebral endplates. Microelectrode methods have been developed to study nutrient diffusion and endplate permeability. Mechanical stimuli modify disk cell activity. Scoliosis is associated with decreased endplate permeability, a factor that may play a role in disk degeneration and scoliosis progression.

Nucleus pulposus herniations are far less common in the thoracic spine than at the cervical and lumbar regions. Traditionally, diagnosis of thoracic disc herniations has been challenging because the signs and symptoms are often subtle early in their course. As a result, delays in diagnoses are common. Because they are uncommon as well as difficult to diagnosis, the neurosurgical community has sparse data on which to base good clinical decision making for the treatment of these herniations. In this review the authors seek to place the phenomenon of thoracic disc disease into the context of its pathophysiology. After a careful evaluation of the available clinical, pathological, and basic science data, a case is made that the cause of nucleus pulposus herniations in the thoracic spine is similar to those occurring in the lumbar and cervical regions. The lower incidence of herniations is ascribed primarily to the reduced allowable flexion at the thoracic level compared with the lumbar and cervical levels. To a lesser extent, the contribution of the ribs to weight-bearing may also play a role. Further review of clinical data suggests that thoracic disc herniations, like herniated cervical and lumbar discs, may be asymptomatic and may respond to conservative therapy. Similarly, good surgery-related results have been reported for herniated thoracic discs, despite the more challenging nature of the surgical procedure. The authors conclude that treatment strategies for thoracic disc herniations may logically and appropriately follow those commonly used for the cervical and lumbar levels.

Objective: The purpose of this study was to determine whether pain location indicated in pain drawings was related to the specific lumbar disc level(s) that was abnormal in appearance and painful upon discographic injection., Design: Data were collected prospectively., Setting: This study was conducted in a spine specialty clinic., Patients: The study group consisted of 187 patients (118 men, 69 women; mean age = 37.2 years, range = 18-62 years) with low back pain with or without leg pain. All patients were undergoing computed tomography (CT)/discography at the three lowest lumbar levels for diagnostic purposes., Interventions: Pain drawings were completed the day of but prior to undergoing discography. Discographic pain responses were recorded with respect to the similarity to the patient's clinical symptoms. Pain drawings were classified based on the presence or absence of pain in five areas: low back and/or buttocks, posterior thigh, posterior leg, anterior thigh, and anterior leg. The drawings were scored with the system described by Ransford et al. (1976, Spine 1: 127-34), and those likely to be indicative of psychological problems were analyzed separately (n = 43)., Outcome Measures: Results were determined by analyzing the relation between the location of pain in the drawings and the specific lumbar disc level(s) found to be painful and disrupted by discography., Results: There was a significant relation between pain location indicated in the drawing and the lumbar disc level(s) identified as clinically painful and disrupted by CT/discography (p < 0.05, chi-square). Pain limited to the low back and buttocks was frequently associated with the absence of disc pathology (58.3%). When pain in the posterior thigh or leg was present but there was no pain in the anterior drawing, patients frequently had a positive L5-S 1 disc (> or =75%). In patients with anterior thigh pain, with or without posterior thigh or leg pain, the L4-5 disc was frequently symptomatic (>63%). The pattern of no posterior thigh or leg pain but with pain radiating into the leg anteriorly was most commonly associated with the L3-4 disc (71.4%)., Conclusions: The results of this study indicate that pain drawings may be helpful in identifying which specific discs are associated with pain complaints. As with any evaluation, the drawings should be considered in combination with findings from other assessments.

Two cases of intervertebral disk infection in 2 3-year-old boys are presented. The study reported on the anamnesis, clinical, laboratory and instrumental findings as well as therapy in both cases. Diagnosis was suspected on the basis of pain, refusal to assume any position that flexes the spine and irritability. Low-grade fever, the moderate increment of inflammatory indexes and the characteristic changes seen in 1 case on Magnetic Resonance Imaging (MRI) only and in the other one on both Technetium 99m polyphosphate bone-scanning and MRI verified the clinical diagnosis. Furthermore the authors briefs discuss the differential diagnosis of disc-space inflammation and several acute and subacute diseases of infancy and childhood some of them not localized in the spine (myopathy, appendicitis, peritonitis, urinary infections) for which discitis may be often mistaken.

A study was made of the association between disc degeneration observed in plain radiographs, in discograms (Adams' classification), and instability expressed as abnormal angular movement of lumbar vertebrae. The series included 169 discs in 77 consecutive patients (42 men, 35 women) whose mean age was 34 (range 16-46) years. Discography was more sensitive than plain radiography in the diagnosis of disc degeneration was more common in men than in women (Chi square test, chi 2 = 9.88, p less than 0.05). An increase in disc degeneration was observed in lower lumbar segments (Chi square test, chi 2 = 48.63 p less than 0.001). However, no association between abnormal angular movement and discogram type was observed (Chi square test, chi 2 = 2.63, p less than 0.05). It seems that disc degeneration seldom results in abnormal angular movement and instability of the lumbar spine. Therefore, flexion-extension radiography may only have limited diagnostic value.

Low-back pain is a common ailment. Much is known of the pain-sensitive structures of the low back, but for a patient with acute low-back pain the cause can rarely be defined. Although the biochemical properties of the intervertebral discs and their degenerative changes have been unraveled, it is difficult to distinguish between pathological degeneration and normal changes due to aging. As a consequence of the problems in diagnosing back diseases, the most common measure of low-back morbidity in epidemiologic studies has been the occurrence of symptoms. A wide spectrum of work- and individual-related factors have been found to be associated with low-back pain, but little is known about the extent to which these factors are etiologic and the extent to which they are symptom-precipitating or symptom-aggravating.

There are strong indications that whole body vibrations are involved in the pathophysiology of different spinal aberrations known or assumed to generate back pain and sciatica. There also are several possible pathogeneses for these pathologic changes, although the proofs still are inconclusive or lacking. A better understanding of the relationships between vibration and spinal disorders in the near future will help us to prevent the occurrence of some of the problems causing pain and disability.

Swelling of the intervertebral disc nucleus pulposus may be a contributing factor in lower back pain syndromes. We have designed and tested a new osmometer for in vitro determination of nucleus pulposus swelling pressure. The functional principle of the osmometer involves compressing a sample of nucleus pulposus with nitrogen gas until saline pressure gradients across a 0.45-micron Millipore filter are eliminated. Swelling pressures of both pooled dog and pooled pig lumbar disc nucleus pulposus were measured on the new osmometer and were compared with swelling pressure determined using the equilibrium dialysis technique. The osmometer measured swelling pressures comparable to those obtained by the dialysis technique. This osmometer provides a rapid, direct, and accurate measurement of swelling pressure of the nucleus pulposus.

Diurnal changes in the loads acting on the spine affect the water content and height of the intervertebral discs. We have reviewed the effects of these changes on spinal mechanics, and their possible clinical significance. Cadaveric lumbar spines subjected to periods of creep loading show a disc height change similar to the physiological change. As a result intervertebral discs bulge more, become stiffer in compression and more flexible in bending. Disc tissue becomes more elastic as its water content falls, and its affinity for water increases. Disc prolapse becomes more difficult. The neural arch and associated ligaments resist an increasing proportion of the compressive and bending stresses acting on the spine. Observations on living people show that these changes are not fully compensated for by modified muscle activity. We conclude that different spinal structures are more heavily loaded at different times of the day. Therefore, the time of onset of symptoms and signs, and any diurnal variation in their severity, may help us understand more about the pathophysiology of low back pain and sciatica.

The experimental data about the strain of intervertebral discs and vertebral bodies under physiologic loads are described; the relation between tissue strain, mechanically induced damage and clinical symptoms in the region of the lumbar spine is discussed. With reference to a paper by Kirkaldy-Willis and Farfan on "Instability of the Spine" a new representation of the interrelation between mechanical factors, pathologic changes and psychic influences in the development of low back pain is given.

Anatomical data on lumbar spine allow to insist on the spinal motion segments and on their nerves, all essential notions to understand lumbar pain.