Background

Intervertebral disc cells exist in a challenging physiological environment. Disc degeneration occurs early in life implying that disc cells may no longer be able to maintain a functional tissue. We hypothesise that disc cells have a stress response different from most other cells because of the disc environment. We have compared the stress response of freshly isolated and cultured bovine nucleus pulposus (NP) cells with bovine dermal fibroblasts, representative of cells from a vascularised tissue.

Background

Proteoglycans (PGs) have long been known to be important to the functioning of the intervertebral disc. The most common PG is aggrecan, but there are also small leucine-rich proteoglycans (SLRPs) which constitute only a small percentage of the total PGs. However, they have many important functions, including organising the collagen, protecting it from degradation and attracting growth factors to the disc. We have examined how the core proteins of these molecules vary in intervertebral discs from patients with different pathologies.

Introduction: Several small leucine-rich proteoglycans (SLRPs) are involved in the regulation of collagen fibril size(s) in a variety of different soft and hard musculosk-eletal tissues. In the intervertebral disc (IvD) the major SLRPs involved in regulation of types I & II collagen fibril size are believed to be decorin, fibromodulin and lumican. Research into IvD degeneration and backpain is hampered by a lack of specific biomarkers to detect and monitor the disease process. We have discovered that two keratan sulphate (KS) substituted members of the SLRP family, Keratocan and Lumican (that are major KS-pro-teoglycans found in cornea) were unusually expressed in extracts from degenerative disc tissues.

Methods: Non-degenerate disc tissue (n=10) was obtained from 2 scoliosis patients and degenerate disc tissue from 11 patients undergoing surgery. The degenerate discs were graded using criteria described by Pfir-rman et al (Spine26: 1873; 2001). Tissue samples were extracted with 4M guanidine HCl and after dialysis subjected to SDS-PAGE and Western blot analyses using monoclonal antibodies that recognise epitopes on kera-tocan and lumican.

Results & Discussion: Keratocan was not found in the non-degenerate disc tissue but was present in all degenerate IvD tissues tested. Lumican showed and increased expression in extracts of degenative IvD tissues. Our working hypothesis is that the increased expression of these two SLRPs in degenerative disc tissue results from a reparative depostion of a type I collagen fibrillar ‘scar’. This unusual expression suggests their potential as biomarkers for detecting the onset of degenrative disc disease.

Background: Many studies have examined magnetic resonance images (MRI) with a view to the anatomy and signaling properties of the intervertebral disc and adjacent tissues in asymptomatic populations. In this study we have examined MRIs of a discrete population of patients undergoing surgery for symptomatic disc herniations.

Methods: Sixty patients (aged 23–66 years, mean 41.5±8.4) had sagittal T1 and T2- weighted turbo spin echo imaging of the lumbar spine prior to surgery. One disc was herniated at L2-3, 3 at L3-4, 22 at L4-5 and 31 at L5-S1; 3 patients had herniations at both L4-5 and L5-S1. The images were scored for disc narrowing and signal, degree of anterior and posterior bulging and herniation, and assessed for Modic I and II endplate changes and fatty degeneration within the vertebrae. These were carried out for each of 6 discs (T12-S1) for all patients (ie 360 discs and 720 endplates).

Results: There were trends of increasing disc narrowing, disc bulging and fatty degeneration with increasing age in these patients. 83% of patients had disc bulging, 53% had endplate irregularities and 44% had fatty degeneration. There was a significant correlation between patient weight and fatty degeneration. 7.5% of vertebrae (in 22% of patients) demonstrated Modic I changes whilst Modic II changes were seen in 14% of vertebrae (40% of patients). This is considerably higher than the incidence reported in asymptomatic individuals where Modic I changes were seen in 0.7% of vertebrae (3% of individuals) and Modic II changes in 1.9% of vertebrae (10% of individuals).

Conclusion: There is a higher incidence of Modic I and II changes in disc herniation patients than in asymptomatic individuals.

Introduction: Autologous chondrocyte implantation is routinely used for the repair of articular cartilage defects. A similar method may be employed to treat degenerate intervertebral discs or other connective tissues. A system in which cells could not only be delivered, but also retained would offer advantages compared to ACI. Such a vehicle would also allow a homogenous distribution of cells throughout the defect and enhance nutrient penetration to the seeded cells.

Methods: Bovine nucleus cells were isolated via enzyme digestion and expanded in number to passage 3. The cells were resuspended in 0.8% alginate and loaded into poly vinyl alcohol (PVA) cubes. These constructs were placed into a solution of calcium chloride to ‘gel’ the alginate. Constructs were cultured in DMEM+10% FBS within 15ml conical tubes rotated at 37°C for up to 28 days. Cell distribution/morphology and proliferation were assessed on H& E and Ki-67 stained sections, respectively. The re-expression of a disc cell phenotype was assessed using toluidine blue staining and immunohistochemistry (with antibodies to collagen types I, II, IIA, VI and X, and to the glycosaminoglycans, chondroitin-4- and -6-sulphate and keratan sulphate. RT-PCR was performed using oligonucleotide primers to collagen types I, II and X, aggrecan, link protein, and small leucine-rich PGs.

Results: H& E staining of 10μm-thick cryosections revealed an even distribution of loaded cells throughout the scaffold at day 1 being maintained through to day 28. Toluidine blue staining revealed the presence of GAGs, increasing with time. Ki-67 revealed approximately 5% of cells were proliferating at all time points. Immunohistochemistry demonstrated the production of collagen types I, II, IIA, VI and X and the glycosaminoglycans, chondroitin-4-, -6 and keratan sulphate. RT-PCR results showed mRNA expression of fibromodulin throughout the experiment, lumican at days 14, 21 and 28. Types II and X collagen were present at days 21 and 28.

Conclusions: Combining 0.8% alginate with PVA retained 100% of the seeded cells and allowed an even distribution of cells throughout the scaffold. The immunohistochemistry and RT-PCR demonstrated that the system allowed the bovine nucleus cells to express phenotypic markers expressed by disc cells in vivo. These preliminary results indicate that the PVA/alginate system could act as a suitable delivery device for cells during autologous repair of the intervertebral disc or other connective tissues such as meniscus.

Introduction: Proteoglycans are found both in the annulus fibrosus and nucleus pulposus of the intervertebral disc and contribute to the hydration of the tissue (aggrecan) and the regulation of matrix assembly (small proteoglycans) [1]. Whilst loss of proteoglycan is the main chemical change in disc degeneration seen in back pain patients, little is known of the events leading to and controlling this loss. In this study the metabolism of the most common proteoglycan, aggrecan, and others including decorin, biglycan, lumican, fibromodulin and versican, together with collagen types I and II were studied in diseased and normal discs.

Methods: Ten discs from patients aged 11–57 years (mean:39±15) with scoliosis (n=1), spondylolisthesis (n=1) and low back pain (n=8), were graded for macroscopic degeneration (Grades 1–4). Three ‘normal’ cadaveric discs from 3 individuals aged 25–27 years (mean 26±1) were also investigated. Disc was either snap-frozen (for RNA isolation) or the proteoglycans extracted with 4M GuHCl. Total RNA was isolated and RT-PCR performed using various oligonucleotide primers. GuHCl-extracted proteoglycan fragments were analysed using Western blotting with a number of antibodies to aggrecan metabolites, collagen metabolites and small leucine-rich proteoglycans.

Results: Intervertebral discs contain a very heterogenous population of proteoglycans demonstrating extensive enzymic degradation, particularly with increasing age and macroscopic degeneration such as is seen in back pain patients. Younger, less degenerate discs contained more biglycan than the older, more degenerate discs. However, the mRNA gene expression analyses demonstrated little cellular activity and potential synthetic response, there was very little expression of particularly in comparison to osteoarthritic cartilage cells which show considerable synthetic capability for all the major matrix components.

Discussion: Our analyses indicate that several biochemical, catabolic and biosynthetic changes occur in disc matrix molecules which are likely to contribute to loss of disc function with ageing and degeneration. The loss of biosynthetic capability of cells is very important in considering the potential of newer therapeutic modalities such as cellular repair and genetic engineering for the treatment of degenerative disc disease.

Problem Chronic disabling pain in the sacrococcygeal region is regarded by clinicians with great dismay because of unpredictability of the treatment outcome. The subject is under- represented in the literature.

Method Thirty eight patients with intractable coccydynia had imaging investigations for the spine other than X-rays. Six of these patients were also investigated by means of sacrococcygeal and intercoccygeal discography. The excised specimen with intact sacrococcygeral joint was sent for histological examination in 22 patients. Patients’ assessment of the benefit of coccygectomy was conducted by telephonic interview.

Results After a mean post surgical follow up of 6.75 years (range 2–16 yrs), results were available for 31 out of 38 patients.

16 patients benefited greatly from the surgery and 6 benefited to some extent, giving an overall good result of 71%. 7 patients had no or little relief from surgery (29%).

Moderate to severe degenerate changes in SC and IC joints on histology were found in 59% of patients. 91.6 % of these patients did well with surgery. Only 60 % of those with mild changes did well.

Discography was possible in five out of six attempted cases. Two were positive and both did well from surgery. Three patients had negative discographies and two of them had a poor result and one had only some relief.

Conclusions Degenerate changes in sacrococcygeal discs give rise to pain. Surgical results are better in those with a severe degree of degenerative change. It is possible to identify these with discography, though a larger study needs to be carried out.

Background: Growth and development of the intervertebral disc and its adjacent vertebrae is regulated via relative levels of cell proliferation, cell death and hypertrophy, and through extracellular matrix synthesis or degradation [1]. The synthesis of matrix molecules in the growing spine of embryonic rats has been reported in some detail [2,3]. In addition, increased levels of apoptotic disc cell death have been described in normal ageing, disc degeneration and in a murine model of disc spondylosis [4,5]. However, levels of cell proliferation in the developing spine have not been formally investigated.

Methods/Results: BALB/c mice were injected with the thymidine analogue, bromodeoxyuridine (BrdU), at weeks 1–4 postnatally and killed 1 or 24 hours later. The lumbar spines were decalcified and tissue sections immunostained for BrdU-incorporation. The intervertebral disc was fully formed at weeks 1–4, consisting of a notochordal nucleus pulposus, lamellar anulus fibrosus, and cartilaginous endplates between the disc and vertebral growth-plates. BrdU-immunopositivity was most marked in 1 week old mice, particularly in the proliferative zone of the growth-plate and the apophyseal ring. By 4 weeks, few, if any, BrdU-labelled cells were present in the disc, but some positivity remained in the apophyses. There were more paired BrdU-labelled cells at 24 hours than 1 hour post-injection in all regions, indicating likely clonal growth of these cells.

Conclusions: Cell proliferation forms an important part of the growth of the vertebrae, but also features in the early postnatal growth of the murine intervertebral disc. An understanding of how proliferation in these cell populations is regulated will help augment repair and regenerative responses in damaged adult discs or scoliosis.

Introduction: Degeneration of the intervertebral disc is characterised by loss of normal cell activity, disc matrix and loss of disc height. There is currently much interest in using cells to effect a biological repair in connective tissues, eg autologous chondrocyte implantation for cartilage repair. Intervertebral discs have a low cell density, with those cells present often being unhealthy and necrotic. Hence, identification of an alternative source of cells for autologous disc repair could be beneficial. Thus we have investigated other types of connective tissue cells to determine if they may be encouraged to undertake a disc cell phenotype.

Materials and Methods: Cells were enzymatically/mechanically extracted from bovine coccygeal discs (annulus and nucleus), skin, bone marrow, periosteum and tendon and the efficiency and proliferation rates assessed. Dermal fibroblasts and bone marrow cells were also grown in a 3D alginate system and compared to disc nucleus pulposus cells for phenotypic expression from 0–28 days. Cell phenotype was assessed via morphology, immunohistochemistry, Western blotting and RT-PCR for mRNA expression.

Results: All cell types could be extracted and proliferated in monolayer, with a flattened and fibroblast-like morphology. Proliferation was slowest for bone marrow cells (4 times slower than nucleus pulposus cells). Cells cultured in alginate became rounded with chondrocyte-like morphology. They remained viable for 4 weeks, but with little replication. Expression or production of proteoglycans, both aggrecan and the small proteoglycans (especially fibromodulin) and collagen types I, II and X was demonstrated for all cell types. There was, however, a difference in the timescale of production between some cell types.

Conclusions: Plasticity of different cell types is well known and the connective tissue cells investigated in this study are capable of responding to the environment in which they are cultured. They can synthesise matrix molecules typically produced by disc cells in vivo and hence warrant further investigation as a potential source of cells for biological repair of the intervertebral disc.

Background: Intervertebral motion is often assumed to be altered with back pain, however, the patterns are inaccessible to measurement in live subjects. A method for digitally tracking and analysing fluoroscopic images of the vertebrae of subjects who are undergoing standardised passive motion has recently been brought into clinical use for the assessment of surgical fusions. We have studied the differences between the behaviour of spinal linkages in subjects who are asymptomatic, and those who have had fusion operations. This paper describes the reliability, ranges and qualitative features of intervertebral motion patterns in 27 asymptomatic subjects and 3 fusion patients.

Methods and results: Thirty asymptomatic male volunteer subjects aged 19–40, underwent 2 –20 second sessions of fluoroscopic screening during 80 degrees of lumbar spine bending within 20 minutes of each other. Intervertebral sidebending motion from L2–5 was measured in 27 subjects whose images were judged suitable for tracking. Approximately 120 digitised images throughout each motion sequence were analysed 5 times by 2 blinded observers for intervertebral range and each result averaged. The intra-subject biological error (RMS), for range of intervertebral motion was 2.75° for Observer1 and 2.91° for Observer 2. The interobserver error for tracking the same screenings was 1.86° (RMS). At almost all levels, these motion patterns were remarkably regular.

Four male patients aged 33, 44, 45 and 52 years, who had undergone different spinal stabilisation procedures consisting of flexible stabilisation (DNESYS), posterior instrumented fusion, and anterior interbody fusion with facet fixation were investigated. Images were acquired and analysed in the same way except that a larger number of images (500 per screening) was utilised in each case. Four operated levels and 2 adjacent levels were analysed. All motion patterns were easily distinguishable from those of the normal subjects. The PLIF and DYNESYS stabilisations demonstrated no motion at the instrumented levels. The anterior inter-body fusion-transfacet fixation patient was shown to have developed a pseudarthrosis.

Conclusions: Detailed lumbar intervertebral bending patterns in asymptomatic subjects were distinguishable from the fused and adjacent-to fused segments in operated patients. Results suggest that there is sufficient reliability in the method to evaluate lumbar intersegmental ranges and motion patterns for fusion assessment.

Background: Increased nerve growth into degenerated intervertebral discs is associated with discogenic low back pain [1]. Many of these growing nerves are in neo-vascularised areas of the tissue [1,2] and endothelial cells that penetrate the disc express neurotrophic factors [3]. Thus, disc neovascularisation and disc innervation may be closely linked. Whilst disc aggrecan has been found to inhibit sensory nerve growth in vitro [4], the effects of disc aggrecan on endothelial cells are unknown.

Methods/Results: Adapting in vitro assays used previously [4], with HMEC-1 and EAhy-926 cell lines as models of endothelial cell growth, we found that disc aggrecan inhibited endothelial cell migration in a dose-dependent manner. Endothelial cells traversed over collagen substrates until they encountered disc aggrecan substrates (1mg/ml human aggrecan), where they either stopped migrating or, more commonly, changed their direction of movement and aligned to the collagen:aggrecan border (Figure 1). After reaching the aggrecan border, some endothelial cells also migrated away from the disc aggrecan. At lower concentrations of disc aggrecan (0.01mg/ml), no such inhibition of endothelial cell growth was seen.

Conclusions: Loss of aggrecan, increased innervation and neovascularisation are all marked features of disc degeneration [1,2,5]. This study provides evidence that disc aggrecan inhibits endothelial migration and therefore supports a hypothesis that a loss of aggrecan from degenerated discs predisposes the tissue to vascular invasion.

Background: The prospect of a second operative procedure following an apparently unsuccessful spinal fusion is an unwelcome one. Since 1987, we have worked to develop an objective method of measuring the motion between vertebrae from fluoroscopic images. Successive versions have been evaluated for their reliability and validity. However, only the current one combines sufficiently reduced operator interaction with acceptable error limitation to be operationally useful as a tool for reporting findings about graft integrity for spinal surgeons. The current work brings this to an advanced prototype stage.

Methods and results: The measurement of lumbar intervertebral coronal and saggital plane motion in vivo using this technique is in 3 stages: Fluoroscopic screening of patients lying on a passive motion table Co-ordinated real-time digital acquisition of the intensifier images.

Registration of the images of each vertebra by templates which are automatically tracked and whose output is converted to inter-vertebral kinematic parameters and averaged for display and reporting.

Results are currently displayed as inter-vertebral angles throughout the motion that indicate whether or not solid fusion has been achieved. The Instrument Measurement Error is quantifiable and will vary with image quality, but can be improved by averaging. The technology is applicable to any imaging system of sufficient speed and resolution and may, for example, be used with MR in the future.

Conclusions: An advanced prototype version of this device is now approaching readiness for service as a routine procedure for use by specially trained radiographers. Its limitations will be determined mainly by the quality of the intensifier images. This can be expected, in the future, to benefit from yet further advances in the technology.

Objective: This study investigates whether fixation down to lumbar spine only can prevent pelvic tilt compared to pelvic fixation, in the surgical treatment of Duchenne Muscular Dystrophy (DMD).

Design: Retrospective and prospective clinical outcome study, with long-term follow up.

Materials and Methods: Nineteen cases of DMD with scoliosis had early stabilisation (mean age 11.5 years, range 9–16) with sublaminar wires and rods, and pedicle screws up to the lumbar spine. This cohort was followed up for a mean 4.2 years (3–10 years). 31 cases in another centre had late stabilisation (mean age 14.5 years, range 10–17), with Luque rod and sublaminar wire fixation, and pelvic fixation using L-rod (22 cases) configuration or Galveston technique (9 cases) and were followed up for 4.6 years (0.5–11.5 years). Post-op morbidity, Cobb angle correction and pelvic obliquity data were collected retrospectively and prospectively for comparison.

Results: In the lumbar fixation group FVC was 58%, the mean Cobb angle and pelvic obliquity were 19.8° and 9° preoperative, 3.2° and 2.2° direct postoperative, and 5.2° and 2.9° at final follow up respectively. The mean estimated blood loss was 3.3 litres and average hospital stay 7.7 days. In the pelvic fixation group FVC was 44%, the mean Cobb angle and pelvic obliquity were 48° and 19.8° preoperative, 16.7° and 7.2° direct postoperative, and 22° and 11.6° at final follow up respectively. The mean blood loss (4.1 litres) and the average hospital stay (17 days) were significantly higher (p< 0.05) compared to the lumbar fixation group. The pelvic fixation group had higher complication rate at the lower end of fixation. No progression of the pelvic obliquity was noted in the lumbar fixation group during follow up

Conclusion: Lumbar fixation may be adequate for scoliosis in DMD, if the stabilisation is performed early, before the pelvis becomes tilted, and scoliosis becomes significant. The caudal pedicular fixation in the lumbar spine stops rotation of the spine around the rods, and prevent pelvic tilt to occur. Pelvic fixation may be necessary in presence of established pelvic obliquity and larger scoliosis, but is associated with higher morbidity and complications.

Background: The healthy, adult human disc is innervated but the nerves are restricted to the outer few millimetres of the annulus fibrosus. In degenerate discs with associated back pain, however, the nerves are more numerous and penetrate further in.

We have used a sheep model of intervertebral disc degeneration to monitor the presence and organisation of nerves in the disc as degeneration progresses. This model has been used to study morphological and bio-chemical changes of the disc as it degenerates, in addition to associated alterations in end-plate vascularity and vertebral bone remodelling. One aspect of this model which has not been studied to date is how the innervation of the disc may change with the onset of degeneration. This is the object of the present study.

Materials and Methods: Four-year old, skeletally mature Merino wether sheep (n=64) were divided randomly into lesion and control groups. A surgical incision was created in the anterolateral annulus in the L1–L2 and L3–L4 discs of the lesion group. The control group received the same retroperitoneal surgical approach but the annulus was not incised. Intact lumbar discs encompassed by adjacent vertebral bodies were removed at 3,6,12 and 26 months post operation. Specimens were fixed, decalcified and paraffin embedded before sectioning (7μ thick, vertical sagittal sections) and stained immunohistochemically with the neuronal marker, PGP9.5, together with standard histological stains.

Results: The incised region of the outer annulus underwent collagenous re-organisation, consistent with an active repair process as early as three months post-operatively. However, the inner annular lesion had a poor repair response and propagated with time, sometimes through to the nucleus. In contrast, remodelling of the outer annular lamellae occurred across the cut region. For example, in one sample at two years post injury there were up to six lamellae “bridging the gap”. Nerves were present in all samples but in the sham animals they were very few and confined to the very outer annulus or longitudinal ligament. In the operated animals, nerves were more extensive, occurring in the matrix adjacent to the fissure where there was often blood vessel ingrowth. The maximum number of nerves was seen at 12 months post-operatively, before diminishing in number at 24 months post-op. This paralleled the presence and extent of blood vessel penetration in this experimental model.

Conclusions: We have used an animal model to follow longitudinally the penetration of nerves into the ovine intervertebral disc in association with disc degeneration. Whilst we obviously cannot assess back pain in these animals, and not all nerves are nociceptive, nerves nevertheless are a pre-requisite for the perception of pain. Hence the greater numbers, size and penetration of nerves into degenerate discs demonstrated here has important implications not only for the aetiopathogenesis of degenerative disc disease but also for the treatment of its associated symptoms. Further characterisation of this innervation, i.e. whether autonomic or sensory, may provide an indication as to its nociceptive potential.

Introduction: Intervertebral disc degeneration occurs with ageing and is often associated with back pain. During such degeneration, gross morphological differences between the central nucleus pulposus (NP) and outer annulus fibrosus (AF) are lost and the disc loses hydration and height due to decreased proteoglycan content. The cartilage endplate may also become calcified and this blocks the passage of nutrients into the disc, causing cell death and further degeneration. A potential therapy of degeneration is “re-inflation” of the disc with the use of hydrogels seeded with autologous disc cells. In this study, we have assessed the ability of a variety of hydrogels to support intervertebral disc cell growth.

Method: Intervertebral disc cells were isolated enzymatically from bovine tails and cultured as a monolayer in 10% foetal calf serum in DMEM containing antibiotics and ascorbic acid. This stimulates the cells to proliferate and thereby produces increased cell numbers. The cells were then seeded onto various hydrogels including hyaluronic acid (HA), 2-hydroxyethyl methacrylate (HEMA), N’N’ dimethyl methacrylate (NNDMA) and polyacryloyl morpholine (AMO) before harvesting at set time points of 1, 3, 6 and 9 days for hyaluronic acid and 1, 7, 14, 21, and 28 days for the other hydrogels. Cell number, morphology, viability and adherence to or migration into the hydrogels were assessed. Cell proliferation was also determined by immunostaining for the Ki67 antigen.

Results: Disc cells became incorporated in the HA gel, adopted a spherical morphology and remained viable for up to nine days. However, after a few days, a large proportion of the cells began to migrate through the gel to form a monolayer on the bottom of the tissue culture well. These monolayered cells became fibroblastic and proliferated. NP cells appeared to proliferate to a greater extent than AF cells both in monolayer and in suspension. Ki67 antigen immunostaining confirmed cell proliferation. On the non-porous HEMA, NNDMA and AMO, both cell types adhered and adopted a fibroblast-like morphology. Cell adhesion was greatest to the HEMA. NNDMA and AMO had lower levels of cell adherence. Both cell types became incorporated into the porous materials and adopted a rounded morphology. Cell incorporation appeared to be greatest into porous HEMA.

Conclusion: These initial studies show that intervertebral disc cells will adhere to or migrate into a variety of hydrogels and remain viable. The morphology and proliferative capacity of cells derived from both the AF and NP were responsive to the structure of the hydrogel with which they were cultured. Thus, cells were able to become fibroblastic or chondrocytic. Further analyses will reveal whether matrix synthesis by disc cells is similarly responsive to the hydrogel format. The results of these experiments suggest that the hydrogels tested have potential as support matrices in intervertebral disc repair to provide relief from discogenic low-back pain.

Purpose of the study: To study clinical, radiological and pathological features of this rare condition and to observe the effect of surgery on the relief of presenting symptoms.

Materials, Methods and Results: between February 1989 to May 1999, more than 200 spinal operations were carried out at Oswestry, amongst which we found 11 patients with 13 symptomatic lumbar synovial cysts. Nine patients were female and 2 were male. Among the symptoms produced, sciatica was present in 10 out of 11 patients, neurologic claudication was present in 6 patients and only one patient had neurologic deficit. All the patients suffered with back pain, which was either of facetal origin or mechanical back pain.

Radiological investigations revealed that all patients had evidence of facet arthrosis. Seven patients had degenerative spondylolisthesis. Degenerative disc disease was also seen in 7 patients.

The contents of the cysts varied from serous fluid to chalky white material to gelatinous grey material. One cyst contained calcium pyrophosphate crystals. Another cyst contained hydroxyapatite crystals. Seven cysts which contained deposition of bone debris in the cyst wall also revealed an (giant cell and macrophage) inflammatory reaction to this bone debris. In all patients complete resolution of sciatica, neurologic claudication and neurologic deficit was observed after surgery. However, after a minimum follow up of two years the back pain persisted in all but one patient.

Conclusion: Lumbar synovial cyst is a rare condition, more common in females, elderly, and occurs most commonly in association with degenerative disease of the spine, although it can also be caused by other conditions like trauma, or rheumatoid arthritis. When they cause compression of the dura or nerve roots, they present with symptoms like sciatica and neurologic claudication, which resolve promptly after surgery. However, patients also have a long history of back pain from the associated degenerative spinal disease which usually does not resolve unless it is addressed separately and patients need to be warned regarding this.

Mature human intervertebral disc cells have generally been described as being either fibroblast-like or chondrocyte-like; i.e. appearing either elongated and bipolar or rounded/oval. Fibroblast-like cells are observed within the outer regions of the anulus fibrosus whilst chondrocyte-like cells are found in the more central regions of the disc. However, a few reports have noted that in some circumstances disc cells appear to extend more elaborate cytoplasmic processes into their surrounding extracellular matrix. In this study, we have examined healthy and pathological human intervertebral discs for the presence of the cytoskeletal elements, F-actin and vimentin.

Tissues examined included discs of no known pathology, discs with spondylolithesis, scoliosis specimens taken from the convex and concave sides, and degenerated discs. F-actin was not readily observed within discs cells but was a marked feature of vascular tissue within the disc and occasionally seen in infiltrating cells. Vimentin was more readily seen within cells of the inner anulus fibrosus and nucleus pulposus. In general, disc cell morphology was fibrocyte or chondrocyte-like; however, in spondylolisthetic discs, cells with numerous cytoplasmic projections were frequently observed.

The differential morphologies and cytoskeletal composition observed in disc cells may be indicative of variations in mechanical strains and/or pathologies, or indeed of cell function.

The aim of this study was to identify potential inflammatory mediators in herniated and non-herniated intervertebral disc. It has been suggested that inflammation of the nerve root is a pre-requisite for disc herniations to be symptomatic. What leads to this inflammation is a matter of conjecture; one possible cause may be inflammatory mediators released from the herniated disc tissue itself. In this study we have examined discs from individuals with and without disc herniations to determine if there is a different degree of occurrence.

Twenty two discs from 21 patients with disc herniation were examined together with four discs from patients with other disc disorders and five age-matched discs from individuals obtained at autopsy. Samples were studied for the presence of blood vessels and inflammatory cytokines: IL-1α and β, IL-6, INOS, MCP1, TNFα, TSG-6 and thromboxane.

Of the herniated discs 10 were protrusions, six extrusions and six sequestrations. There was less of all the cytokines in the non-herniated discs than found in the herniated, with very little immunostaining for iNOS or IL-1α in any samples. Staining was seen in all herniated samples for IL-1β, but in fewer for IL-six and MCP1 (86%), thromboxane (68%), TNFα (64%) and TSG-6 (59%). The presence of cytokines was strongly associated with the presence of blood vessels. Protruded discs had less TNFα and thromboxane than sequestrated or extruded discs.

Cytokines appear to play an active role in the aetiopathogenesis of disc herniations. Some may be involved in the stimulation of degradative enzymes and hence resorption of, for example, sequestrations, whereas others may be responsible for an inflammatory response in the surrounding tissues such as nerve roots.

Although an increased and deeper innervation of painful and degenerate intervertebral discs (IVDs) has been reported, the mechanisms that regulate nerve growth into the IVD are largely unknown. In other tissues, proteoglycans have been found to act as nerve guidance molecules that, generally speaking, inhibit nerve growth. As disc degeneration is characterised by a loss of proteoglycans, we assessed the effects of IVD proteoglycans on nerve growth and guidance.

Using in vitro assays of nerve growth, we found that human disc proteoglycans inhibited nerve attachment, neurite extension and induced sensory growth cone turning in a dose-dependent manner. Digestions with chondroitinase ABC or keratinase abrogated these inhibitory effects. Proteoglycans of the anulus fibrosus were more inhibitory than those from the nucleus pulposus.

Disc proteoglycans inhibit nerve growth and this inhibitory activity may dependent on proteoglycan glycosylation and/or sulfation. A loss of proteoglycans from degenerative discs may therefore predispose the discs to nerve invasion.