Purpose of the study

In a recent study, O'Leary et al. [2005] reported their observations on the patterns of Charité disc prosthesis motion under physiologic loads. The purpose of this study was to investigate whether the motion patterns observed in the in vitro model are replicated in clinical practice.

Sub-optimal positioning of the implant is thought to be related to poor outcome after Lumbar Disc Replacement. Our aim was to analyse the impact of implant position in the outcome of Charite III Disc Replacement implants.

160 Charite III Lumbar Disc Replacements that were implanted between 1990 and 2000. The average age was 46 years with 62 Males and 98 Female subjects. An independent observer (HN) administered Pain score (VAS 1–10) for Low Back Pain (LBP) and Oswestry Disability Index (ODI). These clinical outcome parameters were compared with coronal and sagittal position of the implants from the latest available radiographs. Those with operation at L3L4 (small numbers = 20) and inadequate radiographs were excluded.

48 implants were optimally placed and 70 implants were placed sub optimally. Both the groups were in similar age groups (45.02 years, SD 7.61 and 48.31 years, SD 8.04). Clinical: No statistical or clinically significant difference was observed in LBP on VAS (4.92 V/S 4.41), ODI (42.8 V/S 38.0) and in Patient Satisfaction at an average follow up of 70 months. Average movement at optimally placed discs at L4L5 was 4.4o(95% CI 2.3 – 6.7) and at L5S1 was 5.9o(95% CI 4.2 – 7.5) and at sub optimally placed disc at L4L5 was 3.8o(95% CI 2.4 – 5.1) and at L5S1 was 3.8o(95% CI 2.3 – 5.3).

Clinical and radiological results after Charite III Disc Replacement is NOT dependent on positioning of implants. Movements at optimally placed implants are better but is of questionable clinical relevance.

Aim: To analyse the impact of implant position in the outcome of Charite III Disc Replacement implants.

Methodology: 160 Charite III Lumbar Disc Replacements that were implanted between 1990 and 2000. The average age was 46 years with 62 Males and 98 Female subjects. An independent observer (HN) administered Pain score (VAS 1–10) for Low Back Pain (LBP) and Oswestry Disability Index (ODI). These clinical outcome parameters were compared with coronal and sagittal position of the implants from the latest available radiographs. Those with operation at L3L4 (small numbers = 20) and inadequate radiographs were excluded.

Results: 48 implants were optimally placed and 70 implants were placed sub optimally. Both the groups were in similar age groups (45.02 years, SD 7.61 and 48.31 years, SD 8.04). Clinical: No statistical or clinically significant difference was observed in LBP on VAS (4.92 V/S 4.41), ODI (42.8 V/S 38.0) and in Patient Satisfaction at an average follow up of 70 months. Movements: Average movement at optimally placed discs at L4L5 was 4.4o(95% CI 2.3–6.7) and at L5S1 was 5.9o(95% CI4.2–7.5) and at sub optimally placed disc at L4L5 was 3.8o(95% CI 2.4–5.1) and at L5S1 was 3.8o(95%CI 2.3–5.3).

Conclusions: Clinical and radiological results after Charite III Disc Replacement is NOT dependent on positioning of implants.

Ethics approval: None

Interest Statement: None

Objective and Background: This study investigated the effects of IL-1 on human intervertebral disc cells (IVD). IL-1 has been implicated in the degradation of IVD, in particular the up-regulation of Matrix Metalloproteinases (MMPs) and the down regulation of proteoglycan synthesis. However very little is known of the effects of IL-1 on human IVD cells. Here, we have investigated the effects of both IL-1 α and IL-1 β on nucleus pulposus (NP) and Annulus fibrosus (AF) cells isolated from human degenerate IVD.

Methods: Human IVD tissue was obtained from disc replacement surgery and separated into NP and AF tissue, cells were cultured within an alginate bead system for 5 weeks before treatment with IL-1 α and IL-1 β for 48 hours. Following treatment, RNA was extracted and Real time RT-PCR was performed to investigate gene expression of IL-1 gene family, matrix proteins and degrading enzymes MMPs and ADAMTS.

Results: Interleukin 1 α showed a more potent response than IL-1 β and in addition NP cells were more sensitive than AF cells. In summary, IL-1 showed a positive feedback loop causing an up-regulation of α and β genes. IL-1 Ra was also up-regulated but to a lesser extent than IL-1 α and IL-1 β. A negative feedback loop was seen with inhibition of the IL-1 receptor gene upon treatment with IL-1. MMPs and ADAMTS showed up-regulation upon treatment with IL-1. In addition IL-1 down regulated the matrix protein’s collagen type II and Aggrecan.

Conclusions: This study demonstrates that IL-1 causes up-regulation in discal cells of the major degrading enzymes involved in discal degeneration, and a down regulation of the major matrix components within the IVD. Suggesting that IL-1 plays a major in process of discal degeneration.

Objective and Background: Interleukin 1 has been implicated in the progression of degenerative disc disease, however little data is available on the expression and production of IL-1 within degenerate discal cells. A few studies, have investigated herniated disc tissue but the results from these studies have been inconsistent. This study investigated the gene expression of IL-1 α, β, Ra and the receptor type I in discs removed at surgery from 7 prolapsed, 3 Scoliosis and 15 Degenerative discs (DD). In addition immunohistochemistry (IHC) was used to localise IL-1 α and IL-1 β within normal, and degenerate discs.

Methods: Human IVD tissue was obtained from disc replacement surgery and separated into nucleus pulposus (NP) and annulus fibrosus (AF) tissue, cell isolation using collagenase treatment was carried out, and RNA extraction on the cells performed immediately. Real time RT-PCR was then used to investigate gene expression of IL-1 gene family. IHC for IL-1 α and IL-1 β was also performed on paraffin embedded normal and degenerate disc samples.

Results: Expression of the IL-1 family genes was present at low levels within prolapsed disc samples. In contrast levels within scoliosis patents were the highest of the 3 disease states, however in both prolapsed discs and those from scoliosis patients a balance of IL-1 α/β to IL-1 Ra existed. Within samples from DD this balance was lost, with levels of IL-1 α and IL-1 β greatly exceeding levels of IL-1 Ra. In addition levels of IL-1 α and β showed an increase with age and were highest in those samples from the AF than the NP. IHC demonstrated both IL-1 α and IL-1 β protein within the NP and AF cells of the degenerate discs.

Conclusion: This study has demonstrated the mRNA expression of all members of the IL-1 family within IVD and in addition the chondrocytes within the disc produced IL-1 α and IL-1 β protein. The imbalance of IL-1 α/β to IL-1 Ra within those samples from degenerate discs but not prolapsed or scoliotic discs suggests a role for IL-1 within discal degeneration.

Aims: The intervertebral disc (IVD) consists of three structurally distinct areas; a nucleus pulposus (NP), annulus fibrosus (AF) and two cartilage endplates that together form a functional unit that allow flexibility of the spinal column and load transfer from adjoining vertebrae. The NP and AF contain cells that are phenotypically similar to chondrocytes found in articular cartilage. They also produce the 2 major matrix components aggrecan and collagen-type I and II. One feature of IVD degeneration is breakdown of the cartilage matrix. Using soluble growth factors could stimulate new matrix formation and help regenerate degraded discal cartilage. The aim of this study was to demonstrate the presence of four growth factor receptors within the IVD.

Methods and Results: Using immunohistochemsitry, we targeted expression of four growth factor receptors, (BMPRII, FGFR3, IGFR-1 and TGFβII), in biopsies taken from normal and degenerate IVD. Receptor expression was scored across regions of the disc using a peer-reviewed system that assessed the proportion of cells expressing a particular antigen and the average level of expression for those cells. For FGFR3, IGFR-1 and TGFβII, cells of the outer part of NP and inner AF expressed significantly higher receptor levels. The expression BMPRII deviated from that pattern and was present at higher levels in the inner and outer NP than in the AF. Although there were significant differences between FGFR3 expression in normal and degenerate biopsies, that was not the case for the other receptors. Growth factor receptor expression was also detectable on the ingrowing neurons and blood vessels that characterise part of the disease aetiology.

Conclusion: In conclusion, all of the receptors were found in the IVD, predominantly within the NP, suggesting that, addition of the ligands for these receptors may elicit a physiological response from disc chondrocytes.

Objectives and Background: This study investigated a simple, novel, in vitro culture system which enables the in situ investigation of human intervertebral disc (IVD) cell function in healthy and diseased IVD in explant culture. Studies investigating the function of cells in IVD tissue are scarce. Whilst there is a paucity of realistic animal models of human IVD disease and in vivo study of human tissue remains impracticable, the only possible approaches remain in-situ molecular biology applied to tissue sections of biopsied tissue, which suffers from lacking a dynamic dimension. Or in vitro studies, of which cell culture lacks physiological relevance and explant cultures are subject to loss of tissue integrity and altered cellular behaviour. We have investigated a system that preserves the structure of the tissue and cellular phenotype within an explant culture system.

Methods: Human IVD tissue was obtained from disc replacement surgery and separated into nucleus pulposus (NP) and annulus fibrosus (AF) tissue, which was then cultured in either a Perspex ring or unconstrained in tissue culture medium for up to 3 weeks. The effectiveness of this system to maintain tissue integrity and cell function was tested using microscopy and either tinctoral histochemistry or immunohistochemistry.

Results: Unconstrained in medium, IVD tissue expanded and structural integrity was disturbed. The number of cells expressing type I collagen increased and aggrecan decreased by comparison with directly harvested tissue. In contrast the tissue in the Perspex rings maintained its structure and at the end of 3 weeks the cellular parameters were the same as in the newly harvested tissue.

Conclusions: This is the first reported system to preserve cell function of discal explants for long periods in tissue culture. This system will be a useful tool for a wide range of investigations of IVD biology that have not hitherto been possible.

Introduction: Treatment of thoracolumbar fractures remains controversial. The treatment options are conservative management or operative treatment, either through a posterior or anterior approach. Surgery through an anterior approach provides excellent decompression through vertebrectomy and the ability to correct the deformity. Stabilisation with Moss cage and Kaneda device remains unproven.

Methods and Results: This is a retrospective study of 55 consecutive patients with thoracolumbar fractures operated on between 1993–99. Indications for surgery were: neurological deficit, two or three column injury causing instability or significant kyphotic deformity .

There were 34 male and 21 female patients, mean age 33 years old. Trauma was caused by a fall from a height, either due to accident (30 patients) or suicide attempt (5), RTAs (14), sporting injury (6). Other injuries included multiple level spinal fractures (9 patients), pelvic (5), calcaneal (3), talar (1) and malleolar (1) fractures.

Surgery was performed on the next available list unless there was an indication for emergency intervention, (mean 5 days post injury, range 1–19). Post-operative hospital stay averaged 17 days (7–59).

Forty-seven patients underwent an anterior procedure alone, whilst eight patients had combined anterior and posterior instrumentation and fusion. Mean operative time was 207 minutes (150–360) and blood loss 2670 ml (985– 7000).

Nineteen patients (35% of all) had neurological deficit. Neurological status improved post-op in 85% of these patients, remained the same in nine per cent and there was a nerve root injury in one patient (revision case) which has almost recovered. Other complications included five chest infections, three UTIs, one incisional hernia, four implant problems and eight patients with thigh pain.

Results were analysed according to return to work and the Oswestry Disability Score with a mean follow-up of three years. Thirty-eight patients (69%) returned to the same occupation held before the injury, 11 patients (20% ) had a lighter job and six patients ( 11% ) are not working with litigation going on. Oswestry Disability Score post-op was 24% (4%–72%).

Conclusion: Compared to the natural history of conservatively treated thoracolumbar fractures, surgical treatment with anterior decompression and stabilisation with Moss cage and Kaneda device offers considerable advantages. It enables a thorough decompression and has the advantage of providing greater deformity correction than the traditional posterior approach while instrumenting fewer vertebrae, thus preserving spinal motion segments. Early mobilization of the patients is a major advantage.

A prospective study to evaluate the design, outcome and complications of the AcroFlex titanium/polyolefin artificial lumbar disc replacement.

11 subjects with single-level discographically proven discogenic pain of at least six months duration and refractory to conservative treatment underwent Total Disc Replacement (TDR) using the AcroFlex TDR. Surgery was performed by an anterior retroperitoneal approach. The following outcome measures were recorded pre-operatively, at 6 weeks and 3, 6, 12 and 24 months: Visual Analogue Score (VAS), Oswestry Disability Index (ODI), Low Back Outcome Score (LBOS), and SF-36. Physical examination and radiological assessment (plain radiographs, flexion/extension views, cine-radiography) were performed at the same time intervals. Complications and reoperations were recorded.

11 patients were enrolled since April 1998 (7 male / 4 female). The mean age was 41. 3 years. All patients have been followed for a minimum of two years.

Surgery averaged 136 minutes with 143 mls blood loss. There were no operative complications. The average length of stay was 6. 1 days. The mean VAS reduced from 8. 8 to 4. 4 at two years. ODI improved from 51. 3 (mean) to 20. 9 (mean) at 24 months. The mean LBOS of 18. 4 improved to 47. 3 at two years.

Patients showed improvement in all subsets of the SF-36. Radiological examination confirmed a mean flexion/extension arc of 6. 6 degrees with restoration of native disc height. Adverse events included one disc expulsion (under radiological observation), one autofusion (F/E views still confirm movement) and one catastrophic rubber failure requiring revision to combined anterior/posterior interbody fusion. As a result of this case all patients underwent ultra fine cut CT scans. An additional 4 cases showed small anterior tears in the rubber and are currently asymptomatic.

The two-year outcome of the AcroFlex TDR is reported in 11 patients. Improvements in VAS, ODI, LBOS and all domains of the SF-36 were reported by 10 of 11 patients. Radiological outcome confirmed preservation of movement and restoration of disc height. Adverse events including disc expulsion, autofusion and rubber failure demand continued vigilance.

Objective: Movement in an artificial disc would be assumed to be a necessary function of the disc. The purpose of this study was to establish whether, if any, relationship existed between movement in the artificial disc and outcome.

Subjects: 25 patients who had received an artificial disc prosthesis were assessed using radiological methods. Despite many vagaries in the measurement of X-rays, fluoroscopy was used to assess gross movement and end of flexion/extension views used to measure degrees of motion.

Outcome measures: Oswestry disability score.

Results: A very clear relationship has been established between motion in the artificial disc and outcome.

Conclusions: It is likely that spinal fusion will ultimately give way to disc replacement. Although spinal fusion has been shown in the Swedish spine series to produce good outcomes for significant numbers of patients, it remains to be seen whether the retention of motion will enhance outcome in low back pain patients. This series suggests that the retention of motion is an important component in the outcome of surgery in back pain sufferers.

Introduction: The Charite Mark 3 disc prosthesis has been used by the senior author for ten years. There has always been a question mark over the wear properties of the high density polyethylene spacer used in this prosthesis.

Methods: Ten patients who have received Charite implants, eight, nine and ten years ago were subjected to helical CT scanning. Slices at 3 mm. intervals were taken across the prosthetic levels. Fifteen prostheses were studied. Four clinicians, two of whom were radiologists and one a spinal fellow, assessed the CT scans against a standard protocol. Since the original heights of the prostheses were known, it was possible to measure prosthetic height and therefore get an estimate of wear. In addition, areas of osteolysis around the prostheses were estimated, again as a sign of wear.

Results: Remarkably little wear or wear debris was noted around the 15 prostheses.

Conclusions: Although this is a small series, it confirms that the medium-term performance of this prosthesis as far as wear is concerned is good.

Background: Current treatments for Low back pain (LBP) are often empirical and few directed at the underlying disorder, altered discal cell metabolism, which precipitates the problem. The use of gene therapy to manipulate discal metabolism to treat LBP is an interesting possibility. The Intervertebral disc (IVD) is a therapeutic target in LBP, and one approach to gene therapy would be to isolate IVD chondrocytes (IVDC) and transfer genes Ex Vivo into these cells. Subsequent reinjection of these genetically altered cells into the lumbar IVD, would permit the expression of the trans-gene in vivo, generating the therapeutic protein within the IVD.

Methods: To test the viability of this approach, we isolated human IVDC from patients undergoing surgery, grew them Ex vivo and transfected them with the marker gene LacZ, using an adenovirus vector and the CMV promoter. Expression of the gene was then measured using X-gal staining for the gene product ~-galactosidase.

Results: IVDC infected with adenovirus/CMV-LacZ showed maximal LacZ expression 2 days post infection, with almost 50% of cells displaying X-gal positivity within monolayer cultures and 100% infection within alginate culture, gene expression was maintained up to 4 weeks and control cultures showed no LacZ expression.

Conclusion: This study shows that human IVDC can be transfected with a foreign gene using the adenovirus vector. The gene transduction of a therapeutic gene into IVDC, could provide long lasting effect. In addition the use of inducible promoters could allow for the autoregulation of gene expression.

Introduction: The artificial disc consists of proprietary polyolefin rubber core bonded between two titanium endplates. It has been developed for the treatment of symptomatic disc degeneration with the aim of providing segmental stability and motion following wide disc space clearance. It was designed to have similar properties to a normal adult human intervertebral disc when working in conjunction with the retained anulo-vertebral tissues and the supporting musculoligamentous system.

Methods: Over 120 discs were used to biomechanically characterize the Device. Range of motion tests were designed and performed to measure the axial compression, torsional, and shear stiffness of the artificial disc and to compare this with the known values for the human lumbar disc. Pullout test was performed to evaluate the immediate and short-term stability of the inserted device by assessing the mechanical resistance to pullout or expulsion. To assess the ability of the implant to withstand average daily living loads throughout its predicted life, compression and compressive shear fatigue testing were performed.

Discussion: The device was found to replicate many of the physiologic characteristics of the in-vivo FSU. The quasi-static testing showed the device to have higher strength values than the highest in-vivo loads and displacements. Fatigue testing showed the smallest device endurance limit of 3,500N at ten million cycles.

The results demonstrate that the failure modes of the device contain sufficient safety margins to support the use of the device in a prospective clinical study.

Purpose and Background: We have previously reported our investigations of nerve ingrowth into intervertebral discs (IVD) from patients with mechanical low back pain. We have shown that in discs that are painful on discography (pain level discs) nerves actively grow into the deep annulus fibrosus and nucleus pulposus. Nerve ingrowth accompanies blood vessel ingrowth and advances into the nucleus pulposus from the end plate. The morphology and neurochemistry of these nerves indicate them to be nociceptive.

The growth of non-myelinated pain fibres in other settings is regulated by the cytokine Nerve Growth Factor (NGF). In this study, we have investigated the production and distribution of NGF, or more particularly its active isoform – NGF-β, and its receptors, in diseased intervertebral discs in order to establish whether this cytokine might be responsible for the observed nerve ingrowth in this situation.

Methods: Tissue sections of 21 pain level, 15 non-pain level diseased and 12 normal intervertebral discs, taken at the time of spinal surgery, and from cadavers, were probed by radioactive in situ hybridisation (ISH) for expression of NGF-β, and by immunohistochemistry (IHC) for its high and low affinity receptors (trk-A and p75 respectively). In addition, either serial sections were stained with cell specific markers (CD31 – endothelial cell, PGP9.5 – neurones, GAP43 – actively growing nerves) or sections were doubled stained (two antibodies or both ISH and IHC).

Results: We have demonstrated that NGF-β is synthesised by the endothelial cells of blood vessels growing into the IVD from the end plate. The high affinity receptor is expressed by those small nerve fibres that accompany the vessels and in their offshoots in pain level discs that are growing from perivascular nerves into the disc. In addition to their expressing the nerve specific molecule PGP9.5, the trk-A positive cells also express the nerve growth associated protein GAP43.

Conclusion: The data indicate that nerve ingrowth into IVD is regulated by NGF-β. We have localised this production to the endothelial cells of ingrowing blood vessels. NGF-β is a potential therapeutic target for the management of back pain.

Background: Low back pain (LBP) is a major cause of disability. However, current treatments are often empirical and few are directed at the underlying disorder, altered discal cell metabolism, which precipitates the problem. The use of gene therapy to manipulate discal metabolism to treat LBP is an interesting possibility. The Intervertebral disc (IVD) is a therapeutic target in LBP, and one approach to gene therapy would be to isolate IVD chondrocytes (IVDC) and transfer genes ex vivo into these cells. Subsequent reinjection of these genetically altered cells into the lumbar IVD, would permit the expression of the transgene in vivo, generating the therapeutic protein within the IVD.

Methods: To test the viability of this approach, we isolated human IVDC from patients undergoing surgery, grew them ex vivo and transfected them with the marker gene LacZ, using an adenovirus vector and the CMV promoter. Expression of the gene was then measured using X-gal staining for the gene product _-galactosidase. Post infection, some cells were treated with forskolin for 24 hours to assess whether expression of the transgene could be manipulated.

Results: IVDC infected with adenovirus/CMV-LacZ showed maximal LacZ expression 2 days post infection, with almost 50% of cells displaying X-gal positivity. Cells maintained a low level of expression for the remaining 12 days of the study. Control cultures showed no LacZ expression. Cells treated with forskolin after infection with adenovirus/CMV-LacZ exhibited 4 times the level of _-galactosidase activity seen in unstimulated cultures.

Conclusion: This study shows that human IVDC can be transfected with a foreign gene using the adenovirus vector. The gene transduction of a therapeutic gene into IVDC could provide a long lasting effect. In addition, the use of inducible promoters could allow for the autoregulation of gene expression.

Purpose and Background: There is increasing evidence that events within the diseased intervertebral disc (IVD) are mediated by locally synthesised cytokines. A prominent histological, imaging and surgical feature of IVD disease is degradation of the cartilaginous discal matrix. Whilst the mechanism by which this is mediated is unknown, in other situations where connective tissues are degraded degradation is the result of production of matrix-degrading enzymes by local connective tissue cells stimulated by cytokines, particularly the beta isoform of interleukin-1 (IL-1β). Included amongst these disorders is osteoarthritis (OA) of diarthrodial joints. OA has many similarities to the discal “degeneration” seen in mechanical back pain syndromes. In the current study, we have used a combination of in-situ techniques to establish if IL-1β is responsible for stimulating matrix degradation in the IVD.

Methods: Using a combination of radioactive in-situ hybridisation (ISH) and competitive in situ zymography (ISZ) we have studied expression of IL-1β and IL-1R – its type 1 receptor (ISH) and matrix degradation (ISZ) in five diseased lumbar IVD taken at spinal fusion surgery and 10 cadaveric IVD (five normal and five diseased). The nucleus pulposus (NP) was separated from the annulus fibrosus and diced into 0.5cm cubes. Half the cubes (typically three) were fixed in formalin and processed into paraffin wax for ISH, and half were used for ISZ. For ISH, 5 μm sections of paraffin-embedded tissue were reacted with cDNA probes radiolabelled with 35S to 580 and 530 base segments of the IL-1β and IL-1R molecules. Hybridisation was disclosed using autoradiography. For ISZ, 50 μm vibratome sections were placed into wells on microscope slides precoated with gelatin. Sections were incubated for 10 days, half in culture medium and half in medium supplemented with human recombinant IL-1 receptor antagonist (IL-1Ra – an inhibitor of IL-1). Sections were photographed at daily intervals to detect evidence of gel degradation.

Results: Chondrocytes within patient and cadaveric diseased but not normal discs expressed mRNA for both IL-1β and IL-1R. By ISZ, the same cells degraded gelatin. Degradation was inhibited by recombinant IL-1Ra.

Conclusion: This study shows that chondrocytes of diseased discs express IL-1 and its receptor. The same cells produced matrix-degrading enzymes by a mechanism that can be inhibited by the IL-1 inhibitor IL-1Ra. IL-1 is a potential therapeutic target for the management of IV disc disease.