Introduction: Wide laminectomy has been the accepted treatment of choice for stenosis in the lumbar spine. Recently, bilateral laminotomy has been proposed as an alternative decompressive technique for spinal canal stenosis. There have been no biomechanical studies to determine the in vitro difference in stability between these techniques.

Objective: To determine the in vitro difference in stability in a functional spinal unit (FSU) following bilateral laminotomy, and compare it to the instability resulting from laminectomy.

Methods: Six fresh human cadaver lumbar spines were injured sequentially at the L4-5 level: bilateral laminotomy and laminectomy. The normal and injured spines were subjected to flexion, extension, lateral bending and torsional moments. The three-dimensional motion behaviour of each spine before and after the two injuries was recorded using a magnetic motion sensor. The data from all five spines was pooled for statistical analysis.

Results: With flexion and extension loading, bilateral laminotomy induced significantly less sagittal angulation and translation in the FSU than did laminectomy. Significant increases in coronal translation occurred with laminectomy in spines subjected to lateral bending loads. There were no significant differences between the two techniques in coronal plane angulation with lateral bending loads and torsional loads.

Discussion: Adequate exposure of the lateral recesses requires limited medial facetectomy with both laminotomy and laminectomy. With laminotomy, the lamina and posterior ligamentous structures are preserved. This is aimed at decreasing the potential late development of spinal instability associated with laminectomy. The increase in motion seen with laminectomy in sagittal angulation / translation, and coronal translation in this in vitro model, may represent clinical instability, and may be responsible for continued symptomatology in these patients. Preservation of the lamina, spinous processes, and the posterior ligamentous structures significantly enhances the biomechanical stability of the FSU.

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.

Introduction: Recent cadaveric studies have identified neovascularisation and neoneuralisation as probable mechanisms in the causation of discogenic pain. Calcium pyrophosphate deposits have been observed in discs in several studies. Their significance in the causation of discogenic pain is unclear. Direct correlation between the pain site and histological features can be verified by aware state endoscopic visualisation.

Aim and Objectives: The study aims to examine and correlate the presence of neovascularisation, crystalline pyrophosphate deposits in the disc, and discogenic pain by spinal probing and discography under endoscopic visualisation.

Material and Methods: Tissue removed from intervertebral discs of 224 patients during surgery was examined directly, and polarised microscopy was used to identify the presence of calcium pyrophosphate and neovascularisation. Their presence was correlated to diagnostic provocative findings of spinal probing and discography and intradiscal distortion during aware state endoscopy.

Results: Calcium Pyrophosphate: Twenty out of 224 patients (9%) demonstrated calcium pyrophosphate in the discs. Fourteen had pain reproduced on probing or discography. Thirteen out of 20 patients (65%) had either an annular collection or leak at the index level. 6 had an extradiscal cause of pain. One hundred percent of the patients with annular collections or leaks had pain on spinal probing or discography. Sixteen patients with pyrophosphate deposits did not have neovascularisation.

Neovascularisation: Thirty seven out of 224 patients (16.5%) showed neovascularisation in the disc. Four discs had crystalline pyrophosphate deposits. Thirty three out of 37 (90%) had pain on probing and/or discography. Out of four patients who had no pain on probing or discography, two had demonstrated tears during previous discographic procedures which were treated with laser annealing. These patients had disc bulges and compressive radiculopathy.

Conclusion: The presence of pyrophosphate in the disc without a tear or leak does not directly render them tender to provocation. The presence of pyrophosphate is not correlated to neovascularisation. Annular tears or leaks are not directly correlated to the presence of pyrophosphates. There is a high correlation between pain provocation and neovascularisation.

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.

Objective: To analyse the incidence and gravity of reported complications that arise in spinal surgery and assess the comparative safety, or otherwise, of Endoscopic Laser Foraminoplasty.

Methods: The Spinal Foundation, Rochdale, has performed 958 Endoscopic Laser Foraminoplasty procedures and holds a comprehensive database of the results of all operations carried out in this manner. The records of these procedures provided the basis for a comparison of the safety of Endoscopic Laser Foraminoplasty to that found for other spinal surgical techniques as reported in the literature.

Nine hundred and fifty eight procedures have been performed on 716 patients. Complications that arose during the operation and the postoperative phase of six weeks following the procedure were elicited from patient records. This data was correlated and compared to a meta-analysis of randomised controlled trial data available on complications arising during and after conventional spinal surgery. The ‘SPSS’ and ‘CIA’ statistical packages were used to draw conclusions as to the safety of endoscopically assisted laser spinal surgery.

Results: The cohort integrity of operative and review records at six weeks after surgery was 100%. In 958 ELFs performed, 24 complications occurred in 23 patients. There were nine cases of discitis (one infective) (0.9%), one dural tear (0.1%), one deep wound infection (0.1%), two patients suffered a foot drop (one transient) (0.2%), one myocardial infarction (0.1%), one erectile dysfunction (0.1%) and one patient who developed panic attacks post-operatively (0.1%). This amounts to an overall surgical complication rate of 1.6%.

MRI follow up of clinically symptomatic patients highlighted eight residual disc herniations (0.8%).

Meta analysis of randomised controlled trials of conventional spinal surgery for adult onset degenerative disc disease and/or sciatic pain reported overall complication rates for fusion (11.8%), decompression (7.6%), discectomy (6.0%) and chemonucleolysis (9.6%).

Conclusions: The complication rate of Endoscopic Laser Foraminoplasty is shown to be significantly lower than that reported following conventional spinal surgery (P < 0.01). From these results it must therefore be concluded that ELF as a treatment for chronic low back pain and sciatica presents less risk to a patient than conventional methods of spinal surgery.

Perceived knowledge suggests that patients with Failed Back Surgery and a poor psychological profile would respond poorly to surgical interventions. This comparative study was designed to identify if there was a significant difference in the outcome following endoscopic spinal intervention in patients with Failed Back Surgery when compared to those who had no previous interventions.

Between April 1997 and November 1998, 54 patients with failed open back surgery and 85 without previous interventions were included in the study, underwent aware state pain source identification and endoscopic foraminal interventions. Pre- and post-operative assessment at 2 years was made using the Distress and Risk Assessment Method (DRAM), Oswestry Disability Index (ODI) and a Visual Analogue Pain Scale (VAPS). A Mann-Whitney U and Wilcoxon-Signed Rank tests were performed.

Patients with failed back surgery demonstrated greater psychological distress, disability (p < 0.05) and pain pre-operatively than those who underwent primary endoscopic interventions. Post-operatively both groups demonstrated significant improvement and no difference was found in the Zung, DRAM, ODI and VAPS scores.

With aware state pain source identification, targeted minimal intervention and discrete tissue ablation patients with failed back surgery with associated depression can demonstrate favourable physical and psychometric outcomes.

Introduction of new surgical intervention need assessment of the true results by eliminating cognitive dissonance and the placebo effect. Significant time must elapse since the procedure to derive conclusions. With the initial gratifying results of Endoscopic Foraminoplasty a retrospective analysis of the data was performed to identify if the outcome was accurate and not a placebo effect.

Early postoperative Data (6 weeks and 6 months) derived from questionnaires on 91 patients with Endoscopic Foraminoplasty (April 1997 and November 1998), which included the Oswestry Disability Scale and a Visual Analogue Pain Scale was compared with the data at 2 years (late). A t-test was used to assess the difference between the Oswestry Disability scores from the two questionnaires and a Wilcoxon Signed Rank test for the Visual Analogue Pain Scale.

No significant difference between the Visual Analogue Pain Scores at 6 weeks to 6 months and 2 years post-operation was noted. There was however, a marginal improvement (p= 0.05) in Oswestry Index over two years period.

The initial outcome of Endoscopic Laser Foraminoplasty was sustained or improved at the end of two years and was not a placebo effect.

The view that patients low back pain presenting with ‘abnormal’ psychometric and poor DRAM scores predict an unsatisfactory surgical outcome is considered controversial. This prospective study was designed to identify if DRAM Scores (Scores of Distress Risk Assessment Method) is a predictive determinant or a reactive instrument in regard to the outcome of Endoscopic Foraminoplasty.

One hundred and eighty-five patients (86 males and 99 females) underwent an Endoscopic Laser Foraminoplasty between April 1997 and November 1998. Pre- and postoperative assessment at 2 years was made using the Oswestry Disability Scale, and the Visual Analogue Pain Scale and the DRAM scores. Patients were categorised by their pre-op DRAM score. A Kruskal-Wallis analysis of variance and a regression analysis were performed.

There was significant improvement in disability and pain scores at two years. (p< 0.05). A significant difference in median DRAM between the preoperative and postoperative score at two years was noted. While the DRAM score predicted the patients’ disability and pain it failed to predict the change in outcome.

The DRAM score highlights individuals in distress who may need psychological support and physical treatment for optimum benefit from endoscopic spinal intervention and not be used to deny a surgical intervention.

This study evaluates the results of Endoscopic Foraminoplasty on 30 consecutive patients followed for a minimum of 2 years.

The objective has been to assess the efficacy of endoscopic aware state pain source definition combined with endoscopic decompression of the foramen, mobilisation and neurolysis of the exiting and transiting nerves and ablation of osteophytes in patients with spondylolytic spondylolisthesis.

This prospective study involved Endoscopic Foraminoplasty performed on 16 males, and 14 females with an average age of 46 years (36–72 years). They were followed for an average period of 34 months (28–41 months).

One-hundred percent cohort integrity was maintained at the final follow up. Results were analysed using the percentage change in Oswestry Disability Index, and percentage change in visual analogue pain (VAP) scores. Using a percentage change in Oswestry Disability Index of 50 or more to determine good and excellent outcomes, 75% (22 out of 30) exceed this value with five (17%) having 100% benefit for the procedure.

These results indicate that Endoscopic Laser Foraminoplasty provides a minimalist means of exploring the extra-foraminal zone, the listhetic defect, the foramen and its contents, and the epidural space and performing decompression, discectomy, osteophytectomy, perineural neurolysis in patients with spondylolytic-spondylolisthes. Done in an aware state, it serves to identify and localise the source of pain generation.