Spondylolytic spondylolisthesis is one of the common causes of mechanical low back pain in adults. Conservative treatment of such cases, particularly for the low grade slips, remains the mainstay of management. When patients’ symptoms are marked and not responsive to conservative therapy, the surgical option can be considered. Up to the time of writing this abstract [January 2003], arthrodesis of the affected motion segment with or without instrumentation is the standard surgical option for treating mechanical low back pain. Results of different types of arthrodesis for treating such condition had been reported in literature, including posterior fusion, posterolateral fusion, and posterior and anterior interbody fusion.

Between 1993 and 1998, seventy- five adult patients with grade I or II lytic spondylolisthesis were treated by in situ posterolateral fusion and segmental instrumentation using the Oswestry Pedicle Screw System, with or without extended Gill’s procedure. The indications for surgical intervention in these cases were significant reduction in the quality of life with persistent low back pain and/or leg pain after a minimum of six months conservative therapy. Confirmatory imaging studies consistent with the clinical data should also be obtained before deciding the surgical option. The average operative time was 2.5 hours [range 2–4 hours). The average blood loss was 850 mls (range 300–2300 mls)

After an average follow-up of 60.7 months (range 24–95 months) clinical results were excellent and good in 92%, and radiological union was achieved in 94% of patients. Complications included 2 cases with superficial wound infection, one case with deep wound infection, and four of the patients went to non-union.

In conclusion, with a careful patient selection, patients with instrumental insitu posterolateral fusion gained a satisfactory clinical and radiological outcome and the results were maintained for an adequate postoperative period.

Background: To determine whether the operation of LSD destabilizes the lumbar spine and leads to an increase in any pre-existing scoliosis or spondylolisthesis. Lumbar spondylosis, which commonly includes a degenerative listhesis and a scoliosis, is the commonest cause for stenosis in the lumbar spine. The standard operation for spinal stenosis remains a laminectomy with fixation and fusion in the presence of possible instability. The laminectomy, however, destabilises the spine and the instrumented fusion makes it a much bigger operation in patients often not best placed to cope with it. The more limited operation of LSD, which has previously been reported to this society, avoids a simultaneous fusion or instrumentation and has been shown to give long term symptomatic relief (1) Its possible effect on the stability of the spine has not previously been reviewed.

Methods: A retrospective clinical and radiological review of consecutive patients operated on for degenerative spinal canal stenosis with either a pre-existing scoliosis or degenerative listhesis or both. Sixty-one patients (44 female and 17 male) with a mean age at operation of 72.8ys (range: 54–85). Pre-operatively 35patients (57%) had a degenerative listhesis, 14 patients (23%) a lumbar scoliosis and 12 (20%) had both. The mean postoperative follow-up was three years (range from one to fourteen years).

Results: None of the 47 patients with a preoperative degenerative spondylolisthesis had any change in grade of the listhesis. Also no patient developed a new spondylolisthesis.

Of the 26 patients with a preoperative scoliosis, 10 progressed by a mean of 4.9° (range 2°–15°)

Conclusion: The results show that the operation of LSD was not associated with the development of a spondylolisthesis or a further progression of a pre-existing listhesis, and no patient developed a scoliosis. In those who had a scoliosis pre-operatively, 38% progressed and this only to a degree which we believe falls within the natural progression to be expected in such a group of patients. We believe these results support the view that the operation of Limited Segmental Decompression for spinal stenosis does not significantly destabilize the spine, even in a group that would appear most vulnerable, and as such there is no indication in such cases to consider a simultaneous instrumentation and fusion.

Objectives: To evaluate the clinical and radiological outcome following anterior interbody fusion using a femoral cortical allograft packed in the centre with autogenous iliac graft combined with posterior pedicle fixation.

Design: A prospective study of 30 consecutive adult patients diagnosed with lumbar degenerative disc disease.

Summary of background data: Various fusion options have been described in the literature with various clinical and radiological outcomes. Narrowing of the disc space is thought to be the primary cause of all the potential secondary spondylotic changes; the ideal corrective surgery would be one that reconstitutes the disc space interval. A hybrid graft consisting of a femoral cortical allograft (FCA) ring packed in the centre with autogenous cancellous iliac graft seems to be an ideal option as one should capitalize on the mechanical strength of the cortical ring and the biological strength of the cancellous autogenous graft.

Methods: 15 patients with failed back surgery, 15 patients with primary degenerative disc disease. Mean age was 43 years. All patients had preoperative radiographs, MRI scanning, discography was not used in this study. All femoral allografts were processed by freeze drying and sterilized using ethylene oxide. The protocol for surgery consisted of:

* Left sided retroperitoneal muscle splitting approach

Results: There were no complications from using the allograft. Intraoperative and postoperative complications were seen in 3 patients. After a minimum follow up of 2 years good clinical outcome was achieved in 83 % using Ricciardi et al criteria, solid fusion was achieved in 98%.

Conclusion: The results in this study continue to support the efficacy of using hybrid interbody grafts to achieve a successful fusion, however there is discrepancy between the radiological and clinical outcome which merits additional investigations

Introduction: Intra-Discal Electrothermal Therapy (IDET) has been used to treat chronic discogenic low back pain. A novel intradiscal decompression catheter has been developed to reduce local disc bulging in cases of contained prolapse. This new catheter is inserted percutaneously into a disc and advanced under radiographic control into a postero-lateral position targeting the herniation. The decompression catheter uses more focused heating and higher temperatures than previous devices and is intended to provide a local decompression of the disc through a thermally mediated reduction in nuclear volume. The purpose of this study was to investigate changes in internal stress profiles following use of the new catheter.

Methods: Five cadaveric lumbar ‘motion segments’ were dissected from two spines (age 64–84 yrs). Each segment was compressed, normally to 1 kN, while a miniature pressure transducer was withdrawn from posterior to anterior across the mid-sagittal diameter of the disc producing a baseline stress profile. A decompression catheter was inserted into the disc and its position confirmed with plain radiography. The temperature of the catheter was increased to 90°C over a period of 14 minutes. Stress profiles were then repeated.

Results: Stress profiles in three of the five segments showed changes consistent with degenerative change. In these discs stress profiles following ‘treatment’ showed up to a 35% reduction in the magnitude of stress peaks in the posterior annulus. There was very little change in the distribution of stress in the two non-degenerate discs. Stress in the nucleus appeared unchanged in all discs.

Conclusions: Treatment of degenerate discs with the decompression catheter lead to a measurable alteration in annular stress peaks associated with degenerative discs, while non-degenerate discs were unaffected. These preliminary findings of an ongoing study suggest that the novel decompression catheter has a biomechanical effect in certain classes of disc.