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.

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.

Objective: To evaluate the long term results of an operation developed to decompress the roots at the stenotic level, preserve the midline structures, and not use instrumentation or fusion.

Design: A retrospective clinical and radiological review of consecutive patients operated on for spinal stenosis secondary to lumbar spondylosis.

Subjects: One hundred and sixty patients (eighty seven female and seventy three male) with a mean age at operation of sixty eight (range 40–90). Sixty one patients (38%) had a degenerative listhesis causing stenosis. The mean post operative follow-up was twenty two months (range two months to fourteen years).

Summary of background data: Lumbar spondylosis, commonly involving degenerative listhesis, is the commonest cause for spinal stenosis in the lumbar spine. Surgery offers the only permanent cure. The standard procedure remains a laminectomy with fixation and fusion in the presence of possible instability. The laminectomy destabilises the spine and the instrumented fusion makes it a much bigger operation in patients often not best placed to cope with it. There is a need, therefore, for an effective operation that does not compromise spinal stability.

Results: At six weeks one hundred and forty one patient (85%) reported relief of leg pain and a further nine patients were improved at three to six months. 52% of the patients reported a concomitant improvement in back pain. The results were sustained at follow-up.

The operation was not responsible for the development of a new spondylolisthesis. A minimal increase in an existing degenerative listhesis was seen in two patients only without compromise of their good results. There was no revision surgery at any of the operated levels.

Conclusions: The operation of segmental spinal decompression for degenerative lumbar spinal stenosis has been found to be effective, safe, and give good long term results, without compromising the existing spinal stability. Patient selection and attention to operative technique are essential.

Objectives: To establish the side incidence of acute lumbar disc prolapse and to determine whether there is a correlation between the side of the prolapse and hand dominance.

Design: A retrospective study of consecutive cases of acute lumbar disc prolapse in which the diagnosis was confirmed at operation and the patients contacted about hand dominance.

Summary of background data: The side incidence of operatively confirmed disc herniation does not appear to have been reported.

Lifting and turning with the trunk in the flexed position is the commonest cause of an acute disc prolapse. Flexion and rotation of the lumbar spine, under load, may also give rise to unilateral fractures in the lumbar spine in fast bowlers in cricket and in eighty percent of these cases the fracture occurs on the opposite side to the bowling arm (ref 1.) Given that the majority of the population (eighty nine percent) are right handed it was speculated that the incidence of lumbar disc prolapse might not be equal and might be greater on the side opposite the dominant hand.

Methods: From a review of case notes one hundred and twenty six patients were identified in which a sequestrated disc fragment was confirmed at operation. The side of the prolapse was noted. These patients were contacted to determine their hand dominance.

Results: Fifty nine patients (47%) had a disc prolapse on the right side and sixty seven (55%) had a disc prolapse on the left side. There was no statistically significant difference in the numbers.

Ninety two of the one hundred and twenty six patients contacted about their hand dominance responded: eighty three patients (90.2%) were right handed, eight (8.7%) were left handed and one patient (1.1%) was ambidextrous. Of the eighty three right handed patients, forty (48.2%) had a left sided disc prolapse and forty three (51.8%) had a right sided disc prolapse.

Conclusion: This study revealed no difference in the side incidence of lumbar disc prolapse. There was no correlation either with the side of the prolapse and hand dominance.

The findings are considered to support the view that a disc prolapse, and the side on which it occurs, is not a consequence of a single unilateral action but an end product of pre-existing disc degeneration in a midline structure.