Introduction: Epidural steroid injection is commonly used for treatment of sciatica. Traditionally these have been administered through a needle inserted in the posterior mid line via an interlaminar (IL) route. However, in recent years the transforaminal (TF) route of administration has become popular. Potential advantages of the TF route include greater accuracy of injection (with radiological confirmation) and placement of the needle tip closer to the point at which the nerve is compressed.

Methods: Consecutive patients from the practices of 2 surgeons that use an IL technique were compared with those from the practices of 2 other surgeons that use a TF technique. Inclusion criteria were leg pain accompanied by a radiological diagnosis of nerve root compression. Both patients with disc prolapse and spinal stenosis were included. Treatment outcome was measured using the Roland-Morris (RM) Score, the Sciatica Frequency and Bothersome Index (SFBI) and the Euroqol (EQ-5D) questionnaire obtained at recruitment and three months after the epidural steroid injection. A global assessment (GA) of outcome; where patients were asked whether they were

much better,

Patients were also asked the duration of any relief obtained. Statistical methods utilized included the two tailed t-test, the Wilcoxon Rank Sum test, Odds ratio (OR) and the Chi Squared Test.

Results: 39 patients received an interlaminar epidural steroid injection and 25 received a transforaminal epidural steroid injection (total 64 patients). Follow-up was achieved for 36/39 (92.3%) and 25 (100%) patients respectively. The median pre-test RM score was 11 (range 3–11) for both groups. Post test RM score was 12(6–16) for the IL group and 3 (6–10.5) for the TF group (p=0.01). Median pre-test SFBI was 25 (0–46) and 26 (4–46) for the IL and TF groups respectively. Post test SFBI was 22 (0–46) and 18 (0–41) for the IL and TF groups respectively (p=0.003). Median pre- test EQ-5D was 0.54 for both groups (range 0.06–0.72 for the IL group and 0.08–0.72 for the TF group). Post test EQ-5D was 0.55 (0.06–1) for the IL group and 0.66 (0.06–1) (p=0.21). According to their GA, 11.1% felt much better, 33.3% felt better and 55.6% felt unchanged at 3 months in the IL group. 64% felt much better, 34% better and 12% felt unchanged in the transforaminal group. The proportion of patients having relief for 3 months or more after the injections was 3/36 (8.3%) for the IL group and 10/25 (40%) for the TF group. The transforaminal injection was 7 times more likely to result in pain relief at 3 months. (OR 7.3 95% CI 1.5 – 45.8, p=0.003).

Discussion: Epidural steroid injection by the transforaminal route is more effective then by the interlaminar route in the short term relief of sciatica.

Introduction This is a Prospective Comparative cohort study to determine the change in the Low Back Outcomes Score (LBOS) after intensive non-operative, multi-disciplinary treatment for low back pain and to compare this with data collected from earlier cohorts undergoing surgical fusion. Recently published Randomised Controlled Trials have been inconclusive regarding the benefits of surgery compared with rehabilitation for low back pain. We examine this question using the Low Back Outcome Score (LBOS) as an outcome measure.

Methods The LBOS was acquired prior to and two years following treatment in cohorts undergoing fusion or rehabilitation for low back pain. Follow up was 70% and 90% respectively. The surgical group had a lower starting LBOS ( 18 v 27) but the rehabilitation group had a higher proportion of cases involved in compensation, litigation, and who were not working.

Results A significantly greater improvement in LBOS was seen in the surgically treated group than was seen in the rehabilitation group (18 v 10)

Discussion Although we do not propose surgery before non-operative treatments are exhausted, these results suggest that surgical treatment can have significant benefits for selected patients who have not improved despite a state of the art rehabilitation programme.

Introduction: The development of scoliosis in pinealectomised chickens was first observed by Machida¹ and since reported by others. That melatonin deficiency following pinealectomy may be a factor in causing scoliosis has been postulated. The relationship between pinealectomy, scoliosis and serum melatonin levels has been subject to experimental investigations. This study reports the incidence and type of scoliosis in pinealectomised, sham operated and unoperated chickens, and related serum melatonin levels.

Methods: Serum melatonin levels were obtained at sacrifice up to six weeks postoperatively. Radiological and histological examination of the spine was performed.

Results: The vertebral motion segment comprises a synovial joint lacking any discs. 19% of the un-operated group had a sharp angular deformity in contrast to the smooth curve seen in adolescent idiopathic scoliosis (AIS). There was a 38% incidence of scoliosis after sham operation (mostly of the angular variety) and a 75% incidence in the pinealectomy group (of which half were smooth curves similar to those in human AIS. Melatonin was not abolished by pinealectomy or sham operation but was at significantly lower levels than in the unoperated group. There was no difference in Melatonin levels between birds with the two types of curves.

Discussion: The avian spine has fundamental structural differences with the human. There is a natural incidence of short angular scoliosis that increases with posterior fossa surgery in the chicken. We confirm that scoliosis similar to AIS forms after pinealectomy but it is not directly related to diminished melatonin levels.

Introduction The purpose of this study is to present the results of the fi rst 28 cases operated on by one of the authors.

Methods The study is a prospective single cohort study. The technique is applicable to approximately half of the adolescent idiopathic cases requiring surgery in a busy spinal deformity practice. Clinical radiological and patient derived outcome data was collected pre-operatively and at six weeks, three months, 12 months and 24 months post-operatively. The series comprises 27 females and one male. The median age was 18 years (range 10 to 46). A median of four portals was used (range 3 to 5), six discs were excised (range 4 to 8) and seven levels were instrumented (range 5 to 9). Operating time was a median of 5.5 hours (range 4 to 7). Median blood loss was 450 ml (range 20 to 2000 ml).

Results Rib humps were corrected from a mean of 160° to 60°. The Cobb angle was converted from a mean of 55° to a mean of 21°: a correction rate of 62%. Sagittal alignment has improved: the sagittal plumb line moving a mean of two centimetres anteriorly. A significant improvement in outcome from a pre-op median of 59 to a post op median of 67 as measured by the SRS instrument has been observed. Follow-up is for a mean of 12 months (range 1 to 25). There has been one case of rod breakage at one year. This has not affected the clinical outcome and this case has now been followed for two years. There has been one case of frozen shoulder involving the dependant intra-operative shoulder that resolved after several months. There has been no blood transfusion and no loss of correction in any case to date.

Conclusions The thoracoscopic technique has proven safe and effective. A more cosmetic wound is achieved and the trunk muscles are spared. One or two levels in the thoraco-lumbar spine are spared from fusion.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.

Introduction: Although it is well recognized that the outer annulus is innervated, the relative densities of innervation of different regions of the disc have not been quantitated. We present here the first comparative analysis of the innervation of the innervation of different regions of the lumbar intervertebral disc.

Methods: A sheep model was used allowing evaluation of the whole motion segment. Four sheep spines were used. One was processed for PGP 9.5 immunoflourescence and three were processed for PGP 9.5 immunoperoxidase histochemistry. Serial sagittal sections were obtained and a count was made of the densities of innervation of different regions of the endplate and annulus. These were compared to identify which areas of the disc and endplate are most innervated.

Results: The endplate innervation is concentrated centrally adjoining the nucleus. The mean density of innervation of the central endplate was 0.44 (SEM 0.07) nerves/ mm² while the mean density of the peripheral endplate was 0.10 (SEM 0.03) nerves/ mm² (p= 0.0001). There was no significant difference between the overall endplate and annulus innervation densities 0.52 (SEM 0.1) v 0.37 (SEM 0.07) p=0.2. But the peri-annular connective tissue, external to the outer annulus contained the densest innervation of any region in the motion segment 1.05 (SEM 0.16).

Discussion: The lumbar intervertebral disc has a meagre innervation. This is concentrated in the peri-annular connective tissue and the central endplate. While receptor threshold is more closely related to nociceptive function than innervation density, these findings have important implications for any treatment of discogenic pain.

INTRODUCTION: Although it is well recognised that the outer annulus is innervated, the relative densities of innervation of different regions of the disc have not been quantitated. We present here the first comparative analysis of the innervation of the innervation of different regions of the lumbar intervertebral disc.

METHODS: A sheep model was used allowing evaluation of the whole motion segment. Four sheep spines were used. One was processed for PGP 9.5 immunofluorescence and three were processed for PGP 9.5 immunoperoxidase histochemistry. Serial sagittal sections were obtained and a count was made of the densities of innervation of different regions of the endplate and annulus. These were compared to identify which areas of the disc and endplate are most innervated.

RESULTS: The endplate innervation is concentrated centrally adjoining the nucleus. The mean density of innervation of the central endplate was 0.44 (SEM 0.07) nerves/mm2 while the mean density of the peripheral endplate was 0.10 (SEM 0.03) nerves/ mm² (p= 0.0001). There was no significant difference between the overall endplate and annulus innervation densities 0.52 (SEM 0.1) v 0.37 (SEM 0.07) p=0.2. But the peri-annular connective tissue, external to the outer annulus contained the densest innervation of any region in the motion segment 1.05 (SEM 0.16).

DISCUSSION: The lumbar intervertebral disc has a meagre innervation. This is concentrated in the peri-annular connective tissue and the central endplate. While receptor threshold is more closely related to noci-ceptive function than innervation density, these findings have important implications for any treatment of discogenic pain.

Introduction: This is a prospective study of a series of consecutive cases of Os Odontoideum focussing on CT and MRI data. Both congenital and post-traumatic aetiologies have been proposed in the literature. This can lead to confusion in a medico-legal and clinical setting.

Methods: Radiological, CT and MRI data from 26 consecutive cases of cranio-cervical anomalies were collected prospectively. Demographic details, the presence of any recent or remote traumatic aetiology and the clinical presentation were obtained from the medical record. A reconstructed mid-sagittal CT was examined for the thickness of the arch of C1, the size and location of the Os and the morphology of the atlantodens joint. The presence of any cord impression or signal change was obtained from the MRI.

Results: 18 cases of Os Odontoideum were identified. Only one had a history of significant trauma remote from presentation. All adults had an abnormal archdens joint configuration (the ‘Jigsaw’ sign) with one exception. The atlantodens ratio was significantly greater in all cases of Os odontoideum indicating a relatively thickened anterior arch of the atlas. One case of non-union of a dens fracture presenting five or more years after the injury was identified in this series. Neither in this case nor two cases of transverse ligament rupture and two cases of Ossiculum terminale, was a thickened arch or an abnormal atlantodens joint observed. 12 of the cases presented after traumatic injury to the neck. In only three of these was there any abnormal neurological signs.

Conclusions: Os Odontoideum has a characteristic appearance of the anterior C1 arch and the atlantodens joint as viewed on CT. These radiological signs are not observed after dens fractures. They may be taken to indicate a congenital aetiology for the condition. Patients with Os odontoideum are able to tolerate moderate to severe levels of injury without sustaining significant acute cord damage.

Introduction: The purpose of this study is to present the current results of a series of 21 cases operated on over the past two years. This is the only series of this type in Australia to date. Although the technique was first reported four years ago, two year results have not been reported or published.

Methods: This study is a prospective single cohort study. The technique is applicable to approximately half of the adolescent idiopathic cases requiring surgery in a busy spinal deformity practice. Clinical radiological and patient derived outcome data are collected pre-operatively and at six weeks, three months, 12 months and 24 months post operatively.

Results: The series comprised 17 females and 1 male. Median age was 16 years (range 10–37). A median of four portals was used (range 3–5), six discs excised (range 4–8) and seven levels instrumented (range 5–9). Operating time was a median of 6 h (range 4.5–7). Median blood loss was 300 ml (range 20–2000). Mean intra-operative x-ray time was 160 s (range 130–190). Rib hump was corrected from a mean of 170 to 70. The Cobb angle was converted from a mean of 510 to a mean of 240, a correction rate of 52%. There has been no loss of correction in any case to date. Further to the minor complications outlined last year there has been one case of persistent postoperative deltoid pain from the dependant shoulder that resolved after several days.

Discussion: The thoracoscopic technique has proven safe and effective. A more cosmetic wound is achieved and one or two levels in the thoracolumbar spine are spared from fusion.