To compare the clinical outcomes of instrumented fusion for single level degenerative spondylolisthesis with local bone versus iliac crest bone graft.

Fifty patients (32 female, 18 males) operated on by the author over a 3 year period were reviewed. All cases had a single level decompression and instrumented fusion for a degenerative spondylolisthesis. 25 patients had iliac crest graft and 25 had morcelised local bone graft. Patients were followed up for 6 months. Pre and postoperative visual analogue pain scores and Roland disability scores were recorded. Inpatient notes were reviewed for duration of surgery and duration of stay.

There was no difference in age, sex and severity of pre operative symptoms between the two groups. There was no significant difference in improvement in Roland score between the two groups but pain scores were lower in the local graft group although this was not statistically significant. Duration of surgery (140 vs 175min) and hospital stay (4.3 vs 5.1 days) were lower in the local bone graft group.6 patients in the iliac crest graft group complained of donor site pain vs none in the local graft group at 6 months.

Usage of morcelised local bone graft resulted in clinical outcomes comparable to iliac crest bone graft in patients undergoing decompression and fusion for a single level degenerative spondylolisthesis. Duration of surgery, hospital stay and donor site pain are reduced when local bone was utilised.

Cervical Cord Neuropraxia (CCN) and incomplete cord injuries such as Central Cord Syndrome (CCS) are more prevalent in patients with congenitally narrow spinal canals. The aim of this study was to identify if racial groups were over represented in patients with incomplete cord injuries, and if there was an ethnic variation in mid sagittal cervical spine diameter in the general population.

CT scan was used to measure the mid sagittal diameter of the C3 to C7 cervical vertebrae in a group of 166 sequential trauma patients who had CT scans of the cervical spine at Middlemore Hospital. Patient’s race was that declared by the patient. Four different observers used computer digitisation to measure the mid sagittal diameters and mean sagittal diameter for each level. Measurements were compared between races.

Maori cervical spine canals were found to be 1mm smaller than Europeans (P values less than 0.005) whilst Polynesians had on average a 2mm smaller mid sagittal diameter compared to Europeans (all P values less than 0.001).

This study has demonstrated that Polynesians were over represented in the group of patients who experienced CCS or Transient Cervical Neuropraxia. CT scan assessment demonstrated that both Maoris and Polynesians had significantly narrower canals than their European counterparts. The implications of this study are that Maori and Polynesians involve in high impact activities such as rugby may be at increased risk of incomplete or complete spinal cord injuries. There is however no reliable screening tool available for congenital spinal canal stenosis.

Introduction Cervical cord neuropraxia (CCN) and incomplete cord injuries such as central cord syndrome (CCS) are more prevalent in patients with congenitally narrow spinal canals. At Middlemore Hospital, Polynesian and Maori males are frequent in that group of patients who have experienced a single episode of CCN or CCS. The aim of this study was determine if these racial groups were over-represented in patients with incomplete cord injuries, and if there was an ethnic variation in mid-sagittal diameter of the cervical spine in the general population.

Methods A chart review of all patients who experienced either CCS or CCN in the absence of significant fracture dislocation or disc prolapse was performed. The ethnic origin of these patients was noted. CT scan was used to measure the mid-sagittal diameter of the spinal canal from C3 to C7 in a group of 166 sequential trauma patients who had CT scans of the cervical spine at Middlemore Hospital. Patient’s race was that declared by the patient. Four different observers used computer digitisation to measure the mid-sagittal diameters and mean sagittal diameter for each level. Measurements were compared between races.

Results Between 2000 and 2004, eight patients (7 males, 1 female) were noted to have a central cord syndrome or cervical neuropraxia in the absence of fracture dislocation, acute disc prolapse or developmental spinal stenosis. Five patients were Polynesian, two Maori and one European. CT scan assessment of the 166 patients noted Maori cervical spine canals to be 1mm smaller than Europeans (P values less than .005 at all levels of the C-spine) whilst Polynesians had on average 2mm smaller mid-sagittal diameter compared to Europeans (all P values less than 0.001).

Discussion Patients with congenital reduction in spinal canal diameter have an increased risk of transient neuropraxia (Torg J. J Bone Joint Surg. 1996), neurological injury (Matsura P et al. J Bone Joint Surg. 1989) and more significant myelopathy in the presence of trauma (Eismont FJ et. al. Spine 1984). This study demonstrates that Polynesians were over-represented in the group of patients who experienced central cord syndrome or transient cervical neuropraxia. CT scan assessment demonstrated that both Maoris and Polynesians had significantly narrower canals than their European counterparts. Previous studies have demonstrated that South African blacks have significantly narrow mid-sagittal diameter than Caucasians (Taitz C. Clin Anat. 1996). The implications of this study are that Maori and Polynesians involved in high impact activities such as rugby may be at increased risk of incomplete or complete spinal cord injuries. There is however no reliable screening tool available for congenital spinal canal stenosis.

To assess the outcome and safety of transarticular C1-C2 screw fixation

The clinical and radiological outcomes of 15 patients treated with posterior atlantoaxial transarticular screw fixation and posterior wiring was assessed at a minimum follow up of six months. Indications for fusion were rheumatoid arthritis in eight (instability in six and secondary degenerative changes in two), non union odontoid fracture four, symptomatic osodontoideum one, C1-C2 arthrosis one and irreducible odontoid fracture one. Fusion was assessed with plain x-rays including flexion – extension films.

Twenty nine screws were placed under fluroscopic guidance. Bilateral screws were placed in 14 patients and a single screw in one patient. This patient had a single screw placed due to the erosion of the controlateral C2 pars by an anomolous vertebral artery. All patients had radiological union. Two screws (7%) were malpositioned, neither was associated with clinical sequelae. No neurological or vascular injuries were noted.

Transarticular C1-C2 fusion yielded a 100% fusion rate. The risk of neurological or vascular injury can be minimised by thorough assessment of pre operative CT scans to assess position of the vertebral artery and use of intra operative lateral and AP fluroscopy.

To assess the outcome and safety of transarticular C1–C2 screw fixation. The clinical and radiological outcomes of 15 patients treated with posterior atlanto-axial transarticular screw fixation and posterior wiring was assessed at a minimum follow up of 6 months. Indications for fusion were rheumatoid arthritis in 8 (instability in 6 and secondary degenerative changes in 2), non-union odontoid fracture 4, symptomatic os-odontoideum one, C1–C2 arthrosis one and irreducible odontoid fracture one. Fusion was assessed with plain x-rays including flexion extension films.

Twenty nine screws were placed under fluoroscopic guidance. Bilateral screws were placed in 14 patients and a single screw in one patient. This patient had a single screw placed due to the erosion of the contralateral C2 pars by an anomalous vertebral artery. All patients had radiological union. Two screws (7%) were malpositioned; neither was associated with clinical sequelae. No neurological or vascular injuries were noted.

Transarticular C1–C2 fusion yielded a 100% fusion rate. The risk of neurological or vascular injury can be minimised by thorough assessment of pre operative CT scans to assess position of the vertebral artery and use of intra operative lateral and AP fluoroscopy.

Introduction: Eighty percent of individuals experience low back pain in their lifetime. This is often due to disc injury or degeneration. Conservative treatment of discogenic pain is often unsuccessful whilst surgery with the use of spacers or fusion is non-physiological.

Aim: To develop an animal model to assess the viability of autologous disc cell therapy.

Methods: The fat sand rat (Psammomys obesus obesus) was chosen because of its predisposition to the early development of spondylosis. Using microsurgical techniques fragments of annulus and nucleus were harvested from a single disc in 50 sand rats. Vascular clips were placed on the adjacent psoas muscle to mark the harvested level. Disc material was initially cultured in a monolayer then transferred into a three-dimensional culture medium of agarose. This technique yields greater cellular proliferation and the development of cell growth in colonies. Cells were labelled with bromodeoxyuridine for later immunohistochemical identification. Twenty thousand cells in a carrier medium were then reimplanted at a second operation at an adjacent disc level in the same animal. The rat was subsequently sacrificed and the histology of the disc space was reviewed.

Results: To date, 50 primary disc harvests and 30 reimplantations have been performed. Two rats died prior to reimplantation. All histological specimens confirmed the presence of viable transplanted disc cells.

Conclusions: Autologous disc cell transplantation can be performed in the rat. Further modification of these techniques may lead to the development of autologous disc cell therapy comparable to that currently successfully used in hyaline cartilage defects of synovial joints in humans.

Purpose/introduction: 80% of individuals experience low back pain in their lifetime. This is often due to disc injury or degeneration. Conservative treatment of discogenic pain is often unsuccessful whilst surgery with the use of spacers of fusion is non-physiological. The aim of this study was to develop an animal model to assess the viability of autologous disc cell therapy.

Method: The Fat Sand Rat (Psammomys obesus obesus) was chosen due to its predisposition to the early development of spondylosis. Using microsurgical techniques fragments of annulus and nucleus were harvested from a single disc in 52 sand rats. Vascular clips were placed on the adjacent psoas muscle to mark the harvested level. Disc material was initially cultured in monolayer then transferred into a three dimensional culture media of agarose. This technique yields greater cellular proliferation and the development of cell growth in colonies. Cells were labelled with Bromodeoxyuridine for later immunohistochemical identification. 20 000 cells in a carrier media were then re-implanted at a second operation at an adjacent disc level in the same animal. The rat was subsequently euthanised and the histology of the disc space reviewed.

Results: To date 52 primary disc harvests and 20 reimplantations have been performed. 15 rats have been euthanised and sectioned. Average age at primary surgery was 6.8 months reimplantation eight months and euthanisation 11.2 months. Cell colony viability was inversely related to rat age at harvest. Immunohistochemical analysis of colony extracellular matrix revealed production of type 1 and 2 collagen, chondroitin and keratin sulphate Two rats died prior to reimplantation. All histological specimens confirm the presence of viable transplanted disc cells. Transplanted cells did not alter the progression of degenerative changes on x-ray.

Conclusion: Autologous disc cell transplantation can be performed in the rat. Further modification of these techniques may lead to the development of autologous disc cell therapy comparable to that currently successfully used in hyaline cartilage defects of synovial joints in humans.