Introduction: The intricate biomechanical function of the alar ligaments in the craniocervical articular complex has received considerable scientific attention. While allowing the greatest range of axial rotation of the entire spine with 40° to each side, definitive restraint at the extremes of motion by the alar ligaments is of vital importance. Detailed knowledge of the function of these ligaments is essential for comprehending the factors leading to potentially devastating instability.

Methods: Bilateral alar ligaments including the bony entheses were removed from six adult cadavers aged 65–89 years within 48 hours of death. All specimens were judged to be free of abnormalities with the exception of non-specific degenerative changes. Dimensions of the alar ligaments were measured. Schematic multipla-nar reconstruction of axial atlanto-axial rotation was done in the transverse and frontal planes for the neutral position and for rotation to 30° and 40° in the neutral plane to assess schematic fibre elongation during axial rotation and to determine the change in the angle of insertion at the odontoid and condylar entheses. This was repeated with a 1mm descending translation of the occipital condyles at 30° and 3mm descending translation of the occipital condyles at 40° rotation.

Results: The average diameter of the odontoid process measured in the sagittal plane was 10.6 mm (SD 1.1). The longest fibre length was measured from the posterior border of the odontoid enthesis to the posterior border of the condylar enthesis with an average of 13.2 mm (SD 2.5) and the shortest between the lateral (anterior) border odontoid enthesis and the anterior condylar enthesis with an average of 8.2 mm (SD 2.2). Attachment areas of the enthesis revealed an average of 60 mm2 (SD 12.4) for the odontoid and 50,6 mm2 (SD12.6) for the condylar enthesis. Schematic fibre elongation reaches 27,1% for the longest fibres at 40° axial rotation. This is reducible to 7,8% elongation by 3mm caudal translation of the atlas.

Conclusions: This theoretical model confirms that the bi-convex shape of atlanto-axial joint allows for rotation when modelled with oblique alar ligaments. This provides baseline for further research with functional MRI which will be useful for rheumatoid and post traumatic spine.

Cervical spine disorders represent a good proportion of the daily practice of many neurosurgeons. The rapidly increasing knowledge base on spinal conditions and the progressive complexity of surgical interventions appear to be generating a renewed interest in this evolving subspecialty among neurosurgical trainees. In order to assess the current level of spinal surgery training and conveyed competence in dealing with spinal disorders, a self assessment questionnaire was devised and distributed to the neurosurgical trainees attending the EANS (European Association of Neurosurgical Society) training courses. 126 questionnaires were returned with a return rate of 32%. The majority of trainees responding to the questionnaire were in their final (6th) year of training or had completed their training (60,3% of total) representing 25 European nations. A separate analysis of the data pertaining to cervical spine disorders revealed 80% of the trainees completing their training in University hospitals with cervical spine injuries predominantly managed by neurosurgeons (75%). In their practical skill assessment, 78% of the senior trainees were competent in the treatment of cervical disc herniation and cervical spinal stenosis in their anterior microsurgical techniques. In emergency management of cervical spinal trauma, 45% of the senior trainees were competent in being able to perform procedures without direct supervision. Regarding skills in anterior and posterior cervical stabilisation techniques, 33% and 15% respectively were competent in performing as well as dealing with complications & difficulties that may arise. Spinal surgery training in European residency programs has clear strength in the traditional areas of microsurgical decompression for spinal stenosis and disc herniation. Deficits are revealed in the management of spinal trauma and spinal conditions requiring the use of implants, with the exception of anterior cervical stabilisation. In order to achieve a high level of competency, EANS trainees advocate the development of a post-residency spine sub-specialty training program.

Introduction: We report the result of cervical osteotomy in 11 patients using a controlled reduction technique and assess the safety and efficacy of this operation. Methods: Between 1993 and 2006, 11 patients with ankylosing spondylitis underwent correction of cervical kyphosis utilizing an extension osteotomy at the C7/T1 junction. The procedure was carried out under general anaesthesia with spinal cord monitoring. Lateral mass screws were placed from C3–C6 and thoracic pedicle screws placed from T2 to T5. After completion of the osteotomy, the reduction manoeuvre was carried out by the senior surgeon lifting the halo, while bilateral temporary malleable rods (fixed to cervical lateral mass screws) were allowed to pass through top loading thoracic pedicle screws, before tightening by the assistant when the desired position had been achieved. The temporary malleable rods were then replaced with definitive rods, thereby creating a solid internal fixation. A halo vest was maintained for 12 weeks to support the instrumentation and allow the fusion mass to develop.

Results: Surgery was performed on 10 males and one female. The mean age at surgery was 56 years (range 40–74). Duration of symptoms averaged 2.7 years (range 1–5 yrs). The average duration of surgery was 4.7 hours (range 3–6.5) with a mean blood loss of 1938cc (range 1000–3600). The mean follow up was 6.5 years (range 2–13). The mean pre-op chin brow vertical angle was 54º (range 20–70) reducing to 7º (range 2–20) at final follow-up. The mean pre-operative kyphotic angle was 19.2º reducing to minus 34º at final follow up. Restoration of normal forward gaze was achieved in all cases. No patient suffered spinal cord injury or permanent nerve root palsy.

Conclusion: Cervico-thoracic osteotomy is a potentially hazardous procedure. The technique described reduces the risk of translation during the reduction manoeuvre thereby reducing the risk of serious neurological injury.

Introduction: Conventional reduction techniques for high-grade isthmic spondylolisthesis do not address important anatomical constraints on the L5 and S1 nerve roots, thereby leading to a significant risk of neurological deficit. We describe a novel three-stage reduction technique carried out in one operative session that respects these anatomical constraints. We report the results in seven cases.

Methods: Between 2000 and 2006, four female and three male adolescents with high-grade spondylolisthesis (grade 3 or greater) underwent this 3 stage procedure which included: I) extensive posterior decompression of L5 and S1 nerve roots plus sacral dome osteotomy. II) anterior L5/S1 discectomy. III) reduction of spondylolisthesis with pedicle screw fixation and posterior lumbar interbody fusion using interbody cages. Somatosensory and motor evoked potentials were used during the procedure. Patients were followed up for a mean of 4 years (range1–6). Sagittal balance was restored and assessed by measuring sacral slope, lumbosacral angle, pelvic incidence and pelvic tilt.

Results: The mean age at surgery was 14.7 years (range 12–17) and average duration of symptoms was 13.7 months (range6–24). Mean operative time was 6.5 hours (range 5–8), with a mean blood loss of 2242cc (range1400–4200). The mean pre-op slip angle was 57°(range 45°–100°) and the mean post-op slip angle was 37.5°(range28°–57°). Anatomical reduction was achieved in six patients and one patient with spondyloptosis was reduced to grade 2. Sagittal balance was restored in all patients. There were no permanent neurological complications. One patient with grade 4 spondylolisthesis developed transient right L5 nerve root palsy which fully recovered within 3 months.

Conclusion: The safety and efficacy of this 3 stage reduction and stabilization procedure showed that immediate reduction of high grade spondylolisthesis with minimal risk of neurological deficit is possible. The procedure is technically demanding and should be performed by spinal surgeons familiar with the principles of anterior and posterior fusion.