Background: Sacral tumours are commonly diagnosed late and therefore are often large and at an advanced stage before treatment is instituted. The late presentation means that curative surgical excision is technically demanding¹. Total en-bloc sacrectomy is fraught with potential complications: deep infection, substantial blood loss, large bone and soft tissue defects, bladder, bowel and sexual dysfunction, spinal-pelvic non-union, and gait disturbance². The aim of the current study was two-fold: firstly to detail the technique used by the senior author and chronicle how this has evolved; and secondly to present the complications and outcome of nine total en bloc sacrectomies.

Methods: We retrospectively analysed of total en-bloc sacrectomies between 1991 and 2004. Nine patients (2M, 7F, mean age at surgery 39 years, range 21 – 64yrs) with a diagnosis of primary sacral tumour underwent total en-bloc sacrectomy under the care of the senior author. The mean follow-up was 50.2 months (range: 3.5 – 161 mths). Patients’ functional outcome was evaluated using the Functional Independence Measure (FIM) instrument and the SF-36. Intra-operative and postoperative complications (including disease progression) were documented.

Results: Surgical technique has evolved from single stage surgery without and with colostomy to two stage surgery with colostomy. Currently, the first stage includes an anterior lumbar interbody fusion at L4/L5 retaining the L5 nerve roots. In the second stage an L4 to pelvic fusion is performed posteriorally. The dura is tied and divided just below the L5 roots. The mean total operating time was 13.3 hrs (range: 8 – 20.1hrs); the mean total blood loss 14.1 ltrs (range: 4.2 – 33 ltrs). There were two revision L4 to pelvic fusions for pseudoarthroses. The mean length of hospital stay was 8.9mths (range: 2 – 36mths). One patient had a recurrence and died 2 years after her surgery. Of the surviving 8 patients the results from the functional outcome scores were variable. Three patients are able to walk independently; the remaining 5 are all mobile but require differing degrees of assistance to walk.

Conclusion: Total en bloc sacrectomy is a major surgical undertaking but our series has shown that it is probably justified in view of the fact that 8 out of 9 patients have had no tumour recurrence and all are able to walk.

Objective: To document the incidence of adjacent superior segment facet joint violation following transpedicular instrumentation in the lumbar spine as it has been postulated that this can lead to long term deterioration There has been no study so far determining this incidence.

Design: Patients undergoing lumbar fusion were prospectively evaluated with a CT scan and plain radiographs six months following surgery. These were blindly and independantly evaluated by a consultant radiologist and a research fellow.

Subjects: 106 patients (212 top level facet screws) between 1996 and 1999 were evaluated. All patients had their screws and instrumentation inserted through a Wiltse muscle splitting approach and a lateral entry point in the pedicle so as to reduce the risk of facetal impingement. ¹

Outcome Measures: Kappa co-efficient and chi-squared analysis.

Results: The Kappa co-efficient for the CT scan and plain radiographs were 0.88 and 0.39 respectively. On the CT scan both observers noted facet joint impingement in just over 20% of the screws and just over 30% of the patients. The impingement was independent of the level and diagnosis (p> 0.05) and it occurred with uniform incidence in each of the year.

Conclusion: This study raises the theoretical possibility of long term deterioration in the clinical results following the use of transpedicular instrumentaion.

Objectives: To determine if high quality, thin slice (1–3)mm CT scan images would allow proper evaluation of interbody fusion through titanium cages in view of the fact that there are no universally accepted radiological criteria. ¹

Design: Patients undergoing interbody lumbar fusion were prospectively evaluated with a CT scan and plain radiographs six months following surgery. These were blindly and independently evaluated by a consultant radiologist and a research fellow. They were assessed for bridging bony trabeculation both through and surrounding the cages as well as for changes at the cage endplate interface.

Subjects: Fifty-three patients (156 cages) undergoing posterior lumbar interbody fusion using titanium inter-body cages were evaluated. Posterior elements were used to pack the cages and no graft was packed outside the cages.

Outcome Measures: Kappa co-efficient and chi-squared analysis.

Results: On the CT scan both observers noted bridging trabeculation in 95%of the cages-Kappa 0.85, while on radiographs they were present in only 4%-Kappa 0.74. Both observers also identified bridging trabeculation surrounding the cages on the CT scans in 90%-Kappa 0.82, while on the radiographs this was 8%-Kappa 0.86. Radiographs also did not identify all the loose cages.

Conclusions: High quality CT scan images can demonstrate bridging bony trabeculation following the use of titanium interbody cages. It also demonstrated consistent bone growth outside the cages inspite of not using any bone graft.

In normal, physiological circumstances there is ample room in the spinal canal to accommodate the spinal cord. Our study aimed to identify the degree of compromise of the spinal canal which could be anticipated in various atlantoaxial pathological states. We examined paired atlas and axis vertebrae using high-definition radiography and simultaneous photography in both normal and simulated pathological orientations in order to measure the resultant dimension of the spinal canal and its percentage occlusion.

At the extreme of physiological axial rotation (47°) the spinal canal is reduced to 61% of its cross-sectional area in neutral rotation. The spinal cord is thus safe from compromise.

Atlantoaxial subluxation of up to 9 mm reduces the area of the spinal canal, in neutral rotation, to 60% with no cord compromise. Any rotation is, however, likely to cause cord compression.

The mechanism of fixation in atlantoaxial rotatory subluxation could be explained by bony interlocking of the facet joint, reproducible in dry bones.

Lateral oblique radiographs are considered important for the identification of spondylolytic lesions, but these projections will give a clear view only when the radiological beam is in the plane of the defect. We studied the variation in orientation of spondylolytic lesions on CT scans of 34 patients with 69 defects.

There was a wide variation of angle: only 32% of defects were orientated within 15° of the 45° lateral oblique plane. Lateral oblique radiographs should not be considered as the definitive investigation for spondylolysis.

We suggest that CT scans with reverse gantry angle are now more appropriate than oblique radiography for the assessment of spondylolysis. Variation in the angle of the defect may also need consideration when direct repair is being planned.

We reviewed retrospectively the role of monitoring of somatosensory spinal evoked potentials (SSEP) in 99 patients with neuromuscular scoliosis who had had operative correction with Luque-Galveston rods and sublaminar wiring.

Our findings showed that SSEP monitoring was useful and that a 50% decrease in the amplitude of the trace optimised both sensitivity and specificity. The detection of true-positive results was higher than in cases of idiopathic scoliosis, but the method was less sensitive and specific and there were more false-negative results. In contrast with the findings in idiopathic scoliosis, recovery of the trace was associated with a 50% to 60% risk of neurological impairment.

Only one permanent injury occurred during the use of this technique, and any temporary impairment resolved within two months.

In a prospective trial we performed MRI of the spine and hind brain in 31 patients with scoliosis of onset between the ages of four and 12 years.

In eight patients (26%) there was a significant neuroanatomical abnormality; there were six cases of Chiari-1 malformation associated with a syrinx, one isolated Chiari-1 malformation and one astrocytoma of the cervical spine. Four of these patients had left-sided curves.

There were no clinical features which could reliably identify those patients with abnormalities on MRI. In particular, the unilateral absence of abdominal reflexes was found to be non-specific (1 of 8 of patients with neuroanatomical abnormalities (12.5%) v 2 of 23 with normal scans (8.7%)).

In view of the established risks of surgical correction of scoliosis in the presence of undecompressed syringomyelia and the possible improvement that may follow decompression of the foramen magnum, we feel that MRI of all patients with scoliosis of juvenile onset should be obligatory.