Background

Established hip and knee arthroplasty registers exist in many countries but this is not the case with spinal implants. Moreover, in the case of a rod intended to guide spinal growth in a child and then be removed, the definition of ‘failure’ (revision) used for hip or knee arthroplasty is inappropriate. How can the performance of such spinal implants be judged?

The MAGnetic Expansion Control (MAGEC) system is used increasingly in the management of early-onset scoliosis. Good results have been published, but there have been recent reports identifying implant failures that may be associated with significant metallosis surrounding the implants. This article aims to present the current knowledge regarding the performance of this implant, and the potential implications and strategies that may be employed to identify and limit any problems.

We urge surgeons to apply caution to patient and construct selection; engage in prospective patient registration using a spine registry; ensure close clinical monitoring until growth has ceased; and send all explanted MAGEC rods for independent analysis.

The MAGEC system may be a good instrumentation system for the treatment of early-onset scoliosis. However, it is innovative and like all new technology, especially when deployed in a paediatric population, robust systems to assess long-term outcome are required to ensure that patient safety is maintained.

Cite this article: Bone Joint J 2017;99-B:708–13.

Aim

To identify patterns in referral and the management pathway of patients with primary bone tumours of the spine referred to the Orthopaedic Spine Unit in order to recommend ways to improve the service.

Background: Selective lumbar nerve root blocks (SLNRB) are widely used as a diagnostic tool. The usefulness of this technique depends on the ability to accurately infiltrate the desired nerve root without blocking the traversing nerve root to the next level. The aim of this retrospective study was to ascertain the accuracy of SLNRB’s in adult deformity.

Method: 30 SLNRB’s were performed by one surgeon on patients with adult deformity.Pre-operative AP + lateral lumbar films were used to quantify the degree of deformity using the Schwab grading system. An AP fluoroscopic film was taken and analysed to determine the flow of injectate in relation to pedicle anatomy. The results were analysed to determine the accuracy of SLN-RB’s in adult deformity.

Results: Of the 30 patients with deformity 17 needle tips were positioned lateral to the middle third of the pedicle and 13 under the middle third of the pedicle. Of the 17 needle tips placed laterally 8 (47%) had flow into the nerve root sheath, 6 (35%) into the nerve root sheath + canal and 3 (17%) into the canal alone. Overall accuracy with no epidural spread was 40% compared the published standard of 61%.

Conclusions: The accuracy of SLNRB in adult deformity was significantly less than the published standard in patients without deformity. In addition the accuracy of SLNRB with needle tip position lateral to the pedicle was only 47% compared to 96% in previous studies. The suggestion of this author is that contrast is used in all SLNRB’s in patients with deformity in order to allow accurate clinical interpretation of results.

Objectives: To evaluate the early coronal and sagittal correction of main thoracic adolescent idiopathic scoliosis using pedicle screw instrumentation and to determine whether implant density influences correction.

Methods and results: 49 consecutive patients with Lenke I main thoracic adolescent idiopathic scoliosis underwent single stage posterior correction and instrumented spinal fusion with pedicle screw fixation between 2006 and 2008. All surgeries were performed in a single institution by a single surgeon using identical surgical technique and type of instrumentation. Pre- and postoperative radiographs were analyzed. The pre-operative main thoracic curve of 60.0 ± 13.4° was corrected to 17.4 ± 6.9° (69.9% correction) on the post-operative radiographs. The pre-operative thoracic kyphosis of 20.0 ± 10.2° decreased to 11.6 ± 4.9° post-operatively. There was a significant correlation between decrease in sagittal kyphosis and magnitude of coronal Cobb angle correction (P = 0.002). There was no correlation between implant density and magnitude of coronal or sagittal curve correction, with and without curve flexibility taken into consideration.

Conclusions: Pedicle screw constructs provided excellent coronal correction of thoracic idiopathic scoliosis, however this was at the expense of sagittal contour. Decrease in sagittal kyphosis correlated with magnitude of coronal correction. Bilateral segmental pedicle screw fixation did not improve curve correction compared with unilateral or alternate segmental fixation.

Ethics approval: None required. Caldicott and Data Protection Approval No. 661.

Interest Statement: None.

Background: To evaluate bone mineral density in patients with scoliosis of different causes and compare it to the expected values for the age, gender and body mass.

Methods: A Prospective, observational case series. From October 2003 to December 2004, Bone Mineral Density (BMD) of patients with different types of Scoliosis was recorded. Patients listed for corrective spinal surgery in our institute were included in the study (Total of 68 patients). BMD on lumbar spine and whole body was measured by DXA scan and recorded in form of Z-scores. Z-scores = number of Standard Deviations (SD) above or below age matched norms; it is age and gender specific standard deviation scores. Data collected using the same DXA scan equipment and software.

There were 29 patients with Adolescent Idiopathic Scoliosis and 7 patients with congenital or infantile scoliosis. Z-scores from patients with neuromuscular scoliosis also included, 10 patients with cerebral palsy and 11 with muscular dystrophies (mainly Duchenne MD). There were also 3 patients with Neurofbromatosis and 8 patients with other conditions (miscellaneous). Outcome measures were bone mineral density in patients with different types of scoliosis in form of Z-scores.

Results: Bone mineral density was significantly lower than normal for the age, gender and body mass in all patients with neuromuscular scoliosis; whole body z-score in group with cerebral palsy was −1.00 and −1.30 in muscular dystrophies group. Lumbar spine BMD was even lower in lumbar spine, mean z-score, – 4.51 in cerebral palsy and −2.36 in muscular dystrophies (mainly Duchenne MD). In idiopathic Scoliosis group mean BMD was markedly lower than normal for the age, gender and body mass, mean z-score = – 1.87, however whole body BMD was within the normal range, mean z-score = +0.124. Similar results were found in congenital and infantile scoliosis group, mean lumber z-score= – 1.36 and whole body z-score, – 0.30. In patients with neurofibromatosis, there were low BMD on spine, mean z-score was −1.19 while whole body z-score was + 0.19. In group of patients with other miscellaneous causes of scoliosis or syndromic scoliosis lumbar mean z-score= −2.22 and whole body mean z-score was −1.67.

Conclusion: This study showed that BMD on spine was lower than normal for the age, gender and body mass in all patients with scoliosis and the condition was even worse in neuromuscular and sydromic scoliosis. There was no correlation between spine BMD and whole body BMD. Spine BMD was lower than normal in almost all patients even when whole body BMD was within normal range. Thus we believe that DXA scan is a useful adjunct in the preoperative assessment of scoliotic patients prior to spinal surgery.

Objective: The purpose of this study is to determine the accuracy of the push-pull radiographs in predicting the surgical correction in neuromuscular scoliosis.

Study Design: Retrospective radiographic review.

Subjects: Radiographs of 26 patients with neuromuscular scoliosis secondary to Duchennes Muscular Dystrophy were reviewed. All the patients had a posterior instrumented correction of the deformity by the same surgeon with the Universal Spinal System. Duchennes Muscular Dystrophy was chosen as a model for neuromuscular scoliosis since it represents a homogenous group with regards to the spinal deformity.

Outcome measures: The Cobb angle, the translation of the apex of the deformity from the central sacral line, pelvic tilt and the number of motion segments in the curve were compared between pre-operative erect, push-pull view and the post-operative radiographs. Results were analysed using student’s t test for significance and Pearson’s coefficient for correlation with the SPSS software.

Results: A correlation was seen in the form of an improvement in the Cobb angle, pelvic tilt and the apical translation when comparing the push-pull views and the post-operative radiographs. The improvement was statistically significant.

Conclusion: The push-pull view provides an adequate assessment of the fl exibility that guides a safe deformity correction.

Objective: To assess the effect of spinal surgery and nocturnal ventilation on lung function and survival in patients with scoliosis secondary to Duchenne Muscular Dystrophy.

Study design: Prospective, observational study by a single observer (Research Physiotherapist).

Subjects: 80 patients with Duchenne Muscular Dystrophy were treated between 1986 and 2002. During this period 40 patients underwent a spinal fusion at a mean age of 14.05y (95 % CI 13.6 – 14.6). Nocturnal ventilation was commenced when symptoms and signs of respiratory failure were evident. The mean FVC at commencement of nocturnal ventilation was 0.41 litres. The patients were divided into 2 groups based on whether they received nocturnal ventilation. A total of twenty eight patients received nocturnal ventilation and 52 did not. The groups were further sub-divided based on whether they had spinal fusion. There were fourteen patients in each sub-group of the ventilated group and 26 patients in each sub-group of those that were not ventilated.

Outcomes: Serial forced vital capacity (FVC) measurements and survival measured by Kaplan Meir survival analysis.

Results: The mean vital capacity dropped from 1.41 l (95 % CI 1.21 – 1.61) to 1.13 (95 % CI 0.893 – 1.37), a year post-operatively. This was not associated with the development of respiratory compromise. The vital capacity improved gradually, reaching the pre-operative level before it declined again. The shortest survival was seen in patients who received neither surgery nor ventilation (median survival 19.7y). The patients who received surgery but no ventilatory support were not as good as the patients that were ventilated but did not have surgery (median survival 24.3y). The best results were seen in the patients who had both surgery and ventilation (median survival 26.4y). The worst prognosis is in patients with early onset symptomatic cardiomyopathy (6 patients, with a median survival of 16.3y).

Conclusion: Nocturnal ventilation is the most important factor in the improvement in survival of patients with Duchennes muscular dystrophy. Spinal surgery is also beneficial and the best results are in those patients who have both.

We studied MR images of the spine in a consecutive series of 100 patients with acute compression of the spinal cord due to metastases. All patients had documented neurological deficit and histologically proven carcinoma. MRI was used to localise bony metastatic involvement and soft-tissue impingement of the cord. A systematic method of documenting metastatic involvement is described.

A total of 43 patients had compression at multiple levels; 160 vertebral levels were studied. In 120 vertebrae (75%), anterior, lateral and posterior bony elements were involved. Soft-tissue impingement of the spinal cord often involved more than one quadrant of its circumference. In 69 vertebrae (43%) there was concomitant anterior and posterior compression. Isolated involvement of a vertebral body was observed in only six vertebrae (3.8%).

We have shown that in most cases of acute compression of the spinal cord due to metastases there is coexisting involvement of both anterior and posterior structures.