Aims. The aim of this study was to assess the accuracy of pedicle screw placement, as well as intraoperative factors, radiation exposure, and complication rates in adult patients with degenerative disorders of the thoracic and lumbar spines who have undergone robotic-navigated spinal surgery using a contemporary system. Methods. The authors reviewed the prospectively collected data on 196 adult patients who had pedicle screws implanted with robot-navigated assistance (RNA) using the Mazor X Stealth system between June 2019 and March 2022. Pedicle screws were implanted by one experienced spinal surgeon after completion of a learning period. The accuracy of pedicle screw placement was determined using intraoperative 3D fluoroscopy. Results. A total of 1,123 pedicle screws were implanted: 1,001 screws (89%) were placed robotically, 63 (6%) were converted from robotic placement to a freehand technique, and 59 (5%) were planned to be implanted freehand. Of the robotically placed screws, 942 screws (94%) were determined to be Gertzbein and Robbins grade A with median deviation of 0.8 mm (interquartile range 0.4 to 1.6). Skive events were noted with 20 pedicle screws (1.8%). No adverse clinical sequelae were noted in the 90-day follow-up. The mean fluoroscopic exposure per screw was 4.9 seconds (SD 3.8). Conclusion. RNA is highly accurate and reliable, with a low rate of abandonment once mastered. No adverse clinical sequelae occurred after implanting a large series of pedicle screws using the latest generation of RNA. Understanding of patient-specific anatomical features and the real-time intraoperative identification of risk factors for suboptimal screw placement have the potential to improve accuracy further. Cite this article: Bone Joint J 2023;105-B(5):543–550

Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

Aims

The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

Aims

CRP is an acute-phase protein that is used as a biomarker to follow severity and progression in infectious and inflammatory diseases. Its pathophysiological mechanisms of action are still poorly defined. CRP in its pentameric form exhibits weak anti-inflammatory activity. The monomeric isoform (mCRP) exerts potent proinflammatory properties in chondrocytes, endothelial cells, and leucocytes. No data exist regarding mCRP effects in human intervertebral disc (IVD) cells. This work aimed to verify the pathophysiological relevance of mCRP in the aetiology and/or progression of IVD degeneration.

Aims

This study aimed to evaluate rasterstereography of the spine as a diagnostic test for adolescent idiopathic soliosis (AIS), and to compare its results with those obtained using a scoliometer.

Aims

The aim of this study was to determine whether early surgical treatment results in better neurological recovery 12 months after injury than late surgical treatment in patients with acute traumatic spinal cord injury (tSCI).

Aims

The aim of the study was to determine if there was a direct correlation between the pain and disability experienced by patients and size of their disc prolapse, measured by the disc’s cross-sectional area on T2 axial MRI scans.

Aims

Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques.

Aims

Although lumbosacral transitional vertebrae (LSTV) are well-documented, few large-scale studies have investigated thoracolumbar transitional vertebrae (TLTV) and spinal numerical variants. This study sought to establish the prevalence of numerical variants and to evaluate their relationship with clinical problems.

Aims

The aim of this study was to assess the reliability of using MRI scans to calculate the Spinal Instability Neoplastic Score (SINS) in patients with metastatic spinal cord compression (MSCC).

Aims

The aim of this study was to identify factors associated with poor outcome following coccygectomy on patients with chronic coccydynia and instability of the coccyx.

Aims

To report the outcome of spinal deformity correction through anterior spinal fusion in wheelchair-bound patients with myelomeningocele.

Objectives. To employ a simple and fast method to evaluate those patients with neurological deficits and misplaced screws in relatively safe lumbosacral spine, and to determine if it is necessary to undertake revision surgery. Methods. A total of 316 patients were treated by fixation of lumbar and lumbosacral transpedicle screws at our institution from January 2011 to December 2012. We designed the criteria for post-operative revision scores of pedicle screw malpositioning (PRSPSM) in the lumbosacral canal. We recommend the revision of the misplaced pedicle screw in patients with PRSPSM = 5′ as early as possible. However, patients with PRSPSM < 5′ need to follow the next consecutive assessment procedures. A total of 15 patients were included according to at least three-stage follow-up. Results. Five patients with neurological complications (PRSPSM = 5′) underwent revision surgery at an early stage. The other ten patients with PRSPSM < 5′ were treated by conservative methods for seven days. At three-month follow-up, only one patient showed delayed onset of neurological complications (PRSPSM 7′) while refusing revision. Seven months later, PRSPSM decreased to 3′ with complete rehabilitation. Conclusions. This study highlights the significance of consecutively dynamic assessments of PRSPSMs, which are unlike previous implementations based on purely anatomical assessment or early onset of neurological deficits.and also confirms our hypothesis that patients with early neurological complications may not need revision procedures in the relatively broad margin of the lumbosacral canal. Cite this article: X-J. Lin. Treatment strategies for early neurological deficits related to malpositioned pedicle screws in the lumbosacral canal: A pilot study. Bone Joint Res 2016;5:46–51

Aims

The aim of this retrospective study was to compare the correction achieved using a convex pedicle screw technique and a low implant density achieved using periapical concave-sided screws and a high implant density. We hypothesized that there would be no difference in outcome between the two techniques.

The ratio of the sagittal diameter of the cervical canal to the corresponding diameter of the vertebral body has been described as a reliable means for assessing stenosis of the canal and detecting those at risk of cervical neuropraxia. The use of ratio techniques has the advantage of avoiding variation in magnification when direct measurements are made from plain radiographs. We examined the reliability of this method using plain lateral radiographs of unknown magnification and CT scans. We also assessed other possible ratios of anatomical measurements as a guide to the diameter of the canal. Our findings showed a poor correlation between the true diameter of the canal and the ratio of its sagittal diameter to that of the vertebral body. No other more reliable ratio was identified. The variability in anatomical morphology means that the use of ratios from anatomical measurements within the cervical spine is not reliable in determining the true diameter of the cervical canal

Aims

The aim of this study was to systematically compare the safety and accuracy of robot-assisted (RA) technique with conventional freehand with/without fluoroscopy-assisted (CT) pedicle screw insertion for spine disease.

Aims

The aim of this study is to test the hypothesis that three grades of sagittal compensation for standing posture (normal, compensated, and decompensated) correlate with health-related quality of life measurements (HRQOL).

We undertook a retrospective study investigating the accuracy and safety of percutaneous pedicle screws placed under fluoroscopic guidance in the lumbosacral junction and lumbar spine. The CT scans of patients were chosen from two centres: European patients from University Medical Center Hamburg-Eppendorf, Germany, and Asian patients from the University of Malaya, Malaysia. Screw perforations were classified into grades 0, 1, 2 and 3. A total of 880 percutaneous pedicle screws from 203 patients were analysed: 614 screws from 144 European patients and 266 screws from 59 Asian patients. The mean age of the patients was 58.8 years (16 to 91) and there were 103 men and 100 women. The total rate of perforation was 9.9% (87 screws) with 7.4% grade 1, 2.0% grade 2 and 0.5% grade 3 perforations. The rate of perforation in Europeans was 10.4% and in Asians was 8.6%, with no significant difference between the two (p = 0.42). The rate of perforation was the highest in S1 (19.4%) followed by L5 (14.9%). The accuracy and safety of percutaneous pedicle screw placement are comparable to those cited in the literature for the open method of pedicle screw placement. Greater caution must be taken during the insertion of L5 and S1 percutaneous pedicle screws owing to their more angulated pedicles, the anatomical variations in their vertebral bodies and the morphology of the spinal canal at this location. Cite this article: Bone Joint J 2015; 97-B:1111–17

Aims

Diagnosis of cauda equina syndrome (CES) remains difficult; clinical assessment has low accuracy in reliably predicting MRI compression of the cauda equina (CE). This prospective study tests the usefulness of ultrasound bladder scans as an adjunct for diagnosing CES.

With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety.

Cite this article: Bone Joint J 2020;102-B(3):371–375.

Aims

Significant correction of an adolescent idiopathic scoliosis in the coronal plane through a posterior approach is associated with hypokyphosis. Factors such as the magnitude of the preoperative coronal curve, the use of hooks, number of levels fused, preoperative kyphosis, screw density, and rod type have all been implicated. Maintaining the normal thoracic kyphosis is important as hypokyphosis is associated with proximal junctional failure (PJF) and early onset degeneration of the spine. The aim of this study was to determine if coronal correction per se was the most relevant factor in generating hypokyphosis.

Aims

Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery.

We studied 52 patients, each with a lumbosacral transitional vertebra. Using MRI we found that the lumbar discs immediately above the transitional vertebra were significantly more degenerative and those between the transitional vertebrae and the sacrum were significantly less degenerative compared with discs at other levels. We also performed an anatomical study using 70 cadavers. We found that the iliolumbar ligament at the level immediately above the transitional vertebra was thinner and weaker than it was in cadavers without a lumbosacral transitional vertebra. Instability of the vertebral segment above the transitional vertebra because of a weak iliolumbar ligament could lead to subsequent disc degeneration which may occur earlier than at other disc levels. Some stability between the transitional vertebra and the sacrum could be preserved by the formation of either an articulation or by bony union between the vertebra and the sacrum through its transverse process. This may protect the disc from further degeneration in the long term

Mesenchymal stem-cell based therapies have been proposed as novel treatments for intervertebral disc degeneration, a prevalent and disabling condition associated with back pain. The development of these treatment strategies, however, has been hindered by the incomplete understanding of the human nucleus pulposus phenotype and by an inaccurate interpretation and translation of animal to human research. This review summarises recent work characterising the nucleus pulposus phenotype in different animal models and in humans and integrates their findings with the anatomical and physiological differences between these species. Understanding this phenotype is paramount to guarantee that implanted cells restore the native functions of the intervertebral disc. Cite this article: Bone Joint Res 2013;2:169–78

Aims

The aim of this study was to evaluate the outcome of spinal instrumentation in haemodialyzed patients with native pyogenic spondylodiscitis. Spinal instrumentation in these patients can be dangerous due to rates of complications and mortality, and biofilm formation on the instrumentation.

Aims

The aim of this study was to investigate the clinical and radiographic outcomes of microendoscopic laminotomy in patients with lumbar stenosis and concurrent degenerative spondylolisthesis (DS), and to determine the effect of this procedure on spinal stability.

Aims

The aim of this study was to determine the efficacy of repeat epidural steroid injections as a form of treatment for patients with insufficiently controlled or recurrent radicular pain due to a lumbar or cervical disc herniation.

There is ambiguity concerning the nomenclature and classification of fractures of the ring of the second cervical vertebra (C2). Disruption of the pars interarticularis which defines true traumatic spondylolisthesis of C2, is often wrongly called a pedicle fracture. Our aim in this study was to assess the influence of asymmetry on the anatomical and functional outcome and to evaluate the criteria of instability established by Roy-Camille et al. We studied the plain radiographs and CT scans of 24 patients: 13 were judged to be asymmetrical, ten were considered unstable and 14 stable. Treatment was with a Minerva jacket in 15 fractures and by operation in nine. Surgery was undertaken in patients with severe C2 to C3 sprains. One patient with an unstable lesion refused operation and was treated conservatively with a poor radiological result. Our study showed that asymmetry of the fracture did not affect the outcomes of treatment and should not therefore influence decisions in treatment. The criteria of Roy-Camille seem to be reliable and useful. We prefer the posterior approach to the cervical spine, which allows both stabilisation of the fracture and correction of a local kyphosis

Aims

Although we often encounter patients with an aortic aneurysm who also have diffuse idiopathic skeletal hyperostosis (DISH), there are no reports to date of an association between these two conditions and the pathogenesis of DISH remains unknown. This study therefore evaluated the prevalence of DISH in patients with a thoracic aortic aneurysm (AA).

Aims

We present the results of correcting a double or triple curve adolescent idiopathic scoliosis using a convex segmental pedicle screw technique.

Aims

We aimed to retrospectively assess the accuracy and safety of CT navigated pedicle screws and to compare accuracy in the cervical and thoracic spine (C2-T8) with (COMB) and without (POST) prior anterior surgery (anterior cervical discectomy or corpectomy and fusion with ventral plating: ACDF/ACCF).

Objectives

Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL).

Objectives

Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens.

Aims

This study aimed to determine the relationship between pedicle-lengthening distance and bulge-canal volume ratio in cases of lumbar spinal stenosis, to provide a theoretical basis for the extent of lengthening in pedicle-lengthening osteotomies.

Objectives

Pedicle-lengthening osteotomy is a novel surgery for lumbar spinal stenosis (LSS), which achieves substantial enlargement of the spinal canal by expansion of the bilateral pedicle osteotomy sites. Few studies have evaluated the impact of this new surgery on spinal canal volume (SCV) and neural foramen dimension (NFD) in three different types of LSS patients.

Percutaneous placement of pedicle screws is a well-established technique, however, no studies have compared percutaneous and open placement of screws in the thoracic spine. The aim of this cadaveric study was to compare the accuracy and safety of these techniques at the thoracic spinal level. A total of 288 screws were inserted in 16 (eight cadavers, 144 screws in percutaneous and eight cadavers, 144 screws in open). Pedicle perforations and fractures were documented subsequent to wide laminectomy followed by skeletalisation of the vertebrae. The perforations were classified as grade 0: no perforation, grade 1: < 2 mm perforation, grade 2: 2 mm to 4 mm perforation and grade 3: > 4 mm perforation. In the percutaneous group, the perforation rate was 11.1% with 15 (10.4%) grade 1 and one (0.7%) grade 2 perforations. In the open group, the perforation rate was 8.3% (12 screws) and all were grade 1. This difference was not significant (p = 0.45). There were 19 (13.2%) pedicle fractures in the percutaneous group and 21 (14.6%) in the open group (p = 0.73). In summary, the safety of percutaneous fluoroscopy-guided pedicle screw placement in the thoracic spine between T4 and T12 is similar to that of the conventional open technique.

Cite this article: Bone Joint J 2015;97-B:1555–61.

The widespread use of MRI has revolutionised the diagnostic process for spinal disorders. A typical protocol for spinal MRI includes T1 and T2 weighted sequences in both axial and sagittal planes. While such an imaging protocol is appropriate to detect pathological processes in the vast majority of patients, a number of additional sequences and advanced techniques are emerging. The purpose of the article is to discuss both established techniques that are gaining popularity in the field of spinal imaging and to introduce some of the more novel ‘advanced’ MRI sequences with examples to highlight their potential uses.

Cite this article: Bone Joint J 2015;97-B:1683–92.

We investigated the incidence of anomalies in the vertebral arteries and Circle of Willis with three-dimensional CT angiography in 55 consecutive patients who had undergone an instrumented posterior fusion of the cervical spine.

We recorded any peri-operative and post-operative complications. The frequency of congenital anomalies was 30.9%, abnormal vertebral artery blood flow was 58.2% and vertebral artery dominance 40%.

The posterior communicating artery was occluded on one side in 41.8% of patients and bilaterally in 38.2%. Variations in the vertebral arteries and Circle of Willis were not significantly related to the presence or absence of posterior communicating arteries. Importantly, 18.2% of patients showed characteristic variations in the Circle of Willis with unilateral vertebral artery stenosis or a dominant vertebral artery, indicating that injury may cause lethal complications. One patient had post-operative cerebellar symptoms due to intra-operative injury of the vertebral artery, and one underwent a different surgical procedure because of insufficient collateral circulation.

Pre-operative assessment of the vertebral arteries and Circle of Willis is essential if a posterior spinal fusion with instrumentation is to be carried out safely.

Cite this article: Bone Joint J 2014;96-B:535–40.

Few studies have examined the order in which a spinal osteotomy and total hip replacement (THR) are to be performed for patients with ankylosing spondylitis. We have retrospectively reviewed 28 consecutive patients with ankylosing spondylitis who underwent both a spinal osteotomy and a THR from September 2004 to November 2012. In the cohort 22 patients had a spinal osteotomy before a THR (group 1), and six patients had a THR before a spinal osteotomy (group 2). The mean duration of follow-up was 3.5 years (2 to 9). The spinal sagittal Cobb angle of the vertebral osteotomy segment was corrected from a pre-operative kyphosis angle of 32.4 (SD 15.5°) to a post-operative lordosis 29.6 (SD 11.2°) (p < 0.001). Significant improvements in pain, function and range of movement were observed following THR. In group 2, two of six patients had an early anterior dislocation. The spinal osteotomy was performed two weeks after the THR. At follow-up, no hip has required revision in either group. Although this non-comparative study only involved a small number of patients, given our experience, we believe a spinal osteotomy should be performed prior to a THR, unless the deformity is so severe that the procedure cannot be performed.

Cite this article: Bone Joint J 2014;96-B:360–5.

The aim of this study was to evaluate the feasibility of using the intact S1 nerve root as a donor nerve to repair an avulsion of the contralateral lumbosacral plexus. Two cohorts of patients were recruited. In cohort 1, the L4–S4 nerve roots of 15 patients with a unilateral fracture of the sacrum and sacral nerve injury were stimulated during surgery to establish the precise functional distribution of the S1 nerve root and its proportional contribution to individual muscles. In cohort 2, the contralateral uninjured S1 nerve root of six patients with a unilateral lumbosacral plexus avulsion was transected extradurally and used with a 25 cm segment of the common peroneal nerve from the injured leg to reconstruct the avulsed plexus.

The results from cohort 1 showed that the innervation of S1 in each muscle can be compensated for by L4, L5, S2 and S3. Numbness in the toes and a reduction in strength were found after surgery in cohort 2, but these symptoms gradually disappeared and strength recovered. The results of electrophysiological studies of the donor limb were generally normal.

Severing the S1 nerve root does not appear to damage the healthy limb as far as clinical assessment and electrophysiological testing can determine. Consequently, the S1 nerve can be considered to be a suitable donor nerve for reconstruction of an avulsed contralateral lumbosacral plexus.

Cite this article: Bone Joint J 2015; 97-B:358–65.

The purpose of this study was to determine whether it would be feasible to use oblique lumbar interbody fixation for patients with degenerative lumbar disease who required a fusion but did not have a spondylolisthesis.

A series of CT digital images from 60 patients with abdominal disease were reconstructed in three dimensions (3D) using Mimics v10.01: a digital cylinder was superimposed on the reconstructed image to simulate the position of an interbody screw. The optimal entry point of the screw and measurements of its trajectory were recorded. Next, 26 cadaveric specimens were subjected to oblique lumbar interbody fixation on the basis of the measurements derived from the imaging studies. These were then compared with measurements derived directly from the cadaveric vertebrae.

Our study suggested that it is easy to insert the screws for L1/2, L2/3 and L3/4 fixation: there was no significant difference in measurements between those of the 3-D digital images and the cadaveric specimens. For L4/5 fixation, part of L5 inferior articular process had to be removed to achieve the optimal trajectory of the screw. For L5/S1 fixation, the screw heads were blocked by iliac bone: consequently, the interior oblique angle of the cadaveric specimens was less than that seen in the 3D digital images.

We suggest that CT scans should be carried out pre-operatively if this procedure is to be adopted in clinical practice. This will assist in determining the feasibility of the procedure and will provide accurate information to assist introduction of the screws.

Cite this article: Bone Joint J 2013;95-B:977–82.

We reviewed 212 consecutive patients with adolescent idiopathic scoliosis who underwent posterior spinal arthrodesis using all pedicle screw instrumentation in terms of clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51 patients), the correction was performed over two rods using bilateral segmental pedicle screws. In Group 2 (161 patients), the correction was performed over one rod using unilateral segmental pedicle screws with the second ^{rod providing stability of the construct through two-level screw fixation at proximal and distal ends. The mean age at surgery was 14.8 years in both groups. Comparison between groups showed no significant differences with regard to age and Risser grade at surgery, pre- and post-operative scoliosis angle, coronal Cobb correction, length of hospital stay and SRS scores. Correction of upper thoracic curves was significantly better in Group 1 (p = 0.02). Increased surgical time and intra-operative blood loss was recorded in Group 1 (p < 0.001 and p = 0.04, respectively). The implant cost was reduced by mean 35% in Group 2 due to the lesser number of pedicle screws.}

Unilateral and bilateral pedicle screw techniques have both achieved excellent deformity correction in adolescent patients with idiopathic scoliosis, which was maintained at two-year follow-up. This has been associated with high patient satisfaction and low complication rates.

Clinical, radiological, and Scoliosis Research Society-22 questionnaire data were reviewed pre-operatively and two years post-operatively for patients with thoracolumbar/lumbar adolescent idiopathic scoliosis treated by posterior spinal fusion using a unilateral convex segmental pedicle screw technique. A total of 72 patients were included (67 female, 5 male; mean age at surgery 16.7 years (13 to 23)) and divided into groups: group 1 included 53 patients who underwent fusion between the vertebrae at the limit of the curve (proximal and distal end vertebrae); group 2 included 19 patients who underwent extension of the fusion distally beyond the caudal end vertebra.

A mean scoliosis correction of 80% (45% to 100%) was achieved. The mean post-operative lowest instrumented vertebra angle, apical vertebra translation and trunk shift were less than in previous studies. A total of five pre-operative radiological parameters differed significantly between the groups and correlated with the extension of the fusion distally: the size of the thoracolumbar/lumbar curve, the lowest instrumented vertebra angle, apical vertebra translation, the Cobb angle on lumbar convex bending and the size of the compensatory thoracic curve. Regression analysis allowed an equation incorporating these parameters to be developed which had a positive predictive value of 81% in determining whether the lowest instrumented vertebra should be at the caudal end vertebra or one or two levels more distal. There were no differences in the Scoliosis Research Society-22 outcome scores between the two groups (p = 0.17).

In conclusion, thoracolumbar/lumbar curves in patients with adolescent idiopathic scoliosis may be effectively treated by posterior spinal fusion using a unilateral segmental pedicle screw technique. Five radiological parameters correlate with the need for distal extension of the fusion, and an equation incorporating these parameters reliably informs selection of the lowest instrumented vertebra.

Cite this article: Bone Joint J 2014;96-B:1082–9.

This short contribution aims to explain how intervertebral disc ‘degeneration’ differs from normal ageing, and to suggest how mechanical loading and constitutional factors interact to cause disc degeneration and prolapse. We suggest that disagreement on these matters in medico-legal practice often arises from a misunderstanding of the nature of ‘soft-tissue injuries’.

We describe 13 patients with cerebral palsy and lordoscoliosis/hyperlordosis of the lumbar spine who underwent a posterior spinal fusion at a mean age of 14.5 years (10.8 to 17.4) to improve sitting posture and relieve pain. The mean follow-up was 3.3 years (2.2 to 6.2).

The mean pre-operative lumbar lordosis was 108^° (80 to 150^°) and was corrected to 62^° (43^° to 85^°); the mean thoracic kyphosis from 17^° (-23^° to 35^°) to 47^° (25^° to 65^°); the mean scoliosis from 82^° (0^° to 125^°) to 22^° (0^° to 40^°); the mean pelvic obliquity from 21^° (0^° to 38^°) to 3^° (0^° to 15^°); the mean sacral slope from 79^° (54^° to 90^°) to 50^° (31^° to 66^°). The mean pre-operative coronal imbalance was 5 cm (0 cm to 8.9 cm) and was corrected to 0.6 cm (0 to 3.2). The mean sagittal imbalance of -8 cm (-16 cm to 7.8 cm) was corrected to -1.6 cm (-4 cm to 2.5 cm). The mean operating time was 250 minutes (180 to 360 minutes) and intra-operative blood loss 0.8 of estimated blood volume (0.3 to 2 estimated blood volume). The mean intensive care and hospital stay were 3.5 days (2 to 8) and 14.5 days (10 to 27), respectively. Three patients lost a significant amount of blood intra-operatively and subsequently developed chest or urinary infections and superior mesenteric artery syndrome.

An increased pre-operative lumbar lordosis and sacral slope were associated with increased peri-operative morbidity: scoliosis and pelvic obliquity were not. A reduced lumbar lordosis and increased thoracic kyphosis correlated with better global sagittal balance at follow-up. All patients and their parents reported excellent surgical outcomes.

Lordoscoliosis and hyperlordosis are associated with significant morbidity in quadriplegic patients. They are rare deformities and their treatment is challenging. Sagittal imbalance is the major component: it can be corrected by posterior fusion of the spine with excellent functional results.

Cite this article: Bone Joint J 2014;96-B:800–6.

Ventral screw osteosynthesis is a common surgical method for treating fractures of the odontoid peg, but there is still no consensus about the number and diameter of the screws to be used. The purpose of this study was to develop a more accurate measurement technique for the morphometry of the odontoid peg (dens axis) and to provide a recommendation for ventral screw osteosynthesis.

Images of the cervical spine of 44 Caucasian patients, taken with a 64-line CT scanner, were evaluated using the measuring software MIMICS. All measurements were performed by two independent observers. Intraclass correlation coefficients were used to measure inter-rater variability.

The mean length of the odontoid peg was 39.76 mm (sd 2.68). The mean screw entry angle α was 59.45° (sd 3.45). The mean angle between the screw and the ventral border of C2 was 13.18° (sd 2.70), the maximum possible mean converging angle of two screws was 20.35° (sd 3.24). The measurements were obtained at the level of 66% of the total odontoid peg length and showed mean values of 8.36 mm (sd 0.84) for the inner diameter in the sagittal plane and 7.35 mm (sd 0.97) in the coronal plane. The mean outer diameter of the odontoid peg was 12.88 mm (sd 0.91) in the sagittal plane and 11.77 mm (sd 1.09) in the coronal plane. The results measured at the level of 90% of the total odontoid peg length were a mean of 6.12 mm (sd 1.14) for the sagittal inner diameter and 5.50 mm (sd 1.05) for the coronal inner diameter. The mean outer diameter of the odontoid peg was 11.10 mm (sd 1.0) in the sagittal plane and 10.00 mm (sd 1.07) in the coronal plane. In order to calculate the necessary screw length using 3.5 mm cannulated screws, 1.5 mm should be added to the measured odontoid peg length when anatomical reduction seems possible.

The cross-section of the odontoid peg is not circular but slightly elliptical, with a 10% greater diameter in the sagittal plane. In the majority of cases (70.5%) the odontoid peg offers enough room for two 3.5 mm cannulated cortical screws.

Cite this article: Bone Joint J 2013;95-B:536–42.

The management of spinal deformity in children with univentricular cardiac pathology poses significant challenges to the surgical and anaesthetic teams. To date, only posterior instrumented fusion techniques have been used in these children and these are associated with a high rate of complications. We reviewed our experience of both growing rod instrumentation and posterior instrumented fusion in children with a univentricular circulation.

Six children underwent spinal corrective surgery, two with cavopulmonary shunts and four following completion of a Fontan procedure. Three underwent growing rod instrumentation, two had a posterior fusion and one had spinal growth arrest. There were no complications following surgery, and the children undergoing growing rod instrumentation were successfully lengthened. We noted a trend for greater blood loss and haemodynamic instability in those whose surgery was undertaken following completion of a Fontan procedure. At a median follow-up of 87.6 months (interquartile range (IQR) 62.9 to 96.5) the median correction of deformity was 24.2% (64.5° (IQR 46° to 80°) vs 50.5° (IQR 36° to 63°)).

We believe that early surgical intervention with growing rod instrumentation systems allows staged correction of the spinal deformity and reduces the haemodynamic insult to these physiologically compromised children. Due to the haemodynamic changes that occur with the completed Fontan circulation, the initial scoliosis surgery should ideally be undertaken when in the cavopulmonary shunt stage.

Cite this article: Bone Joint J 2014;96-B:94–9.

We investigated the spinopelvic morphology and global sagittal balance of patients with a degenerative retrolisthesis or anterolisthesis. A total of 269 consecutive patients with a degenerative spondylolisthesis were included in this study. There were 95 men and 174 women with a mean age of 64.3 years (sd 10.5; 40 to 88). A total of 106 patients had a pure retrolisthesis (R group), 130 had a pure anterolisthesis (A group), and 33 had both (R+A group).

A backward slip was found in the upper lumbar levels (mostly L2 or L3) with an almost equal gender distribution in both the R and R+A groups. The pelvic incidence and sacral slope of the R group were significantly lower than those of the A (both p < 0.001) and R+A groups (both p < 0.001). The lumbar lordosis of the R+A group was significantly greater than that of the R (p = 0.025) and A groups (p = 0.014). The C7 plumb line of the R group was located more posteriorly than that of the A group (p = 0.023), but was no different from than that of the R+A group (p = 0.422). The location of C7 plumb line did not differ between the three groups (p = 0.068). The spinosacral angle of the R group was significantly smaller than that of the A group (p < 0.001) and R+A group (p < 0.001).

Our findings imply that there are two types of degenerative retrolisthesis: one occurs primarily as a result of degeneration in patients with low pelvic incidence, and the other occurs secondarily as a compensatory mechanism in patients with an anterolisthesis and high pelvic incidence.

Cite this article: Bone Joint J 2013;95-B:1244–9.

The purpose of this study was to investigate the clinical predictors of surgical outcome in patients with cervical spondylotic myelopathy (CSM). We reviewed a consecutive series of 248 patients (71 women and 177 men) with CSM who had undergone surgery at our institution between January 2000 and October 2010. Their mean age was 59.0 years (16 to 86). Medical records, office notes, and operative reports were reviewed for data collection. Special attention was focused on pre-operative duration and severity as well as post-operative persistence of myelopathic symptoms. Disease severity was graded according to the Nurick classification.

Our multivariate logistic regression model indicated that Nurick grade 2 CSM patients have the highest chance of complete symptom resolution (p < 0.001) and improvement to normal gait (p = 0.004) following surgery. Patients who did not improve after surgery had longer duration of myelopathic symptoms than those who did improve post-operatively (17.85 months (1 to 101) vs 11.21 months (1 to 69); p = 0.002). More advanced Nurick grades were not associated with a longer duration of symptoms (p = 0.906).

Our data suggest that patients with Nurick grade 2 CSM are most likely to improve from surgery. The duration of myelopathic symptoms does not have an association with disease severity but is an independent prognostic indicator of surgical outcome.

Cite this article: Bone Joint J 2013;95-B:966–71.

There are many causes of paraspinal muscle weakness which give rise to the dropped-head syndrome. In the upper cervical spine the central portion of the spinal cord innervates the cervical paraspinal muscles. Dropped-head syndrome resulting from injury to the central spinal cord at this level has not previously been described. We report two patients who were treated acutely for this condition. Both presented with weakness in the upper limbs and paraspinal cervical musculature after a fracture of C2. Despite improvement in the strength of the upper limbs, the paraspinal muscle weakness persisted in both patients. One ultimately underwent cervicothoracic fusion to treat her dropped-head syndrome.

While the cause of the dropped-head syndrome cannot be definitively ascribed to the injuries to the spinal cord, this pattern is consistent with the known patho-anatomical mechanisms of both injury to the central spinal cord and dropped-head syndrome.

This study prospectively compared the efficacy of kyphoplasty using a Jack vertebral dilator and balloon kyphoplasty to treat osteoporotic compression fractures between T10 and L5. Between 2004 and 2009, two groups of 55 patients each underwent vertebral dilator kyphoplasty and balloon kyphoplasty, respectively. Pain, function, the Cobb angle, and the anterior and middle height of the vertebral body were assessed before and after operation. Leakage of bone cement was recorded. The post-operative change in the Cobb angle was significantly greater in the dilator kyphoplasty group than in the balloon kyphoplasty group (−9.51° (sd 2.56) vs −7.78° (sd 1.19), p < 0.001)). Leakage of cement was less in the dilator kyphoplasty group. No other significant differences were found in the two groups after operation, and both procedures gave equally satisfactory results in terms of all other variables assessed. No serious complications occurred in either group.

These findings suggest that vertebral dilator kyphoplasty can facilitate better correction of kyphotic deformity and may ultimately be a safer procedure in reducing leakage of bone cement.

We describe a modified technique of micro-decompression of the lumbar spine involving the use of an operating microscope, a malleable retractor and a high-speed burr, which allows decompression to be performed on both sides of the spine through a unilateral, hemi-laminectomy approach. The first 100 patients to be treated with this technique have been evaluated prospectively using a visual analogue score for sciatica and back pain, the MacNab criteria for patient satisfaction, and functional assessment with the Oswestry Disability Index.

After a period of follow-up from 12 months to six years and four months, sciatica had improved in 90 patients and back pain in 84 patients. Their result was graded as good or excellent by 82 patients according to the MacNab criteria, and 75 patients had subjective improvement in their walking distance. Late instability developed in four patients.

Lumbar micro-decompression has proved to be safe, with few complications. Postoperative instability requiring fusion was uncommon, and less than using traditional approaches in published series.

We describe the results of a prospective case series of patients with spondylolysis, evaluating a technique of direct stabilisation of the pars interarticularis with a construct that consists of a pair of pedicle screws connected by a U-shaped modular link passing beneath the spinous process. Tightening the link to the screws compresses bone graft in the defect in the pars, providing rigid intrasegmental fixation. We have carried out this procedure on 20 patients aged between nine and 21 years with a defect of the pars at L5, confirmed on CT. The mean age of the patients was 13.9 years (9 to 21). They had a grade I or less spondylolisthesis and no evidence of intervertebral degeneration on MRI. The mean follow-up was four years (2.3 to 7.3). The patients were assessed by the Oswestry Disability Index (ODI) and a visual analogue scale (VAS). At the latest follow-up, 18 patients had an excellent clinical outcome, with a significant (p < 0.001) improvement in their ODI and VAS scores. The mean ODI score at final follow-up was 8%. Assessment of the defect by CT showed a rate of union of 80%. There were no complications involving the internal fixation.

The strength of the construct removes the need for post-operative immobilisation.

Objectives

To evaluate the neck strength of school-aged rugby players, and to define the relationship with proxy physical measures with a view to predicting neck strength.

Diastematomyelia is a rare congenital abnormality of the spinal cord. This paper summarises more than 30 years’ experience of treating this condition. Data were collected retrospectively on 138 patients with diastematomyelia (34 males, 104 females) who were treated at our hospital from May 1978 to April 2010. A total of 106 patients had double dural tubes (type 1 diastematomyelia), and 32 patients had single dural tubes (type 2 diastematomyelia). Radiographs, CT myelography, and MRI showed characteristic kyphoscoliosis, widening of the interpedicle distance, and bony, cartilaginous, and fibrous septum. The incidences of symptoms including characteristic changes of the dorsal skin, neurological disorders, and congenital spinal or foot deformity were significantly higher in type 1 than in type 2. Surgery is more effective for patients with type 1 diastematomyelia; patients without surgery showed no improvement.

The effect of rheumatoid arthritis on the anatomy of the cervical spine has not been clearly documented. We studied 129 female patients, 90 with rheumatoid arthritis and 39 with other pathologies (the control group). There were 21 patients in the control group with a diagnosis of cervical spondylotic myelopathy, and 18 with ossification of the posterior longitudinal ligament. All had plain lateral radiographs taken of the cervical spine as well as a reconstructed CT scan. The axial diameter of the width of the pedicle, the thickness of the lateral mass, the height of the isthmus and internal height were measured. The transverse diameter of the transverse foramen (d1) and that of the spinal canal (d2) were measured, and the ratio d1/d2 calculated.

The width of the pedicles and the thickness of the lateral masses were significantly less in patients with rheumatoid arthritis than in those with other pathologies. The area of the transverse foramina in patients with rheumatoid arthritis was significantly greater than that in the other patients. The ratio of d1 to d2 was not significantly different. A high-riding vertebral artery was noted in 33.9% of the patients with rheumatoid arthritis and in 7.7% of those with other pathologies. This difference was statistically significant. In the rheumatoid group there was a significant correlation between isthmus height and vertical subluxation and between internal height and vertical subluxation.

This review of the literature presents the current understanding of Scheuermann’s kyphosis and investigates the controversies concerning conservative and surgical treatment. There is considerable debate regarding the pathogenesis, natural history and treatment of this condition. A benign prognosis with settling of symptoms and stabilisation of the deformity at skeletal maturity is expected in most patients. Observation and programmes of exercise are appropriate for mild, flexible, non-progressive deformities. Bracing is indicated for a moderate deformity which spans several levels and retains flexibility in motivated patients who have significant remaining spinal growth.

The loss of some correction after the completion of bracing with recurrent anterior vertebral wedging has been reported in approximately one-third of patients. Surgical correction with instrumented spinal fusion is indicated for a severe kyphosis which carries a risk of progression beyond the end of growth causing cosmetic deformity, back pain and neurological complications. There is no consensus on the effectiveness of different techniques and types of instrumentation. Techniques include posterior-only and combined anteroposterior spinal fusion with or without posterior osteotomies across the apex of the deformity. Current instrumented techniques include hybrid and all-pedicle screw constructs.

Previous studies on the anatomy of the lumbar spine have not clarified the precise relationship of the origin of the lumbar roots to their corresponding discs or their angulation to the dural sac. We studied 33 cadavers (25 formalin-preserved and eight fresh-frozen) and their radiographs to determine these details.

All cadavers showed a gradual decrease in the angle of the nerve root from L1 to S1. The origin of the root was found to be below the corresponding disc for the L1 to L4 roots. In the formalin-preserved cadavers 8% of the L5 roots originated above, 64% below and 28% at the L4/L5 disc. In the fresh cadavers the values were 12.5%, 62.5% and 25%, respectively. For the S1 root 76% originated above and 24% at the L5-S1 disc in the formalin-preserved cadavers and 75% and 25%, respectively, in the fresh cadavers.

A herniated disc usually compresses the root before division of the root sleeve. Thus, compression of the thecal sac before the origin of the root sleeve is common for L1 to L5 whereas compression at the root sleeve is common for S1.

Our findings are of value in understanding the pathophysiology of prolapse of the disc and in preventing complications during surgery.

In a prospective observational study we compared the two-year outcome of lumbar fusion by a simple technique using translaminar screws (n = 57) with a more extensive method using transforaminal lumbar interbody fusion and pedicular screw fixation (n = 63) in consecutive patients with degenerative disease of the lumbar spine. Outcome was assessed using the validated multidimensional Core Outcome Measures Index. Blood loss and operating time were significantly lower in the translaminar screw group (p < 0.01). The complication rates were similar in each group (2% to 4%). In all, 91% of the patients returned their questionnaire at two-years. The groups did not differ in Core Outcome Measures Index score reduction, 3.6 (sd 2.5) (translaminar screws) vs 4.0 (sd 2.8) (transforaminal lumbar interbody fusion) (p = 0.39); ‘good’ global outcomes, 78% (translaminar screws) vs 78% (transforaminal lumbar interbody fusion) (p = 0.99) or satisfaction with treatment, 82% (translaminar screws) vs 86% (transforaminal lumbar interbody fusion) (p = 0.52).

The two fusion techniques differed markedly in their extent and the cost of the implants, but were associated with almost identical patient-orientated outcomes.

Extensive three-point stabilisation is not always required to achieve satisfactory patient-orientated results at two years.

Thoracic back pain caused by osteoarthritis of a single costovertebral joint is a poorly recognised condition. We report a series of five patients who were successfully treated by resection arthroplasty of this joint.

Each had received a preliminary image-guided injection of local anaesthetic and steroid into the joint to confirm it as the source of pain. The surgical technique is described. There were no complications. The pain improved from a mean of 7.0 (6 to 8) on a visual analogue scale to 2.0 (0 to 4) post-operatively. The final post-operative Oswestry disability index was a mean of 19.4 (9 to 38).

Isolated osteoarthritis of a costovertebral joint is a rare but treatable cause of thoracic back pain. It is possible to obtain excellent short- and intermediate-term relief from pain with resection arthroplasty in appropriately selected patients.

Traumatic atlanto-occipital dislocation in adults is usually fatal and survival without neurological deficit is rare. The surgical management of those who do survive is difficult and controversial. Most authorities recommend posterior occipitoaxial fusion, but this compromises cervical rotation. We describe a case in which a patient with a traumatic atlanto-occipital disruption but no neurological deficit was treated by atlanto-occipital fusion using a new technique consisting of cancellous bone autografting supported by an occipital plate linked by rods to lateral mass screws in the atlas. The technique is described in detail. At one year the neck was stable, radiological fusion had been achieved, and atlantoaxial rotation preserved.

The rationale behind this approach is discussed and the relevant literature reviewed. We recommend the technique for injuries of this type.

Seven men with a mean age of 63.9 years (59 to 67) developed dysphagia because of oesophageal compression with ossification of the anterior longitudinal ligament (OALL) and radiculomyelopathy due to associated stenosis of the cervical spine. The diagnosis of OALL was made by plain lateral radiography and classified into three types; segmental, continuous and mixed. Five patients had associated OALL in the thoracic and lumbar spine without ossification of the ligamentum flavum.

All underwent removal of the OALL and six had simultaneous decompression by removal of ossification of the posterior longitudinal ligament or a bony spur. All had improvement of their dysphagia. Because symptomatic OALL may be associated with spinal stenosis, precise neurological examination is critical. A simultaneous microsurgical operation for patients with OALL and spinal stenosis gives good results without serious complications.

This study assessed the frequency of acute injury to the spinal cord in Irish Rugby over a period of ten years, between 1995 and 2004. There were 12 such injuries; 11 were cervical and one was thoracic. Ten occurred in adults and two in schoolboys. All were males playing Rugby Union and the mean age at injury was 21.6 years (16 to 36). The most common mechanism of injury was hyperflexion of the cervical spine and the players injured most frequently were playing at full back, hooker or on the wing. Most injuries were sustained during the tackle phase of play. Six players felt their injury was preventable. Eight are permanently disabled as a result of their injury.