We studied 12 consecutive patients with facet joint dislocation in the cervical spine to assess the incidence, site and clinical sequelae of occlusion of the extracranial vertebral artery. Intra-arterial digital subtraction angiography was performed after the orthopaedic management of the dislocations. This demonstrated vertebral artery occlusion (one bilateral) in five of the seven patients with bilateral dislocations and in four of the five patients with unilateral dislocations. Two of the nine patients with vertebral artery occlusion had neurological deficits above the level of the injury, all of which resolved spontaneously within two months. In our experience, a distraction-flexion injury appears to be the most common cause of closed traumatic vertebral artery occlusion

Transarticular screws at the C1 to C2 level of the cervical spine provide rigid fixation, but there is a danger of injury to a vertebral artery. The risk is related to the technical skill of the surgeon and to variations in local anatomy. We studied the grooves for the vertebral artery in 50 dry specimens of the second cervical vertebra (C2). They were often asymmetrical, and in 11 specimens one of the grooves was deep enough to reduce the internal height of the lateral mass at the point of fixation to ≤2.1 mm, and the width of the pedicle on the inferior surface of C2 to ≤2 mm. In such specimens, the placement of a transarticular screw would put the vertebral artery at extreme risk, and there is not enough bone to allow adequate fixation. Before any decision is made concerning the type of fixation to be used at C2 we recommend that a thin CT section be made at the appropriate angle to show both the depth and any asymmetry of the grooves for the vertebral artery

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

Background: Vertebral artery injuries are often not diagnosed because they are asymptomatic. But there is information that up to 19% of all patients who incur trauma to the lower cervical spine have vertebral artery injuries. This incidence increase in flexion-distraction injuries. It is unclear as to the individual contribution of various force loads and resultant deformity on the etiology of these injuries. Purpose: To evaluate the degree of vertebral artery deformation and potential injury in staged flexion-distraction deformities of the cervical spine. Study design: Thirtyfive fresh frozen cervical spine specimens underwent vertebral artery cannulization and angiography to determine the static influence of the four stages of subaxial flexion-distraction injuries as described by Allen et al. on the vertebral artery patency. Methods: Each specimen was examined radiographically so as to exclude any preexisting cervical deformities. A cannula was inserted into the isolated cranial and caudal stumps of the vertebral arteries and perfused with contrast agent. A fluoro image intensifier recorded deformation in dye fluid passage in the four stages of flexion-distraction injuries. Results: No significant deformation in vertebral artery flow was noted in the flexion-distraction stage I injuries within the physiological range of cervical flexion. Flexion-distraction type II and III injuries demonstrated considerable impairment to vertebral artery dye flow in proportion to the degree of vertebral deformity. Manipulating the dislocated vertebral segments into a localized lordosis further impaired vertebral vessel patency. Coexisting rupture of the vertebral radicular vessel was a constant finding in stage II and III injuries. Longitudinal stretch deformities of the vertebral artery were limited primarily to the injured vertebral segments. Stage IV injuries resulted in irreversible disruption of vertebral dye flow. Conclusion: The static deformity of flexion-distraction stage II to IV subaxial cervical injuries results in significant objective compression of the vertebral vasculature, what seems to have consequences in treatment and establishing the diagnosis

We present seven children with atlantoaxial rotatory fixation (AARF) of more than three months’ duration after an injury to the upper cervical spine. The deformity was irreducible by skull traction. MRI and MR angiography (MRA) of the vertebral arteries were performed in four children. The patients were neurologically intact. Thrombosis of the ipsilateral vertebral artery was noted in two patients. The deformity was gradually corrected and stabilised after transoral release of the atlantoaxial complex, skull traction and posterior atlantoaxial fusion. Soft-tissue interposition and contractures within the atlantoaxial complex prevented closed reduction. MRI and MRA of the vertebral arteries were useful in elucidating the pathology of chronic atlantoaxial rotatory fixation

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

Injuries of the cervical spine can be classified into six categories according to a mechanistic system describing the biomechanical deficiencies incurred in a cervical spine injury. However high velocity flexion compression loads cause multiple contiguous and noncontiguous fractures due to multiple force vectors. A universal classification system cannot be applied. Instability exists if there is greater than 3.5 mm of translation or greater than 11 degrees of angulation as compared to other segments. The degree of ligamentous injury on MRI correlates with instability in patients with lateral mass facet fractures, with rupture of multiple ligaments including the anterior longitudinal, posterior longitudinal, interspinous, or facet capsule. Patients with less than 13 mm of narrowing of the sagittal canal are predisposed to neurologic injury. Vertical compression injuries cause canal occlusion and vertebral column shortening. The timing of surgery in cases of spinal cord injury is controversial. There is no difference in outcome between early (< 72 hours) and late (> 5 days) surgery. However, there remains at least a theoretical benefit to early surgery. Compression-flexion injuries result in loss of the anterior column by compression followed by the posterior column in distraction. The injury is considered unstable if there is a vertical cleavage fracture of the vertebral body or displacement. Treatment includes a cervical orthosis or halo for minor injuries, depending on the degree of kyphosis. Major injuries with displacement should be treated surgically by anterior corpectomy and plate or an anterior/posterior fusion, depending on the degree of posterior instability. The most common level of vertical-compression injuries is at the C6 or C7 level. Minimally displaced injuries can be treated with a collar or halo. Fragmentation and peripheral displacement of the bony fragments needs a halo followed by surgery and this may include an anterior corpectomy and plating. Distraction-flexion injuries may result in facet sub-luxation with less than 25% displacement, or dislocation of one (UFD) or both (BFD) facet joints. When there is 3 mm of translation (25%), the canal is occluded 20–25%. With 6mm of translation (50%), there is 40–50% canal occlusion. MRI can help analyse the soft tissue and ligamentous injuries. In UFD, all posterior ligamentous structures including joint capsule, and half the disc annulus are disrupted. Disruption of ALL and PLL is not necessary to create a UFD. In addition to the posterior structures, the ALL, the PLL and disc are disrupted in BFD. Rupture of the intervertebral disc may include posterior herniation or circumferential disruption. All distraction flexion injuries should be reduced closed. The necessity of a preoperative MRI is undetermined. Preoperative MRI is recommended if there is an unreliable exam due to the patient being uncooperative, if there is neurological worsening with, or failure of closed reduction. If the patient is neurologically intact and closed reduction successful, a posterior cervical fusion is advocated if there is no evidence of an extruded disc on the post reduction MRI. If the closed reduction failed, or MRI indicated, and there is no evidence of a herniated disc, an open posterior reduction followed by fusion is performed. Anterior discectomy with reduction, a graft and a plate is performed for a herniated disc. Compression-extension injuries fail by compression of the posterior elements followed by distraction of the anterior elements. There are unilateral or bilateral fractures of the laminae/neural arch with degrees of displacement. Undisplaced neural arch fractures can be treated with a cervical orthosis or halo. Displaced neural arch fractures are treated with a posterior cervical fusion. There are two stages in the distraction-extension injury group. The anterior longitudinal ligament is disrupted with possibly a transverse fracture of the body. With more major injuries, there is a significant displacement injuring the posterior column. Stage 1 injuries can be treated with a halo and Stage 2 with an anterior decompression and fusion with a plating device. There are two stages to lateral flexion injuries. Minor injuries include asymmetric centrum fracture and a unilateral arch fracture. In addition, there is displacement of the body with contralateral ligamentous failure in major injuries. The treatment for Stage 1 is usually a collar while treatment for Stage 2 is usually a posterior cervical fusion. Posterior stabilization procedures may be performed with wires and cables with or without rods. Posterior clamps usually are not recommended; while plates and screws are preferred. The plates and screws are biomechanically superior to wiring and avoid canal penetration. They are ideal when there is loss of the posterior elements. Pedicle fixation should be considered when operating on the C2 or C7 level. One in five patients may have complete disruption of vertebral artery blood flow. This occurs most commonly with flexion-distraction or flexion-compression injuries. Vertebral artery evaluation is recommended in patients with flexion injuries and symptoms consistent with vertebral artery insufficiency. It is important to understand the mechanism of injury; to understand which elements are compromised. We have to get the appropriate imaging studies, we have to be cognizant of the fact that the vertebral artery may be injured, or there may be an associated herniated disc. We have to understand the degree of instability, which dictates the appropriate treatment and we have to understand the risk benefit of the specific internal fixation systems that we use

Introduction: Oblique corpectomy is a surgical technique of spinal cord decompression through a limited bone resection of the postero lateral corner of the vertebral bodies. In this study the results of this technique applied in cases of spondylotic myelopathy and tumors are presented. Methods: The oblique corpectomy is achieved through a lateral approach with control and sometimes transposition of the VA. It can be used at any level from C2 to T1 and on as many levels as required from 1 to 5. It was mostly applied on cervical spondylotic myelopathy (N=157) or radiculopathy (N=89) but also on hourglass tumors (neurinomas N=67, meningiomas N=7, hemangioblastoma N=1, paraganglioma N=1) and different tumors N=49 involving the lateral part of the vertebral body such as osteoïd osteomas N=8, chordomas N=11, aneurysmal cyst N=3, sarcomas N=4. The total series includes 126 tumors. In most cases preservation of the main part of the vertebral bodies permitted to avoid bone grafting and plating. However stabilization procedure is still necessary when more than one disc are resected and when the discs are soft and not collapsed. Results: Excellent decompression was obtained in every case of spondylotic myelopathy and radiculopathy. Clinical results are similar to those obtained by any other techniques of decompression through anterior approach but without the complications related to grafting and plating. Improvement of the preoperative score was noted in 79% of patients with myelopathy stabilization in 13% and worsening in 8%. In patients with radiculopathy, good and excellent results were obtained in 85%. A better decompression of the intervertebral foramen is achieved through the oblique corpectomy since the whole length of the cervical nerve root from the dural sac to the vertebral artery can be decompressed. Instability requiring further stabilization procedure was observed only in 3 cases which in fact were preoperatively unstable. Complete tumor resection was achieved in every case especially for the lateral part located into the intervertebral foramen and around the vertebral artery. Even tumors extending from the outside of the spine to the intradural space could be entirely removed through the same approach. Grafting and plating were realized in 13 out of the 126 cases of tumor. Conclusion: Oblique corpectomy techniques is a safe technique which permits to decompress the spinal cord and cervical nerve roots from spondylotic elements and tumors. As compared to other techniques, it achieves a better decompression on the lateral part of the spinal canal and on the intervertebral foramen up to the vertebral artery. In many cases it does not require any complementary stabilization technique and avoids the use of instrumentation

INTRODUCTION: Oblique corpectomy is a surgical technique of spinal cord decompression through a limited bone resection of the posterolateral corner of the vertebral bodies. In this study the results of this technique applied in cases of spondylotic myelopathy and tumours are presented. METHODS: The oblique corpectomy is achieved through a lateral approach with control and sometimes transposition of the VA. It can be used at any level from C2 to T1 and on as many levels as required from 1 to 5. It was mostly applied on cervical spondylotic myelopathy (N=157) or radiculopathy (N=89) but also on hourglass tumours (neurinomas N=67, meningiomas N=7, hemangioblastoma N=1, paraganglioma N=1) and different tumours N=49 involving the lateral part of the vertebral body such as osteoid osteomas N=8, chordomas N=11, aneurysmal cyst N=3, sarcomas N=4. The total series includes 126 tumours. In most cases preservation of the main part of the vertebral bodies permitted to avoid bone grafting and plating. However stabilisation procedure is still necessary when more than one disc is resected and when the discs are soft and not collapsed. RESULTS: Excellent decompression was obtained in every case of spondylotic myelopathy and radiculopathy. Clinical results are similar to those obtained by any other techniques of decompression through anterior approach but without the complications related to grafting and plating. Improvement of the pre-operative score was noted in 79% of patients with myelopathy stabilisation in 13% and worsening in 8%. In patients with radiculopathy, good and excellent results were obtained in 85%. A better decompression of the intervertebral foramen is achieved through the oblique corpectomy since the whole length of the cervical nerve root from the dural sac to the vertebral artery can be decompressed. Instability requiring further stabilisation procedure was observed only in three cases which in fact were pre-operatively unstable. Complete tumour resection was achieved in every case especially for the lateral part located into the intervertebral foramen and around the vertebral artery. Even tumours extending from the outside of the spine to the intradural space could be entirely removed through the same approach. Grafting and plating were realised in 13 out of the 126 cases of tumour. CONCLUSION: Oblique corpectomy technique is a safe technique which permits to decompress the spinal cord and cervical nerve roots from spondylotic elements and tumours. As compared to other techniques, it achieves a better decompression on the lateral part of the spinal canal and on the intervertebral foramen up to the vertebral artery. In many cases it does not require any complementary stabilisation technique and avoids the use of instrumentation

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

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

Atlanto-axial rotatory fixation (AARF) is uncommon and is usually associated with a history of trauma to the neck or an upper respiratory tract infection. In patients who present early, correction of the deformity with traction and orthoses has been reported. Owing to failure of reduction, patients presenting late (more than a month after the condition developed) have been treated with an in situ C1/C2 fusion. Follow-up of in situ fusions has shown both progression of the deformity and correction through compensatory mechanisms. Over a five-year period seven AARF patients (16%), ranging in age from 5 to 11 years, presented more than three months after injury. All patients had a ‘cock robin’ posture and were neurologically intact. In three patients the injury was sustained in a fall from a tree and in four it was due to a motor vehicle accident. Two patients sustained additional fractures. All patients had CT scans. In four patients MR scans and MR angiography were used to evaluate the pathology in the atlanto-axial complex, including the vertebral artery, and revealed soft-tissue interposition in the atlanto-axial joint and atlantodental interval. There was thrombosis of the vertebral artery in two patients. Clinical and radiological correction of the deformity was achieved with transoral release and skull traction, followed by fusion. While in previous studies there has been speculation on the causes of failure of closed reduction, MRI and the transoral procedure identified the pathology in this uncommon condition

Purpose: Upper cervical spine stabilization in children can be challenging due to anatomic abnormalities such as incomplete posterior elements, vertebral artery variability and small patient size. Several techniques have been described for stabilization of the upper cervical spine, each with its own advantages and disadvantages. Since the introduction of the technique by Harms, many authors have shown C1 lateral mass screws to be safe and effective in the stabilization of the upper cervical spine in adults. No large series of paediatric C1 lateral mass screw fixation has been reported in the literature. The purpose of this study was to describe the indications, technique, and outcomes of C1 lateral mass screw fixation in a consecutive series of 11 paediatric patients. Method: A database generated retrospective review of all patients who underwent C1 lateral mass screw fixation as part of an upper cervical spine stabilization construct was performed. In all patients the C2 dorsal root ganglion was sacrificed. Patient demographics and clinical outcomes were obtained through chart review. Radiographs immediately post-operatively, at six-weeks, three-months, and final follow-up were reviewed. Results: Eleven consecutive paediatric patients underwent bilateral C1 lateral mass screw fixation for a variety of conditions including C1-C2 instability, deformity, congenital malformation, trauma, as well as revision surgery. The average age was 10 years (range 4 to 16 years) with a mean follow-up of 11 months (range 6 – 18 months). There were no iatrogenic vertebral artery, hypoglossal nerve or spinal cord injuries. All 11 patients had solid fusion clinically and radiographically, with no loss of fixation. The C2 dorsal root ganglion was sacrificed in all patients with resulting minor occipital parasthaesia that progressively diminished in severity. Conclusion: This is the largest series of consecutive patients reported in the literature to date showing that the technique is safe and effective, with acceptable morbidity when applied to the paediatric population. We believe that C1 lateral mass screws offer significant advantages over traditional fixation techniques when the C1 vertebra is to be included in an upper cervical instrumented construct

Introduction and Aims: C1 lateral mass screw fixation offers a powerful alternative biomechanical fixaion for upper cervical disorders. The anatomical constraints to this fixation have not been described yet and are essential to ensure avoidance of neurovascular damage. Method: Fifty patients (including five patients with rheumatoid arthritis) underwent upper cervical CT scans. Analysis of these CT scans involved use of calibrated scan measurements to identify the midpoint of the posterior lateral mass, the dimensions of the lateral mass, the direction of optimum screw passage, the position of the vertebral foramen at C1 and the ideal entry point for lateral mass screw fixation. Results: The average length of screw within the lateral mass was 20mm with 13.5mm of screw not in bone, behind the lateral mass, but necessary to allow rod placement posteriorly adjacent to other fixation points. The safest entry point was directly beneath the medial edge of the lamina origin. The ideal direction of screw angulation is parallel with the posterior arch, in the saggital plane. This entry point was on average 8.8mm from the vertebral artery foramen laterally and 5.8mm from the medial aspect of the lateral mass. Vertical space available for sublaminar screw placement was 3mm or less in 9% of lateral masses. Conclusion: C1 lateral mass screws are best placed beneath the lamina origin, parallel with the arch in the saggital plane using an entrypoint in line with the medial edge of the lamina origin. An entry point under the midpoint of the lamina origin, or passing through the lamina at its attachment to the lateral mass, is likely to damage the vertebral artery in a significant proportion of cases

Introduction: C1 lateral mass screw fixation offers a powerful alternative biomechanical fixation for upper cervical disorders. The anatomical constraints to this fixation have not been described yet and are essential to ensure avoidance of neurovascular damage. Methods: 50 patients (including 5 patients with rheumatoid arthritis) underwent upper cervical CT scans. Analysis of these CT scans involved use of calibrated scan measurements to identify the midpoint of the posterior lateral mass, the dimensions of the lateral mass, the direction of optimum screw passage, the position of the vertebral foramen at C1 and the ideal entry point for lateral mass screw fixation. Results: The average length of screw within the lateral mass was 20 mm with 13.5mm of screw not in bone, behind the lateral mass, but necessary to allow rod placement posteriorly adjacent to other fixation points. The safest entry point was directly beneath the medial edge of the lamina origin. The ideal direction of screw angulation is parallel with the posterior arch, in the saggital plane. This entrypoint was on average 8.8 mm from the vertebral artery foramen laterally and 5.8 mm from the medial aspect of the lateral mass. Vertical space available for sublaminar screw placement was 3mm or less in 9% of lateral masses. Discussion: C1 lateral mass screws are best placed beneath the lamina origin, parallel with the arch in the saggital plane using an entrypoint in line with the medial edge of the lamina origin. An entry point under the midpoint of the lamina origin, or passing through the lamina at its attachment to the lateral mass, is likely to damage the vertebral artery in a significant proportion of cases

Background: A 9- year-old child with osteogenesis imperfecta and severe cervical kyphosis associated with wedged vertebrae and progressive neurological deterioration is presented. There is no report of upper cervical kyphosis associated with wedged vertebrae in osteogenesis imperfecta in the literature. We discuss the methods and difficulties in the surgical management of this condition and to highlight the appropriate surgical approach. Methods: Methods:A 9-year-old girl presented with progressive cervical kyphosis and quadriparesis. At the age of 3 years she underwent posterior cervical fusion (C1–C6) for instability and deformity. Radiological and laboratory investigations confirmed the diagnosis of osteogenesis imperfecta. Radiographs of the cervical spine revealed a kyphotic deformity of 120° Magnetic Resonance Imaging (MRI) and Computerised Tomography (CT) scans showed anterior cord compression due to wedged vertebrae at C3 and C4. MRI-Angiography was performed pre-operatively to identify the anatomical position of the vertebral arteries. A modified anterolateral approach to the upper cervical spine was performed. Anterior C3 and C4 corpectomies with interbody fusion with cage and plate fixation was carried out. Results: Postoperatively the patient made a full neurological recovery and significant correction of the deformity was achieved and correction was maintained at final follow-up. Conclusion: Cervical kyphotic deformity in Osteogenesis Imperfecta is uncommon. Association of this condition with wedged vertebrae is rare. Surgical decompression of the upper cervical spine with severe kyphosis is a challenging problem. Which surgical approach should be used is controversial? There are difficulties exposing wedged vertebrae by a standard anterior or chin split approach to perform vertebrectomy. Costo-transversectomy has been used successfully in patients with Gibbous deformity in the thoracic spine but due the presence of vertebral artery in the cervical spine posterolateral approach is impossible. We have used a modified anterolateral approach to overcome this problem. Spinal stabilisation in children with Osteogenesis Imperfecta and poor bone quality is another challenge. We have used a small diameter MOSS cage with maxillofacial plate and screws to achieve stabilisation and fusion. The purpose of this report is to highlight the importance of diagnosis of progressive cervical kyphotic deformity in children with osteogenesis imperfecta and also to describe the difficulties encountered with surgical management of this condition

We reviewed 161 patients, from four centres in Switzerland, who had undergone posterior fusion of the upper cervical spine with transarticular screw fixation of the atlanto-axial joints. They were followed up for a mean 24.6 months. The vertebral artery and the medulla escaped injury and only 5.9% of the complications were directly related to the screws. The rate of pseudarthrosis was 0.6%

1. Nineteen patients with classical rheumatoid arthritis complicated by severe subluxation of the cervical spine are reported. 2. Thirteen patients had atlanto-axial subluxation. This was the only level ofinvolvement in ten. 3. The next most frequent level to be involved was C.4-5. This occurred in five patients. 4. Eleven patients required surgery for symptoms or signs of spinal cord compression or vertebral artery insufficiency. 5. Operations included six posterior fusions, three anterior fusions and two laminectomies. 6. The differential diagnosis, the radiological findings, the indications for surgery and the results of treatment are discussed

1. The spinal branches of the vertebral artery were injected with a suspension of barium sulphate and the blood supply of the vertebral bodies of the lower four or five cervical vertebrae investigated radiologically. 2. Beneath the posterior longitudinal ligament there is a free dorsal arterial plexus from which a large branch arises to enter the back of the vertebral body. This vessel terminates abruptly at the centre of the body where numerous, much smaller, branches radiate towards the upper and lower surfaces. 3. The possible significance of the form of the intravertebral arteries is considered in relation to embolic lesion in vertebral bodies