Aims

The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing.

We carried out a cadaver study of 16 iliolumbar veins in order to define the surgical anatomy. Two variants were found; a single vein at a mean distance of 3.74 cm from the inferior vena cava (11 of 16) and two separate draining veins at a mean distance from the vena cava of 2.98 cm for the proximal and 6.24 cm for the distal stem (5 of 16). Consistently, the proximal vein tore on attempted medial retraction of the great vessels. The mean length of the vein was 1.6 cm and its mean width 1.07 cm. Three stems were shorter than 0.5 cm. Two or more tributaries usually drained the iliacus and psoas muscles, and the fifth lumbar vertebral body. The obturator nerve crossed all veins superficially at a mean of 2.76 cm lateral to the mouth. In four of these, this distance was less than 1.5 cm. Usually, the lumbosacral trunk crossed deep, at a mean distance of 2.5 cm lateral to the mouth, but in three veins, this distance was 1 cm or less. Our findings emphasise the need for proper dissection of the iliolumbar vein before ligature during exposure of the anterior lumbar spine

Aims

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

Vertebroplasty, which is the percutaneous injection of bone cement into vertebral bodies has recently been used to treat painful osteoporotic compression fractures. Early clinical results have been encouraging, but very little is known about the consequences of augmentation with cement for the adjacent, non-augmented level. We therefore measured the overall failure, strength and structural stiffness of paired osteoporotic two-vertebra functional spine units (FSUs). One FSU of each pair was augmented with polymethyl-methacrylate bone cement in the caudal vertebra, while the other served as an untreated control. Compared with the controls, the ultimate failure load for FSUs treated by injection of cement was lower. The geometric mean treated/untreated ratio of failure load was 0.81, with 95% confidence limits from 0.70 to 0.92, (p < 0.01). There was no significant difference in overall FSU stiffness. For treated FSUs, there was a trend towards lower failure loads with increased filling with cement (r. 2. = 0.262, p = 0.13). The current practice of maximum filling with cement to restore the stiffness and strength of a vertebral body may provoke fractures in adjacent, non-augmented vertebrae. Further investigation is required to determine an optimal protocol for augmentation

A radiological study of 50 patients with thoracic Scheuermann's disease revealed two types of lateral spinal curvature. A total of 43 lateral curves was present in 35 of the patients. Thirteen were apical at the same level as the Scheuermann's kyphosis and were due to vertebral-body wedging in the coronal plane; these curves had a mean Cobb angle of 15 degrees, occurred with equal prevalence in boys and girls and were directed equally to right and left. Thirty curves occurred in regions of compensatory lordosis (mean 5.6 degrees) situated above or, more commonly, below the Scheuermann's kyphosis. These scolioses had a mean Cobb angle of 16 degrees, were more often convex to the right than to the left and were significantly more prevalent in girls than in boys. The presence of these kyphoses and scolioses in the same spine, separated by only a few vertebrae, emphasises the importance of the sagittal plane in idiopathic spinal deformities and strongly suggests that idiopathic scoliosis and Scheuermann's disease share a common pathological process

Biopsies of lumbar multifidus muscles were obtained at operation on seventeen patients aged from fifteen to fifty-eight with lumbar spinal derangement, and further material was taken from the cadavers of three subjects aged from nineteen to fifty-one. Sections were prepared to show the presence of ATPase activity, so distinguishing Fast from Slow types of muscle fibre. The normal mosaic pattern arising from the intermingling of fibres from Fast and Slow motor units was seen in sections from cadaveric material and from many of the biopsies. With age and limited lumbar flexibility, the Fast fibres became relatively smaller but with increasing variation in size, suggesting a reduced capacity for phasic activity. The presence of positive root signs was associated with a greater proportion of Slow fibres, and in some patients with the occurrence of atrophied Fast fibres, giving rise to differences in the populations of the two fibres in neighbouring fascicles. The results suggest that multifidus adopts an increasingly postural role with advancing age and with disabling lesions of the lumbar spine

1 . Standard lumbar laminectomy was performed at multiple levels in thirty dogs, and manipulations were carried out in the spinal canal to observe their effects on periradicular adhesion formation. The canal was scarified, packed with Gelfoam, or treated with three varieties of Silastic membranes. The results were serially assessed from three days to twelve weeks by gross observation, nerve conduction studies, histological examination of transverse sections of the spine, myelin study of lumbar roots and micropaque study of the arterial supply to the roots. 2. The results were consistent biologically. The principal source of scar is dorsally in the fibrous tissue elements of the erector spinae muscle mass. This scar, the laminectomy membrane, covers the laminectomy defect and extends into the canal bilaterally to adhere to the dura and nerve roots. 3. Gelfoam does not contribute to scar formation, but instead acts as an effective interposing membrane. Silastic membranes are capable of providing protection against nerve root adhesions without interfering with the anatomical or physiological integrity of the nerves. 4. Certain clinical implications of the study are discussed

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.

Objectives

Degenerative disc disease (DDD) and osteoarthritis (OA) are relatively frequent causes of disability amongst the elderly; they constitute serious socioeconomic costs and significantly impair quality of life. Previous studies to date have found that aggrecan variable number of tandem repeats (VNTR) contributes both to DDD and OA. However, current data are not consistent across studies. The purpose of this study was to evaluate systematically the relationship between aggrecan VNTR, and DDD and/or OA.

Aims

There is no consensus about the best method of achieving equal leg lengths at total hip arthroplasty (THA) in patients with Crowe type-IV developmental dysplasia of the hip (DDH). We reviewed our experience of a consecutive series of patients who underwent THA for this indication.

The loss of cervical lordosis in radiographs of patients presenting with neck pain is sometimes ascribed to muscle spasm. We performed a cross-sectional study of the prevalence of 'straight' cervical spines in three populations: 83 patients presenting to an accident department with acute neck pain, 83 referred to a radiology department with chronic neck problems, and 80 radiographs from a normal population survey carried out in 1958. Curvature was assessed on lateral radiographs both subjectively and by measurement. The prevalence of 'straight' cervical spines was 19% in the acute cases and 26% in the chronic cases. The 95% confidence interval for the difference was -6.4% to +19.3%. In the normal population 42% showed a straight spine, but a further third of these films had been taken in a position of cervical kyphosis; this probably reflects a difference in positioning technique. Women were more likely than men to have a straight cervical spine, with an odds ratio of 2.81 (95% CI 1.23 to 6.44). Our results fail to support the hypothesis that loss of cervical lordosis reflects muscle spasm caused by pain in the neck

We undertook a comparative study of magnetic resonance imaging (MRI) vertebral morphometry of thoracic vertebrae of girls with adolescent idiopathic thoracic scoliosis (AIS) and age and gender-matched normal subjects, in order to investigate abnormal differential growth of the anterior and posterior elements of the thoracic vertebrae in patients with scoliosis. Previous studies have suggested that disproportionate growth of the anterior and posterior columns may contribute to the development of AIS. Whole spine MRI was undertaken on 83 girls with AIS between the age of 12 and 14 years, and Cobb’s angles of between 20° and 90°, and 22 age-matched controls. Multiple measurements of each thoracic vertebra were obtained from the best sagittal and axial MRI cuts. Compared with the controls, the scoliotic spines had longer vertebral bodies between T1 and T12 in the anterior column and shorter pedicles with a larger interpedicular distance in the posterior column. The differential growth between the anterior and the posterior elements of each thoracic vertebra in the patients with AIS was significantly different from that in the controls (p < 0.01). There was also a significant positive correlation between the scoliosis severity score and the ratio of differential growth between the anterior and posterior columns for each thoracic vertebra (p < 0.01). Compared with age-matched controls, the longitudinal growth of the vertebral bodies in patients with AIS is disproportionate and faster and mainly occurs by endochondral ossification. In contrast, the circumferential growth by membranous ossification is slower in both the vertebral bodies and pedicles

Between 1978 and 1988 a total of 27 operations were performed on 26 patients for cervical myelopathy due to rheumatoid disease in the subaxial spine. Three different causes were recognised: the first group had cord compression due to subluxation of the cervical spine itself (6 patients); the second had cord compression occurring from in front, with rheumatoid lesions of vertebral bodies or discs (6); the third had compression from behind the cord due to granulation tissue within the epidural space (14). Group I was treated by closed reduction of the subluxation followed by surgical fusion either from in front or behind. Group II was decompressed by subtotal resection of the involved vertebral bodies and discs, followed by interbody fusion. The patients in group III were decompressed by laminectomy and excision of fibrous granulation tissue from the epidural space. Good recovery of neurological function was observed after 18 of the operations, fair recovery after five, poor recovery followed three, and one was worse. Myelopathy recurred in four patients, all of whom had had anterior interbody fusion

1. A twenty-six-year-old woman was paraplegic because of a benign giant-cell tumour which had destroyed the body of the twelfth thoracic vertebra completely and the bodies of the eleventh thoracic and first lumbar vertebrae partially. The tumour had expanded into both pleural cavities and displaced the aorta forward and to the left. The extent and topography of the tumour were evaluated before operation by angiography. The function of the spinal cord had not been improved significantly by laminectomy. It was therefore decided to attempt extirpation of the tumour by removing all remaining parts of the three vertebrae involved. 2. After the removal of the tumour, only the spinal cord with the thecal sac bridged the gap between the tenth thoracic and second lumbar vertebrae. The gap was bridged with struts of cortical bone from both tibiae and with two strong plates, all secured with steel wire. The metal was removed five months later because it had become loose. Gradual shortening and angulation of the spine then occurred, together with progressive resorption of the cortical grafts. Nevertheless, the operation restored the function of the spinal cord; the patient regained ability to walk and full control of the bladder

1. One hundred and twenty cervical spines removed at routine necropsy from elderly patients dying in a general hospital have been examined. 2. There was some degree of degeneration of intervertebral discs in 110 cases–in forty-six this was severe. 3. Degenerative disc disease was found at an earlier age in men; mild damage preceded severe degeneration and collapse by about a decade. 4. Discs of the lower spine were most frequently and most severely affected. 5. Alterations of the normal cervical lordosis were produced by disc disease in thirty-two cases. 6. Osteoarthritis of the apophysial joints was found in seventy-eight, and by contrast to disc degeneration was commonest in the mid-cervical and upper cervical regions. In eighteen it was severe. 7. Degeneration and scarring of nerve roots was frequently associated with diseased discs; apophysial joint arthritis was found to be an important additional factor when it occurred in the lower cervical region. 8. No nerve root changes could be attributed to ischaemia resulting from narrowing or distortion of the vertebral arteries. 9. Cystic arachnoidal diverticula which excavate the posterior root ganglia were found in thirty-six cases

1. In this investigation one was impressed by the close relationship that exists between the constituent parts of the intervertebral discs and the surrounding supporting structures. The part that is responsible for the maintenance of a co-ordinated balance between these structures, and hence for the effective mechanism of the spine, is the nucleus pulposus. 2. The cruciate arrangement of the annulus fibrosus is related to spinal function, and the angle of intersection of consecutive laminae of the annulus fibrosus is more or less constant. 3. In the Bantu it was found that the interspinous and supraspinous ligaments differ from the classical descriptions given in anatomical text-books. 4. The movements taking place between two vertebrae are comparable to those of a rocking-horse. 5. Narrowing of a disc is a progressive process which is the result of the disturbances in the balance between the components of the force to which a disc is subjected. The process is initiated by the loss of nucleus pulposus content. 6. With the approximation of two adjacent vertebrae a disturbance of the relations of the structures in the intervertebral foramen was noted. On anatomical grounds, when a disc is narrowed it appears that the most likely structures to cause pressure on the nerve root are not the disc itself, but the superior articular processes with their overlying ligamentum flavum

1. The intervertebral disc is an organic viscous elastic structure capable of maintaining very great loads without disintegration. 2. Recovery of the disc after deformation depends upon: a) the imbibition of tissue fluid by the disc, b) the removal of the deforming force. Complete recovery is modified by the duration of the force. 3. Factors that interfere with the elasticity of the disc are: extreme youth (immaturity of the disc), chronic wasting diseases (general nutritional disturbance), and local pathological changes in the bodies of the vertebrae which interrupt or damage its blood supply. The intervertebral disc reaches its greatest state of efficiency in adult life—that is, when the nucleus pulposus has disappeared as an entity. The function of the disc appears not to depend upon the presence of the nucleus : rather does the presence of the nucleus indicate immaturity of the disc. 4. The highly resilient elastic nature of the vertebral column is provided by the intervertebral discs, which constitute one-third of the whole length of the column. 5. The imbibition of fluid requires further investigation. It appears that from lacunae in the adjacent bodies finger-like pockets dip into the discs and that fluid passes through the lining membrane of these pockets

Aims

We compared the clinical and radiological outcomes of using a polyetheretherketone cage with (TiPEEK) and without a titanium coating (PEEK) for instrumented transforaminal lumbar interbody fusion (TLIF).

The long-term results of 17 patients who had had fusion in situ for severe lumbosacral spondylolisthesis are reported. The average follow-up was 14 years with a range of 7 to 20 years. The average age at operation was 16 years. At follow-up seven patients had occasional backache but only one patient had changed his job and no patient had lost any time off work in the previous year. Nine patients felt that their deformity had been improved and all but one patient still rated the results as excellent up to 20 years after the operation. Although all the patients had persistent foreshortening of the trunk only two patients were aware of any cosmetic deformity. There had been no significant increase in forward slip since the previous follow-up examination five years after the operation. There were no late complications nor significant degenerative changes in the lumbar spine. It is concluded that although fusion in situ does little to improve cosmesis very few patients complain about their appearance and that it is a safe and reliable method of treatment for severe spondylolisthesis which has stood the test of time