1) A case is reported of paraplegia with normal radiographic appearances in which cervical cord damage was shown at autopsy to have been due to hyperextension injury. 2) The mechanism of such injuries is discussed, together with the differential diagnosis from acute prolapse of an intervertebral disc. 3) The grave dangers of using the fully extended position of the cervical spine in the management of these cases is noted

1. Seven cases of sacral extradural cyst are reported. 2. The etiology and clinical features are discussed and the literature reviewed. 3. The differential diagnosis is discussed; certain features, useful in making the diagnosis of sacral extradural cysts, are recorded. 4. When a cyst causes symptoms excision brings relief. Because some cysts are symptomless, it is important to exclude an accompanying prolapsed intervertebral disc

The pre-operative lumbar spine radiographs of 200 consecutive patients who had undergone discectomy for prolapsed intervertebral disc were reviewed. Prolapse was recognized as bulging or sequestration of the disc with consequent root compromise. Measurement of the lumbar level of the interiliac line was shown to correlate with the level of disc prolapse and the incidence of transitional vertebrae at the lumbosacral junction was significantly higher than normal. A pathological value for the lumbosacral angle could not be identified

Cadaveric lumbar intervertebral joints were loaded to simulate the erect standing posture (lordosis), and the erect sitting posture (slightly flexed). The results show that, after the intervertebral disc has been reduced in height by a period of sustained loading, the apophysial joints resist about 16 per cent of the intervertebral compressive forces in the erect standing posture, whereas in the erect sitting posture they resist none. The implications of this in relationship to degenerative changes and to low backache are discussed

1. Of 456 patients with features of herniated intervertebral disc eight were under twenty years of age. 2. Differences in the pattern of clinical presentation of the herniated disc syndrome in adults and in adolescents are discussed. 3. Whereas in the adult conservative treatment is usually successful, this is not so in the adolescent, in whom the symptoms and signs tend to persist for many months. 4. It is suggested that in the adolescent conservative treatment should not be prolonged despite the absence of neurological deficit; operation should be undertaken early after confirmation of the diagnosis by myelography

We reviewed the magnetic resonance (MR) images of eight adults with acute hyperextension-dislocation of the cervical spine. The images were obtained to evaluate damage to the spinal cord. All eight patients had disruption of the anterior longitudinal ligament and of the annulus of the intervertebral disc, and separation of the posterior longitudinal ligament from the subjacent vertebra. Some, but not all, showed widening of the disc space, posterior bulging or herniation of the nucleus pulposus, and disruption of the ligamentum flavum. The MR demonstration of these ligament injuries, taken with the clinical and radiographic findings, establishes the mechanism of hyperextension-dislocation, confirms the diagnosis, and is relevant to management

The action of fast bowling in the game of cricket is known to cause injuries to the lumbar spine. We studied a group of 16- to 18-year-old fast bowlers, selected for special training in Western Australia. All 24 had MR scans of the spine, 22 had radiographs and CT scans; in 20 the bowling technique was analysed biomechanically. There was a high incidence of back pain and this was always associated with a radiological abnormality. Pars interarticularis defects were diagnosed in 54% and intervertebral disc degeneration in 63%. Bowling actions which involved counter-rotation were associated with a higher incidence of both injuries

A retrospective study of 32 patients with primary tumours of the cauda equina is presented. Most of the patients were initially diagnosed as having prolapsed intervertebral discs and treated accordingly. The correct diagnosis was eventually made, usually after a long delay, and confirmed by myelography. Treatment consisted of laminectomy and excision of the tumour. Only one tumour was frankly malignant; all the remaining patients were relieved of their pain and the majority recovered completely. The exceptions were those patients with long-standing neurological deficits; this highlights the importance of early diagnosis and correct treatment before irreparable damage occurs

The lumbar spines of 22 patients were examined for disc degeneration by magnetic resonance imaging (MRI) and by discography. The results from 50 intervertebral discs visualised by both techniques were independently assessed and graded on a five-point scale from normality to gross degeneration and then compared. In 44 discs the results agreed. Of the six discs which gave differing results, four discrepancies were due to observer error and two to incorrect placement of the discographic needle. MRI was shown to be more accurate than discography in the diagnosis of disc degeneration. It has several major advantages, which should make it the investigation of choice

1. Previous studies of the movements of the lumbar spine are criticised in the light of new observations from radiograph tracings. It is shown that, contrary to recent teaching, the lumbar spine is a very mobile part of the vertebral column. 2. The movement of the lumbar spine is analysed. It is shown that the lower vertebrae have the most movement, and that the range gradually becomes less in the upper lumbar spine. 3. This movement may be roughly correlated with the incidence of spurs arising from the anterior margin of the vertebral bodies. 4. These spurs are shown to arise in the anterior longitudinal ligament; they are probably caused by intermittent pressure from the intervertebral disc lying behind the ligament

Magnetic resonance imaging (MRI) was used to compare the appearance of the spine in 20 adolescents with proven symptomatic intervertebral disc herniations with that in 20 asymptomatic patients who acted as controls. Abnormality in the signal from the nucleus pulposus of one or more discs was present in all patients, while only four of the 20 controls had any abnormal signals. In all the patients the symptomatic disc produced an abnormal signal and in most a herniated fragment of the nucleus pulposus was identified. Fifteen of the 20 patients had multiple-disc abnormality: six had three abnormal discs and nine had two. This suggests there was an underlying diathesis in patients who later developed disc herniation

Twenty-four children with infantile or juvenile idiopathic scoliosis had their spines corrected and solidly fused posteriorly before the age of eleven years. The growth of the fusion area was then accurately measured for a mean of 4.5 years during the adolescent growth spurt. During this period all longitudinal growth in the posterior elements ceased. The vertebral bodies continued to grow anteriorly, but the thick posterior fusion prevented the development of a lordosis. Initially the anterior growth was accommodated by narrowing of the intervertebral disc spaces, but eventually the vertebral bodies bulged laterally towards the convexity and pivoted on the posterior fusion, giving rise to loss of correction, increasing vertebral rotation and recurrence of the rib hump

Spines are often stabilised posteriorly by internal fixation and anteriorly by a bone graft. The effect of an autologous bone graft from the iliac crest on implant loads is unknown. We used an internal spinal fixation device with telemetry to measure implant loads for several body positions and activities in nine patients before and after anterior interbody fusion. With the body upright, implant loads were often higher after than before fusion using a bone graft. Distraction of the bridged region led to high implant loads in patients with a fractured vertebra and to marked changes in load in those with degenerative instability. Leaving the lower of the bridged intervertebral discs intact led to only small changes in fixator load after anterior interbody fusion. A bone graft alone does not guarantee a reduction of implant loads

The use of a composite osteochondral device for simulating partial hemiarthroplasty was examined. The device was composed of a polyvinyl alcohol hydrogel and a titanium fibre mesh, acting as artificial cartilage and as porous artificial bone, respectively. The titanium fibre mesh was designed to act as an interface material, allowing firm attachment to both the polyvinyl alcohol gel (through injection moulding) and the femoral joint surface (through bony ingrowth). We implanted 22 of these devices into canine femoral heads. Histological findings from the acetabular cartilage and synovial membrane, as well as the attachment of the prosthesis to bone, were examined up until one year after operation. No marked pathological changes were found and firm attachment of the device to the underlying bone was confirmed. The main potential application for this device is for partial surface replacement of the femoral head after osteonecrosis. Other applications could include articular resurfacing and the replacement of intervertebral discs

We present a review of 553 patients who underwent surgery for intractable sciatica ascribed to prolapsed lumbar intervertebral disc. One surgeon in one institution undertook or supervised all the operations over a period of 16 years. The total number of primary discectomies included in the study was 531, of which 42 subsequently required a second operation for recurrent sciatica, giving a revision rate of 7.9%. Factors associated with reoperation were analysed. A contained disc protrusion was almost three times more likely to need revision surgery, compared with extruded or sequestrated discs. Patients with primary protrusions had a significantly greater straight-leg raise and reduced incidence of positive neurological findings compared with those with extruded or sequestrated discs. These patients should therefore be selected out clinically and treated by a more enthusiastic conservative programme, since they are three times more likely to require revision surgery

A series of experiments showing how posture affects the lumbar spine is reviewed. Postures which flatten (that is, flex) the lumbar spine are compared with those that preserve the lumbar lordosis. Our review shows that flexed postures have several advantages: flexion improves the transport of metabolites in the intervertebral discs, reduces the stresses on the apophyseal joints and on the posterior half of the annulus fibrosus, and gives the spine a high compressive strength. Flexion also has disadvantages: it increases the stress on the anterior annulus and increases the hydrostatic pressure in the nucleus pulposus at low load levels. The disadvantages are not of much significance and we conclude that it is mechanically and nutritionally advantageous to flatten the lumbar spine when sitting and when lifting heavy weights

We have reviewed 37 patients under the age of 18 years with lesions of the lumbar posterior end plate. All but one were active in sport, and most were seen because of low back pain. An abnormality was commonly found at the inferior rim of the body of L4 and at the superior rim of the sacrum. All adjacent intervertebral discs showed a decrease of signal intensity on the T2-weighted MRI. In 12 patients there was no interposed tissue at the posterior end-plate lesions. When disc material had migrated posteriorly none protruded beyond the posterior margin of the end plate, the dissociated portion of which was the main element compressing neural tissue. The posterior end-plate lesion should be regarded as a vertebral non-articular osteochondrosis

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.

The spinal stenosis syndrome is a potential hazard when congenital or developmental narrowing of the bony canal, particularly in its lateral recesses where it can be demonstrated by axial tomography, places the emergent nerve root and its blood supply at risk to further small compressive elements. When lumbar disc degeneration allows rotatory and lateral instability, posterolateral bulging of the annulus fibrosus into the root canal occurs when weight is taken on the ipsilateral lower limb. Symptoms of the spinal stenosis syndrome do not arise until the development of this instability. To relieve the symptoms, the nerve root must be freely mobilised and decompressed by full lateral decompression, with partial or total facetectomy if necessary, by enucleation of the intervertebral disc and by removal of the posterolateral portions of the annuli fibrosi