Discogenic low back pain is a common cause of disability, but its pathogenesis is poorly understood. We collected 19 specimens of lumbar intervertebral discs from 17 patients with discogenic low back pain during posterior lumbar interbody fusion, 12 from physiologically ageing discs and ten from normal control discs. We investigated the histological features and assessed the immunoreactive activity of neurofilament (NF200) and neuropeptides such as substance P (SP) and vasoactive-intestinal peptide (VIP) in the nerve fibres. The distinct histological characteristic of the painful disc was the formation of a zone of vascularised granulation tissue from the nucleus pulposus to the outer part of the annulus fibrosus along the edges of the fissures. SP-, NF- and VIP-immunoreactive nerve fibres in the painful discs were more extensive than in the control discs. Growth of nerves deep into the annulus fibrosus and nucleus pulposus was observed mainly along the zone of granulation tissue in the painful discs. This suggests that the zone of granulation tissue with extensive innervation along the tears in the posterior part of the painful disc may be responsible for causing the pain of discography and of discogenic low back pain

1. Compression forces are mainly absorbed by the vertebral body. The nucleus pulposus, being liquid, is incompressible. The tense annulus bulges very little. On compression the vertebral end-plate bulges and blood is forced out of the cancellous bone of the vertebral body into the perivertebral sinuses. This appears to be the normal energy-dissipating mechanism on compression. 2. The normal disc is very resistant to compression. The nucleus pulposus does not alter in shape or position on compression or flexion. It plays no active part in producing a disc prolapse. On compression the vertebral body always breaks before the normal disc gives way. The vertebral end-plate bulges and then breaks, leading to a vertical fracture. If the nucleus pulposus has lost its turgor there is abnormal mobility between the vertebral bodies. On very gentle compression or flexion movement the annulus protrudes on the concave aspect–not on the convex side as has been supposed. 3. Disc prolapse consists primarily of annulus; it occurs only if the nucleus pulposus has lost its turgor. It then occurs very easily as the annulus now bulges like a flat tyre. 4. I have never succeeded in producing rupture of normal spinal ligaments by hyperextension or hyperflexion. Before rupture occurs the bone sustains a compression fracture. On the other hand horizontal shear, and particularly rotation forces, can easily cause ligamentous rupture and dislocation. 5. A combination of rotation and compression can produce almost every variety of spinal injury. In the cervical region subluxation with spontaneous reduction can be easily produced by rotation. If disc turgor is impaired this may occur with an intact anterior longitudinal ligament and explains those cases of tetraplegia without radiological changes or a torn anterior longitudinal ligament. The anterior longitudinal ligament can easily be ruptured by a rotation force and in my experience the so-called hyperextension and hyperflexion injuries are really rotation injuries. 6. Hyperflexion of the cervical spine or upper thoracic spine is an anatomical impossibility. In all spinal dislocations a body fracture may or may not occur with the dislocation, depending upon the degree of associated compression. In general, rotation forces produce dislocations, whereas compression forces produce fractures

1. The normal anatomy of the intervertebral disc of immature rabbits is described. 2. An account is given of the changes that occur after an operative incision in the ventral part of the intervertebral discs of rabbits which allowed the escape of the nucleus pulposus. The account is based on observations made on fifty-five young animals killed at intervals during the twenty-five months after operation. 3. The superficial part of the wound in the annulus heals rapidly by active fibrosis. Thereafter there is a chondrification of the ventral region of the disc, followed by ossification. A prominent bony ridge ultimately ankyloses the vertebrae adjoining the disc. 4. The site of the nucleus pulposus is eventually occupied by a dense pad of fibrocartilage. A tongue of this tissue projects into the deep median part of the wound which remains unhealed. 5. A hypothesis is submitted regarding the mechanism of rupture of the annulus fibrosus and prolapse of the nucleus pulposus in man; this hypothesis is based in part on the observations of lesions in discs not subjected to operation

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

1. A hypothesis outlining an auto-immune mechanism for antibody production against autogenous nucleus pulposus is presented. 2. Auto-antibodies to autogenous nucleus pulposus have been experimentally produced in rabbits. 3. These antibodies are cell-bound within lymphoid cells and are greatest in primary lymph nodes. This antibody is demonstrated by a positive pyronin reaction. 4. Lymphoid cells fixed in Carnoy's fluid and stained for pyronins also show a distinct natural yellow fluorescence. This fluorescence occurs only in the cytoplasm of those cells which are pyronin-positive and presumably producing antibody. 5. The lymph node phase of the reaction is greatest at four days and is sustained for three weeks. A secondary generalised lymph node response occurs in all lymph nodes at six weeks

We studied the presence of anabolic growth factors in human herniated intervertebral discs (IVD) using a reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Messenger RNA (mRNA) was isolated from the nucleus pulposus using oligo (dT). 25. superparamagnetic beads and probing with gene-specific primers in RT-PCR. mRNA coding for TGF-α (3/10), EGF (0/10), TGF-β1 (0/10) and TGF-β3 (2/10) or the EGF receptor (EGF-R; 0/10) and TGF-β type-II receptor (0/10) was found only occasionally. Beta-actin was always present and positive sample controls confirmed the validity of the RT-PCR assay. These RT-PCR findings were confirmed using immunohistochemical staining of EGF and TFG-β, whereas TGF-α protein was always found associated with discocytes. We conclude that the nucleus pulposus of the herniated IVD is vulnerable to proteolytic degradation and depletion of proteoglycans due to the lack and/or low production of anabolic growth factors/receptors which could increase the local synthesis of the extracellular matrix

Percutaneous nucleotomy is a relatively new technique for treating lumbar disc herniation. There is no agreement as to the volume of disc material to be removed. A long-term study of clinical and radiological data from patients treated by percutaneous nucleotomy was designed to identify the factors associated with favourable and unfavourable outcomes. We studied 42 patients for at least ten years; the mean follow-up was 10.9 years. They were divided into two subgroups to assess the value of preserving the nucleus pulposus in the central area of the disc. The overall success rate for both subgroups was 50%. A decrease in disc height on plain radiography and a decrease in signal intensity on MRI were observed more infrequently in patients in whom the nucleus pulposus in the central area of the disc had been preserved, than in those in whom it had been extensively removed. These adverse radiological findings correlated closely with increased low back pain during the first one to two years after operation and a poorer overall outcome. We conclude that percutaneous nucleotomy is most likely to be successful when the central area of the disc is preserved

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

The anatomical studies, basic to our understanding of lumbar spine innervation through the sinu-vertebral nerves, are reviewed. Research in the 1980s suggested that pain sensation was conducted in part via the sympathetic system. These sensory pathways have now been clarified using sophisticated experimental and histochemical techniques confirming a dual pattern. One route enters the adjacent dorsal root segmentally, whereas the other supply is non-segmental ascending through the paravertebral sympathetic chain with re-entry through the thoracolumbar white rami communicantes. Sensory nerve endings in the degenerative lumbar disc penetrate deep into the disrupted nucleus pulposus, insensitive in the normal lumbar spine. Complex as well as free nerve endings would appear to contribute to pain transmission. The nature and mechanism of discogenic pain is still speculative but there is growing evidence to support a ‘visceral pain’ hypothesis, unique in the muscloskeletal system. This mechanism is open to ‘peripheral sensitisation’ and possibly ‘central sensitisation’ as a potential cause of chronic back pain

1. The technique of nucleography, in which a radio-opaque watery solution of iodine is injected into the nucleus pulposus for contrast-radiography, is described. 2. The merits of the procedure in demonstrating the shape and condition of nucleus are discussed

A description is given of a mutation in the mouse which reduces the size of the nucleus pulposus in the intervertebral disc of the adults. The discs of these mice show greatly accelerated age changes. The consequences of a similar mutation in man are discussed

One hundred and twenty-seven cases of intervertebral disc calcification in children, including 11 previously unreported cases, have been analysed. A distinction is made between symptomatic and asymptomatic patients, whose age, sex and spinal distributions of the calcifications have been shown to differ. Radiologically detectable protrusions and later resorption of the calcifications are common events in symptomatic children, but are unrecorded in asymptomatic children. The spinal distribution of paediatric calcifications is quite different to that of adult and canine calcifications of the nucleus pulposus

A prospective study of 480 patients who underwent enzymatic dissolution of the nucleus pulposus with chymopapain is reported. Seventy per cent of patients with the clincial criteria for a disc herniation had a favourable response to chemonucleolysis. The commonest cause of failure was persistent back pain. In patients with sequestered discs or lateral recess stenosis surgical intervention was not made more difficult by chemonucleolysis. Those with a previous operation, spinal stenosis or psychogenic components to the disability had very poor results. Complications were few and easily managed

By polarising microscope and x-ray crystallographic techniques the annulus fibrosus has been shown to consist of regularly oriented sheets of collagen fibres. These results have been interpreted in terms of an elastic mechanism whereby thrust from the nucleus causes increased girth in the annulus. It is suggested that this is accomplished by a change in the angle between the axis of the fibres in adjacent uniaxial layers of the annulus. Furthermore, the loss of elasticity of the intervertebral disc associated with age would seem to be mainly due to changes occurring in the nucleus pulposus

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

1. As a result of degenerative changes in the intervertebral disc, nuclear tissue often herniates through its confining structures. These lesions are common, even in children, and often lead to difficulty in diagnosis. 2. The radiological manifestations of nuclear herniations into the spongiosa of the vertebral body, through the anterior part of the annulus fibrosus, beneath the epiphysial ring, and through the posterior part of the annulus are described and illustrated. The clinical significance of these radiological appearances and their pathological basis is indicated. 3. An understanding of the significance of the radiological findings in herniation of the nucleus pulposus and a careful correlation with the clinical features of the case are necessary for accurate diagnosis

The follow-up of these seventy-three cases suggested the following conclusions:. 1. The clinical signs alone are not always sufficient to make the diagnosis of herniated nucleus pulposus with sufficient accuracy. 2. When positive, myelography was reliable as a means of localising the hernia. 3. In doubtful cases in which conservative treatment failed a clearly positive myelography turned the scale for a well-indicated operation. 4. In doubtful cases a clearly negative myelography has often rightly been a contra-indication for laminectomy. 5. No serious complication from the use of water-soluble contrast medium for myelography has been encountered

The role of antibiotics in the treatment of disc-space infection is controversial. This study assessed the tissue penetration of flucloxacillin and cephradine into the normal intervertebral disc after intravenous administration of a bolus dose of antibiotic. Twenty-five discs were removed from 12 adolescent patients having anterior spinal surgery to correct scoliosis; antibiotic had been administered between 30 minutes and four hours before operation. Despite high blood levels, no antibiotic could be detected by bioassay or by high-pressure liquid chromatography (h.p.l.c.) in any of the specimens from the nucleus pulposus or the annulus fibrosus

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 studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally distributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogenic pain

Our study establishes a rabbit model of disc degeneration which requires neither a chemical nor physical injury to the disc. Disc degeneration similar to that seen in man was created at levels proximal (L4-L5) and caudal (L7-S1) to a simulated lumbar fusion and was studied for up to nine months after arthrodesis. Loss of the normal parallel arrangement of collagen bundles within the annular lamellae was observed in intervertebral discs adjacent to the fusion at three months. By six months there was further disorganisation as well as loss of distinction between the lamellae themselves. By nine months the structure of the disc had been replaced by disorganised fibrous tissue, and annular tears were seen. There was an initial cellular proliferative response followed by loss of chondrocytes and notochordal cells in the nucleus pulposus. Degeneration was accompanied by a decrease in the monomer size of proteoglycans. Narrowing of the disc space, endplate sclerosis and the formation of osteophytes at adjacent disc spaces were observed radiologically

Herniated intervertebral disc tissue has been shown to produce a number of proinflammatory mediators and cytokines, but there have been no similar studies using discs from patients with discogenic low back pain. We have compared the levels of production of interleukin-6 (IL-6), interleukin-8 (IL-8) and prostaglandin E. 2. (PGE. 2. ) in disc tissue from patients undergoing discectomy for sciatica (63) with that from patients undergoing fusion for discogenic low back pain (20) using an enzyme-linked immunoabsorbent assay. There was a statistically significant difference between levels of production of IL-6 and IL-8 in the sciatica and low back pain groups (p < 0.006 and p < 0.003, respectively). The high levels of proinflammatory mediator found in disc tissue from patients undergoing fusion suggest that production of proinflammatory mediators within the nucleus pulposus may be a major factor in the genesis of a painful lumbar disc

Magnetic resonance imaging (MRI) of the spine produces images which reflect the chemical composition of the intervertebral disc. We have conducted a prospective study of the serial changes in the MRI appearance of the intervertebral disc after chemonucleolysis with the enzyme chymopapain. Fourteen patients were studied after single-level chemonucleolysis and the results compared with a control group of 17 discs in six patients who had diagnostic discography without enzyme insertion. A consistent pattern of gradual loss of signal from the nucleus pulposus culminating in complete loss of nuclear signal was seen in all cases after chemonucleolysis. Chymopapain therefore produced MRI changes analogous with premature gross disc degeneration. The rate at which this occurred varied; complete loss of signal took at least six weeks. Transitory minor end-plate changes were present in five patients, probably representing a mild chemical discitis. No similar changes were seen in the discography group

1. The uptake of S. 35. labelled sodium sulphate has been studied autoradiographically in the intervertebral disc of the young rabbit. 2. The sojourn of the isotope in the tissues includes an intracellular phase of approximately twenty-four hours, followed by an extracellular phase. 3. The cells exhibiting by far the greatest affinity for the sulphate ion are the peripheral groups of cells of the nucleus pulposus, while the chondrocyte-like cells of the cartilaginous segment of the annulus fibrosus are also fairly active. The central cells of the nucleus and the fibroblasts of the outer one-third of the annulus have a much lower uptake. 4. By analogy with similar studies on hyaline cartilage, and on the basis of correlation between the alcinophilia of the tissues and the concentration of the label, both before and after hyalase digestion of the tissue, it is considered that in the young rabbit disc, as in articular cartilage, the sulphate is incorporated primarily into chondroitin sulphate. 5. The elimination of the isotope from the nucleus at twenty-four days and the persistence of the label in the annulus fibrosus at thirty-two days tends to suggest that the metabolic turnover of acid mucopolysaccharide is considerably slower in the annulus than in the nucleus

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

The fourth lumbar vertebrae and L4-5 discs from six cadaveric lumbar spines were subjected to detailed strain gauge analysis under conditions of controlled loading. With central compression loads, maximal compressive strain was found to occur near the bases of the pedicles and on both superficial and deep surfaces of the pars interarticularis, which emphasises the importance of the posterior elements of lumbar vertebrae in transmitting load. Radial bulge and tangential strain of the disc wall were maximal at the posterolateral surface, in agreement with the fact that disc degeneration and prolapse commonly occur there. Under posterior offset loads simulating extension, both compressive and tensile strains were found to be increased on both surfaces of the pars interarticularis, which suggests that hyperextension may lead to stress fractures and spondylolisthesis. Posterior offset loads also increased the radial bulge of the posterior disc wall and tangential strain at the anterior surface of the disc. Anterior offset loads simulating flexion increased the radial bulge of the anterior disc wall and tangential strain at the posterior surface of the disc. These findings are compatible with movement of the nucleus pulposus within the disc during flexion and extension. This hypothesis was supported by post-mortem discography

Two groups of intervertebral discs, one normal, as obtained from the post-mortem room, the other prolapsed, as removed at operation, have been compared by chemical analysis of their principal constituents. There is a progression of chemical changes associated with the ageing of the normal disc. This shows not only the expected slight increase in collagen as age advances, but also, surprisingly, that the polysaccharide content rises to a maximum in the fourth decade, in the same way as does polysaccharide in costal cartilage. In prolapsed discs the ageing process is superseded by a different and distinctive progression, which advances, not according to age, but according to the duration of the prolapse. There is a critical level to which the polysaccharide content must apparently fall, irrespective of the normal level for the patient's age, before a prolapse occurs. Normal ageing probably consists in the breakdown of a particular polysaccharide/protein linkage, with coincident "maturation" of collagen. In the prolapsing disc multiple, and possibly different, linkages are rapidly broken down. This depolymerisation of a gel structure must be presumed to be the basis of the decreased imbibition capacity of the nucleus pulposus, and to be the source of the hydrostatic abnormalities which result in disc prolapse. In both normal and prolapsing discs the products of mucopolysaccharide breakdown appear to participate in the metabolism of collagen

Forty-two consecutive patients with suspected lumbar disc protrusions were studied prospectively to compare the diagnostic accuracy of low-field strength MRI with that of radiculography. Thirty patients subsequently underwent surgical exploration at 33 levels and the operative findings were compared to both methods of diagnostic imaging. All patients had MRI studies, whilst 29 patients also had radiculography. Both studies were evaluated without prior knowledge of the clinical signs, operative findings or the results of other imaging techniques. MRI predicted the correct diagnosis in 29 of the 33 levels explored, an accuracy of 88%. All discs proven to be abnormal demonstrated a reduced signal from the nucleus pulposus. There were two false positive results and two doubtful cases but no false negatives. Radiculography predicted the correct diagnosis in 24 of 32 levels explored, an accuracy of 75%. There were two false positive results, five doubtfuls and one false negative. The overall accuracy when both tests were considered rose to 94%. Of the remaining 12 patients all except one showed good correlation between the MRI and radiculographic findings. These results indicate that low field strength MRI is slightly better than radiculography in diagnosing lumbar disc protrusions

Aims

To systematically evaluate whether bracing can effectively achieve curve regression in patients with adolescent idiopathic scoliosis (AIS), and to identify any predictors of curve regression after bracing.

Aims

The aim of this study was to investigate whether the type of cervical disc herniation influences the severity of symptoms at the time of presentation, and the outcome after surgical treatment.

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

The aim of this study was to determine the differences in spinal imaging characteristics between subjects with or without lumbar developmental spinal stenosis (DSS) in a population-based cohort.

Although success has been achieved with implantation of bone marrow mesenchymal stem cells (bMSCs) in degenerative discs, its full potential may not be achieved if the harsh environment of the degenerative disc remains. Axial distraction has been shown to increase hydration and nutrition. Combining both therapies may have a synergistic effect in reversing degenerative disc disease. In order to evaluate the effect of bMSC implantation, axial distraction and combination therapy in stimulating regeneration and retarding degeneration in degenerative discs, we first induced disc degeneration by axial loading in a rabbit model.

The rabbits in the intervention groups performed better with respect to disc height, morphological grading, histological scoring and average dead cell count. The groups with distraction performed better than those without on all criteria except the average dead cell count.

Our findings suggest that bMSC implantation and distraction stimulate regenerative changes in degenerative discs in a rabbit model.

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.

The pathophysiology of intervertebral disc degeneration has been extensively studied. Various factors have been suggested as influencing its aetiology, including mechanical factors, such as compressive loading, shear stress and vibration, as well as ageing, genetic, systemic and toxic factors, which can lead to degeneration of the disc through biochemical reactions. How are these factors linked? What is their individual importance? There is no clear evidence indicating whether ageing in the presence of repetitive injury or repetitive injury in the absence of ageing plays a greater role in the degenerative process. Mechanical factors can trigger biochemical reactions which, in turn, may promote the normal biological changes of ageing, which can also be accelerated by genetic factors. Degradation of the molecular structure of the disc during ageing renders it more susceptible to superimposed mechanical injuries.

This review supports the theory that degeneration of the disc has a complex multifactorial aetiology. Which factors initiate the events in the degenerative cascade is a question that remains unanswered, but most evidence points to an age-related process influenced primarily by mechanical and genetic factors.

We report on two cases of infective spondylodiscitis caused by Gemella haemolysans in otherwise healthy patients. This organism has only rarely been identified as a cause of bone and joint infection, with only two previous reports of infective spondylodiscitis.

We describe the clinical features, investigations and treatment options.

The belief that an intervertebral disc must degenerate before it can herniate has clinical and medicolegal significance, but lacks scientific validity. We hypothesised that tissue changes in herniated discs differ from those in discs that degenerate without herniation. Tissues were obtained at surgery from 21 herniated discs and 11 non-herniated discs of similar degeneration as assessed by the Pfirrmann grade. Thin sections were graded histologically, and certain features were quantified using immunofluorescence combined with confocal microscopy and image analysis. Herniated and degenerated tissues were compared separately for each tissue type: nucleus, inner annulus and outer annulus.

Herniated tissues showed significantly greater proteoglycan loss (outer annulus), neovascularisation (annulus), innervation (annulus), cellularity/inflammation (annulus) and expression of matrix-degrading enzymes (inner annulus) than degenerated discs. No significant differences were seen in the nucleus tissue from herniated and degenerated discs. Degenerative changes start in the nucleus, so it seems unlikely that advanced degeneration caused herniation in 21 of these 32 discs. On the contrary, specific changes in the annulus can be interpreted as the consequences of herniation, when disruption allows local swelling, proteoglycan loss, and the ingrowth of blood vessels, nerves and inflammatory cells.

In conclusion, it should not be assumed that degenerative changes always precede disc herniation.

Cite this article: Bone Joint J 2013;95-B:1127–33.

Lumbar disc herniation (LDH) is uncommon in youth and few cases are treated surgically. Very few outcome studies exist for LDH surgery in this age group. Our aim was to explore differences in gender in pre-operative level of disability and outcome of surgery for LDH in patients aged ≤ 20 years using prospectively collected data.

From the national Swedish SweSpine register we identified 180 patients with one-year and 108 with two-year follow-up data ≤ 20 years of age, who between the years 2000 and 2010 had a primary operation for LDH.

Both male and female patients reported pronounced impairment before the operation in all patient reported outcome measures, with female patients experiencing significantly greater back pain, having greater analgesic requirements and reporting significantly inferior scores in EuroQol (EQ-5D-index), EQ-visual analogue scale, most aspects of Short Form-36 and Oswestry Disabilities Index, when compared with male patients. Surgery conferred a statistically significant improvement in all registered parameters, with few gender discrepancies. Quality of life at one year following surgery normalised in both males and females and only eight patients (4.5%) were dissatisfied with the outcome. Virtually all parameters were stable between the one- and two-year follow-up examination.

LDH surgery leads to normal health and a favourable outcome in both male and female patients aged 20 years or younger, who failed to recover after non-operative management.

Cite this article: Bone Joint J 2015;97-B:1675–82.

No previous studies have examined the physical characteristics of patients with cauda equina syndrome (CES). We compared the anthropometric features of patients who developed CES after a disc prolapse with those who did not but who had symptoms that required elective surgery. We recorded the age, gender, height, weight and body mass index (BMI) of 92 consecutive patients who underwent elective lumbar discectomy and 40 consecutive patients who underwent discectomy for CES. On univariate analysis, the mean BMI of the elective discectomy cohort (26.5 kg/m² (16.6 to 41.7) was very similar to that of the age-matched national mean (27.6 kg/m², p = 1.0). However, the mean BMI of the CES cohort (31.1 kg/m² (21.0 to 54.9)) was significantly higher than both that of the elective group (p < 0.001) and the age-matched national mean (p < 0.001). A similar pattern was seen with the weight of the groups. Multivariate logistic regression analysis was performed, adjusted for age, gender, height, weight and BMI. Increasing BMI and weight were strongly associated with an increased risk of CES (odds ratio (OR) 1.17, p < 0.001; and OR 1.06, p <  0.001, respectively). However, increasing height was linked with a reduced risk of CES (OR 0.9, p < 0.01). The odds of developing CES were 3.7 times higher (95% confidence interval (CI) 1.2 to 7.8, p = 0.016) in the overweight and obese (as defined by the World Health Organization: BMI ≥ 25 kg/m²) than in those of ideal weight. Those with very large discs (obstructing > 75% of the spinal canal) had a larger BMI than those with small discs (obstructing < 25% of the canal; p < 0.01). We therefore conclude that increasing BMI is associated with CES.

Modern principles for the treatment of open fractures include stabilisation of the bone and management of the soft tissues. Wound debridement and irrigation is thought to be the mainstay in reducing the incidence of infection. Although numerous studies on animals and humans have focused on the type of irrigation performed, little is known of the factors which influence irrigation. This paper evaluates the evidence, particularly with regard to additives and the mode of delivery of irrigation fluid.

Normal saline should be used and although many antiseptics and antibiotics have been employed, no consensus has been reached as to the ideal additive. Despite the advocates of high-pressure methods highlighting the improved dilutional ability of such techniques, the results are inconclusive and these irrigation systems are not without complications.

New systems for debridement are currently being investigated, and an ideal method has yet to be determined.

Cervical spinal disc replacement is used in the management of degenerative cervical disc disease in an attempt to preserve cervical spinal movement and to prevent adjacent disc overload and subsequent degeneration. A large number of patients have undergone cervical spinal disc replacement, but the effectiveness of these implants is still uncertain. In most instances, degenerative change at adjacent levels represents the physiological progression of the natural history of the arthritic disc, and is unrelated to the surgeon. Complications of cervical disc replacement include loss of movement from periprosthetic ankylosis and ossification, neurological deficit, loosening and failure of the device, and worsening of any cervical kyphosis. Strict selection criteria and adherence to scientific evidence are necessary. Only prospective, randomised clinical trials with long-term follow-up will establish any real advantage of cervical spinal disc replacement over fusion.

A rat model of lumbar root constriction with an additional sympathectomy in some animals was used to assess whether the sympathetic nerves influenced radicular pain. Behavioural tests were undertaken before and after the operation.

On the 28th post-operative day, both dorsal root ganglia and the spinal roots of L4 and L5 were removed, frozen and sectioned on a cryostat (8 μm to 10 μm). Immunostaining was then performed with antibodies to tyrosine hydroxylase (TH) according to the Avidin Biotin Complex method. In order to quantify the presence of sympathetic nerve fibres, we counted TH-immunoreactive fibres in the dorsal root ganglia using a light microscope equipped with a micrometer graticule (10 x 10 squares, 500 mm x 500 mm). We counted the squares of the graticule which contained TH-immunoreactive fibres for each of five randomly-selected sections of the dorsal root ganglia.

The root constriction group showed mechanical allodynia and thermal hyperalgesia. In this group, TH-immunoreactive fibres were abundant in the ipsilateral dorsal root ganglia at L5 and L4 compared with the opposite side. In the sympathectomy group, mechanical hypersensitivity was attenuated significantly.

We consider that the sympathetic nervous system plays an important role in the generation of radicular pain.

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.