Cell clusters in intervertebral disc degeneration: an attempted repair mechanism aborted via apoptosis.

Cell clusters are a histological hallmark feature of intervertebral disc degeneration. Clusters arise from cell proliferation, are associated with replicative senescence, and remain metabolically, but their precise role in various stages of disc degeneration remain obscure. The aim of this study was therefore to investigate small, medium, and large size cell-clusters. For this purpose, human disc samples were collected from 55 subjects, aged 37-72 years, 21 patients had disc herniation, 10 had degenerated non-herniated discs, and 9 had degenerative scoliosis with spinal curvature <45°. 15 non-degenerated control discs were from cadavers. Clusters and matrix changes were investigated with histology, immunohistochemistry, and Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Data obtained were analyzed with spearman rank correlation and ANOVA. Results revealed, small and medium-sized clusters were positive for cell proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) in control and slightly degenerated human discs, while large cell clusters were typically more abundant in severely degenerated and herniated discs. Large clusters associated with matrix fissures, proteoglycan loss, matrix metalloproteinase-1 (MMP-1), and Caspase-3. Spatial association findings were reconfirmed with SDS-PAGE that showed presence to these target markers based on its molecular weight. Controls, slightly degenerated discs showed smaller clusters, less proteoglycan loss, MMP-1, and Caspase-3. In conclusion, cell clusters in the early stages of degeneration could be indicative of repair, however sustained loading increases large cell clusters especially around microscopic fissures that accelerates inflammatory catabolism and alters cellular metabolism, thus attempted repair process initiated by cell clusters fails and is aborted at least in part via apoptosis.

Physical disruption of intervertebral disc promotes cell clustering and a degenerative phenotype.

To test the hypothesis that physical disruption of an intervertebral disc disturbs cell-matrix binding, leading to cell clustering and increased expression of matrix degrading enzymes that contribute towards degenerative disc cell phenotype. Lumbar disc tissue was removed at surgery from 21 patients with disc herniation, 11 with disc degeneration, and 8 with adolescent scoliosis. 5 µm sections were examined with histology, and 30-µm sections by confocal microscopy. Antibodies were used against integrin α5beta1, matrix metalloproteinases (MMP) 1, MMP-3, caspase 3, and denatured collagen types I and II. Spatial associations were sought between cell clustering and various degenerative features. An additional, 11 non-herniated human discs were used to examine causality: half of each specimen was cultured in a manner that allowed free 'unconstrained' swelling (similar to a herniated disc in vivo), while the other half was cultured within a perspex ring that allowed 'constrained' swelling. Changes were monitored over 36 h using live-cell imaging. 1,9-Di-methyl methylene blue (DMMB) assay for glycosaminoglycan loss was carried out from tissue medium. Partially constrained specimens showed little swelling or cell movement in vitro. In contrast, unconstrained swelling significantly increased matrix distortion, glycosaminoglycan loss, exposure of integrin binding sites, expression of MMPs 1 and 3, and collagen denaturation. In the association studies, herniated disc specimens showed changes that resembled unconstrained swelling in vitro. In addition, they exhibited increased cell clustering, apoptosis, MMP expression, and collagen denaturation compared to 'control' discs. Results support our hypothesis. Further confirmation will require longitudinal animal experiments.

Nerves and blood vessels in degenerated intervertebral discs are confined to physically disrupted tissue.

Nerves and blood vessels are found in the peripheral annulus and endplates of healthy adult intervertebral discs. Degenerative changes can allow these vessels to grow inwards and become associated with discogenic pain, but it is not yet clear how far, and why, they grow in. Previously we have shown that physical disruption of the disc matrix, which is a defining feature of disc degeneration, creates free surfaces which lose proteoglycans and water, and so become physically and chemically conducive to cell migration. We now hypothesise that blood vessels and nerves in degenerated discs are confined to such disrupted tissue. Whole lumbar discs were obtained from 40 patients (aged 37-75 years) undergoing surgery for disc herniation, disc degeneration with spondylolisthesis or adolescent scoliosis ('non-degenerated' controls). Thin (5-µm) sections were stained with H&E and toluidine blue for semi-quantitative assessment of blood vessels, fissures and proteoglycan loss. Ten thick (30-µm) frozen sections from each disc were immunostained for CD31 (an endothelial cell marker), PGP 9.5 and Substance P (general and nociceptive nerve markers, respectively) and examined by confocal microscopy. Volocity image analysis software was used to calculate the cross-sectional area of each labelled structure, and its distance from the nearest free surface (disc periphery or internal fissure). Results showed that nerves and blood vessels were confined to proteoglycan-depleted regions of disrupted annulus. The maximum distance of any blood vessel or nerve from the nearest free surface was 888 and 247 µm, respectively. Blood vessels were greater in number, grew deeper, and occupied more area than nerves. The density of labelled blood vessels and nerves increased significantly with Pfirrmann grade of disc degeneration and with local proteoglycan loss. Analysing multiple thick sections with fluorescent markers on a confocal microscope allows reliable detection of thin filamentous structures, even within a dense matrix. We conclude that, in degenerated and herniated discs, blood vessels and nerves are confined to proteoglycan-depleted regions of disrupted tissue, especially within annulus fissures.

Significance of cartilage endplate within herniated disc tissue.

PURPOSE: Disc herniations sometimes contain hyaline cartilage fragments, but their origins and significance are uncertain. METHODS: Herniations were removed surgically from 21 patients (aged 35-74 years) whose main symptom was sciatica (10 patients) or back pain (11 patients). Frozen sections, 5 µm thick, were examined histologically, and antibodies were used to label the matrix-degrading enzyme MMP 1, pro-inflammatory mediator TNFα, and cell proliferation marker Ki-67. Proportions of each tissue type were quantified by image analysis. Cartilage and bone components of the endplate were examined in 7-µm frozen sections from 16 cadaveric spines, aged 61-98 years. RESULTS: Cartilage fragments were found in 10/21 herniations. They averaged 5.0 mm in length, comprised 25 % of the herniation area, and two had some bone attached. Hyaline cartilage was more common in herniations from patients with sciatica (7/10) than with back pain (3/11, P = 0.050), and the area (%) of the herniation occupied by the cartilage was greater in sciatica patients (P < 0.05). Cartilage fragments showed little evidence of swelling, proteoglycan loss or inflammatory cell invasion, although cell clustering was common, and TNFα was sometimes expressed. Each cartilage fragment showed at least one straight edge, as if it had been peeled off the bony endplate, and this mechanism of failure was demonstrated in preliminary mechanical experiments. CONCLUSION: Disc herniations often include hyaline cartilage pulled from the vertebral endplates. Cartilage fragments show little swelling or proteoglycan loss, and may be slow to resorb, increasing the risk of persisting sciatica. Loss of cartilage will increase endplate permeability, facilitating endplate inflammation and disc infection.

A Radiological Evaluation of Lateral Vertebral Subluxation Associated With Spinal Stenosis in the Lumbar Spine in Degenerative Scoliosis.

STUDY DESIGN: Retrospective longitudinal cohort. OBJECTIVE: To evaluate the different patterns of stenosis with lateral subluxation in degenerative lumbar scoliosis (DLS). SUMMARY OF BACKGROUND DATA: Lateral subluxation of the vertebra is commonly seen in DLS. Different patterns of subluxation occur at different levels of the spine and are often associated with neurological compression that can be symptomatic requiring treatment. The pattern and location of the stenosis are variable in DLS. No study to date has evaluated the site of stenosis seen on magnetic resonance imaging with respect to the different patterns or locations of lateral subluxation. METHODS: The standing radiographs and supine magnetic resonance imaging scans of 35 consecutive patients with DLS were analyzed and demonstrated lateral listhesis on standing radiographs (average age, 70.2 years). Subluxation level, amount of listhesis, subluxation angle, axial rotation, and pattern or location of spinal stenosis were noted. RESULTS: There were 60 subluxations in 35 patients. Open subluxations resulted in predominantly contralateral lateral recess and foraminal stenosis (71%; 17 of 24 patients). Closed dislocations demonstrated an ipsilateral pattern of stenosis (82%; 14 of 17 patients). Open subluxations were most commonly present at L3-4 toward the convex apex, whereas closed subluxations were identified on the concavity of the curve, with L1-2 most frequently involved (53%; 9 of 17 patients). An association was identified with open dislocations involving the mid-lumbar spine and closed subluxations at L1-2 (p < .001). CONCLUSIONS: Open and closed subluxations in DLS result in different patterns of spinal stenosis. The presence of unilateral stenosis should alert the clinician to the possibility of spinal deformity and lateral subluxation. After careful review of the anteroposterior standing radiograph, any lateral subluxation and its type can be determined. This may assist decision making in how to treat the stenosis when deformity is present.

The use and abuse of abbreviations in orthopaedic literature.

INTRODUCTION: Abbreviations are commonly used in medical literature. Their use has been associated with medical errors and they can be a source of irritation and misunderstanding. There are strict guidelines for their use. This study analysed the use of abbreviations in orthopaedic literature and compared adherence with guidelines in a general orthopaedic and spinal journal. It also examined orthopaedic professionals' understanding of abbreviations. SUBJECTS AND METHODS: The use of abbreviations in articles over a 3-month period in a general orthopaedic and spinal journal was analysed. The number of abbreviations and adherence with guidelines was recorded. A group of orthopaedic healthcare professionals were tested for their understanding of abbreviations. RESULTS: Almost half of all abbreviations were not properly used and 30% of abbreviations were never defined. Abbreviations were used significantly more often in the spinal journal. Only 40% of abbreviations were correctly defined by the orthopaedic professionals tested. CONCLUSIONS: Guidelines regarding the use of abbreviations are not being adhered to by authors or editors. The poor understanding of abbreviations underlines the importance of minimising their use and defining abbreviations when they are used.

Lumbar disc degeneration below a long arthrodesis (performed for scoliosis in adults) to L4 or L5.

A retrospective analysis of adults treated with long instrumented fusion for scoliosis from the thoracic spine proximally to L4 or L5. To evaluate the long-term clinical outcomes as well as radiological changes in distal unfused mobile segments and to evaluate factors that may predispose to distal disc degeneration and/or poor outcome. A total of 151 mobile segments in 85 patients (65 female), mean age 43.2 (range 21-68), were studied. Curve type, number of fused levels and pelvic incidence were recorded. Clinical outcome was measured using the Whitecloud function scale and disc degeneration using the UCLA disc degeneration score. Spinal balance, local segmental angulations and lumbar lordosis were measured pre- and post-operatively as well as at the most recent follow up--mean 9.3 years (range 7-19). A total of 62% of patients had a good or excellent outcome. Eleven had a poor outcome of which ten underwent extension of fusion--five for pain alone, three for pain with stenosis and two for pseudarthroses. Pre-operative disc degeneration was often asymmetric and was slightly greater in older patients. Overall, there was a significant deterioration in disc degeneration (P < 0.0001) that did not correlate with clinical outcome. Disc degeneration correlated with the recent sagittal balance (Anova F = 14.285, P < 0.001) and the most recent lordosis (Anova F = 4.057, P = 0.048). The post-operative sagittal balance and local L5-S1 sagittal angulation correlated to L4 and L5 degeneration, respectively. There was no correlation between degeneration and age, pre-operative degenerative score, pelvic incidence, sacral slope, number of fused levels or distal level of fusion. Disc degeneration does occur below an arthrodesis for scoliosis in adults which does not correlate with clinical outcome. The correlation of loss of sagittal balance with disc degeneration may be as a result of degeneration causing the loss of balance or vice versa, i.e. sagittal imbalance causing degeneration. Immediate post-operative imbalance correlates with degeneration of the L4/5 disc, which may imply the latter.

The symptom of night pain in a back pain triage clinic.

STUDY DESIGN: Prospective longitudinal study of patients attending a back pain triage clinic with night pain. OBJECTIVE: To assess the importance of the symptom of night pain in patients attending a back pain triage clinic. SUMMARY OF BACKGROUND DATA: The 1994 US Agency for Health Care Policy and Research guidelines suggest nighttime pain should be used as a "red flag." Night pain is known to occur in many conditions, and although common in patients with known serious pathology, the prevalence of night pain in a back pain triage clinic is not known. METHODS: A total of 482 consecutive patients attending a back pain triage clinic were assessed, including history of frequency and duration of night pain. Clinical examination was performed, and demographic data obtained. Magnetic resonance imaging was performed if indicated according to local guidelines. Oswestry, visual analog scales (for pain), and hospital anxiety depression scale, patient-based outcome scores were obtained. RESULTS: There were 213 patients who had night pain, with 90 having pain every night. No serious pathology was identified. Patients with night pain had 4.95 hours continuous sleep (range 2-7) and were woken 2.5 times/night (range 0-6). Patients with pain every night had higher Oswestry, visual analog scale, and hospital anxiety depression scale scores than those who did not. CONCLUSIONS: Although it is a significant and disruptive symptom for patients, these results challenge the specificity of the presence of night pain per se as a useful diagnostic indicator for serious spinal pathology in a back pain triage clinic.

Long-term results of Schollner costoplasty in patients with idiopathic scoliosis.

STUDY DESIGN: A retrospective analysis of patients with idiopathic scoliosis treated with Schollner costoplasty. OBJECTIVE: To evaluate the long-term effects of Schollner costoplasty on rib hump and respiratory function SUMMARY BACKGROUND DATA: Costoplasty is an established technique to improve chest wall deformity in patients with scoliosis. Concerns have been raised of the long-term effects of costoplasty on respiratory function in adults. No long-term studies of this procedure exist. METHODS: A total of 25 patients with idiopathic scoliosis rib hump deformity underwent Schollner costoplasty. There were 12 patients who underwent surgery on the convexity alone, and 13 underwent additional "concave surgery" (6 Silastic [Dow Corning Corp., Midland, MI] implants, 7 concave lengthenings). Five patients underwent simultaneous spinal arthrodesis. The remaining patients underwent delayed procedures (0.4 -19 years) following the index operation. Vital capacity (VC) and rib hump were measured before and after surgery, and at each attendance thereafter. RESULTS: Mean follow-up was 10.8 years. Average reduction in rib hump was 38 mm at 6 months and 29 mm at long-term. There was no significant difference in the preoperative and long-term VC (P = 0.4), although at 6 months after surgery, there was a significant reduction in VC of 5.1%(P = 0.03). Subgroup analysis (convex only, concave lengthening, concave Silastic) revealed a similar pattern for rib hump correction and maintenance of VC in the long-term for each group. There was no significant difference between adults and adolescents in terms of both the reduction in rib hump and the VC (P = 0.2 and 0.3) CONCLUSIONS: Rib hump correction and lung function are preserved in the long-term following Schollner costoplasty in both adults and adolescents.

A comparison of traditional protractor versus Oxford Cobbometer radiographic measurement: intraobserver measurement variability for Cobb angles.

STUDY DESIGN: A comparison between measurement of radiographs using a traditional protractor method and the Oxford Cobbometer, which has the potential to reduce error. OBJECTIVE: To assess measurement variability of Cobb angles using the Oxford Cobbometer and to compare it to that of measurements made using the traditional protractor method. SUMMARY OF BACKGROUND DATA: Studies of the Cobb method have multiple sources of error and subsequent intraobserver variability. Estimates of intraobserver variability are from 2.8 degrees to 10 degrees. METHOD: Fifty-three scoliosis curves were measured by 3 examiners. Two measurement sets were performed using the traditional protractor method and two measurement sets performed using the Oxford Cobbometer. RESULTS: For the protractor method, intraobserver variability was 9.01 degrees (95% confidence interval 7.32-10.88). For the Cobbometer method, the value was 5.77 degrees (95% confidence interval 3.25-7.63). The difference between error for construction and Cobbometer methods was significant (P < 0.001). CONCLUSIONS: This study demonstrates a lower intraobserver variability for the Oxford Cobbometer compared to the traditional construction method. The Oxford Cobbometer, besides being quick and easy to use, does not require the drawing of lines on films or the use of wide diameter radiographic markers and hence removes some sources of intrinsic error incurred during the traditional method of measuring Cobb angles.

The aetiology and outcome of 170 ulnar nerve lesions confirmed with electrophysiological testing.

The authors have studied 148 consecutive patients with 170 electrophysiologically confirmed ulnar nerve lesions, who were followed up for one to six years (median 3.8 years) to determine clinical progress and outcome. Injury and intra-operative pressure accounted for 12.9% and 7.1% of lesions respectively; 58.2% were idiopathic with no identified clinical aetiological factor. Eighty-three percent received non-operative treatment initially; 21% of these required operative intervention following further clinical/electrophysiological assessment. Partial or complete recovery occurred in 92% of intra-operative, 64% of idiopathic and 50% of injury cases respectively. Ulnar nerve lesions predominate in males and can be treated non-operatively providing clinical and electrophysiological monitoring is possible. Bilaterality is common and should be excluded. Lesions due to injury have a worse prognosis than those caused by direct continuous or repeated pressure, inflammation or where no aetiological factor exists.