Introduction. The response of the intervertebral disc to asymmetric forces may accelerate degeneration through changes in the matrix. Macroscopically, the disc sustains structural changes that may play a part in the progression of a scoliotic curve. Molecularly, disc degeneration is the outcome of the action of matrix metalloproteases (MMPs), members of a family of enzymes that bring about the degradation of extracellular matrix components. In this study we measured in vivo the expression of MMPs in a rat scoliotic intervertebral disc and studied the effect of the degree of the deformity on their production. Methods. Asymmetric forces were applied in the intervertebral disc between the ninth and tenth vertebrae at the base of a rat tail with the use of a mini Ilizarov external fixator, under anaesthesia. Animals were categorised into three groups according to the degree of the deformity. In group I, the deformity that was applied on the intervertebral disc was 10°, in group II 30°, and in group III 50°. All the animals used were female Wistar rats before adulthood, to take into account the effect of growth for the study of intervertebral disc changes. The intact intervertebral discs outside the fixator were used as controls. After the rats' death on day 35, the tails were prepared and analysed with an immunohistochemical protocol for chromogenic detection and location of MMPs 1 and 12 in tissue sections of the intervertebral discs. Results. We recorded an increase of the concentration of the MMPs in all groups compared with controls. The quantity of the MMPs increased as the degree of the deformity progressed. MMPs were detected mainly in fibrocartilage cells of the degenerative part, which were formed as result of the compression forces. We detected a differentiation of a large number of disc cells into chondrocytes at the transitional zone of the intervertebral disc adjacent to the vertebral end plates. Conclusions. The application of asymmetric forces on the intervertebral discs of a rat tail results in an increase of MMP expression in the disc cells. The amount of MMPs produced is proportional to the degree of the deformity and has an asymmetrical pattern of distribution into the intervertebral disc

Aims

The aim of this study was to determine the diagnostic utility of histological analysis in spinal biopsies for spondylodiscitis (SD).

Aims

The aims of this study were to evaluate the clinical and radiological outcomes of instrumented posterolateral fusion (PLF) performed in patients with rheumatoid arthritis (RA).

This short contribution aims to explain how intervertebral disc ‘degeneration’ differs from normal ageing, and to suggest how mechanical loading and constitutional factors interact to cause disc degeneration and prolapse. We suggest that disagreement on these matters in medico-legal practice often arises from a misunderstanding of the nature of ‘soft-tissue injuries’.

We evaluated the efficacy of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E-BMP-2) in a mini-pig model of spinal anterior interbody fusion. A total of 14 male mini-pigs underwent three-level anterior lumbar interbody fusion using polyether etherketone (PEEK) cages containing porous hydroxyapatite (HA). Four groups of cages were prepared: 1) control (n = 10 segments); 2) 50 μg E-BMP-2 (n = 9); 3) 200 μg E-BMP-2 (n = 10); and 4) 800 μg E-BMP-2 (n = 9). At eight weeks after surgery the mini-pigs were killed and the specimens were evaluated by gross inspection and manual palpation, radiological evaluation including plain radiographs and micro-CT scans, and histological analysis. Rates of fusion within PEEK cages and overall union rates were calculated, and bone formation outside vertebrae was evaluated. One animal died post-operatively and was excluded, and one section was lost and also excluded, leaving 38 sites for assessment. This rate of fusion within cages was 30.0% (three of ten) in the control group, 44.4% (four of nine) in the 50 μg E-BMP-2 group, 60.0% (six of ten) in the 200 μg E-BMP-2 group, and 77.8% (seven of nine) in the 800 μg E-BMP-2 group. Fusion rate was significantly increased by the addition of E-BMP-2 and with increasing E-BMP-2 dose (p = 0.046). In a mini-pig spinal anterior interbody fusion model using porous HA as a carrier, the implantation of E-BMP-2-loaded PEEK cages improved the fusion rate compared with PEEK cages alone, an effect that was significantly increased with increasing E-BMP-2 dosage.

Cite this article: Bone Joint J 2013;95-B:217–23.

There have been very few reports in the literature of gout and pseudogout of the spine. We describe six patients who presented with acute sciatica attributable to spinal stenosis with cyst formation in the facet joints. Cytopathological studies confirmed the diagnosis of crystal arthropathy in each case.

Specific formation of a synovial cyst was identified pre-operatively by MRI in five patients. In the sixth, the diagnosis was made incidentally during decompressive surgery. Surgical decompression alone was undertaken in four patients. In one with an associated degenerative spondylolisthesis, an additional intertransverse fusion was performed. Another patient had previously undergone a spinal fusion adjacent to the involved spinal segment, and spinal stabilisation was undertaken as well as a decompression.

In addition to standard histological examination material was sent for examination under polarised light which revealed deposition of urate or calcium pyrophosphate dihydrate crystals in all cases.

It is not possible to diagnose gout and pseudogout of the spine by standard examination of a fixed specimen. However, examining dry specimens under polarised light suggests that crystal arthropathy is a significant aetiological factor in the development of symptomatic spinal stenosis associated with cyst formation in a facet joint.