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Purpose: To investigate the microscopic fibrous integration between the intervertebral disc, cartilage endplates and vertebral endplates in human lumbar spines of varying degrees of degeneration using differential interference contrast (DIC) optics. Weakness at these junctions is considered to be an important factor in the aetiology of disc herniations., Methods: Magnetic resonance images (MRIs) of cadaveric lumbar spines were graded for degeneration and motion segments from a range of degenerative grades isolated and bisected sagittally. Following fixation and decalcification, these were cut into segments containing anterior or posterior annulus fibrosus or nucleus pulposus. The segments were cryo-sectioned and sections visualised using both standard light and DIC microscopy., Results: Detachment at the interface between the disc and vertebrae increased with greater degenerative grade (from 1.9 % in Grade I to 28 % in Grade V), especially at the boundary between the cartilage and vertebral endplates. DIC microscopy revealed the fibrous organisation at the IVD-cartilage endplate interface with structural features, such as annular lamellae branching and nodal insertions in the nucleus pulposus region; these have been previously observed in ovine spines, but were less uniform in humans. Structural integrity of the IVD and cartilage endplate was also lost with increasing degeneration., Conclusions: This preliminary study shows that microscopic structural features may act to maintain attachment between the IVD and CEP in the human spine. Loss of structural integrity in this region may destabilise the spine, possibly altering the mechanical environment of the cells in the disc and so potentially contribute to the aetiopathogenesis of IVD degeneration.

Purpose: The objective of this study was to establish the prevalence and significance of ossicles of lumbar articular facets (OLAF) in young athletes with backache diagnosed by multi-detector computed tomography (MDCT)., Materials and Methods: The MDCT examinations of the lumbar spine carried out for suspected spondylolysis on 46 consecutive symptomatic young athletes presenting to a sports injury clinic over a 1-year period were retrospectively reviewed. OLAF study included detailed correlation with the structural and morphological stress features of the posterior neural arches. This was then compared with a control group composed of 39 patients., Results: Twenty-three OLAF were identified in 15 patients. Eleven of the 15 patients with ossicles had posterior element stress changes (PEST)/pars defects. In the control group, two OLAF were identified in two patients, one demonstrating PEST changes., Conclusion: The high prevalence of OLAF in young symptomatic athletes compared with the asymptomatic control group is indicative of stress fractures. The non-united articular process fractures should be regarded as part of the spectrum of stress-induced changes in the posterior neural arch in the same way as spondylolysis. MDCT with volumetric acquisition and multi-planar reformation is the most reliable investigation in the diagnosis of OLAF., Key Points: 1) This CT study supports a traumatic aetiology for lumbar articular facets ossicles. 2) OLAF represent part of a spectrum of stress-induced changes in the posterior neural arch. 3) OLAF are associated with typical spondylolysis. 4) OLAF can be overlooked on reverse gantry angle computed tomography (RG-CT). 5) OLAF may account for some of the discrepancy between radionuclide and RG-CT studies.

Objective: The majority of lumbar facet joint cysts (LFJCs) are located in the spinal canal, on the medial aspect of the facet joint with characteristic diagnostic features. When they migrate away from the joint of origin, they cause diagnostic problems., Materials and Methods: In a 7-year period we examined by computed tomography (CT) and magnetic resonance (MR) imaging five unusual cases of facet joint cysts which migrated from the facet joint of origin., Results: Three LFJCs were identified in the right S1 foramen, one in the right L5-S1 neural foramen and one in the left erector spinae and multifidus muscles between the levels of L2-L4 spinous process., Conclusions: Awareness that spinal lesions identified at MRI and CT could be due to migrating facet joint cyst requires a high level of suspicion. The identification of the appositional contact of the cyst and the facet joint needs to be actively sought in the presence of degenerative facet joints.

Purpose: To evaluate retrospectively the magnetic resonance (MR) imaging features of Chance-type flexion-distraction injuries., Materials and Methods: The authors' institutional review board does not require its approval or patient informed consent for retrospective studies. Imaging data were reviewed retrospectively for 24 patients (15 male, nine female; mean age, 28 years; range, 9-71 years) who had sustained radiographically typical Chance-type flexion-distraction injuries. The posterior vertebral body height remained unchanged or was increased in these patients. Two radiologists recorded a variety of bone and soft-tissue abnormalities seen with MR imaging. Based on consensus, the documented findings were sequentially analyzed to determine their frequencies., Results: Combined bone and soft-tissue injuries occurred in 23 (96%) of 24 patients, were more common than soft-tissue damage alone (one [4%] of 24 patients), and occurred primarily at the thoracolumbar junction. Contiguous vertebral injury was seen in 20 (83%) of 24 patients, usually in the form of anterosuperior vertebral endplate edema, while noncontiguous injury occurred in eight (33%) of 24 patients. Extensive subcutaneous and paraspinal muscle edema was seen in all patients and extended over several segments. Posterior osteoligamentous complex disruption also occurred in all patients. Horizontally oriented fractures of the posterior neural arches produced an MR imaging pattern that the authors call the sandwich sign, which consists of linear hemorrhage framed by marrow edema. This sign was seen in 12 (50%) of 24 patients. In seven (29%) of 24 patients, a fracture line extending from a damaged pedicle was seen to exit through the contralateral posterosuperior aspect of the vertebral body, with extension of the fracture fragments into the spinal canal., Conclusion: A spectrum of features is discernible with MR imaging in Chance-type injuries.