Endplate Shape Research Articles

Correlation of end plate shape on MRI and disc degeneration in surgically treated patients with degenerative disc disease and herniated nucleus pulposus

The sagittal profile of the lumbar end plates on magnetic resonance imaging (MRI) has not been investigated in patients with degenerative disc disease (DDD) or herniated nucleus pulposus (HNP). To examine the shape of the end plates in patients treated surgically for a) low back pain or b) radiculopathy with HNP. Furthermore, to investigate the correlation between end plate shape and disc degeneration on the one, and end plate shape and symptoms on the other. Retrospective review of charts and radiographs. The charts, operative reports, preoperative lateral plain radiographs, and MRI scans of 178 patients (85 with low back pain and 93 with HNP) were reviewed. End plate shape was determined on midsagittal MRI cuts, disc degeneration was graded on T2 sequences, and disc height was measured on lateral plain radiographs from L1 to S1 in all patients. Student t-test and chi(2) test were used to detect significant differences and associations. Flat and irregular levels were most common in the lower lumbar spine. The L5/S1 segment was flat in most cases, due to a flat sacral end plate. In DDD patients, disc degeneration on MRI and plain radiographs worsened from concave to flat, to irregular levels. In HNP patients, MRI demonstrated concave levels to be less degenerated, whereas no difference was detected between flat and irregular levels. Disc height of irregular levels was well preserved in HNP patients. Comparing the two groups, flat levels were more degenerated on MRI in HNP patients. Despite similar degrees of degeneration on MRI, concave and irregular levels in DDD patients had lower disc heights. A higher frequency of symptoms was found in flat and irregular levels for both patient groups. The sagittal profile of end plates in the lumbar spine was described for patients with DDD on the one and HNP on the other. A higher association with symptoms was observed for flat and irregular levels in both patient groups. In DDD patients, disck degeneration on both MRI and plain radiographs increased from concave to flat, to irregular levels. In HNP patients, MRI demonstrated concave levels to be less degenerated, whereas no difference was detected between flat and irregular levels. Disc height of irregular levels was well preserved in HNP patients. Comparing the two groups of patients, flat levels were more degenerated on MRI in HNP patients. Despite similar degrees of degeneration on MRI, concave and irregular levels in DDD patients had lower disc heights. The correlation of symptoms and disc degeneration with the end plate shapes is not definitive evidence of end plate remodeling around degenerated discs. It may simply represent the higher rate of disc degeneration in the lower lumbar levels. This analysis did not provide any hints as to which degenerated discs are more likely to herniated and cause leg symptoms or cause predominantly low back pain.

The relation between vertebral endplate shape and lumbar disc herniations.

Blinded review of selected and un-selected computed tomographic myelograms. To determine whether shape of the vertebral body endplate margins is a risk factor for the development of symptomatic lumbar disc herniations. The law of LaPlace for a fluid-filled tube suggests that anular tension could be related to endplate shape and a propensity for disc herniation. It was hypothesized that the law of Laplace could apply to the lumbar spine because of to the cylindrical shape of the lumbar disc and its high water content in nonelderly individuals. It was further hypothesized that differences in the radius of the curvature could place stresses on the anulus that would make posterior disc herniations more likely with "rounder" endplates. Ninety-seven contrast computed tomography scans were reviewed at transitional L4-L5 and L5-S1 in patients under 60 years of age, without previous spine surgery and without spondylolisthesis. Determinations of disc herniations and measurements of endplates were performed by blinded observers. A ratio of these measurements was used to determine the relative circularity of the endplate. Height, weight, body mass index, and disc endplate size and shape were related to the presence of disc herniation. By multiple logistic regression, only endplate shape was strongly related to disc herniations. Endplate area was a less significant factor in men. The shape of the vertebral body margin at the endplate is an important factor contributing to the development of disc herniations at L4-L5 and L5-S1.

The Effects of a Deflecting Plate and Rotor End Plates on Performances of Savonius-type Wind Turbine

The effects of the shape of rotor end plates on rotor performances have been investigated empirically by using five kinds of the Savonius rotors. The optimum shape of the end plate has been found from experimental results, and it has been revealed that the contribution of the lift force to the rotor power is considerably large. Then, by using a deflecting plate placed in front of the rotor, it has been attempted to improve the performances of the Savonius-type wind turbine. By the use of the deflecting plate, the power has been increased about 24 %. It has been also proved that the deflecting plate can be used as a speed control device or a protection device of the Savonius-type wind turbine.