Determination of inter-spinous process distance in the lumbar spine

Abstract

IntroductionA key factor in the evaluation of lumbar spine trauma is the position of the spinous processes in relation to each other as an indication of the status of the posterior stabilising structures. More or less severe separation of the spinous processes can result in a loss of mechanical support from the posterior spinal structures, and consequently in potential instability of the injured spinal segment. The exact amount of separation of the posterior elements that indicates such an injury on conventional radiographs is, however, not known. The increase in interspinal process distance at the location of an injury of a lumbar spinal segment should be compared with the "normal" interspinal process distance at adjacent levels in the lumbar Abstract Fracture of a spinal segment with minimal or no compression of the vertebral body can be highly unstable. Screening for such an injury in the lumbar spine is often obstructed in a multi-injured patient, because of difficulty in obtaining adequate sagittal radiographs. The position of the spinous processes in relation to each other is the key for proper evaluation of the status of the posterior stabilising structures. The amount of separation or axial rotation of the posterior part of the vertebra that can occur before failure of the posterior structures has not been unambiguously defined. Despite this, it can be assumed that severe separation of the spinous processes indicates a more or less pronounced loss of mechanical support. An analysis of how the posterior spinous processes relate to each other on an anteroposterior (AP) radiograph could obviate this problem. A new, simple and reproducible radiographic tool is presented for screening of an eventual rupture of posterior structures of the lumbar spine. This method is based on measurements of the variation in interspinal process distance between adjacent levels in lumbar spine in a normal population. Two hundred normal AP radiographs of non-injured thoracolumbar spine were studied. The interspinal process distance was measured as the distance between the cranial ends of the adjacent projections of spinous processes on AP radiographs. The mean values and 99% confidence limits for changes in the interspinal process distances between adjacent spinal levels were determined and analysed in relation to age, gender and spinal segment level. An upper limit of a normal difference in distance between the spinous processes at two adjacent levels was determined to be 7-10 mm, depending on age and location in the lumbar spine. A difference in interspinal process distance exceeding 7 mm between two adjacent lumbar levels should alert a surgeon to severe and unstable injury.

Residual mobility of instrumented and non-fused segments in thoracolumbar spine fractures

“…Negative effects in spine fusion have been reported, including pseudoarthosis, spinal stenosis, spondylolysis and accelerated degeneration of non-fused segments [5,28,39,44,48]. The main argument to fuse in thoracolumbar spine fractures is the lack of correction noticed in surgeries without arthrodesis, which is mainly caused by the degeneration of intervertebral discs involved in the fracture [3,9,27,30,31,37,38,43], or by the presence of capsuloligamentous disruptive injuries of the posterior column [34,40,55].…”

Biomechanical Evaluation of the X-Stop Device for Surgical Treatment of Lumbar Spinal Stenosis

“…On the other hand, using coronal x-ray images Zucherman et al 4 observed that the ISP distances were similar in the neutral or standing position before and after X-Stop implantation (51 and 52 mm, respectively) after 12 months in 100 LSS patients with an average age of 70 years. 19 The differences among these studies might be due to different measurement methods and inclusion criteria: Elderly patients of our study had remarkable lumbar degeneration. On the other hand, the 2-dimensional image measurement technique employing plain radiograph might not be able to consistently locate the actual shortest distance of the ISP.…”

Can the Interspinous Distance Predict Kyphosis in Conservative Treatment in Thoracolumbar Burst Fracture? A Retrospective, Diagnostic Study

“…We propose a modified classification system in this study, adding the interspinous opening to the load-sharing classification, and creating the modified load sharing classification (MLSC). For the analysis of the posterior spinal process distance, we used the method proposed by Neumann et al [15] which quantifies the opening of the spinal processes in the posterior vertebral arch in radiographs in anterior-posterior (AP) view, taking into consideration the cranial end of the base of the spinous processes. The averages in adjacent levels were used as standards for normality.…”

“…The most used method to investigate the posterior ligament insufficiency is the analysis of the opening of the spinous processes. Based on the anteriorposterior radiographic analysis of 200 normal subjects, Neumann et al [15] defined the indirect values indicative of this failure that were accurate and reproducible among independent examiners. In clinical practice, most physicians believe that patients with increased interspinous distance have an indirect sign of biomechanical instability due to posterior spinal ligament insufficiency.…”