Lumbar disc herniation, lumbar puncture and spinal anesthesia were usually common situations, which involved the surface localization of L4-SP. The accuracy in identifying L4 using manual palpation by clinicians is limited due to the inter-individual variation in the morphology of L4-SP . Most of studies focus on the mechanisms of diseases affecting it. Even though, there were only a few reports about the inter-individual variation of L4-SP. The objective of the present study was to explore the anatomical features of L4-SP, which may facilitate to find the exact insertion point.
All data about 500 participates were collected by 3D of CT construction from 2014 to 2018. All patients were Han Chinese and aged 18 to 75. Thus, the information in this study had practical significance for the operation in China. By this way, Table 1 indicated that there were statistical differences in BC and the angles between three types. Among them 266 on L4-SP (type Ⅰ, 53.20%), 16 above L4-SP (type Ⅱ, 3.20%), and 218 below L4-SP (type Ⅲ, 43.60%). This can be used to be one of the basis for determining the position of L4-SP. Unlike conventional X-ray analysis, CT provides detailed images of numerous types of tissue as well as the bones and blood vessels, which is a rapid and accurate procedure. In that case, based on anatomical parameters form CT to obtain 3D model, they could locate it accurately and reduce the risk of operation [3, 5, 9]. When it came to some possible reasons, such as anatomatic factors, the size of lumbar spine changes with the development and the growth of human skeletons under the influence of genetic factors, and this kind of physiological diversity may affect the accuracy of palpation [4, 13-15]. Besides, degenerative changes occurring in the lumbar spine can be worse by the influence of patients’ lifestyle. The most common and serious transform was lumbar disc herniation in broken disc herniation and retrograde lumbar disc herniation, which would cause broken fibrous ring, cartilage endplate and nucleus burst out, and then resulting in the height of intervertebral disc changes. In addition, lumbar spondylolisthesis also had high incidence and influence the palpation accuracy, especially in different positions or sports. It is important to find the highest points PSIS to determine the accurate position of L4-SP . On the account of normal physiological factors, the traditional palpation operation is used for normal state. However, there are 8 participates in the study that have 6 lumbar vertebrae, which can not be adopted because of abnormalities.
As to clinic factor, the degree of cooperation between patients and doctors can be an influent factor. Different levels of mistakes when different positions of the examinees took on, even experienced physician may make. If the 3D of CT construction was used to verify the position of the vertebral levels in patients, the risk of the devastating and permanent complications resulting from spinal cord injection can be reduced. In that case, it was clear that adequate knowledge of L4 morphology is necessary for the spinal surgeon in order to avoid damage to the vertebral arteries, spinal cord or nerve roots during fixation interventions involving the posterior cervical spine. Hence, it can more safe for patients with abnormal spinal anatomy and the morbidly obese, particularly in whom have difficulties in palpating anatomical landmarks [17-18]. Therefore, there were a series of errors which may happen in clinical practice. The traditional palpation of L4-SP is not completely exact. The accuracy rate is only 53.20%, and the errors may cause serious consequences .
Nevertheless, there are still some limitations. Though the accuracy of fourth lumbar spinous process palpation can be improved by 3D of CT reconstruction, the operative level of clinician is decisive. Above that, the samples in this research are limited to the southwest and the sample size is not so adequate now. The images resources are limited when it comes to costs and radiation, because it is far more practical that patients' willingness to use radiographs, computed tomography, and MRI are reduced [18, 20].