The Clinical Anatomical Study And Possible Significance Of Thoracic Intraforaminal Ligaments At The Entrance Zone

Thoracic posterior longitudinal ligament ossification is a disease inducing limb sensory and motor disorders and visceral autonomic nerve dysfunction by compressing the spinal cord and thoracic nerve roots.Its incidence is globally increasing year by year and the only effective treatment for this disease is surgical decompression.The spinal cord can be released by 360-degree decompression through posterior circumferential decompression surgery,which is recommended as an efficacious and promising method for treating thoracic posterior longitudinal ligament ossification in recent years.Meanwhile,due to the wide range of surgical decompression,the stimulation of the spinal cord and nerve roots is heavy,which causes the higher incidence of postoperative complications.Among them,cerebrospinal fluid leakage and neurological deterioration are the most common ones reported.According to the related surgical procedures of this approach,it is necessary to operate at the entrance zone of thoracic intervertebral foramen.This area is close to the junction between thoracic nerve roots and the spinal cord,which exists a risk of nerve injury during surgery.At the same time,nerve root sleeves are also located at the entrance zone.Therefore,it may have a certain guidance for pathogenesis and prevention of such postoperative complications to recognize the distribution of ligaments around this area and their relationship with nerve root sleeves.However,the systematic research of thoracic intraforaminal ligaments at the entrance zone is still lack.The subject of this study aims to reveal the specific properties of thoracic intraforaminal ligaments and their connections with thoracic nerve roots and structures around the intervertebral foramen from a clinical anatomical perspective.Moreover,it attempts to clarify the relationship between these ligaments and the postoperative complications through the procedures of posterior circumferential decompression surgery.In this way,spine surgeons are provided with the more detailed anatomic data to better prevent and reduce the occurrence of related surgical complications and further to improve surgical safety.The content of this research is summarized as follows:Objective:To study the morphology and distribution of thoracic intraforaminal ligaments at the entrance zone and evaluate their clinical significance.Methods:10 adult thoracic vertebrae specimens were dissected(5 embalmed cadavers,5 fresh frozen cadavers).Thoracic spines were sawn in the median sagittal plane.Nerve roots were identified within fascia and any surrounding ligamentous attachments were meticulously separated and preserved.The quantity,morphology,origin,insertion,and spatial orientation of these intraforaminal ligaments were observed and recorded under naked eyes and a surgical microscope.The length,width,diameter,and thickness of ligaments were measured under the surgical microscope using a vernier caliper.Results:A total of 943 intraforaminal ligaments were found in 240 thoracic intervertebral foramina,including 917(97.24%)radiating ligaments,which radially connected nerve root sleeves to foraminal walls and 26(2.76%)transforaminal ligaments,which connected bony tissues around intervertebral foramina.Conclusions:Thoracic intraforaminal ligaments are normal structures at the entrance zone.Under physiological conditions,these ligaments play a significant role in supporting,fixing,and protecting thoracic nerve roots.Full realization and proper treatment of radiating ligaments during posterior circumferential decompression surgery may help prevent the occurrence of postoperative complications.