Imaging anatomy study related to unilateral biportal endoscopic lumbar spine surgery.

PURPOSE: To provide lumbar spine anatomical parameters relevant to the UBE technique and explore their intraoperative application. METHODS: CT imaging data processed by Mimics for parametric measurements, including laminar abduction angle (LAA), laminar slope angle (LSA), minimum laminar height (MLH), distance between the inferior margin of the lamina and attachment of the ligamentum flavum onto the cephalad lamina (DLL), distance between the initial point and the middle of the articular process (DIA), and distance from the inferior margin of the lamina to the inferior border of the vertebral body (DLV), and were manually measured. RESULTS: LAA and DIA gradually increase from L1 to L5. At L1, the DIA is approximately the length of 2 drill bits with a diameter of 3 mm (male: 7.77 ± 1.39 mm, female: 7.22 ± 1.09 mm), while at L5, it can reach the length of 4-5 drill bits (male: 14.96 ± 2.24 mm, female: 13.67 ± 2.33 mm). MLH, DLL, and DLV reach their maximum values at the L3 and decrease toward the cranial and caudal ends. The DLL is smallest at L5 (male: 9.58 ± 1.90 mm, female: 9.38 ± 2.14 mm), equivalent to the length of 3 drill bits, while the DLL at L3 is the length of 4-5 drill bits (male: 14.17 ± 2.13 mm, female: 14.01 ± 2.07 mm). CONCLUSION: Referring to the drill diameter during surgery can mark the extent of laminotomy. The characteristics of vertebral plate angles at different lumbar levels can provide references for preoperative incision design.

Effect of L5 spinal canal type on pedicle screw placement based on CT imaging: a retrospective clinical study.

PURPOSE: The objective of this study was to investigate the optimal entry point and pedicle camber angle for L5 pedicle screws of different canal types. METHODS: CT imaging data were processed by Mimics for simulated pedicle screw placement, and PD (Pedicle diameter), PCA (Pedicle camber angle), LD (Longitudinal distance), TD (Transverse distance), and PBG (Pedicle screw breach grade) were measured. Then they were divided into the Round group and Trefoil group according to the type of spinal canal. When comparing PD, PCA, LD, TD, and PBG, the two sides of the pedicle were compared separately, so they were first divided into the round-type pedicle group and the trefoil-type pedicle group. RESULTS: In the round-type pedicle group (n = 134) and the trefoil-type pedicle group (n = 264), there was no significant difference in PD and LD, but there was a significant difference in PCA between the two groups (t = - 4.072, P < 0.05). A statistically significant difference in the distance of the Magerl point relative to the optimal entry point (t = - 3.792, P < 0.05), and the distance of the Magerl point relative to the optimal entry point was greater in the trefoil-type pedicle group than in the round-type pedicle group. CONCLUSION: The optimal entry point for L5 is more outward than the Magerl point, and the Trefoil spinal canal L5 is more outwardly oriented than the Round spinal canal L5, with a greater angle of abduction during pedicle screw placement.

Preoperative quantitative diffusion tensor imaging on the spinal nerve root is a predictor for the surgical outcome of lumbar disc herniation: a prospective study of 117 patients.

BACKGROUND: The diffusion tensor imaging (DTI) parameters (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) are commonly used to provide quantitative information on tissues. This study aimed to evaluate the predictive value of preoperative DTI of the spinal nerve roots in the surgical outcome of lumbar disc herniation (LDH). METHODS: A total of 117 LDH patients were included. According to the postoperative improvement rate, the patients were dichotomized into the unfavorable group (N.=35) and favorable group (N.=82). RESULTS: The favorable group had a younger age (P=0.005) and a shorter disease course (P<0.001) than the unfavorable group. The favorable group had higher affected side FA and ADC and lower healthy/affected FA and ADC ratio than the unfavorable group (all P<0.05). Logistic regression analysis showed that younger age, shorter disease course, higher affected side FA and ADC, lower healthy/affected FA and ADC ratio, and lower healthy side ADC were the independent factors associated with positive surgical outcome. ROC analysis showed that the affected side FA had an excellent predictive performance for the surgical outcome (AUC=0.900). The Healthy/affected FA ratio had a good predictive performance (AUC=0.846). The overall predictive accuracy ranged from 0.91 to 0.92. However, ADC had poor predictive performance (AUC ranged from 0.626 to 0.663). CONCLUSIONS: These results suggested the preoperative affected side FA value had an excellent predictive performance for the surgical outcome of LDH patients. The LDH patients with a higher preoperative affected side FA value were more likely to have a positive surgical outcome.

Effects of Pretreatment of the Dorsal Meningovertebral Ligaments on the Incidence of Intraoperative Cerebrospinal Fluid Leakage: A Comparative Study.

Cerebrospinal fluid leakage can lead to postoperative refractory headaches and meningitis. Dural injury is the main cause of postoperative cerebrospinal fluid leakage. Previously, we performed a comprehensive anatomic study on the dorsal meningovertebral ligaments in the lumbosacral regions and concluded that these ligaments are an anatomic factor leading to dural laceration. However, no clinical study has examined the relationship between dorsal meningovertebral ligaments and the incidence of intraoperative cerebrospinal fluid leakage. The goal of this study was to investigate the effect of prophylactic intraoperative pretreatment of the meningovertebral ligaments on the incidence of cerebrospinal fluid leakage during surgery. [Orthopedics. 2023;46(1):e66-e71.].

Comparison of region-of-interest delineation methods for diffusion tensor imaging in patients with cervical spondylotic radiculopathy.

BACKGROUND: Diffusion tensor imaging is a promising technique for determining the responsible lesion of cervical radiculopathy, but the selection and delineation of the region of interest (ROI) affect the results. This study explored the impact of different ROI sketching methods on the repeatability and consistency of DTI measurement values in patients with cervical spondylotic radiculopathy (CSR). METHODS: This retrospective study included CSR patients who underwent DTI imaging. The images were analyzed independently by two radiologists. Four delineation methods were used: freehand method, maximum roundness, quadrilateral method, and multi-point averaging method. They re-examined the images 6 weeks later. The intra-class correlation coefficient (ICC) was used to investigate the consistency between the two measurements and the reproducibility between two radiologists. RESULTS: Forty-two CSR patients were included in this study. The distribution of the compressed nerve roots was five C4, eight C5, sixteen C6, eleven C7, and two C8. No differences were found among the four methods in fractional anisotropy (FA) or apparent diffusion coefficient (ADC), irrespective of radiologists (all P>0.05). Similar results were observed between the first and second measurements (all P>0.05), but some significant differences were observed for radiologist 2 for the four-small rounds method (P=0.033). The freehand and single largest circle methods were the two methods with the highest ICC between the two measurements and the two radiologists (all ICC >0.90). CONCLUSION: The freehand and single largest circle methods were the most consistent methods for delineating DTI ROI in patients with CSR.

Surgical safe zones for oblique lumbar interbody fusion of L1-5: A cadaveric study.

To evaluate the operating range and morphology of the surgical safe zone for oblique lumbar interbody fusion (OLIF). Twenty embalmed full-torso cadaveric specimens were dissected. The oblique corridor and the distance between adjacent lumbar arteries were measured in a static state and with psoas major retraction. The morphology and size of the safe zone for OLIF and the location of the lumbar sympathetic trunk were also recorded. The oblique corridor of the L1-L5 segments was significantly greater in the retracted state than in the static state (p < 0.05). With psoas major retraction, the distances between adjacent lumbar arteries at L1-4 were significantly greater (p < 0.05) than those in the static state. The lumbar sympathetic trunk is just located in the safe zone and travels downward adjacent to the psoas major. The shape of the safe zone for OLIF was approximately an oblique upward parallelogram at L1/2 and L2/3, an isosceles trapezoid at L3/4, and an irregular quadrangle or triangle at L4/5. The safe zone for OLIF at L1/2, L2/3, and L3/4 was significantly larger during retraction than in the static state (p < 0.05). On the lateral side of the lumbar spine there is a natural surgical safe zone for OLIF, which can provide a sufficient operating space. The safe zone has a certain morphological pattern in L1-5 segments and psoas major retraction can significantly enlarge it.

Finite element analysis of the kinematic coupling effect of the joints around talus when Ponseti manipulation.

BACKGROUND: Little information was obtained from the published papers about the kinematic coupling effect between tarsal bones during Ponseti manipulation. The aim was to explore the kinematic coupling effect of the joints around talus, to investigate the kinematic rhythm and coupling relationship of tarsal joints; to clarify the pulling effect on medial ligament of the ankle during the process of Ponseti manipulation. METHODS: The model of foot and ankle was reconstructed from the Chinese digital human girl No.1 (CDH-G1) image database. Finite element analysis was applied to explore the kinematic coupling effect of the joints around talus. The distal tibia and fibula bone and the head of talus were fixed in all six degrees of freedom; outward pressure was added to the first metatarsal head to simulate the Ponseti manipulation. Kinematic coupling of each tarsal joint was investigated using the method of whole model splitting, and medial ligament pulling of the ankle was studied by designing the model of medial ligament deletion during the Ponseti manipulation. RESULTS: All the tarsal joints produced significant displacement in kinematic coupling effect, and the talus itself produced great displacement in the joint of ankle. Quantitative analysis revealed that the maximum displacement was found in the joints of talonavicular (12.01mm), cuneonavicular (10.50mm), calcaneocuboid (7.97mm), and subtalar(6.99mm).The kinematic coupling rhythm between talus and navicular, talus and calcaneus, calcaneus and cuboid, navicular and cuneiform 1 were 1:12, 1:7, 1:2 and 1:1.6. The results of ligaments pulling showed that the maximum displacement was presented in the ligaments of tibionavicular (mean 27.99mm), talonavicular (21.03mm), and calcaneonavicular (19.18 mm). CONCLUSIONS: All the tarsal joints around talus were involved in the process of Ponseti manipulation, and the strongest kinematic coupling effect was found in the joints of talonavicular, subtalar, calcaneocuboid, and cuneonavicular. The ligaments of tibionavicular, talonavicular, and calcaneonavicular were stretched greatly. It was suggested that the method of Ponseti management was a complex deformity correction processes involved all the tarsal joints. The present study contributed to better understanding the principle of Ponseti manipulation and the pathoanatomy of clubfoot. Also, the importance of cuneonavicular joint should be stressed in clinical practice.

Structure of Lumbar Intervertebral Foraminal Ligaments Based on 3-Dimensional Reconstruction Through Ultrathin Cryomilling of a Human Cadaver.

BACKGROUND: This study aimed to assess the feasibility of using the 3-dimensional (3-D) reconstruction technique based on ultrathin cryomilling to show the lumbar intervertebral foraminal ligaments in situ. METHODS: Cryomilling was performed on an embalmed human cadaver to acquire successive cross-sectional images. In each of the images, the boundaries of lumbar intervertebral foraminal ligaments and their adjacent structures were outlined, labeled, and reconstructed for 3-D modeling. The morphology, attachments, and spatial orientation of ligaments were described. RESULTS: A total of 9 ligaments in 10 lumbar intervertebral foramina (IVFs) were identified and reconstructed. These ligaments can be divided into 5 types. The IVFs were divided into 2 or 3 main portions by the first 4 types of ligaments (transforaminal ligaments, corporotransverse ligaments, "reticular" ligaments, and "Y-shaped" ligaments). The radiating ligaments (the fifth type of ligaments) attached to the surrounding structures of the IVF and were connected directly to the nerve root sleeves. Although there was no indication of neurovascular compromise in this normal specimen, these ligaments limit the space within the bony IVF such that under certain pathologic conditions (e.g., inflammation), their presence would make neurovascular compression more likely than if they were absent. CONCLUSIONS: The 3-D reconstruction technique based on ultrathin cryomilling can effectively show the lumbar intervertebral foraminal ligaments and their anatomical characteristics in situ, providing a new way to clarify the relationships between these ligaments and their adjacent structures.

Biomechanical study of the C5-C8 cervical extraforaminal ligaments.

BACKGROUND: The anatomical distribution of the extraforaminal ligaments in the cervical intervertebral foramina has been well studied. However, detailed descriptions of the biomechanical characteristics of these ligaments are lacking. METHODS: The paravertebral muscles were dissected, and the extraforaminal ligaments and nerve roots were identified. The C5 and C7 or C6 and C8 cervical nerve roots on both sides were randomly selected, and a window was opened on the vertebral lamina to expose the posterior spinal nerve root segments. Five needles were placed on the nerve root and the bone structure around the intervertebral foramen; the distal end of the nerve root was then tied with silk thread, and the weights were connected across the pulley. A weight load was gradually applied to the nerve root (50 g/time, 60 times in total). At the end of the experiment, segments of the extraforaminal ligaments were selectively cut off to compare the changes in nerve root displacement. RESULTS: The displacement of the C5, C6, C7, and C8 nerve roots increases with an increasing traction load, and the rate of change of nerve root displacement in the intervertebral foramen is smaller than that in the nerve root on the outside area (p < 0.05). Extraforaminal ligaments can absorb part of the pulling load of the nerve root; the C5 nerve root has the largest load range. CONCLUSIONS: Cervical extraforaminal ligaments can disperse the tension load on the nerve root and play a role in protecting the nerve root. The protective effect of the C5 nerve root was the strongest, and this may anatomically explain why the C5 nerve roots are less prone to simple avulsion.

Clinical Anatomy and Possible Clinical Significance of the Postcentral Branches of Spinal Arteries in the L1-L5 Levels.

STUDY DESIGN: This was a dissection-based study of 10 embalmed human cadavers. OBJECTIVE: The objective of this study was to identify and describe the postcentral branches in the L1-L5 intervertebral foramina (IVF) and to determine their possible clinical significance. SUMMARY OF BACKGROUND DATA: The lower lumbar segmental arteries have been well studied. However, there are few articles with regard to the postcentral branches in the L1-L5 IVF. MATERIALS AND METHODS: Eighty L1-L5 IVF from 10 embalmed cadavers were studied with a surgical microscope, and the postcentral branches were identified. The branches, origin, insertion, and spatial orientation of the postcentral branches in the L1-L5 IVF were examined. The diameter of the arteries was measured using a Vernier caliper. RESULTS: In our study, the occurrence rate of a postcentral branch was 100.00% in the 80 IVFs. The postcentral branch was routinely divided into the following 2 types: type 1, postcentral branch main trunks (65.00%), which branch from the spinal arteries or lumbar arteries and then divide into 2 branches (superior and inferior branches), and type 2, superior and inferior branches, which branch straight from the spinal arteries (35.00%). The initial portion of the postcentral branches traveled around the anterolateral edge of the disk to the dorsum. CONCLUSIONS: Postcentral branches of spinal arteries are common structures in IVF; there are 2 types of postcentral branches. Thorough understanding of the spinal arteries before percutaneous endoscopic lumbar discectomy may be an important step in reducing intraoperative bleeding and ensuring clear visualization, which may result in significant benefits for patients.

Anatomic morphology and clinical significance of intraforaminal ligaments of the cervical spine.

The cause of cervical spondylotic radiculopathy could be related to the intraforaminal ligaments (IFLs) of the cervical spine. The aim of this study is to identify and describe the IFLs and assess their clinical significance. Six intact cervical spine specimens from adult embalmed cadavers were dissected to expose the cervical nerve roots and their surrounding intraforaminal tissues fully. From the C1-C2 to the C7-T1 intervertebral foramina (IVF), the connective structures between each nerve root and its surrounding foraminal wall were examined under a surgical microscope. The morphology, number, and attachment points of the IFLs of each segment were documented, and the length, width, or diameter and thickness of the ligaments were measured with a vernier caliper. IFLs were observed in all 84 IVFs of the cervical spine. According to their locations, they can be divided into two categories: the first is entrance-zone IFLs, which are radially distributed around the nerve root; the second is mid-zone IFLs, which are thin, strip-shaped fibrous tissues intertwined around the nerve roots, the number of ligaments being considerable but difficult to quantify. Ligament structures have been identified in the IVF of the cervical spine. Under physiological conditions, they could be protective in maintaining the position, shape, and function of nerve roots. However, under pathological conditions, the IFLs of the cervical spine could aggravate the symptoms of cervical nerve root radicular pain associated with other types of compression. Clin. Anat. 32:654-660, 2019. © 2019 Wiley Periodicals, Inc.

The Morphology and Possible Clinical Significance of the Intraforaminal Ligaments in the Entrance Zones of the L1-L5 Levels.

BACKGROUND: The extraforaminal ligaments between the L1-L5 lumbar spinal nerves and the tissues surrounding the intervertebral foramina (IVF) have been well studied. However, little research has been performed to describe the local anatomy of the entrance zones at the L1-L5 level. Detailed anatomic studies of the intraforaminal ligaments (IFLs) in the entrance zones at the L1-L5 levels have not been performed. OBJECTIVES: The objective of this study is to identify and describe the IFLs in the entrance zones of the L1-L5 IVF and to determine their possible clinical significance. STUDY DESIGN: A dissection-based study of 10 fresh-frozen human cadavers. SETTING: Guangdong Provincial Key Laboratory of Medical Biomechanics in Anatomy Department of Southern Medical University. METHODS: Eighty L1-L5 IVF from 10 fresh cadavers were studied, and the IFLs in the entrance zones were identified. The quantities, morphologies, origins, insertions, and spatial orientations of the IFLs in the entrance zones of the L1-L5 IVF were observed. The lengths, widths, diameters, and thicknesses of the ligaments were measured using a vernier caliper. Ten intraforaminal radiating ligaments were removed for histological examination. RESULTS: A total of 197 ligaments were identified in the entrance zones of the 80 L1-L5 IVF, including 191 (96.95%) radiating ligaments and 6 (3.05%) transforaminal ligaments. The thickest ligaments were observed at the L3-L4 IVF. The lengths of the ligaments varied from 0.59 to 11.92 mm. There were 66 (33.50%) ligaments in the superior aspect of the entrance zone of the IVF, 58 (29.44%) ligaments at the anterior aspect, 43 (21.83%) ligaments at the posterior aspect, and 30 (15.23%) ligaments at the inferior aspect. The morphologies of the IFLs were divided into 2 types: the strap type and the trabs type. Histological examination of the meningovertebral ligaments revealed fibrous connective tissue. LIMITATIONS: The major limitation of this study is the lack of actual clinical data from live patients. In addition, future medical biomechanics experiments are expected to contribute more objective data on the strength of the IFLs. CONCLUSIONS: In the lumbar spine, IFLs are common structures in the entrance zones of the L1-L5 IVF, and radiating ligaments are more likely to be present. KEY WORDS: Clinical Anatomy, microdissection, intraforaminal ligament, the entrance zone, L1-L5 intervertebral foramen, endoscopic spinal adhesiolysis, sacral hiatus, cerebrospinal fluid leakage, dural laceration.

Controlled release of FGF-2 and BMP-2 in tissue engineered periosteum promotes bone repair in rats.

The aim of this study was to prepare chitosan-collagen (CS/COL) scaffolds that could release fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein 2 (BMP-2), and to study the effect of this scaffold on bone repair. By improving the double emulsion/solvent evaporation technique, BMP-2 was encapsulated in poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PELA) microcapsules, to the surface of which FGF-2 was attached. The CS/COL scaffold carrying the microcapsules was prepared by freeze-drying. Periosteum derived cells (PDCs) were extracted and cultured on the scaffolds to study their proliferation and differentiation on the scaffolds. In addition, the effects of the scaffolds were investigated on rats with skull defects by micro-computed tomography and histology. We successfully prepared PELA microcapsules with external adherence to FGF-2 and encapsulated with BMP-2. The CS/COL scaffolds were porous and PDCs adhered, proliferated and underwent osteogenic differentiation on the scaffolds. The sequential release of FGF-2/BMP-2 had better osteogenic efficacy than other groups. Our results suggest that CS/COL scaffolds that bind FGF-2 and BMP-2 in combination with PDCs could be a promising new strategy for tissue engineering periosteum.

Morphology and Possible Clinical Significance of the Radiating Extraforaminal Ligaments at the L1-L5 Levels.

STUDY DESIGN: A dissection-based study of 10 fresh-frozen human cadavers. OBJECTIVE: The objective of this study was to identify and describe the radiating extraforaminal ligaments in the exit regions of the L1-L5 intervertebral foramina and to research their possible clinical significance. SUMMARY OF BACKGROUND DATA: The transforaminal ligaments at the L1-L5 intervertebral foramina have been well studied. However, detailed descriptions of the radiating extraforaminal ligaments at L1-L5 are lacking. METHODS: Eighty L1-L5 intervertebral foramina from 10 fresh cadavers were studied, and the extraforaminal ligaments were identified. The quantity, morphology, origin, insertion, and spatial orientation of the extraforaminal ligaments in the L1-L5 regions were examined. The length, width, diameter, and thickness of the ligaments were measured using a vernier caliper. RESULTS: A total of 224 extraforaminal ligaments were identified in the 80 L1-L5 intervertebral foramina, and the occurrence rate of extraforaminal ligaments was 100%. One hundred and eighteen (52.68%) of the extraforaminal ligaments were radiating ligaments, and 106 (47.32%) of the extraforaminal ligaments were transforaminal ligaments. There were 97 (43.30%) ligaments at the superior aspect of the exit regions of the intervertebral foramina, 51 (22.77%) ligaments at the anterior aspect, 44 (19.64%) ligaments at the inferior aspect, and 32 (14.29%) ligaments at the posterior aspect. The morphologies of the extraforaminal ligaments were divided into two types: the strap type and the trabs type. CONCLUSION: Radiating extraforaminal ligaments exist between spinal nerves and nearby structures. Radiating extraforaminal ligaments may be of clinical importance to surgeons. Dissecting the radiating extraforaminal ligaments before percutaneous endoscopic lumbar discectomy may be an important step in reducing postoperative pain, which may result in significant benefits for patients. LEVEL OF EVIDENCE: 3.

A controlled study on the anatomy of cervical extraforaminal ligaments and three-dimensional fast-imaging employing a steady-state acquisition sequence.

PURPOSE: To evaluate the utility of magnetic resonance three-dimensional fast-imaging employing a steady-state acquisition (MR 3D-FIESTA) sequence to study cervical EFLs using the anatomical results of cadavers as the gold standard. METHODS: Part I: The cervical regions of five embalmed adult cadavers were scanned using the MR 3D-FIESTA sequence. Ligamentous structures in the intervertebral foramina (IVFs) between C4 and T1 in the MRI scans were identified by a radiologist. Part II: After the specimens were scanned, gross and microscopic anatomical studies were conducted on the IVFs between C4 and T1 in the specimens by an anatomist. Part III: Using the anatomical results of the cadavers as the gold standard, the utility of the MR 3D-FIESTA sequence for imaging cervical EFLs was evaluated. Specificity, sensitivity, positive and negative predictive values (PPV and NPV, respectively) and accuracy were calculated. RESULTS: The occurrence rate of transforaminal ligaments (TFLs) in the IVFs between C4 and T1 was 42.5%. The results obtained by the radiologist using the MR 3D-FIESTA sequence to identify TFLs are as follows: specificity 96.2%, sensitivity 76.5%, PPV 92.9%, NPV 86.2%, and accuracy 88.4%. CONCLUSION: MR 3D-FIESTA sequences clearly showed cervical EFLs. In the 3D-FIESTA sequence scans that the radiologist believed to indicate the presence of a cervical TFL, the probability that the TFL existed was approximately 93%. When the radiologist believed that no TFL was present in the 3D-FIESTA sequence scan, the probability that a TFL existed was 14%.

The morphology and clinical significance of the intraforaminal ligaments at the L5-S1 levels.

BACKGROUND CONTEXT: The extraforaminal ligaments between the L5 and S1 lumbar spinal nerves and the tissues surrounding the intervertebral foramina have been well studied. However, little research has been undertaken to describe the local anatomy of the intraforaminal portion of the L5-S1 spine and detailed anatomical studies of the intraforaminal ligaments (IFLs) of the L5-S1 have not been performed. PURPOSE: The objective of this study was to identify and describe the IFLs in relation to the L5-S1 intervertebral foramen (IVF) and to determine their clinical significance. STUDY DESIGN: A dissection-based study of five embalmed and five fresh-frozen human cadavers was carried out. METHODS: Twenty L5-S1 intervertebral foramina from five embalmed cadavers and five fresh cadavers were studied, and the IFLs were identified. The quantity, morphology, origin, insertion, and spatial orientation of the IFLs in the L5-S1 region were observed. The length, width, diameter, and thickness of the ligaments were measured with a vernier caliper. This study has been supported by grants from the National Natural Science Foundation of China (Grant No. 31271286) without potential conflict of interest-associated biases in the text of the paper. RESULTS: The IFLs could be found from the entrance zone (inside) to the exit zone (outside) of the L5-S1 IVF. These ligaments were found to be of two types: a radiating ligament, which connected the nerve root sleeves that radiated to the transverse processes and wall of the IVF, and a transforaminal ligament, which connected the structures around the IVF. In our study, the radiating ligaments were found more often than the transforaminal ligaments. CONCLUSIONS: The results demonstrate that IFLs are common structures in the IVF and that there are two types of IFLs: the transforaminal ligaments and the radiating ligaments. Transforaminal ligaments may be the potential cause of back pain. The radiating ligaments may contribute to dura laceration and epidural hemorrhage during endoscopic spinal adhesiolysis through the sacral hiatus, and an appreciation of this relationship might help reduce the risk of such complications.

An anatomical study of lumbar epidural catheterization.

BACKGROUND: We herein provide an analysis of lumbar epidural catheterization, which outlines a detailed anatomical description of the epidural anatomy, and may improve the success rate of neuraxial cannulation. METHODS: Lumbar epidural catheters were placed in 50 adult embalmed cadavers. After catheterization, the lumbar dura and connecting structures between the epidural space and the vertebral body were separated. The positional relationship between the catheter and the posterior epidural space were observed and photographed. RESULTS: Amongst the 50 specimens, the epidural catheter curled into a circle in three cases, entered the intervertebral foramen in two cases, and caused epidural venous damage in five cases. CONCLUSIONS: Meningo-vertebral ligaments exist in the posterior epidural space and connect to the venous plexus, which may contribute to epidural catheter failure, uneven distribution of anaesthesia and epidural hemorrhage. Our study provides anaesthesiologists with a better understanding of the anatomy and may mitigate complications of lumbar epidural catheter placement.

Anatomic study and clinical significance of the dorsal meningovertebral ligaments of the thoracic dura mater.

STUDY DESIGN: A dissection-based study of 18 embalmed thoracic specimens. OBJECTIVE: To investigate the properties and clinical significance of the dorsal meningovertebral ligaments of the thoracic dura mater. SUMMARY OF BACKGROUND DATA: Previously, we performed a comprehensive anatomic study on the dorsal meningovertebral ligaments in the lumbosacral and cervical regions, whereby we concluded that the ligaments were an anatomic factor leading to dural laceration and hemorrhage during flavectomy and laminectomy. Unfortunately, thus far, no systematic anatomic study has been undertaken to examine the dorsal meningovertebral ligaments of the thoracic dura mater. METHODS: Eighteen adult embalmed cadavers were studied, and the morphology, orientation, attachment site, and distribution traits of the dorsal meningovertebal ligaments were observed. In addition, the length, width, or diameter and thickness of the ligaments were measured using a Vernier caliper. Two meningovertebal ligaments were removed for histological examination. RESULTS: In the thoracic region, the dorsal meningovertebral ligaments anchored the dura mater to the lamina or ligamentum flavum. The meningovertebral ligaments displayed a relatively even distribution along the upper thoracic region (T1-T7) and a gradual increase in frequency in the lower thoracic region from T7 to T12. The meningovertebral ligaments protrude into the dura and correspondingly become an integral part of the dura. Some ligaments are accompanied by or are attached to blood vessels. Histological examination of the meningovertebral ligaments revealed fibrous connective tissue. CONCLUSION: The dorsal meningovertebral ligaments exist between the dural sac and ligamentum flavum or lamina in the thoracic spine. Based on their anatomic features, meningovertebral ligaments may be one potential cause for dural laceration and epidural hemorrhage. We propose that, during thoracic flavectomy and laminectomy, the meningovertebral ligaments should first be identified and properly handled, thereby minimizing the occurrence of relevant complications. LEVEL OF EVIDENCE: N/A.

The morphology and clinical significance of the extraforaminal ligaments at the cervical level.

STUDY DESIGN: A dissection-based study of 6 embalmed cadavers. OBJECTIVE: To identify and describe the extraforaminal ligaments (EFLs) in relation to the area of the cervical intervertebral foramina and to evaluate their clinical significance. SUMMARY OF BACKGROUND DATA: EFLs between the lumbar spinal nerves and the tissues surrounding the intervertebral foramens have been well established. However, research work has been undertaken to describe the local anatomy of the extraforaminal part of the cervical spine; detailed anatomic studies of the EFLs of cervical nerves have not been performed. METHODS: One hundred ninety-six cervical intervertebral foramina from 6 adult embalmed cadavers were studied, and the existence and type of the EFLs were identified. The morphology, quantity, origin, insertion, and the spatial orientation of the EFLs in the cervical region were observed, and the length, width, or diameter and thickness of the ligaments were measured with a vernier caliper. RESULTS: The EFLs could be found from the second cervical to the first thoracic spinal nerve. These ligaments could be divided into 2 types: radiating ligaments, which connected the nerve root sleeves that radiated to the transverse processes, the wall of the intervertebral foramina, and even the adjacent nerve root through the small transverse foramen; transforaminal ligaments, which originated from the anteroinferior margin of cranial transverse process and inserts in the superior margin of the anterior tubercle of caudal transverse process crossing the spinal nerve ventrally. CONCLUSION: Between the cervical spinal nerves and nearby structures, there are 2 types of the EFLs. The radiating ligaments may serve as a protective mechanism against traction and play an important role in the positioning of the nerves in the intervertebral foramen. However, in all probability, the transforaminal ligaments may be the underlying cause of the cervical radiculopathy.

The morphology and clinical significance of the dorsal meningovertebra ligaments in the cervical epidural space.

BACKGROUND CONTEXT: The dural sac is anchored within the vertebral canal by connective tissue called meningovertebral ligaments in the epidural space. During flavectomy and laminectomy, inadvertent disruption of the dorsal meningovertebral ligaments may lead to dura laceration and cerebrospinal fluid (CSF) leaks. All the described dorsal meningovertebral ligaments were located in the lumbar region. A rare study is available about dorsal meningovertebral ligaments of the cervical spinal dura to the adjacent vertebrae. PURPOSE: To identify and describe the dorsal meningovertebral ligaments at each cervical level and discuss their clinical significance. STUDY DESIGN: A dissection-based study of 22 embalmed cadavers. METHODS: The anatomy was studied in 22 whole cervical cadavers (11 females, 11 males), prepared with formaldehyde, whose ages at the time of death ranged from 55 to 78 years. The vertebral canal was divided to expose the dural sac and the spinal nerve roots. At all levels of the cervical vertebra, the morphology, quantity, origin, insertion, and spatial orientation of the dorsal meningovertebral ligaments were determined and the length, width or diameter, and thickness of the ligaments were measured with vernier calipers. RESULTS: The dorsal meningovertebral ligaments in the cervical region anchored the posterior dural sac to the ligamentum flavum or laminae. The number of attachment points on the ligamentum flavum was relatively larger than that on the lamina, and the occurrence rate of dorsal meningovertebral ligaments was 100% at C1-C2 and C4--C5. The thickest ligaments were observed at the C1 and C2 vertebrae. The length of the ligaments varied from 1.50 to 35.22 mm, and the orientation of the ligaments mostly was craniocaudal. The morphology of the dorsal meningovertebral ligaments was divided into four types: strip type, cord type, grid type, and thin slice type. CONCLUSIONS: In the cervical spine, the dorsal meningovertebral ligaments exist between the posterior dural sac and the ligamentum flavum or lamina. The dorsal meningovertebral ligaments may be of clinical importance to surgeons. Dissecting the dorsal meningovertebral ligaments before the cervical flavectomy and laminectomy may be an important step in reducing postoperative dura laceration and CSF leaks, which may result in significant benefits for patients and health-care organizations.