Mean Canal-body Ratio among Specimens of Dried Lumbar Vertebrae in the Department of Anatomy of a Medical College: A Descriptive Cross-sectional Study.

Introduction: Lumbar spinal canal stenosis is assumed to be one of the chief causative factors for low back pain. The measurement of lumbar canal and body dimensions has thus become an important tool for the diagnosis and treatment of spinal stenosis. This study aims to find out the mean canal-body ratio among specimens of dried lumbar vertebrae in a medical college. Methods: A descriptive cross-sectional study was done in a medical college from May, 2021 to July, 2021. Ethical clearance was taken from the Institutional Review Committee (Reference number: 0502202103) and whole sampling was done. Seventy-three intact dried lumbar vertebrae were studied for the dimensions of the body and canal in transverse and anteroposterior planes. The findings were recorded and the canal body ratio was calculated using the transverse diameters of the spinal canal and vertebral body. The data obtained were computed and analysed using Microsoft Excel 2013. Point estimate at 95% Confidence Interval was calculated along with mean and standard deviation for continuous data. Results: The mean canal-body ratio was observed to be 0.53±0.032. The vertebral canal-body ratio was observed to be 0.58 in L1 followed by 0.53 in L2, 0.51 in L3, 0.49 in L4 and 0.53 in L5. Conclusions: The mean canal-body ratio observed in the present study was comparable to studies done in similar settings. Keywords: anatomy; bones; lumbar vertebrae.

Pavlov's Ratio of the Cervical Spine in a Korean Population: A Comparative Study by Age in Patients with Minor Trauma without Neurologic Symptoms.

BACKGROUD: There are many studies on the vertebral body-to-canal ratio, the so-called Pavlov's ratio of the cervical spine. However, there are no studies on its relation with age to clarify each bony component's contribution to the spinal canal formation and its size. The aim of this study was to investigate differences and changes in the vertebral body-to-canal ratio according to age in an asymptomatic population. METHODS: This is a cross-sectional study of 280 asymptomatic individuals. A total of 140 men and 140 women representing each decade of life from the first to the seventh were included in this study. The anteroposterior length of the vertebral body and canal from C3 to C6 was measured on sagittal radiographs to calculate the vertebral body-to-canal ratio. RESULTS: The average Pavlov's ratio was significantly larger (p < 0.001) in the first decade of life. The average Pavlov's ratio of the individuals in the first decade of life was 1.09 between C3 and C6 (1.08 at C3, 1.07 at C4, 1.11 at C5, and 1.13 at C6; range, 0.78-1.51). There was no significant difference among the other decades of life. CONCLUSIONS: We assessed the Pavlov's ratio of the cervical spine in an asymptomatic population. It is our belief that the spinal canal size is the largest in the first decade of life, and the Pavlov's ratio becomes almost fixed throughout life after maturity.

Intradural Neuroanatomy in the Cervical Spinal Canal: Importance of a New Anatomic Zone Division and Accurate Assessment of Neural Compression in Myeloradiculopathy Patients.

MINI: This study defined different anatomic zones within the cervical spinal canal and provides detailed anatomical quantitative data for an accurate diagnosis of cervical spondylosis and a safe and effective anterior decompression surgery.

A dissection-based study of 10 embalmed human cadavers. To provide an anatomic basis to examine the underlying mechanisms of cervical spondylosis. Detailed anatomical quantitative data of cervical spine is limited in current literature. Ten cervical spines from C2 to T1 were obtained. We defined three zones from midline to lateral part (zone I, II, and III) and two zones from cranial to caudal (zone P and zone IP) on the coronal plane within the cervical spinal canal. Quantitative anatomy of the zones at different cervical segments were measured including: (1) horizontal widths of zone I, II, and III; (2) length of the cervical spinal cord segment at the ventral rootlets (LV); (3) the pedicle height (PH, zone P) and the inter-pedicle height (IPH, zone IP); (4) the distance between the superior margin of pedicle and the exit of the uppermost ventral nerve rootlet (PN). The value of zone II at C4 was significantly less than that at other levels. The value of zone III increases from C4 to C8, and the values at C7 and C8 were significantly higher than those at C4, C5, and C6. PHs and IPHs were not significantly different between different levels. The values of LV at C4 and C8 were smaller than those of C5, C6, and C7. The value of PN showed an increasing trend. At C4, the uppermost ventral rootlet was at about the same height as C3 pedicle, while C8 uppermost ventral rootlet was at the same level as the inferior part of C6 pedicle. Ventral intradural intersegmental connections were found in three intersegments out of 20 intersegments. The current definition of anatomic zones may be useful for an accurate diagnosis of cervical spondylosis and a safe and effective anterior decompression surgery. Level of Evidence: N/A.

Comparison of the anatomical morphology of cervical vertebrae between humans and macaques: related to a spinal cord injury model.

Non-human primates are most suitable for generating cervical experimental models, and it is necessary to study the anatomy of the cervical spine in non-human primates when generating the models. The purpose of this study was to provide the anatomical parameters of the cervical spine and spinal cord in long-tailed macaques (Macaca fascicularis) as a basis for cervical spine-related experimental studies. Cervical spine specimens from 8 male adult subjects were scanned by micro-computed tomography, and an additional 10 live male subjects were scanned by magnetic resonance imaging. The measurements and parameters from them were compared to those of 12 male adult human subjects. Additionally, 10 live male subjects were scanned by magnetic resonance imaging, and the width and depth of the spinal cord and spinal canal and the thickness of the anterior and posterior cerebrospinal fluid were measured and compared to the relevant parameters of 10 male adult human subjects. The tendency of cervical parameters to change with segmental changes was similar between species. The vertebral body, spinal canal, and spinal cord were significantly flatter in the human subjects than in the long-tailed macaques. The cerebrospinal fluid space in the long-tailed macaques was smaller than that in the human subjects. The anatomical features of the cervical vertebrae of long-tailed macaques provide a reference for establishing a preclinical model of cervical spinal cord injury.

Morphometric study of foramina transversaria in Jordanian population using cross-sectional computed tomography.

Foramina transversaria are bilateral landmarks of human cervical vertebrae. Morphometric analysis of foramina transversaria is valuable in both clinical and academic fields. This study aims to build a novel normative database of the dimensions of foramina transversaria in Jordanian population and to correlate these data with gender and age. For this purpose, axial computer tomographic images of cervical vertebrae of 329 normal individuals were obtained from the Radiology Department at King Abdulla University Hospital. Cases were subdivided into adolescence, youth, and adulthood groups for both genders. Antero-posterior and transverse diameters were measured bilaterally at all cervical vertebral levels. Statistical analysis of measured dimensions was performed using Statistical Package of Social Sciences software. The results showed that the overall mean antero-posterior diameter of foramina transversaria was 6.09 ± 0.60mms and 5.94 ± 0.62mms on the left and on the right sides, respectively. The corresponding mean transverse diameter measured 4.76 ± 0.51mms and 4.62 ± 0.52mms on the left and the right sides, respectively. Foramina transversaria were significantly larger in males compared to females (p = 0.00). Age-related differences were statistically significant for both antero-posterior and transverse diameters in favor of adult age-group, irrespective of vertebral level. The relevance of these findings is discussed.

Imaging anatomy of the vertebral canal for trans-sacral hiatus puncture of the lumbar cistern.

A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal computed tomography-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M = 25:15, with a mean age of 44.9 years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7 mm. Using two-way analysis of variance, there were significant sex differences for needle distances (p = .001), and full and limited sacral curvatures (p = .02, and p = .046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle.

Generational Changes in Lumbar Spinal Canal Dimensions: Findings from a Sample U.S. Population.

OBJECTIVE: Evaluation of lumbar canal dimensions in a Chicago population born in 2 different decades. METHODS: This is a retrospective chart review analyzing computed tomography reconstruction from patients born between 1940 and 1949 (older group) and 1970 and 1979 (younger group). The cross-sectional area (CSA) and anterior-posterior diameter (APD) of the lumbar bony canal was measured at each lumbar level at the level of the pedicle. RESULTS: Our study includes 918 patients, 372 in the young group and 546 in the older group. Older patients have significantly larger CSA and APD at all lumbar levels compared with younger patients. Further, CSA and APD comparisons between ethnicities demonstrate significant differences between individuals of Caucasian, Asian, Hispanic, African American, and Other ethnicities. Lastly, there were no differences in CSA or APD compared with factors known to affect bone health (smoking, steroid use, osteoporosis, cancer history). CONCLUSIONS: As seen in European cohorts, our data suggest that patients born in the 1940s have both larger canal area and larger anterior-posterior diameter compared with the younger generation. These data suggest that significant differences exist between ethnicities. These differences highlight the importance of studying normal anatomical dimensions within different geographical populations and the importance of studying non-modifiable factors as they relate to spinal dimensions and spine patients. Furthermore, spinal canal growth seems to be negatively influenced in younger generations, a rather unexpected but worrying finding.

The Relationship Between Transpedicular Stabilization with Spinal Canal Type.

AIM: To analyze the spinal canal type and spinal structure of patients, to determine appropriate preoperative preparation and surgical procedures to prevent material malposition, which is the most common complication of thoracolumbar posterior transpedicular stabilization (TPTS) and is a determiner of its clinical outcomes. MATERIAL AND METHODS: A total of 214 cases were examined. TPTS procedures carried out on each thoracolumbar spine were evaluated. Twenty parameters were documented and retrospectively examined in each patient. RESULTS: Laminectomy is not helpful for healing unless there is spinal compression and ligamentotaxis is beneficial for healing. The correlation between the structure of the spinal canal and defective screw delivery found (p < 0.05). CONCLUSION: The spinal structure formed around the canal should be the first form to evaluate while TPTS applications to protect the spinal cord, which is the focal point of the spinal structure.

Intraforaminal Dural Septations of the Jugular Foramen: A Cadaveric Study.

OBJECTIVE: The aim of this study was to define the types, prevalences, and diameters of dural septations (DSs) on the inner surface of the jugular foramen (JF) and to describe the distances between the JF, the glossopharyngeal nerve (cranial nerve [CN] IX), vagus nerve (CN X), and accessory nerve (CN XI), the internal acoustic meatus, and nearby surgical landmarks on cadaveric heads. METHODS: Seventeen adult (9 men and 8 women) formalin-fixed cadaveric heads were used to analyze the types and prevalence of DS bilaterally. Diameters and distances between the DS and the adjacent CNs (CN IX-XI) were measured by digital microcaliper. The multiple t test (SPSS version 25) was used to analyze the comparison between both sides via diameters, numbers, distance, length, and thickness of DS. RESULTS: The most frequent type of DS was type I (62.5%, right; 56.3%, left), followed by type II (18.8%, right; 25%, left), type III (12.5%, right; 6.3%, left), and type IV (6.3%, right; 12.5%, left). The mean diameter of the septum was 0.6-1 mm, and the mean length of the dural septa was 4.01 mm (right) and (3.83 mm) left. The difference in the length and thickness of the DS between the genders was statistically significant on both sides (P < 0.05). The DS-CN X and DS-JF distances of women were greater than those of men on the right side (P < 0.05). CONCLUSIONS: The significant differences between dural septum types on the 2 sides of the body may indicate asymmetric location or a variant emerging site of CNs in the same individual.

Can a relatively large spinal cord for the dural sac influence severity of paralysis in elderly patients with cervical spinal cord injury caused by minor trauma?

Retrospective reviewThe degree of spinal cord compression and bony spinal canal stenosis are risk factors for the occurrence of spinal cord injury (SCI) without major fracture or dislocation, but they do not affect the severity of neurological symptoms. However, whether a relatively large spinal cord for the dural sac influences the severity of symptoms in SCI cases is unknown.The purpose of this study was to verify the influence of spinal cord size relative to dural sac on the severity of paralysis in elderly patients with cervical SCI caused by minor trauma.Subjects were 50 elderly patients with SCI caused by falls on flat ground. At 72 hours after injury, neurological assessment was performed using the Japanese Orthopaedic Association (JOA) scoring system. Bony canal anteroposterior diameters (APD) at mid C5 vertebral body were measured with computed tomography. We measured dural sac and spinal cord APD at the injured level and mid C5 with magnetic resonance imaging. Spinal cord compression ratio was calculated by dividing spinal cord at the injured level by spinal cord at mid C5. As the evaluation of spinal cord size relative to the dural sac, spinal cord/dural sac ratio was calculated at the injured level and mid C5. To clarify the factors influencing the severity of paralysis, the relationships between JOA score and those parameters were examined statistically.A significant negative correlation was observed between JOA score and spinal cord/dural sac ratio at mid C5. No clear relationship was observed between JOA score and bony canal APD or spinal cord compression ratio.In elderly patients with SCI caused by minor trauma, a relatively large spinal cord for the dural sac was shown to be a factor that influences the severity of paralysis. This result can be useful for the treatment and prevention of SCI in the elderly.

The retrodural space of Okada and its relevance to CT guided intervention.

The spinal epidural and posterior ligamentous complex spaces are important anatomic regions which are the target of various radiologic procedures in the cervical, thoracic and lumbar spine for the purpose of analgesia and anaesthesia. Given the frequency with which procedures are performed in and around the epidural space, a sound understanding of the associated anatomy is paramount to ensure the safety and efficacy of procedural intervention.

Cervical Canal Morphology: Effects of Neck Flexion in Normal Condition: New Elements for Biomechanical Simulations and Surgical Management.

STUDY DESIGN: Continuous measurements and computation of absolute metrics of cervical subarachnoid space (CSS) and spinal cord (SC) geometries proposed are based on in vivo magnetic resonance imaging and 3D reconstruction. OBJECTIVE: The aim of the study is to offer a new methodology to continuously characterize and to quantify the detailed morphology of the CSS and the cervical SC in 3D for healthy subjects in both neutral supine and flexion. SUMMARY OF BACKGROUND DATA: To the best of our knowledge, no study provides a morphological quantification by absolute indices based on the 3D reconstruction of SC and CSS thanks to in vivo magnetic resonance imaging. Moreover, no study provides a continuous description of the geometries. METHODS: Absolute indices of SC (cross-sectional area, compression ratio, position in the canal, length) and of CSS (cross-sectional area, occupational ratio, lengths) were computed by measures from 3D semi-automatic reconstructions of high resolution in vivo magnetic resonance images (3D T2-SPACE sequence) on healthy subjects (N = 11) for two postures: supine neutral and flexion neck positions. The variability induced by the semi-automatic reconstruction and by the landmarks positioning were investigated by preliminary sensitivity analyses. Inter and intra-variability were also quantified on a randomly chosen part of our population (N = 5). RESULTS: The length and cross-sectional area of SC are significantly different (P < 0.05) in flexion compared with neutral neck position. Spinal cord stays centered in the canal for both postures. However, the cross-sectional area of CSS is submitted to low variation after C3 vertebra for both postures. Occupational ratio (OR) and compression ratio (CR) after C3 are significantly lower in flexion. CONCLUSION: This study presented interpretations of morphological measures: (1) left-right stability (described by the Left-Right eccentricity index) ensured by the denticulate ligaments and the nerve roots attached to the dural sheaths, (2) a Poisson effect of the SC was partially notified through its axial (antero-posterior [AP] diameter, OR, CR) and its longitudinal geometrical descriptions (length of spinal cord [LSC]). Such morphological data can be useful for geometrical finite element modeling and could now be used to compare with injured or symptomatic subjects. LEVEL OF EVIDENCE: 3.

Development and evolution of the tetrapod skull-neck boundary.

The origin and evolution of the vertebrate skull have been topics of intense study for more than two centuries. Whereas early theories of skull origin, such as the influential vertebral theory, have been largely refuted with respect to the anterior (pre-otic) region of the skull, the posterior (post-otic) region is known to be derived from the anteriormost paraxial segments, i.e. the somites. Here we review the morphology and development of the occiput in both living and extinct tetrapods, taking into account revised knowledge of skull development by augmenting historical accounts with recent data. When occipital composition is evaluated relative to its position along the neural axis, and specifically to the hypoglossal nerve complex, much of the apparent interspecific variation in the location of the skull-neck boundary stabilizes in a phylogenetically informative way. Based on this criterion, three distinct conditions are identified in (i) frogs, (ii) salamanders and caecilians, and (iii) amniotes. The position of the posteriormost occipital segment relative to the hypoglossal nerve is key to understanding the evolution of the posterior limit of the skull. By using cranial foramina as osteological proxies of the hypoglossal nerve, a survey of fossil taxa reveals the amniote condition to be present at the base of Tetrapoda. This result challenges traditional theories of cranial evolution, which posit translocation of the occiput to a more posterior location in amniotes relative to lissamphibians (frogs, salamanders, caecilians), and instead supports the largely overlooked hypothesis that the reduced occiput in lissamphibians is secondarily derived. Recent advances in our understanding of the genetic basis of axial patterning and its regulation in amniotes support the hypothesis that the lissamphibian occipital form may have arisen as the product of a homeotic shift in segment fate from an amniote-like condition.

Projection of the Most Anterior Line of the Spinal Canal on Lateral Radiograph: An Anatomic Study for Percutaneous Kyphoplasty and Percutaneous Vertebroplasty.

ABSTRACTPurpose: To measure the projection of the most anterior line of the spinal canal on lateral radiographs of the vertebra (C3-L5) and evaluate the efficacy of the safety line (SL) in preventing intraspinal cement leakage in percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). Materials and Methods: Fifteen adult dry-bone spine specimens were analyzed. The projection of the SL was viewed on lateral radiographs. The distance between the SL and the posterior vertebral body line (PVBL) was measured. Two groups of patients were treated by PKP, and cement injection was stopped either before the PBVL (group 1) or before the SL (group 2) under lateral fluoroscopy. The rate of cement leakage was compared between the two groups. Results: The largest distance between the SL and PVBL was at L1 (5.22 ± 0.62 mm). From L1 to L5, the distance decreased progressively to 1.05 ± 0.64 mm. Similar variation was also observed from L1 to T1 (0.19 ± 0.18 mm). The postoperative computed tomography scan was more sensitive and accurate in detecting intraspinal leakage than radiography in group 1 (p = 0.000); however, there was no significant difference in sensitivity or accuracy between methods in group 2 (p = 0.063). The rate of intraspinal cement leakage was significantly higher in group 1 than group 2 (p = 0.000). Conclusions: The operator should frequently check to ensure that cement injection has stopped upon reaching the SL. Surgeons may benefit from this quantitative anatomical study of PKP and PVP.

Intraspinal characteristics of thoracic spinal nerve roots anomalies.

Purpose: The anomalous anatomical arrangement of the thoracic spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. The aim of this work was to reveal intraspinal anatomical variations of the thoracic spinal nerve roots.Methods: Anatomical study on 43 cadavers with a mean age of 53.7. After opening the spinal canal and dural sac, intradural and extradural anomalies of the thoracic spinal nerve roots were documented. Extradural communicating branches were excised, histologically processed and examined for the presence of nervous tissue.Results: We found 14 cases (32.6%) of intraspinal thoracic nerve root variations: intradural in 8 cases (18.6%), intradural communicating branches in 3 cases (6.97%), extradural anatomical variations occurred 6 cases (13.95%), 2 cases (4.65%) had extradural communicating branches between the nerve roots, 1 case had simultaneous occurrence of intradural and extradural communications (0.23%). All the results are differentiated according to the plexus type. In macroscopic extradural thoracic communicating branch had no nervous tissue on microscopy.Conclusions: This study describes intraspinal anatomical variations of thoracic spinal nerve roots. Knowledge of these variables should help prevent the failure of several medical procedures.

Current occurence of intraspinal intradural and extradural communicating branches in the spinal canal.

THE AIM of this work is to point out the intraspinal anatomical current occurrence interconnections between intradural and extradural nerve roots and their possible participation in radiculopathy. METHODS: The anatomical study was performed in 43 cadavers with a mean age of 53.7. All intradural and extradural rami communicantes between nerve roots were excised and examined histologically for the presence or absence of nervous tissue. RESULTS: Anatomical preparations revealed intradural and extradural rami communicantes in 9 cases (20.9 %), mostly in the cervical region in 5 cases and by plexus formation variations in 5 cases. Multiple extradural rami communicantes were observed in 6 cases (13.95 %), including the simultaneous occurrence of multiple intradural and extradural ones in 5 cases (11.6 %). CONCLUSIONS: This study allowed us to identify and describe unpublished intraspinal current occurrence intradural-extradural rami communicantes of nerve roots and their interrelationships throughout the spinal canal with their potential influence on the clinical picture (Tab. 1, Fig. 4, Ref. 25).

Reference values for the cervical spinal canal and the vertebral bodies by MRI in a general population.

PURPOSE: To provide population-based reference values for cervical spinal canal parameters and vertebral body (VB) width and to study their associations with sex, age, body height, body weight and body mass index (BMI) using MRI. METHODS: Cross-sectional analyses included data from 2,453 participants, aged 21-89 years, of the population-based Study of Health in Pomerania (SHIP) who underwent whole-body MRI at 1.5 Tesla between July 2008 and March 2011. A standardised reading was performed for the C2-C7 cervical spine levels at sagittal T2 TSE weighted sequences. RESULTS: Reference intervals for spinal canal parameters were similar in males and females, while VB width was on average 2.1-2.2 mm larger in males. Age effects were only substantial regarding VB width with a 0.5 mm per ten-year age increase. Body height effects were only substantial regarding the osseous spinal canal and VB width. Body weight and BMI effects are mostly not substantial. CONCLUSIONS: Our study provides MRI-based reference values for the cervical spinal canal parameters in an adult Caucasian population. Except for VB width, associations with sex, age and somatometric measures are mostly small and thus have only limited clinical implications. Some available cut-off values may need a revision because they likely overestimate risks.

Quantitative Analysis of Spinal Canal Areas in the Lumbar Spine: An Imaging Informatics and Machine Learning Study.

BACKGROUND AND PURPOSE: Quantitative imaging biomarkers have not been established for the diagnosis of spinal canal stenosis. This work aimed to lay the groundwork to establish such biomarkers by leveraging the developments in machine learning and medical imaging informatics. MATERIALS AND METHODS: Machine learning algorithms were trained to segment lumbar spinal canal areas on axial views and intervertebral discs on sagittal views of lumbar MRIs. These were used to measure spinal canal areas at each lumbar level (L1 through L5). Machine-generated delineations were compared with 2 sets of human-generated delineations to validate the proposed techniques. Then, we use these machine learning methods to delineate and measure lumbar spinal canal areas in a normative cohort and to analyze their variation with respect to age, sex, and height using a variable-intercept mixed model. RESULTS: We established that machine-generated delineations are comparable with human-generated segmentations. Spinal canal areas as measured by machine are statistically significantly correlated with height (P < .05) but not with age or sex. CONCLUSIONS: Our machine learning methodology demonstrates that this important anatomic structure can be accurately detected and quantitatively measured without human input in a manner comparable with that of human raters. Anatomic deviations measured against the normative model established here could be used to flag spinal stenosis in the future.

Three-Dimensional Computed Tomography Analysis of Spinal Canal Length Increase After Surgery for Adolescent Idiopathic Scoliosis: A Multicenter Study.

BACKGROUND: The most severe complication after surgery for adolescent idiopathic scoliosis is spinal cord injury. There is a relationship between corrective surgery and subsequent elongation of the spinal canal. We sought to investigate which factors are involved in this phenomenon. METHODS: Seventy-seven patients with adolescent idiopathic scoliosis (49 with Lenke type 1 and 28 with type 2) who underwent spinal correction surgery were included. The mean patient age at surgery was 14.2 years (range, 11 to 20 years). The spines of all patients were fused within the range of T2 to L2, and computed tomography (CT) data were retrospectively collected. We measured the preoperative and postoperative lengths of the spinal canal from T2 to L2 using 3-dimensional (3D) CT-based imaging software. We also examined the association between the change in T2-L2 spinal canal length and the radiographic parameters. RESULTS: The length of the spinal canal from T2 to L2 was increased by a mean of 8.5 mm in the patients with Lenke type 1, 12.7 mm in those with type 2, and 10.1 mm overall. Elongation was positively associated with the preoperative main thoracic Cobb angle in both the type-1 group (R = 0.43, p < 0.005) and the type-2 group (R = 0.77, p < 0.000001). The greatest elongation was observed in the periapical vertebral levels of the main thoracic curves. CONCLUSIONS: Corrective surgery for adolescent idiopathic scoliosis elongated the spinal canal. The preoperative proximal, main thoracic, and thoracolumbar/lumbar Cobb angles are moderate predictors of postoperative spinal canal length after scoliosis surgery. CLINICAL RELEVANCE: It is important to understand how much the spinal canal is elongated after surgery to lessen the risk of intraoperative and postoperative neurological complications.