Spinal Canal Growth Research Articles

Sex differences in cervical spinal cord and spinal canal development in Thoroughbred horses.

Cervical vertebral stenotic myelopathy (CVSM), a common cause of cervical spinal cord compression, is a neurological disease characterized by general proprioceptive ataxia and weakness of hindlimbs that tends to develop in young adult Thoroughbred horses. Although male horses seem to be at increased risk for CVSM, the mechanism for the occurrence of sex differences in the prevalence of CVSM is still poorly understood. Hence, we hypothesized that sex differences in the development of cervical spinal cord and spinal canal would affect the development of CVSM. This study aimed to evaluate sex differences in the development of cervical spinal cord and spinal canal in Thoroughbred horses. A total of 29 Thoroughbred horses underwent computed tomographic myelography. Thereafter, the volumes of cervical spinal cord and spinal canal were calculated. Accordingly, male horses had significantly lager cervical spinal cord volume and cervical spinal cord-to-spinal canal volume ratio than those of female horses (P<0.05). Sex differences in the cervical spinal cord-to-spinal canal volume ratio gradually decreased until around 1,400 days of age. Younger male horses have narrower interspace between the cervical spinal cord and spinal canal than younger female horses, suggesting that an imbalanced cervical spinal cord and spinal canal growth is one of the causes of CVSM.

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

Evaluation of lumbar canal dimensions in a Chicago population born in 2 different decades. 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. 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). 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.

Spinal cord evolution in early Homo

The discovery at Nariokotome of the Homo erectus skeleton KNM-WT 15000, with a narrow spinal canal, seemed to show that this relatively large-brained hominin retained the primitive spinal cord size of African apes and that brain size expansion preceded postcranial neurological evolution. Here we compare the size and shape of the KNM-WT 15000 spinal canal with modern and fossil taxa including H. erectus from Dmanisi, Homo antecessor, the European middle Pleistocene hominins from Sima de los Huesos, and Pan troglodytes. In terms of shape and absolute and relative size of the spinal canal, we find all of the Dmanisi and most of the vertebrae of KNM-WT 15000 are within the human range of variation except for the C7, T2, and T3 of KNM-WT 15000, which are constricted, suggesting spinal stenosis. While additional fossils might definitively indicate whether H. erectus had evolved a human-like enlarged spinal canal, the evidence from the Dmanisi spinal canal and the unaffected levels of KNM-WT 15000 show that unlike Australopithecus, H. erectus had a spinal canal size and shape equivalent to that of modern humans. Subadult status is unlikely to affect our results, as spinal canal growth is complete in both individuals. We contest the notion that vertebrae yield information about respiratory control or language evolution, but suggest that, like H. antecessor and European middle Pleistocene hominins from Sima de los Huesos, early Homo possessed a postcranial neurological endowment roughly commensurate to modern humans, with implications for neurological, structural, and vascular improvements over Pan and Australopithecus.

Morphometric Analysis of Vertebral Growth Using Magnetic Resonance Imaging in the Normal Skeletally Immature Spine

Morphometic analysis of the thoracic and lumbar pedicle, vertebral body, and spinal canal in the normal infantile and juvenile patients using magnetic resonance imaging (MRI). To 3-dimensionally characterize the growth of the vertebral column in vivo and define the accurate dynamic growth rate of the normal immature spine. There is a relationship between growth of the spine and the development of spinal deformity. Currently available information regarding vertebral column growth is remarkably limited and poorly defined. The detailed morphologic research is needed to obtain accurate data with regard to growth of the vertebra, including coronal, sagittal, and axial growth information for normal states. A total of 34 pediatric patients with a normal straight spine who had MRI from thoracic vertebra 1 to lumbar vertebra 5 were assigned to 3 groups: infantile group (n = 11), 0 to 3 years of age; juvenile-young group (n = 16), 4 to 7 years of age; and juvenile-old group (n = 7), 8 to 10 years of age. True transverse and midsagittal MRI images were used for pedicle (width and length), vertebral body (height, depth and width), and spinal canal area measurements. The mean increase of the pedicle width and length was 0.7 mm (16%) and 3.2 mm (18%) from the infantile to the juvenile-young, and was 0.9 mm (15%) and 2.2 mm (11%) through the juvenile-old group. The mean increase of the vertebra body width, depth, and height were 3.6 mm (15%), 4.5 mm (27%), and 3.1 mm (27%), respectively, from the infantile to the juvenile-young, and were 2.9 mm (10%), 1.9 mm (9%) and 2.1 mm (15%), respectively, through the juvenile-old group. The mean increase of the spinal canal area was 41 mm (19%) from the infantile to the juvenile-young and was only 1.8 mm (0.7%) through the juvenile-old group. The current study established the growth of the pedicle, spinal canal, and vertebral body in vivo in a sample of normal pediatric subjects. The vertebral growth rate in the infantile and the juvenile-young period was significantly greater than that in the juvenile-old period. Spinal canal growth is associated with the growth of the pedicle width and has little growth after the juvenile-young period. Pedicle screw fixation would be unlikely to influence the size of the spinal canal after the early juvenile period, but may disturb the pedicle growth in length.

Impact of Pedicle Screw Instrumentation with Addition of Crosslink on Growth of Spinal Canal in Young Children

Introduction The use of pedicle screws has been popularized in the treatment of pediatric spinal deformity. Despite many studies regarding the effect of pedicle screws on the immature spine, there is a paucity of data concerning the impact of the screw-rod-crosslink complex on the development of spinal canal in young children. The objective of this study is to determine the influence of the screw-rod-crosslink complex on the development of spinal canal. Materials and Methods This study reviewed 34 patients with congenital scoliosis (14 boys and 20 girls) who were treated with posterior-only hemivertebrectomy and pedicle-screw-based short-segment instrumentation before the age of 5 years. They were followed-up for at least 24 months. Of these patients, 10 underwent only pedicle screw instrumentation without crosslink, and 24 with additional crosslink placement. The vertebrae were divided into three regions as follows: (1) S-CL (screw-crosslink) region, in which the vertebrae were inserted with bilateral pedicle screws and two rods connected with the crosslink; (2) S (screw) region, in which the vertebrae were inserted with bilateral pedicle screws but without crosslink; (3) NS (no screws) region, which comprised vertebrae cephalad or caudal to the instrumented region. The area, anteroposterior and transverse diameters of the spinal canal were measured at all vertebrae on the postoperative and last follow-up computed tomography axial images. The instrumentation-related parameters were also measured, including the distance between the bilateral screws and the screw base angle. The changes in the above measurements were compared between each region to evaluate the instrumentation's effect on the spinal canal growth. Results The mean age at surgery was 37 ± 11 months (range, 21–57 months) and the mean follow-up was 37 ± 13 months (range, 24–68 months). In each region, the spinal canal dimensions significantly increased during the follow-up period. There was no significant difference in the spinal canal growth rate between the S and NS regions or between the S-CL and NS regions. In addition, a comparison of the S-CL and S regions regarding the changes in measurements of the instrumentation construct revealed no significant differences. Conclusion Pedicle-screw-based instrumentation does not cause retardation of the development of spinal canal in young children. Moreover, use of the crosslink added to the screw-rod instrumentation also demonstrates no negative effect on the growth of the spinal canal. Thus, the addition of the crosslink to screw-based instrumentation is recommended to increase fixation stability in growing patients, even in very young pediatric population.

Does addition of crosslink to pedicle-screw-based instrumentation impact the development of the spinal canal in children younger than 5 years of age?

Use of pedicle screws has been popularized in the treatment of pediatric spinal deformity. Despite many studies regarding the effect of pedicle screws on the immature spine, there is no study concerning the impact of addition of crosslink to pedicle-screw-based instrumentation on the development of the spinal canal in young children. This study aims to determine the influence of the screw-rod-crosslink complex on the development of the spinal canal. This study reviewed 34 patients with congenital scoliosis (14 boys and 20 girls) who were treated with posterior-only hemivertebrectomy and pedicle-screw-based short-segment instrumentation before the age of 5 years. The mean age at surgery in this cohort was 37 ± 11 months (range 21-57 months). They were followed up for at least 24 months. Of these patients, 10 underwent only pedicle screw instrumentation without crosslink, and 24 with additional crosslink placement. The vertebrae were divided into three regions as follows: (1) S-CL (screw-crosslink) region, in which the vertebrae were inserted with bilateral pedicle screws and two rods connected with the crosslink; (2) S (screw) region, in which the vertebrae were inserted with bilateral pedicle screws but without crosslink; (3) NS (no screws) region, which comprised vertebrae cephalad or caudal to the instrumented region. The area, anteroposterior and transverse diameters of the spinal canal were measured at all vertebrae on the postoperative and last follow-up computed tomography axial images. The instrumentation-related parameters were also measured, including the distance between the bilateral screws and the screw base angles. The changes in the above measurements were compared between each region to evaluate the instrumentation's effect on the spinal canal growth. The mean follow-up was 37 ± 13 months (range 24-68 months) and the mean age at the last follow-up was 74 ± 20 months (range 46-119 months). In each region, the spinal canal dimensions significantly increased during the follow-up period. There was no significant difference in the spinal canal growth rate between the S and NS regions or between the S-CL and NS regions. Besides, a comparison of the S-CL and S regions regarding the changes in the measurements of the instrumentation construct revealed no significant differences. Pedicle-screw-based instrumentation does not cause retardation of the development of the spinal canal in young children. Moreover, use of the crosslink added to the screw-rod instrumentation also demonstrates no negative effect on the growth of the spinal canal. Thus, the addition of the crosslink to short screw-based instrumentation is recommended as an alternative to increase fixation stability in growing patients, even in very young pediatric population.

X-Ray assessment of the effect of pedicle screw on vertebra and spinal canal growth in children before the age of 7 years

To determine the reliability of pedicle screws placed in children younger than 7 years of age, and to evaluate the effect of pedicle screw insertion on further growth of the vertebra and spinal canal. A retrospective study of 35 consecutive patients through Jan 2003-Dec 2010 for congenital scoliosis in <7 years children was performed at one spine center. Patients undergoing pedicle screw instrumentation of at least two levels, which had been followed-up for at least 24 months were included. Measurements were performed in instrumented and adjacent non-instrumented levels. The effect of pedicle screw insertion on further growth was evaluated. The average age at surgery was 4.4 year (53 months, range, 23-84 months). 190 segments in 35 patients met the inclusion criteria. 77 segments had no screws and 113 had at least one screw. There was a significant difference between the pre-operative and final follow-up values of the measurement of spinal canal and vertebral body parameters (P < 0.001). No significant difference existed between growth rates of vertebral bodies and the sagittal diameters of spinal canal with or without screws. The growth rates of vertebral bodies in lumbar spine were higher than in thoracic spine in both instrumented and adjacent groups. Pedicle screw instrumentation does not cause a retardation effect on the development of vertebral bodies and the spinal canal in children at an early age. It is a safe and reliable procedure to achieve a stable fixation.

Pedicle Screw Implantation in the Thoracic and Lumbar Spine of 1–4-Year-Old Children

This was a retrospective clinical study. To evaluate the safety and accuracy of pedicle screw placement in very young children and to observe its influence on vertebral and spinal canal growth. Although widely used, it is not known if pedicle screw fixation is safe and effective in very young children. Sixteen children, with an average age of 34 months, had received pedicle screw fixation from January 2003 to January 2010. Candidates for surgery were those patients who had hemivertebra deformity (11 patients), eosinophilic granuloma disease with spinal cord compression, and neurological deficit (2 patients), or spinal tuberculosis accompanied with kyphotic deformity (3 patients). The location of involved vertebrae was between T2 and L5. A total of 74 pedicle screws were implanted using a modified free-hand technique. The safety and accuracy of this method, and the influence on vertebral growth, was evaluated using postoperative x-ray and computer tomography scans. The average follow-up was 30.6 months. No patient had any neurological or radicular symptoms related to the placement of pedicle screws. Postoperative computer tomography scans demonstrated a malposition of 5 of the 74 pedicle screws (6.8%). Two screws breached the anterolateral cortical bone of the vertebral body. One screw breached the lateral cortical bone of the pedicle, 1 passed through the anterior vertebral margin by 3 threads, and a third was so laterally placed that it entered into disk space. There was no vessel, visceral complications, or any other adverse effects resulting from these misplacements. No screw was placed so medially that injured the spinal cord. No retardation of vertebral growth was observed in 7 patients who were followed up for at least 3 and up to 7 years. The results indicate that in very young children, pedicle screws can be safely implanted using a modified free-hand implantation technique.

The Effect of Anterior Spinal Fusion on Spinal Canal Development in an Immature Porcine Model

Experimental study. To investigate whether anterior spine fusion in the immature porcine spine has an adverse effect on the development of spinal canal. Neurocentral cartilage (NCC) is located in the posterior vertebral body and responsible for the development of posterior aspect of the spinal canal. Injury to the NCC interferes with the development of the spinal canal. Twelve 8-week-old domestic pigs were used to develop an anterior fusion model. A standard procedure as L3-L4, L4-L5 discectomy, and L3-L5 anterior instrumented spine fusion was performed. To evaluate the development of the spinal canal, all subjects had computed tomography scans before the procedure and at the final follow-up. The spinal canal area was measured at the control level (CL) (L2), arthrodesis level (AL) (L4), superior (L3), and inferior (L5) instrumented level (SIL and IIL). Percent change in spinal canal area from before surgery to final follow-up was also calculated. RESULTS.: Eleven subjects were available for the study. All subjects developed local kyphosis over the fused segments. The average area of L2 (CL) was 0.56 +/- 0.06 cm before surgery. The average areas of the L3 (SIL), L4 (AL), and L5 (IIL) were 0.62, 0.70, and 0.77 cm, respectively. At the final follow-up the average area of L2 was 1.20 cm. The average areas of the SIL, AL, and IIL were 1.16, 1.19, and 1.33 cm, respectively. The percent increase in spinal canal area at the CL was 116.6% whereas it was 85.8%, 71.0%, and 71.2% at SIL, AL, and IIL, respectively. Anterior spinal arthrodesis in the immature porcine spine results in iatrogenic retardation on spinal canal growth. This effect is most likely related to the tethering effect of the interbody fusion over the NCC. Although, it is difficult to directly extrapolate these findings to clinical practice, the spine surgeons operating on pediatric patients should be aware of this possibility.

The Effect of Pedicle Screw Placement With or Without Application of Compression Across the Neurocentral Cartilage on the Morphology of the Spinal Canal and Pedicle in Immature Pigs

Experimental study. To investigate the effects of pedicle screw insertion on spinal canal and pedicle morphology in immature pigs, and, if transpedicular fixation has an effect, to document whether this occurs because of the inhabitance of the screw inside the growth plate (neurocentral cartilage [NCC]) or because of compression applied across the NCC. Transpedicular fixation has been less commonly applied to the pediatric population, especially because of the risk of damage to the NCC. Twelve newborn pigs (4-6 weeks of age) were operated on. Left sided pedicles from L1-L5 were studied, while right sides served as controls. Pigs were randomly assigned into 3 groups: (1) pedicles were probed only; (2) screws were inserted; and (3) after screw insertion, a washer and a nut were engaged at the pedicle entry point so that gradual compression across the NCC was achieved. After 4 months, spiral computerized tomography was used to measure the pedicle lengths and size of the halves of the spinal canal. In group 1, the operated hemi-canal area was not statistically different from the nonoperated side (P = 0.159). Pedicle screw insertion either with (P = 0.007) or without (P = 0.005) compression resulted in smaller hemi-canal area and shorter pedicles at the operated side, respectively (P = 0.008, P = 0.021). Approximately 4% to 9% shortening of the pedicle lengths and 20% to 26% narrowing of the hemi-canal areas on the instrumented side occurred with transpedicular instrumentation (groups 2, 3). Even without compression, pedicle screws passing through the NCC in immature pigs disturb spinal canal growth significantly. Clinical relevance for young children should be studied further.

小児頚椎に発生したＡｎｅｕｒｙｓｍａｌ ｂｏｎｅ ｃｙｓｔの２例

Aneurysmal bone cysts (ABC) arising from the cervical spine in children is relatively rare. Two cases with aneurysmal bone cysts arising from the cervical spine were successfully operated on in order to achieve radical tumor resection and reconstruction cervical spine stability were reported.Case1: A five year-old boy with neck pain and limitation of cervical movements. Clinical and histological investigation revealed ABC at the body of C4. Extensive curettage and bone grafting from C3 to C5 spine were carried out. Complete bony union was achieved. At six years follw-up, no tumor recurrence was seen, the spinal canal had normal growth and the patient had returned to normal activity.Case 2: A twelve year-old girl. Radiological examination and histological findings revealed ABC extensively occupying the body and lamina of C4. Staged resection and reconstruction were done. In the first stage, wide curettage through the posterior approach followed by bone grafting with Luque instrumentation were done. Two weeks later extensive curettage of the C4 lesion, cervical interbody fusion with bone grafting and plating from C3 to C5 were carried out. At three years follow-up, complete bony union was observed with no recurrence of the lesion, nor any disturbance of spinal canal growth.