Review of morphology, development, and evolution of the notarium in birds.

The notarium is a rigid bony structure, which resulted from the fusion of thoracic vertebrae of some pterosaurs and birds. It is high variable, ranging from two to six fused thoracic vertebrae. In this study, we reviewed and analyzed approximately 270 specimens of neornithine birds (representing 80% of the living orders) and some fossils in order to identify the number of fused vertebrae, degree and sites of vertebral fusion, occurrence of sutures, and other structures of potential phylogenetic and functional significance. These data were analyzed using a recent time-calibrated molecular phylogenetic tree and principal component analyses analysis evaluating the relationship with long bones in order to reconstruct macroevolutionary trends related to the evolution of the notarium. The occurrence of this structure shows a mosaic distribution over neornithine phylogeny, originating several times independently, especially during the Paleogene, in predominantly ground-dwelling forms. The notarium of these groups is characterized by: neural spines fused into single structure, intervertebral openings small to absent, large ventral keels forming ventral plates, and fused transverse processes. Derived neornithines, such as aquatic forms and long-legged birds, have a tendency to display a decreased degree of fusion between the vertebrae, which may indicate a reduction or disappearance of the notarium.

The efficacy of single posterior debridement, bone grafting and instrumentation for the treatment of thoracic spinal tuberculosis.

The aim of this study was to investigate the clinical efficacy of single posterior debridement, bone grafting and instrumentation for the treatment of thoracic spinal tuberculosis in adult patients. A retrospective analysis was conducted between June 2013 and September 2017of 88 adult patients with thoracic spinal tuberculosis. All patients were treated with single posterior debridement, bone grafting and instrumentation. The clinical manifestations and laboratory and imageological results were subsequently analysed. All patients were followed for 40.6 ± 4.1 months (range, 36-48 m). Bony fusion was achieved in all bone grafts of thoracic vertebrae. The visual analogue scale scores, erythrocyte sedimentation rate and C-reactive protein levels 6 weeks after surgery and at the final follow up were significantly lower than the preoperative levels (P < 0.05). The postoperative and final follow up kyphosis angles were both significantly smaller than the preoperative kyphosis angles (P < 0.05). The postoperative angle correction rate reached 81.5% and the postoperative angle loss reached only 4.1%. At the last follow up, American Spinal Injury Association improvement was significant, compared with the preoperative levels (P < 0.05). The single posterior approach can achieve satisfactory clinical outcomes in the treatment of thoracic spinal tuberculosis.

Growth-preserving instrumentation in early-onset scoliosis patients with multi-level congenital anomalies.

STUDY DESIGN: Retrospective. OBJECTIVES: To assess final outcomes in patients with early-onset scoliosis (EOS) who underwent growth-preserving instrumentation (GPI). Various types of growth-preserving instrumentation (GPI) are frequently employed, but until recently had not been utilized long enough to assess final outcomes. METHODS: GPI "graduates" with multi-level congenital curves were identified. Graduation was defined as a final fusion or 5 years of follow-up without planned future surgeries. Outcomes included radiographic parameters and complications. RESULTS: 26 patients were included. 11 had associated diagnoses; eight had fused ribs. 17 were treated with traditional growing rods, seven with vertically expandable prosthetic ribs, and two with Shilla procedures. The mean GPI spanned 12.3 levels including 10.7 motion segments, age at index surgery was 5.5 years, treatment spanned 7.5 years, and follow-up was 9.2 years. 24 patients underwent final fusion. Mean major curve decreased from 73° to 49° with index surgery (p < 0.01) and remained unchanged through a final follow-up. Final major curve was < 40° in 9 patients (35%), 40°-60° in 11 patients (42%), and > 60° in 6 patients (23%). None worsened throughout treatment. Mean T1-T12 height increased 2.4 cm with index surgery (p = 0.02) and 5.4 cm total (p < 0.01). T1-T12 height increased in all patients and was ultimately < 18 cm in 10 patients (38%), 18-22 cm in 10 patients (38%), and > 22 cm in 6 patients (23%). On average, there were 2.6 complications per patient, including 1.7 implant failures. 12 patients (46%) experienced ≥ 3 complications; four patients (15%) experienced none. CONCLUSION: We observed successful prevention of deformity progression but substantial residual deformity among GPI graduates with multi-level congenital EOS. Most coronal curve correction was attained during GPI implantation; thoracic height improved throughout treatment. While some favorable results were found, treatment strategies allowing improved deformity correction would be valuable for this challenging population. LEVEL OF EVIDENCE: Therapeutic-III.

Sequential MRI reveals vertebral body wedging significantly contributes to coronal plane deformity progression in adolescent idiopathic scoliosis during growth.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To provide a comprehensive, multi-stage investigation of vertebral body (VB) and intervertebral disc (IVD) coronal plane deformities for adolescent idiopathic scoliosis (AIS) patients with a main thoracic curve type, using a series of sequential magnetic resonance images (MRIs). Despite numerous investigations of AIS deformity at the spinal segmental level, there is little consensus as to the major contributor to the lateral curvature of a scoliotic spine. Moreover, scoliotic deformity is often described along a continuum of progression, with few studies having characterised the change in segmental deformity for AIS patients whose deformity progresses clinically over time. METHODS: 30 female AIS patients with primary thoracic curves were included between 2012 and 2016. Three sequential MRIs were captured for each patient. Datasets were reformatted to produce true coronal plane images of the thoracic spine (T4-L1). Overall curve morphology, coronal plane IVD and VB segmental deformity and rates of growth were analysed. RESULTS: Right-side asymmetry was greater in IVDs (18.5 ± 23.9%) when compared to VBs (8.3 ± 9.2%) (P < 0.05) by third scans. Despite this, 77% of patients demonstrated the majority (> 50%) of their coronal curvature was attributed to VB wedging when measured across all three scans. Regardless of progression status, scan number, or region, the sum of the VB wedging angle was greater than the sum of the IVD wedging angle (all P ≤ 0.05). There was no correlation between the rates of major curve angle progression and standing height increase, VB height growth, or IVD height growth (P > 0.05). CONCLUSIONS: VB wedging contributed more to the lateral deformity observed in primary thoracic subtypes of AIS patients than IVD wedging. While IVDs demonstrated the greatest asymmetric deformity, their relatively smaller height resulted in a smaller proportional change in lateral curve angle compared to the VBs. LEVEL OF EVIDENCE: IV.

Characterizing Use of Growth-friendly Implants for Early-onset Scoliosis: A 10-Year Update.

BACKGROUND: Growth-friendly treatment of early-onset scoliosis (EOS) has changed with the development and evolution of multiple devices. This study was designed to characterize changes in the use of growth-friendly implants for EOS from 2007 to 2017. METHODS: We queried the Pediatric Spine Study Group database for patients who underwent index surgery with growth-friendly implants from July 2007 to June 2017. In 1298 patients, we assessed causes of EOS; preoperative curve magnitude; age at first surgery; patient sex; construct type; lengthening interval; incidence of "final" fusion for definitive treatment; and age at definitive treatment. α=0.05. RESULTS: From 2007 to 2017, the annual proportion of patients with idiopathic EOS increased from 12% to 33% (R=0.58, P=0.006). Neuromuscular EOS was the most common type at all time points (range, 33% to 44%). By year, mean preoperative curve magnitude ranged from 67 to 77 degrees, with no significant temporal changes. Mean (±SD) age at first surgery increased from 6.1±2.9 years in 2007 to 7.8±2.5 years in 2017 (R=0.78, P<0.001). As a proportion of new implants, magnetically controlled growing rods increased from <5% during the first 2 years to 83% in the last 2 years of the study. Vertically expandable prosthetic titanium ribs decreased from a peak of 48% to 6%; growth-guidance devices decreased from 10% to 3%. No change was seen in mean surgical lengthening intervals (range, 6 to 9 mo) for the 614 patients with recorded lengthenings. Final fusion was performed in 88% of patients who had undergone definitive treatment, occurring at a mean age of 13.4±2.4 years. CONCLUSIONS: From 2007 to 2017, neuromuscular EOS was the most common diagnosis for patients treated with growth-friendly implants. Patient age at first surgery and the use of magnetically controlled growing rods increased during this time. Preoperative curve magnitude, traditional growing rod lengthening intervals, and rates of final fusion did not change. LEVEL OF EVIDENCE: Level II.

Growing-rod Graduates With Idiopathic Early-onset Scoliosis Have Comparable Exercise Tolerance to Patients With Surgically Treated Adolescent Idiopathic Scoliosis.

BACKGROUND: Growing-rod (GR) treatment is the current standard for progressive idiopathic early-onset scoliosis (I-EOS) in young children. Despite good radiographic outcomes, the impact of scoliosis treatment on pulmonary functions is not well-defined in this patient population. The aim of this study was to evaluate pulmonary functions and exercise tolerance in I-EOS patients graduated from GR treatment and to compare them with age-matched, surgically treated adolescent idiopathic scoliosis (AIS) patients and healthy controls. METHODS: Eight GR graduates with I-EOS with pulmonary function tests and complete radiographic results were compared with a group of 9 thoracic AIS patients at least 2 years out from posterior fusion. Both groups were also compared with a set of 10 healthy individuals. All subjects underwent cardiopulmonary exercise testing and spirometry to evaluate pulmonary function. RESULTS: Age, sex, height, arm span, weight, residual deformity, and level of instrumentation in GR and AIS patients were similar. In the GR group, forced vital capacity % and forced expiratory volume in 1 second % values were reduced compared with the healthy controls and AIS group (P<0.001, <0.001 and 0.036, 0.046, respectively). Breathing reserve index at lactate threshold (BRILT) was higher in GR and AIS patients (P=0.001 and 0.002, respectively), and was similar between GR and AIS patients (P=0.916). Heart rate at lactate threshold was higher in GR and AIS groups compared with controls (P<0.001 and 0.001, respectively). CONCLUSIONS: AIS and GR patients demonstrated reduced pulmonary reserve and exercise tolerance compared with their peers with no spinal deformity. However, exercise tolerance of I-EOS patients treated with the GR method was similar to that of operated AIS patients. These results suggest a positive impact of GR treatment in children with I-EOS. LEVEL OF EVIDENCE: Level III-cross-sectional comparative study.

Serial Casting in Neuromuscular and Syndromic Early-onset Scoliosis (EOS) Can Delay Surgery Over 2 Years.

BACKGROUND: The primary goal in managing early-onset scoliosis (EOS) is delaying/preventing surgical intervention while allowing improved spinal growth and chest wall and lung development to improve life expectancy. The effectiveness of serial casting for patients with neuromuscular and syndromic EOS is unclear. METHODS: Patients from 2 multicenter registries who underwent serial casting for nonidiopathic scoliosis (NIS) were reviewed retrospectively. Comparisons were made between precasting and postcasting major and compensatory curves and spine height. The need for surgical intervention and any treatment complications were documented. Risk factors for major curve progression from baseline to casting cessation were evaluated via univariate analysis. RESULTS: Forty-four patients (23 females; 21 males) with NIS (26 syndromic, 18 neuromuscular) and a mean age of 3.2 years at baseline were included. Mean follow-up and casting duration was 3.9 and 2.0 years, respectively. There were no statistically significant differences between mean precasting and postcasting major curve (55 vs. 60 degrees; P=0.348), minor curve (31 vs. 33 degrees; P=0.510), or rib-vertebra angle difference (18 vs. 29 degrees; P=0.840). However, thoracic height (15.5 vs. 16.8 cm; P=0.031) and lumbar height (8.9 vs. 9.8 cm; P=0.013) were significantly greater upon casting cessation. Currently, 13 patients (30%) have had successful casting (improvement of major curve ≥10 degrees) while 24 patients (55%) experienced major curve progression (worsening), and 19 patients (43%) required surgical intervention. Mean time from first casting to surgery was 34.5±15.1 months. There were no statistically significant predictors for major curve progression on univariate analysis. CONCLUSIONS: Spinal deformity progression despite casting and the subsequent need for surgical intervention for NIS were significantly higher compared with those reported for idiopathic EOS. However, serial casting did afford a substantial delay in surgical intervention. Ultimately, serial casting for neuromuscular or syndromic EOS is an effective strategy for delaying surgical intervention, despite suboptimal radiographic outcomes. LEVEL OF EVIDENCE: Level III.

Growth guidance constructs with apical fusion and sliding pedicle screws (SHILLA) results in approximately 1/3rd of normal T1-S1 growth.

STUDY DESIGN: Retrospective, multicenter. OBJECTIVE: To investigate clinical outcomes in particular T1-S1 growth in patients with SHILLA instrumentation independent of inventor's reports. Guided growth with apical fusion and sliding pedicle screws (GGC/SHILLA) is an alternative to distraction-based growing rods for the treatment of EOS. A recent report of patients treated with GGC primarily at the center where the procedure was invented reported surprisingly good spinal growth similar to normal growth. METHODS: Retrospective review of EOS patients treated with GGC between 2007 and 2013 was performed from a multicenter database prior to final fusion. Inclusion criteria were < 10 years at index surgery and minimum 2-year follow-up. Patients with GGC performed at the inventor's institution or prior spinal instrumentation were excluded. Predicted normal T1-S1 change during the growth period was calculated for each patient based on Dimeglio's growth rates. RESULTS: 20 patients (mean age at surgery: 5.7 years) with the following diagnoses met inclusion criteria: syndromic (N = 9), neuromuscular (N = 5), idiopathic (N = 3) and congenital (N = 3). Preoperative mean Cobb was 77° (range 33°-111°). Mean increase in T1-S1 length from preoperative to postoperative was 51.5 mm, and change from postoperative to final follow-up was 21.8 mm (4.2 mm/year) which was 36% of predicted growth. 15/20 (75%) patients underwent 21 revision surgeries most commonly for implant complications (N = 26) and 8/20 (40%) underwent definitive fusion at a mean of 5.1 ± 1.2 years after guided growth surgery. CONCLUSION: This study constitutes the largest case series of patients with EOS treated with GGC outside of the inventor's institution. The change in T1-S1 observed through the follow-up period in EOS patients treated with GGC was approximately 1/3rd of predicted normal growth, and less than 1/3rd of growth reported in previous reports. Similar curve correction and complication rates but less T1-S1 growth during the growth period were found compared to prior GGC (SHILLA) series.

Continued vertebral body growth in patients with juvenile idiopathic scoliosis following vertebral body stapling.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To quantitatively measure the rate of growth of vertebral bodies in juvenile idiopathic scoliosis (JIS) treated with vertebral body stapling (VBS). VBS has been suggested to be a safe and effective method for modulating the growth of the young scoliotic spine, but few long-term studies have examined its efficacy. METHODS: Seven patients with JIS 11 years of age or younger underwent VBS with a minimum 6-year follow-up. Vertebral body height on the unstapled and stapled aspects of the curve was measured from initial and final postoperative radiographs and converted into rate of growth per year. Known staple dimensions were used to standardize the measurements between radiographs. Interstaple distance was measured to demonstrate continued growth of the spine. Adjacent vertebral bodies without instrumentation served as an internal control of growth. Each vertebral body (n = 35) was analyzed as an individual experimental unit. RESULTS: The average rate of growth was 0.86 mm/year (standard deviation [SD] 0.44, 95% confidence interval [CI] 0.71-1.0) per vertebral body on the stapled side and 0.83 mm/year (SD 0.46, 95% CI 0.67-0.98) per vertebral body on the unstapled side of the vertebral body. The adjacent vertebral body segments grew at a rate of 0.91 mm/year (SD 0.42, 95% CI 0.66-1.15) on the stapled side and 0.99 mm/year (SD 0.66, 95% CI 0.61-1.37) on the unstapled side, p < 0.01. The distance between staples increased significantly from 3.0 mm (SD 2.0, 95% CI 2.3-3.6) to 8.4 mm (SD 2.4, 95% CI 7.7-9.3). CONCLUSIONS: Vertebral body growth in the presence of VBS occurred at a similar rate on the stapled and unstapled sides of the curve. The high standard deviation of instrumented segment growth further supports the conclusion that VBS is not a reliable method of growth modulation in the young scoliotic spine. LEVEL OF EVIDENCE: IV.

Distraction-based surgeries increase thoracic sagittal spine length after ten lengthening surgeries for patients with idiopathic early-onset scoliosis.

STUDY DESIGN: Retrospective, comparative, multicenter. OBJECTIVES: To determine if the choice of proximal anchor affects thoracic sagittal spine length (SSL) for children with idiopathic early-onset scoliosis (EOS). Debate exists as to whether spine growth is maintained during treatment for EOS. As rib- (RB) and spine-based (SB) distraction procedures may be kyphogenic, the traditional measurement of spine growth on coronal radiographs may not identify out-of-plane increase in spine length. A measure of SSL, along the spine's sagittal arc of curvature, has been validated to reliably assess the length of the thoracic spine. METHODS: Patients with idiopathic EOS treated with distraction-based systems (minimum 5-year follow-up, five lengthening surgeries) with radiographic analysis preoperatively, postimplant (L1), and during lengthening periods (L2-L5, L6-L10) were evaluated with primary outcome of T1-T12 SSL. RESULTS: We identified 34 patients (14 RB, 20 SB) with preoperative age 4.9 years (4.2 RB vs. 5.4 SB), scoliosis 72° (60° RB vs. 77° SB; p < 0.05), kyphosis 39° (50° RB vs. 34° SB; p < 0.05), and SSL 17.8 cm (15.5 RB vs. 18.5 SB; p < 0.05). After initial scoliosis correction from implantation, scoliosis remained constant over time. RB patients had greater kyphosis than SB patients: L1, 46° RB vs. 19° SB (p < 0.05); L2-L5, 50° RB vs. 27° SB (p < 0.05); L6-L10, 56° RB vs. 26° SB (p < 0.05). SSL increased for both groups from preoperative to the tenth lengthening (p < 0.05). As compared with RB patients, SB patients had higher SSL preoperatively and maintained this difference to the tenth lengthening (p < 0.05). After ten lengthening surgeries, when normalized to preoperative SSL, relative thoracic growth was greater for RB (27%) than for SB patients (19%) (p < 0.05). CONCLUSION: Regardless of proximal anchor choice, thoracic length continued to increase during the distraction phase of treatment for idiopathic EOS. LEVEL OF EVIDENCE: Level III.

Differential growth patterns of the abdominal aorta and vertebrae during childhood.

The adult vertebral level of the splanchnic branches of the abdominal aorta relies on a complex series of fusion and regression steps during embryological development, such that variation is common. Little is known however regarding the anatomy of the abdominal aorta in children. This study aimed to investigate the spatial relationship between the abdominal aorta and the vertebral column during childhood development to inform clinical management of pediatric patients. Retrospective multislice computed tomography abdominopelvic angiograms of children aged neonate to 19 years (n = 232) were used to examine vertebral levels of the celiac trunk (CoT), superior mesenteric artery (SMA), inferior mesenteric artery (IMA), and aortic bifurcation (AB) using multiplanar formatting views in OsiriX. The abdominal aorta length, AB angle, and displacement of the aorta from the midline were quantified with the effect of age and sex analyzed using multinomial logistic regression and general linear models. The most frequent origins of CoT, SMA, IMA, and AB were T12, L1, L3, and L4, respectively, with significant variation in vertebral level for each vessel. SMA level was significantly more proximal with age, and CoT and AB demonstrated marked sex differences in vertebral level. As the age of the child increased, AB angle decreased, aortic displacement increased, and the length of the abdominal aorta increased at a slower velocity to the vertebral column (P < 0.001). Our study highlights the variation of the location and geometry of the abdominal aorta in children; this knowledge will positively impact pediatric surgical approaches and endovascular procedures. Clin. Anat. 32:783-793, 2019. © 2019 Wiley Periodicals, Inc.

Pseudopathological vertebral changes in a young individual from Herculaneum (79 C.E.).

Post mortem abnormal modification of bone are known as pseudopathologies. The geochemical characteristic of the burial soil and/or the presence of biological agents may produce marked changes in bone preservation. This could be the case for a young individual, E74, from Herculaneum, which was a Roman town near Naples completely destroyed by the volcanic eruption of Mt. Vesuvius in 79 CE. E74 is an incomplete skeleton of a male individual of 7-8 years of age. Its second and third cervical vertebrae, the eighth thoracic vertebra and the first lumbar vertebra show a septum dividing the vertebral foramen. This condition could be diagnosed as diastematomyelia that consists of the splitting of the spinal cord or cauda equina. In particular Type I malformations consist of two hemicords separated into two dural tubes by a bone septum. The gross anatomy and histological aspects of the vertebrae and their septa were investigated through macroscopic, microscopic, radiographic and chemical analyses. The results demonstrate that the vertebral septum is constituted by three layers of inorganic substances deposited at different times on a thin, probably organic, substrate (original meninges?). The central layer contain framboidal pyrite, that is a sedimentary mineral rarely found in ancient human skeletons. The septum splitting the vertebral canal of individual E74 is consequent to a taphonomic event and is not due to a pathological condition. Distinguishing between ante and post mortem alterations can be a challenging exercise even for the experienced paleopathologists and, as this case indicates, paleopathological diagnoses should be supported by detailed examinations.

Cost Analysis of Magnet-driven Growing Rods for Early-onset Scoliosis at 5 Years.

STUDY DESIGN: Prospective case series of nine children with early-onset scoliosis (EOS) treated by a single surgeon with a novel implant, the magnet-driven growing rod (MdGR) in a publicly funded health care service accounting for "payer costs" (PC) incurred. OBJECTIVE: The aim of this study was to compare the cost-effectiveness of MdGR versus conventional growing rods (CGRs) with respect to the PC incurred for treating EOS at 5 years. SUMMARY OF BACKGROUND DATA: Cost estimate and mathematical modeling study projections of MdGR have shown despite high insertional costs, it breaks even with CGR by 3 to 4 years. However, no clinical study to date exists either supporting or refuting this hypothesis. METHODS: Nine patients with EOS secondary to idiopathic (two), congenital (one), syndromic (three), and neuromuscular (three) etiologies treated by submuscular insertion of MdGR against stringent inclusion criteria formed the study cohort. We collected costs incurred with all aspects of care over the lifetime of device (or at least 5 years) from payers' perspective to compute and report average PC incurred per patient. We performed this cost analysis by comparing the MdGR PC against literature reported PC for CGR at 5 years. RESULTS: There were five single rod (SR) and two dual rod (DR) de novo MdGR insertions, while two patients had conversion of CGR to MdGR. MdGR alone accounted for at least 50% of overall budget. The MdGR was at least 40% more cost-effective in comparison to the CGR (£34,741 vs. £52,293) and there were seven MdGR graduates. CONCLUSION: The first study reporting direct PC incurred in EOS treated by MdGR that is devoid of any mathematical modeling and deterministic sensitivity analysis is presented. The true societal/human cost savings taking into consideration indirect costs are likely to be significantly higher. MdGR is a promising novel implant that may eventually become the "standard of care" for certain EOS etiologies. LEVEL OF EVIDENCE: 4.

[Growth Guidance System in Treatment of Early Onset Scoliosis]. / Systémy usmernovaného rustu v lécbe raných detských skolióz.

PURPOSE OF THE STUDY The Growth Guidance System (GGS) represent a relatively new alternative to the traditional growing systems used for the treatment of early onset scoliosis. Ranking among the main aims of this surgical treatment is a three-dimensional correction of the deformity, maintenance of spinal growth and postponement of the necessity of final treatment by spondylodesis. MATERIAL AND METHODS Our study retrospectively evaluates the results of surgical correction in a group of 35 patients treated by GGS technique. The group consisted of patients with idiopathic, neuromuscular and syndromic spine deformity with the average age of 8 years and 2 months at the time of the surgery. The time of the follow-up is 3 years and 5 months on average. We evaluated the correction of the curve itself, the growth of the spine measured in the thoracic and lumbar part separately, and the growth of the trunk as a whole in the mentioned range on X-ray pictures. RESULTS The average correction of the scoliotic curve was 67%, from 75 preoperative degrees to 20 postoperative degrees. After the first operation 11% elongation of the trunk (from 321 mm to 356 mm) was reached, the thoracic spine was elongated by 10% (from 196 to 217 mm) and the lumbar spine was elongated by 11% (from 125 to 139 mm). The elongation of the trunk by 16% (from 322 to 375 mm) was observed in the cohort of patients with two years postoperative follow-up (21 patients). The total protraction of the trunk by 21% (from 318 to 386 mm) was reached in patients treated by definitive fusion (7 patients). DISCUSSION There is a very low number of studies analysing the long-term clinical results with the use of GGS. The first pilot results indicate that it is a technique allowing to achieve at least comparable results in correction of frontal plane compared with the distraction type of instrumentations. A negative aspect of this method is the abrasion of metal followed by metallosis. The new types of fixation screws enable more effective sliding of rods, maintenance of continuity of body grow by the shifting of rods as well as lower abrasion of the instrumentation. CONCLUSIONS The main advantage of GGS is the limited continuous growth of the spine, partial three-dimensional correction of the deformity, minimisation of inevitable reoperations under general anaesthesia and the possibility to quit a brace. Key words: growth guided system, early onset scoliosis, distraction, spinal growth, spondylodesis.

Sagittal plane parameters in growing rod patients following final fusion.

Almost half of growing rod (GR) patients that undergo final fusion (FF) have an extension of instrumented levels. The purpose of this study was to review sagittal plane radiographic parameters of patients with distal extension of instrumented levels at FF to those whose levels remained the same. Radiographs were assessed preoperatively, after GR insertion/first lengthening, following GR treatment before FFs, and after FF. Measurements included sagittal balance, lumbar lordosis, thoracic kyphosis, and distal junction angle (DJA). Twenty-one patients were included. There was no change in sagittal balance. There was a significant decrease in lordosis and kyphosis following initial GR implantation. Kyphosis and lordosis increased during the GR period, but remained unchanged at time of FF. DJA increased 8° on average. Seven patients had distal extension of instrumented levels at time of FF (average 2 levels, range: 1-4). Indication for distal extension was sagittal plane decompensation in four cases. When comparing patients who had distal extension at the time of FF to those whose levels remained the same, there was no difference in the change in sagittal balance, lordosis, or kyphosis. Final DJA was significantly smaller in those patients with distal extension. Most GR patients that undergo FF demonstrate acceptable correction of sagittal plane radiographic parameters. A small cohort of patients requires distal extension at FF due to sagittal plane decompensation. LEVEL OF EVIDENCE: Level IV, Therapeutic.

Growth Patterns of the Neurocentral Synchondrosis (NCS) in Immature Cadaveric Vertebra.

STUDY DESIGN: Gross anatomic study of osteological specimens. OBJECTIVES: To evaluate the age of closure for the neurocentral synchondrosis (NCS) in all 3 regions of the spine in children aged 1 to 18 years old. SUMMARY OF BACKGROUND DATA: The ossification of the human vertebra begins from a vertebral body ossification center and a pair of neural ossification centers located within the centrum called the NCS. These bipolar cartilaginous centers of growth contribute to the growth of the vertebral body, spinal canal, and posterior elements of the spine. The closure of the synchondroses is dependent upon location of the vertebra and previous studies range from 2 to 16 years of age. Although animal and cadaveric studies have been performed regarding NCS growth and early instrumentation's effect on its development, the effects of NCS growth disturbances are still not completely understood. METHODS: The vertebrae of 32 children (1 to 18 y old) from the Hamann-Todd Osteological collection were analyzed (no 2 or 9 y old specimens available). Vertebrae studied ranged from C1 to L5. A total of 768 vertebral specimens were photographed on a background grid to allow for measurement calibration. Measurements of the right and left NCS, pedicle width at the NCS, and spinal canal area were taken using Scandium image-analysis software (Olympus Soft Imaging Solutions, Germany). The percentage of the growth plate still open was found by dividing the NCS by the pedicle width and multiplying by 100. Data were analyzed with JMP 11 software (SAS Institute Inc., Cary, NC). RESULTS: The NCS was 100% open in all 3 regions of the spine in the 1- to 3-year age group. The cervical NCS closed first with completion around 5 years of age. The lumbar NCS was nearly fully closed by age 11. Only the thoracic region remained open through age 17 years. The left and right NCS closed simultaneously as there was no statistical difference between them. In all regions of the spine, the NCS appeared to close sooner in males than in females. Spinal canal area increased with age up to 12 years old in the cervical and thoracic spine but did not significantly change after age 3 in the lumbar spine. CONCLUSIONS: In conclusion, closure of the NCS differed among the cervical, thoracic, and lumbar spine regions. The NCS reached closure in males before females even though females mature faster and reach skeletal maturity sooner than males. However, it is not determined whether the continued open NCS in females to a later age may be a factor in their increased rate of scoliosis.

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

STUDY DESIGN: 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). OBJECTIVE: To 3-dimensionally characterize the growth of the vertebral column in vivo and define the accurate dynamic growth rate of the normal immature spine. SUMMARY OF BACKGROUND DATA: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Patient-specific Distraction Regimen to Avoid Growth-rod Failure.

STUDY DESIGN: A finite element study to establish the relationship between patient's curve flexibility (determined using curve correction under gravity) in juvenile idiopathic scoliosis and the required distraction frequency to avoid growth rod fracture, as a function of time. OBJECTIVE: To perform a parametric analysis using a juvenile scoliotic spine model (single mid-thoracic curve with the apex at the eighth thoracic vertebra) and establish the relationship between curve flexibility (determined using curve correction under gravity) and the distraction interval that allows a higher factor of safety for the growth rods. SUMMARY OF BACKGROUND DATA: Previous studies have shown that frequent distraction with smaller magnitude of distractions are less likely to result in rod failure. However there has not been any methodology or a chart provided to apply this knowledge on to the individual patients that undergo the treatment. This study aims to fill in that gap. METHOD: The parametric study was performed by varying the material properties of the disc, hence altering the axial stiffness of the scoliotic spine model. The stresses on the rod were found to increase with increased axial stiffness of the spine, and this resulted in the increase of required optimal frequency to achieve a factor of safety of two for growth rods. RESULTS: A relationship between the percentage correction in Cobb's angle due to gravity alone, and the required distraction interval for limiting the maximum von Mises stress to 255 MPa on the growth rods was established. The distraction interval required to limit the stresses to the selected nominal value reduces with increase in stiffness of the spine. Furthermore, the appropriate distraction interval reduces for each model as the spine becomes stiffer with time (autofusion). This points to the fact the optimal distraction frequency is a time-dependent variable that must be achieved to keep the maximum von Mises stress under the specified factor of safety. CONCLUSION: The current study demonstrates the possibility of translating fundamental information from finite element modeling to the clinical arena, for mitigating the occurrence of growth rod fracture, that is, establishing a relationship between optimal distraction interval and curve flexibility (determined using curve correction under gravity). LEVEL OF EVIDENCE: N/A.

Characterization of the age-dependent shape of the pediatric thoracic spine and vertebrae using generalized procrustes analysis.

Generalized Procrustes Analysis (GPA) is a superimposition method used to generate size-invariant distributions of homologous landmark points. Several studies have used GPA to assess the three-dimensional (3D) shapes of or to evaluate sex-related differences in the human brain, skull, rib cage, pelvis and lower limbs. Previous studies of the pediatric thoracic vertebrae suggest that they may undergo changes in shape asa result of normative growth. This study uses GPA and second order polynomial equations to model growth and age- and sex-related changes in shape of the pediatric thoracic spine. We present a thorough analysis of the normative 3D shape, size, and orientation of the pediatric thoracic spine and vertebrae as well as equations which can be used to generate models of the thoracic spine and vertebrae for any age between 1 and 19years. Such models could be used to create more accurate 3D reconstructions of the thoracic spine, generate improved age-specific geometries for finite element models (FEMs) and used to assist clinicians with patient-specific planning and surgical interventions for spine deformity.

The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain).

Ontogenetic studies help us understand the processes of evolutionary change. Previous studies on Neandertals have focused mainly on dental development and inferred an accelerated pace of general growth. We report on a juvenile partial skeleton (El Sidrón J1) preserving cranio-dental and postcranial remains. We used dental histology to estimate the age at death to be 7.7 years. Maturation of most elements fell within the expected range of modern humans at this age. The exceptions were the atlas and mid-thoracic vertebrae, which remained at the 5- to 6-year stage of development. Furthermore, endocranial features suggest that brain growth was not yet completed. The vertebral maturation pattern and extended brain growth most likely reflect Neandertal physiology and ontogenetic energy constraints rather than any fundamental difference in the overall pace of growth in this extinct human.