Differences in spine growth potential for Sanders maturation stages 7A and 7B have implications for treatment of idiopathic scoliosis

PURPOSE

This study aimed to clarify the differences in spine and total body height growth and curve progression between Sanders maturation stage (SMS) 7A and 7B in patients with adolescent idiopathic scoliosis (AIS).

METHODS

This retrospective case-control study involving patients with AIS at SMS 7 evaluated the differential gains in the spine (T1-S1) and total body height and curve progression between SMS 7A and 7B. A validated formula was used to calculate the corrected height, accounting for height loss due to scoliosis. A multivariable non-linear and logistic regression model was applied to assess the distinct growth and curve progression patterns between the SMS 7 subtypes, adjusting for potential confounders.

RESULTS

A total of 231 AIS patients (83% girls, mean age 13.9 ± 1.2 years) were included, with follow-up averaging 3.0 years. Patients at SMS 7A exhibited larger gains in spine height (9.9 mm vs. 6.3 mm) and total body height (19.8 mm vs. 13.4 mm) compared with SMS 7B. These findings remained consistent even after adjustments for curve magnitude. Non-linear regression models showed continued spine and total body height increases plateauing after 2 years, significantly greater in SMS 7A. More SMS 7A patients had curve progression over 10°, with an adjusted odds ratio of 3.31.

CONCLUSION

This study revealed that patients staged SMS 7A exhibited more spine and total body growth and a greater incidence of substantial curve progression than those at 7B. These findings imply that delaying brace discontinuation until reaching 7B could be beneficial, particularly for those with larger curves.

LEVEL OF EVIDENCE

Level III (Case-control study).

Does the Use of Sanders Staging and Distal Radius and Ulna Classification Avoid Mismatches in Growth Assessment with Risser Staging Alone?

BACKGROUND

Although Risser stages are visible on the same radiograph of the spine, Risser staging is criticized for its insensitivity in estimating the remaining growth potential and its weak correlation with curve progression in patients with adolescent idiopathic scoliosis. Risser staging is frequently accompanied by other skeletal maturity indices to increase its precision for assessing pubertal growth. However, it remains unknown whether there is any discrepancy between various maturity parameters and the extent of this discrepancy when these indices are used concurrently to assess pubertal growth landmarks, which are important for the timing of brace initiation and weaning.

QUESTIONS/PURPOSES

(1) What is the chronologic order of skeletal maturity grades based on the growth rate and curve progression rate in patients with adolescent idiopathic scoliosis? (2) What are the discrepancies among the grades of each maturity index for indicating the peak growth and start of the growth plateau, and how do these indices correspond to each other? (3) What is the effectiveness of Risser staging, Sanders staging, and the distal radius and ulna classification in assessing peak growth and the beginning of the growth plateau?

METHODS

Between 2014 and 2017, a total of 13,536 patients diagnosed with adolescent idiopathic scoliosis were treated at our tertiary clinic. Of those, 3864 patients with a radiograph of the left hand and wrist and a posteroanterior radiograph of the spine at the same visits including initial presentation were considered potentially eligible for this study. Minimum follow-up was defined as 6 months from the first visit, and the follow-up duration was defined as 2 years since initial consultation. In all, 48% (1867 of 3864) of patients were eligible, of which 26% (485 of 1867) were excluded because they were prescribed bracing at the first consultation. These patients visited the subsequent clinics wearing the brace, which might have affected body height measurement. Six percent (117 of 1867) of eligible patients were also excluded as their major coronal Cobb angle reached the surgical threshold of 50° and had undergone surgery before skeletal maturity. Another 21% (387 of 1867) of patients were lost before minimum follow-up or had incomplete data, leaving 47% (878) for analysis. These 878 patients with 1139 skeletal maturity assessments were studied; 74% (648 of 878) were girls. Standing body height was measured in a standardized manner by a wall-mounted stadiometer. Several surgeons measured curve magnitude as per routine clinical consultation, skeletal maturity was measured according to the distal radius and ulna classification, and two raters measured Risser and Sanders stages. Reliability tests were performed with satisfaction. Data were collected for the included patients at multiple points when skeletal maturity was assessed, and only up to when brace wear started for those who eventually had bracing. The growth rate and curve progression rate were calculated by the change of body height and major coronal Cobb angle over the number of months elapsed between the initial visit and next follow-up. At each skeletal maturity grading, we examined the growth rate (in centimeters per month) and curve progression rate (in degrees per month) since the skeletal maturity assessment, as well as the mean age at which this maturity grading occurred. Each patient was then individually assessed for whether he or she was experiencing peak growth and the beginning of growth plateau at each timepoint by comparing the calculated growth rate with the previously defined peak growth rate of ≥ 0.7 cm per month and the beginning of growth plateau rate of ≤ 0.15 cm per month in this adolescent idiopathic scoliosis population. Among the timepoints at which the peak growth and the beginning of growth plateau occurred, the median maturity grade of each maturity index was identified as the benchmark grade for comparison between indices. We used the McNemar test to investigate whether pubertal growth landmarks were identified by specific maturity grades concurrently. We assessed the effectiveness of these skeletal maturity indices by the difference in proportions (%) between two benchmark grades in indicating peak growth and the growth plateau.

RESULTS

For girls, the chronological order of maturity grades that indicated peak growth was the radius grade, ulna grade, Sanders stage, and Risser stage. Curve progression peaked between the age of 11.6 and 12.1 years at a similar timing by all maturity indices for girls but was inconsistent for boys. For both sexes, radius (R) grade 6, ulna (U) grade 5, Sanders stage (SS) 3, and Risser stage 0+ were the median grades for peak growth, whereas Risser stage 4, R8/9, U7/8, and SS6/7 indicated the beginning of the growth plateau. The largest discrepancy between maturity indices was represented by Risser stage 0+, which corresponded to six grades of the Sanders staging system (SS2 to SS7) and to R6 in only 41% (62 of 152) of girls in the whole cohort. Despite Risser stage 0+ corresponding to the wide range of Sanders and distal radius and ulna grades, none of the R6, U5, SS3, and Risser stage 0+ was found more effective than another grade in indicating the peak growth in girls. R6 most effectively indicated the peak growth in boys, and Risser stage 0+ was the least effective. For the beginning of the growth plateau in girls, SS6/7 was the most effective indicator, followed by U7/8. Risser stage 4 was the least effective because it indicated 29% (95% CI 21% to 36%; p < 0.001) fewer patients who reached the beginning of the growth plateau than did those with R8/9. Risser stage 4 also indicated 36% (95% CI 28% to 43%; p < 0.001) fewer patients who reached the beginning of the growth plateau than those indicated by U7/8, and it identified 39% fewer patients than SS6/7 (95% CI 32% to 47%; p < 0.001). For boys, similarly, R8/9, U7/8, and SS6/7 were all more effective than Risser stage 4 in identifying when the growth plateau began.

CONCLUSION

Risser stage 0+ corresponds to a wide range of Sanders and distal radius and ulna grades. Risser stage 0+ is least effective in indicating the peak growth in boys, and Risser stage 4 is the least effective maturity grade for indicating when the growth plateau starts in both sexes. The concurrent use of R6 and SS3 can be useful for detecting the peak growth, and SS6/7 in conjunction with U7/8 is most effective in indicating the beginning of the growth plateau. Using a combination of specific grades of Sanders staging and the distal radius and ulna classification can indicate pubertal growth landmarks with reduced risk of underestimating or overestimating skeletal maturity. These findings may aid in refining clinical decision-making of brace initiation and weaning at a more precise timing. Among Risser stage 0, the appearance of R6, U5, and SS3 provide the most effective assessment of peak growth that can indicate the most effective bracing period within which curve progression occurs. For initiation of the growth plateau, Risser 4 is not useful, and SS6/7, R8/9 and U7/8 should be used instead.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Postembryonic screen for mutations affecting spine development in zebrafish

The spine gives structural support for the adult body, protects the spinal cord, and provides muscle attachment for moving through the environment. The development and maturation of the spine and its physiology involve the integration of multiple musculoskeletal tissues including bone, cartilage, and fibrocartilaginous joints, as well as innervation and control by the nervous system. One of the most common disorders of the spine in human is adolescent idiopathic scoliosis (AIS), which is characterized by the onset of an abnormal lateral curvature of the spine of <10° around adolescence, in otherwise healthy children. The genetic basis of AIS is largely unknown. Systematic genome-wide mutagenesis screens for embryonic phenotypes in zebrafish have been instrumental in the understanding of early patterning of embryonic tissues necessary to build and pattern the embryonic spine. However, the mechanisms required for postembryonic maturation and homeostasis of the spine remain poorly understood. Here we report the results from a small-scale forward genetic screen for adult-viable recessive and dominant zebrafish mutations, leading to overt morphological abnormalities of the adult spine. Germline mutations induced with N-ethyl N-nitrosourea (ENU) were transmitted and screened for dominant phenotypes in 1229 F1 animals, and subsequently bred to homozygosity in F3 families; from these, 314 haploid genomes were screened for adult-viable recessive phenotypes affecting general body shape. We cumulatively found 40 adult-viable (3 dominant and 37 recessive) mutations each leading to a defect in the morphogenesis of the spine. The largest phenotypic group displayed larval onset axial curvatures, leading to whole-body scoliosis without vertebral dysplasia in adult fish. Pairwise complementation testing of 16 mutant lines within this phenotypic group revealed at least 9 independent mutant loci. Using massively-parallel whole genome or whole exome sequencing and meiotic mapping we defined the molecular identity of several loci for larval onset whole-body scoliosis in zebrafish. We identified a new mutation in the skolios/kinesin family member 6 (kif6) gene, causing neurodevelopmental and ependymal cilia defects in mouse and zebrafish. We also report multiple recessive alleles of the scospondin and a disintegrin and metalloproteinase with thrombospondin motifs 9 (adamts9) genes, which all display defects in spine morphogenesis. Our results provide evidence of monogenic traits that are essential for normal spine development in zebrafish, that may help to establish new candidate risk loci for spine disorders in humans.

Growth and derived life-history characteristics of the Brazilian electric ray Narcine brasiliensis

The majority of batoids are listed as Threatened (20.4%) or Data Deficient (41%) by the IUCN Red List. A key challenge to assessing Data-Deficient species is obtaining estimates of key life-history characteristics. Here, a Bayesian approach was used to estimate derived life-history characteristics from a growth model applied to the Data-Deficient Brazilian electric ray Narcine brasiliensis. The age of 170 specimens (107 females, 63 males) was estimated from vertebral centra, and total length, disc width, total weight and birth size were used in a joint estimation of sex-specific length-weight models and two-dimensional von Bertalanffy growth models. Estimates of age at length zero, age at maturity, longevity and mortality at age were derived simultaneously. The Bayesian joint modelling approach was robust to small sample sizes by adding a likelihood to constrain L₀ and sharing parameters, such as Brody growth coefficient between length measurements. The median growth parameter estimates were a shared L₀ = 38.8 mm, female L_∞ = 515 mm, 𝑘 = 0.125 and male L_∞ = 387 mm, 𝑘 = 0.194. Age at maturity was estimated to be 7.40-7.49 years for females and 4.45-4.47 years for males, whereas longevity was 22.5-22.6 years for females and 14.2 years for males depending on length measurement. Age-1 natural mortality was estimated to be 0.199-0.207 for females and 0.211-0.213 for males. The derived life-history characteristics indicate N. brasiliensis is earlier maturing, but slower growing relative to other Torpediniformes. These characteristics along with the species' endemism to southern Brazil and high by-catch rates indicate that one of the IUCN Red List threatened categories may be more appropriate for the currently Data-Deficient status. The Bayesian approach used for N. brasiliensis can prove useful for utilizing limited age-growth data in other Data-Deficient batoid species to inform necessary life characteristics for conservation and management.

Vertebral growth and band-pair deposition in sexually mature little skates Leucoraja erinacea: is adult band-pair deposition annual?

Mature male and female little skates Leucoraja erinacea were injected with oxytetracycline and maintained in captivity for 13 months to assess centrum growth and the frequency of band-pair deposition. Sixty per cent of the individuals analysed did not deposit a full band pair over the 13 month period. Thus, a majority of captive skates did not exhibit annual band-pair deposition. Previous research confirms annual band-pair deposition in all juvenile and most adult L. erinacea, therefore sexual maturation may lead to decreased frequency of band-pair formation. Age underestimation of larger, older elasmobranchs is being identified in an increasing number of elasmobranch species including L. erinacea as demonstrated in this study. The effect of age underestimation from band-pair counts on studies that use age-based characteristics needs to be addressed.

Age and growth of three endemic threatened guitarfishes Pseudobatos horkelii, P. percellens and Zapteryx brevirostris in the western South Atlantic Ocean

The age and growth of three endemic threatened guitarfish species were analysed using vertebrae of Pseudobatos horkelii, P. percellens and Zapteryx brevirostris. Edge and marginal-increment analyses were used to evaluate the periodicity of the formation of the band-pairs, suggesting deposition of one band-pair per year, from late winter to late spring. The von Bertalanffy growth model was used to describe the growth of these species with the following parameters, for pooled sexes: P. horkelii L_∞ = 126.93, k = 0.19 and t₀ = -1.51; P. percellens L_∞ = 109.31, k = 0.16 and t₀ = -1.78; Z. brevirostris L_∞ = 60.37, k = 0.24 and t₀ = -1.42. Our results are essential to understanding the resilience and vulnerability of these species to harvest, which can contribute to management and conservation actions of these species.

Periodicity of the growth-band formation in vertebrae of juvenile scalloped hammerhead shark Sphyrna lewini from the Mexican Pacific Ocean

The age of 296 juvenile scalloped hammerhead sharks Sphyrna lewini caught by several fisheries in the Mexican Pacific Ocean from March 2007 to September 2017 were estimated from growth band counts in thin-sectioned vertebrae. Marginal-increment analysis (MIA) and centrum-edge analysis (CEA) were used to verify the periodicity of formation of the growth bands, whereas elemental profiles obtained from LA-ICP-MS transect scans in vertebrae of 15 juveniles were used as an alternative approach to verify the age of the species for the first time. Age estimates ranged from 0 to 10+ years (42-158.7 cm total length; L_T ). The index of average percentage error (I_APE 3.6%), CV (5.2%), bias plots and Bowker's tests of symmetry showed precise and low-biased age estimation. Both MIA and CEA indicated that in the vertebrae of juveniles of S. lewini a single translucent growth band was formed during winter (November-March) and an opaque band during summer (July-September), a period of faster growth, apparently correlated with a higher sea surface temperature. Peaks in vertebral P and Mn content spatially corresponded with the annual banding pattern in most of the samples, displaying 1.19 and 0.88 peaks per opaque band, respectively, which closely matched the annual deposition rate observed in this study. Although the periodicity of growth band formation needs to be verified for all sizes and ages representing the population of the species in the region, this demonstration of the annual formation of the growth bands in the vertebrae of juveniles should lead to a re-estimation of the growth parameters and productivity of the population to ensure that it is harvested at sustainable levels.

Distraction-Based Surgeries Increase Spine Length for Patients With Nonidiopathic Early-Onset Scoliosis-5-Year Follow-up

STUDY DESIGN

Retrospective, comparative.

OBJECTIVES

To determine if distraction-based surgeries will increase spine length in patients with nonidiopathic EOS and whether etiology affects final spine length.

SUMMARY OF BACKGROUND DATA

As early-onset scoliosis (EOS) has many etiologies, it is unclear whether etiology affects the spine length achieved with distraction-based surgeries. Since distraction may produce kyphosis, sagittal spine length (SSL; curved arc length of the spine in the sagittal plane) should be utilized.

METHODS

Patients with nonidiopathic EOS treated with distraction-based systems (minimum 5-year follow-up, 5 lengthenings) were identified from two EOS registries. Radiographic analysis preoperation, postimplant (L1), and after each lengthening (L2-L5, L6-L10, L11-L15) was performed with primary outcome of T1-S1 SSL.

RESULTS

We identified 126 patients (67 congenital, 38 syndromic, 21 neuromuscular) with a mean preoperative age of 4.6 years, scoliosis 75°, kyphosis 48°, and a mean of 12 lengthenings. After initial correction (p < .05), scoliosis remained constant (58° at L11-L15) and kyphosis increased (38° at L1 to 60° at L11-L15) (p < .05). SSL increased for the entire group from 27.1 cm preoperation to 35.3 cm at L11-L15 (p < .05) and during the distraction phase (29.2 cm at L1 to 35.3 cm at L11-L15) (p < .05). Preoperative SSL was higher in neuromuscular compared with congenital patients and maintained that difference until the 10th lengthening. Preoperative SSL did not differ between syndromic and congenital patients (28.0 cm vs. 25.6 cm); however, syndromic patients had greater SSL after implantation (L1: 30.5 cm vs. 26.8 cm) (p < .05) and maintained that difference until the 15th lengthening (37.1 cm vs. 34.3 cm) (p < .05).

CONCLUSION

At minimum 5-year follow-up, distraction-based surgeries increased spine length for all patients with nonidiopathic EOS; however, neuromusculars had higher preoperative spine length compared with congenital patients and maintained that difference until the 10th lengthening. Although congenital and syndromic patients had similar preoperative spine length, syndromic patients had greater SSL after implantation (L1) and maintained that difference until the 15th lengthening.

LEVEL OF EVIDENCE

Level III.

Altered vertebral and femoral bone structure in juvenile offspring of microswine subject to maternal low protein nutritional challenge

Epidemiological studies suggest skeletal growth is programmed during intrauterine and early postnatal life. We hypothesize that bone development may be altered by maternal diet and have investigated this using a microswine model of maternal protein restriction (MPR). Mothers were fed a control diet (14% protein) or isocaloric low (1%) protein diet during late pregnancy and for 2 weeks postnatally. Offspring were weaned at 4 weeks of age to ad lib or calorie-restricted food intake groups. Femur and vertebra were analysed by micro computed tomography in offspring 3-5 months of age. Caloric restriction from 4 weeks of age, designed to prevent catch-up growth, showed no significant effects on bone structure in the offspring from either maternal dietary group. A maternal low protein diet altered trabecular number in the proximal femur and vertebra in juvenile offspring. Cortical bone was unaffected. These results further support the need to understand the key role of the nutritional environment in early development on programming of skeletal development and consequences in later life.

[Etiology and significance of growth disturbances of the spine]

BACKGROUND

The majority of growth disturbances of the spine are acquired and their etiology is still unknown. Both scolioses and sagittal profile disorders are most commonly of idiopathic origin.

ETIOLOGY

The etiology is multifactorial and besides genetic, hormonal and mechanical factors also metabolic components seem to be involved. The risk of progression of an existing deformity is particularly high during the pubertal growth spurt. Accordingly, regular clinical and radiological controls should be carried out in this vulnerable period. Recently, spinal deformities have been classified according to the time of diagnosis rather than according to their etiology, considering the increasing knowledge about the correlation between spinal and thoracic growth and the associated maturation of the lungs. Therefore, the term "early onset scoliosis" considers all deformities of the spine diagnosed before the age of 10 years.

TREATMENT

In the case of failure of conservative treatment options, which have to be applied for as long as possible, definitive spinal fusion surgery should be delayed by the use of growth-sparing surgical techniques, aiming to achieve as normal pulmonary function as possible.

A comparison of growth among growth-friendly systems for scoliosis: a systematic review

BACKGROUND CONTEXT

The optimal method for surgical treatment of early onset scoliosis is currently unknown. Although the aim of growth-friendly systems is to reduce the curve and maintain growth, there is no consensus on how to measure spinal growth during and after the treatment. Different measurements of different segments (T1-S1, T1-T12, instrumented length) are used for different time points to evaluate growth. The aim of this review is to assess what measurements are used and to compare the growth-friendly systems based on spinal growth during treatment.

METHODS

The electronic MEDLINE, EMBASE, and Cochrane databases were systematically searched for original articles that reported growth for traditional growing rods (TGR), vertical expandable prosthetic titanium rib expansion technique (VEPTR), Shilla, magnetically controlled growing rods (MCGR), and Luque-trolley systems. All measurements were recorded, and weighted averages calculated in centimeter per year were compared.

RESULTS

We included 52 studies (26 TGR, 12 MCGR, 6 VEPTR, 4 Luque trolley, 1 Shilla, and 3 mixed). Often only one segment was reported (T1-S1 length in 22 studies, T1-T12 length in two studies, and instrumented length in five studies). The remaining 22 studies reported T1-S1 length in combination with T1-T12 length (15 studies) or instrumented length (eight studies). Spinalgrowth achieved by initial correction only was a considerable 3.9 cm (based on 34 studies) as well as the spinal growth achieved by the final fusion surgery (2.3 cm in four studies). To specifically assess growth achieved with the system, length gain after initial surgery and before final fusion in growth system graduates was considered. Only four TGR studies reported on this "true" spinal growth with 0.6 and 0.3 cm/y in the T1-S1 and T1-T12 segment, respectively.

CONCLUSIONS

Reporting on spinal growth is currently inadequate and does not allow a good comparison of different techniques. However, all systems often report growth similar to Dimeglio's T1-S1 spinal growth of 1 cm/y. It should be recognized though that a considerable portion of the reported spinal growth is the result of the initial and final surgical correction and not due to the growth-friendly implant.

Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil

We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.0 cm disc width; W_D ) and 101 were female (13.0 to 88.5 cm W_D ); females were significantly larger than males. Cross sections of vertebrae showed band-pairs ranging from 0 to > 14 in females and from 0 to 9 in males. New-borns presented an opaque edge at birth in vertebrae without a birthmark. The average percentage of error (APE; %E) for the entire sample provided evidence that ages were repeatable. The mean monthly marginal increment (I_M ) indicates annual band-pair formation from August to November. The annual cycle model for one band-pair deposition provided the best fit to data based on the AIC, with peaks between August and October, similar to that found in the I_M analysis, suggesting an annual formation pattern. A multi-model approach that included four models based on the observed mean W_D at age indicated a modified von Bertalanffy growth model as the best for describing the species growth: W₀ (W_D at birth) = 14.6 cm for both sexes; females W_∞ = 98.61 cm (95% CI = 87.34-114.61 cm); k = 0.112 year^-1 (CI = 0.086-0.148 year^-1 ); males W_∞ = 60.22 cm (CI = 55.66-65.35 cm); k = 0.219 year^-1 (CI = 0.185-0.276 year^-1 ). The age-at-maturity in males and females is 5 years and 7 years, respectively. The age composition shows that most (84%) specimens were aged 0 to 2 years. The information provided here is essential for analytical assessments of H. guttatus, which is subject to significant fishing pressure mainly on new-borns and juveniles.

Achievement of Guided Growth in Children With Low-Tone Neuromuscular Early-Onset Scoliosis Using a Segmental Sublaminar Instrumentation Technique

OBJECTIVES/SUMMARY OF BACKGROUND DATA

Segmental sublaminar spinal instrumentation without fusion results in guided growth and correction of deformity in early-onset scoliosis (EOS). The purpose of this study is to report the outcomes of a series of children with low-tone EOS that were treated surgically with a modification of a Luque trolley technique.

METHODS

This study is a retrospective chart and radiographic review of a single-center series of 13 consecutive children who met inclusion criteria with documented progression of scoliosis greater than 25°. All children received surgical treatment with guided growth without fusion using a modified Luque trolley technique. The children's preoperative, postoperative, and most recent radiographs were assessed for Cobb angle, T1-T12 and T1-S1 height, and sagittal alignment including proximal junctional kyphosis. Surgimap spine software was used for calibration and measurement purposes. Complications and need for repeat and/or secondary surgical procedures were recorded.

RESULTS

The mean age at surgery was 7.4 years (4.6-10.5). On average, 15 segments (13-16) were instrumented. None of the children went on to a spontaneous fusion, and the average growth rate per year from T1-T12 and T1-S1 was 0.9 cm/y and 1.5 cm/y, respectively. The mean total growth from T1-T12 and T1-S1 was 22.3 cm (16.6-30.2) and 37.5 cm (30.1-46.4). A total of three additional surgeries were needed in two children to address complications. There were no mortalities.

CONCLUSIONS

Sublaminar guided growth is a safe and effective treatment in the Low Tone Neuromuscular subset of EOS. Follow-up studies failed to show signs of auto fusion, and implant failure was not observed in our cohort. All children displayed growth postoperatively without the need for multiple distraction-based surgeries. Guided growth minimizes the risks associated with multiple surgical procedures while maintaining correction and allowing for near-normal rates of spinal growth.

Complications of Fusionless Correction of Early Onset Scoliosis Using Dual Growing Rods

BACKGROUND

Growing rods are increasingly used for treatment of early onset scoliosis (EOS) worldwide. Beside promising outcomes, some authors are concerned about high rates of complications. In the current clinical trial, complications of EOS surgery using dual growing rods were investigated.

METHODS

Between June 2006 and February 2017, twenty-two consecutive patients with a coronal curve >45 degrees underwent serial surgical correction using dual growing rods at Shafa Orthopedic hospital, Tehran, I.R. Iran. The rods were secured using hooks or screws or both. The patients were followed for 5.2 ± 1.7 years on average. Wilcoxon test was utilized to compare the pre- and post-operative values. P < 0.05 was considered significant.

RESULTS

The scoliotic and kyphotic curves decreased significantly from 52 ± 24° to 38 ± 19° and from 78 ± 22° to 60 ± 17°, respectively (P < 0.001). Total rate of implant-related complications (IRCs) and surgical site complications (SSCs) were 54.5% (12 patients) and 22.7% (5 patients), respectively. Malpositioned pedicular screw was found in 2 patients.

CONCLUSION

EOS can be effectively corrected using dual growing rods, however, considerable rates of IRC are of concern (54.5%). It seems necessary to compare the efficacy and complication rate of newer devices with those of growing rods in future studies.

Can early-life growth disruptions predict longevity? Testing the association between vertebral neural canal (VNC) size and age-at-death

This study tests the association of vertebral neural canal (VNC) size and age-at-death in a Portuguese skeletal collection from the 19^th-20th century. If the plasticity and constraint model best explains this association, VNC size would be negatively related to mortality risk. If the predictive adaptive response (PAR) model is a better fit, no association can be inferred between VNC size and age-at-death. Ninety individuals were used in this study. The anteroposterior and transverse diameters of all vertebrae were measured. A Cox regression analysis was performed by sex to assess the effect of VNC size on age-at-death, after adjusting for the effects of year of birth and cause of death. Several measurements of VNC diameters have a statistically significant effect on age-at-death, but when the covariates were considered, this association became non-significant. The PAR model seems the best fit to explain the relation between VNC and age-at-death. Individuals who went through stressful events early in life were prepared to face a stressful environment later in life, allowing them to cope with adversity without affecting longevity. However, developmental plasticity may be buffered by maternal capital accumulated over several generations, and health hazards encountered throughout life can contribute to health outcomes and longevity.

Prevalence of spinal abnormalities in Chinook salmon smolt and influence of early rearing temperature and growth rates

Spinal abnormalities can be detected at harvest in around 40% of farmed Chinook salmon in New Zealand. However, whether these abnormalities are present in smolt is unknown. Radiographs of 3,736 smolt were taken immediately prior to transfer to sea water and evaluated for fusions, compressions, vertical shifts, and lordosis, kyphosis and/or scoliosis (LKS). The survey included smolt from two different chilling strategies that had been graded into slow- or fast-growing fish. Overall, 4.34% of Chinook salmon smolt had at least one spinal abnormality, similar to the rates of reported in Atlantic salmon smolt. The rate of abnormality was significantly higher in faster-growing fish. Fusions were most common with 2.68% of smolt affected. Smolt subjected to longer chilling times had lower rates of fusions. Compressions and vertical shifts were both observed in 1.31% of smolt. Although LKS is the most common abnormality of harvested fish, LKS was detected in just five smolt. The results suggest that some fusions in harvest fish have developed at the time of seawater transfer while LKS develops late in the production cycle. Overall, spinal abnormalities are uncommon in Chinook salmon smolt and may be influenced by chilling times and growth rates.

Systematic review of the complications associated with magnetically controlled growing rods for the treatment of early onset scoliosis

PURPOSE

To analyse the complication profile of magnetically controlled growing rods (MCGRs) in early onset scoliosis (EOS).

METHODS

This is a systematic review using PUBMED, Medline, Embase, Google Scholar and the Cochrane Library (keywords: MAGEC, Magnetically controlled growing rods and EOS) of all studies written in English with a minimum of five patients and a 1-year follow-up. We evaluated coronal correction, growth progression (T1-S1, T1-T12) and complications.

RESULTS

Fifteen studies (336 patients) were included (42.5% male, mean age 7.9 years, average follow-up 29.7 months). Coronal improvement was achieved in all studies (pre-operative 64.8°, latest follow-up 34.9° p = 0.000), as was growth progression (p = 0.001). Mean complication rate was 44.5%, excluding the 50.8% medical complication rate. The unplanned revision rate was 33%. The most common complications were anchor pull-out (11.8%), implant failure (11.7%) and rod breakage (10.6%). There was no significant difference between primary (39.8%) and conversion (33.3%) procedures (p = 0.462). There was a non-statistically significant increased complication rate with single rods (40 vs. 27% p = 0.588).

CONCLUSIONS

MCGRs improve coronal deformity and maintain spinal growth, but carry a 44.5% complication and 33% unplanned revision rate. Conversion procedures do not increase this risk. Single rods should be avoided. These slides can be retrieved under Electronic Supplementary material.

Development and Involution of the Notochord in the Human Spine

The availability of a collection of fetal and embryonic spines made possible a review of the involution of the notochord. Results of this histological, histochemical and immunohistochemical study are in accord with the dominant view in the literature that the notochord does not contribute materially to the adult nucleus pulposus. It is also consonant with the expectation that, normally, all chordal cells have disappeared during early childhood, but is not sufficiently detailed to assess the possibility of occasional survivors.

Factors affecting estimates of size at age and growth in grey triggerfish Balistes capriscus from the northern Gulf of Mexico

Growth zones in dorsal spines of grey triggerfish Balistes capriscus from the northern Gulf of Mexico were utilized to estimate growth and examine factors that may affect estimates of size at age. Age was estimated from dorsal-spine sections of 4687 individuals sampled from U.S. waters during 2003-2013, including both fishery-independent (n = 1312) and fishery-dependent (n = 3375) samples. Ninety-six per cent (n = 4498) of these sections were deemed suitable for ageing; average per cent error between two independent readers was 10·8%. Fork length (L_F ) ranged from 65 to 697 mm and age estimates from 0 to 14 years. Both sex and sample source (fishery-independent v. recreational) significantly affected estimated size at age for 2-6 year-old fish. Data were pooled between sources to fit sex-specific von Bertalanffy growth functions. Results for the female model were L_∞  = 387 mm L_F , k = 0·52 year^-1 and t₀  = 0·01 year, while for males L_∞  = 405 mm L_F , k = 0·55 year^-1 and t₀  = 0·02 year. These results were significantly different between sexes and indicate clear sexual dimorphism. Thus, growth should be modelled separately by sex when examining population parameters or conducting stock assessment modelling. The positive bias in estimates of size at age computed for recreational v. fishery-independent samples also has clear implications for stock assessment as growth functions computed with fishery-dependent samples would tend to overestimate stock productivity.

Curve Progression in Adolescent Idiopathic Scoliosis Does Not Match Skeletal Growth

BACKGROUND

Determining the peak growth velocity of a patient with adolescent idiopathic scoliosis (AIS) is important for timely treatment to prevent curve progression. It is important to be able to predict when the curve-progression risk is greatest to maximize the benefits of any intervention for AIS. The distal radius and ulna (DRU) classification has been shown to accurately predict skeletal growth. However, its utility in predicting curve progression and the rate of progression in AIS is unknown.

QUESTIONS/PURPOSES

(1) What is the relationship between radius and ulna grades to growth rate (body height and arm span) and curve progression rate? (2) When does peak curve progression occur in relation to peak growth rate as measured by months and by DRU grades? (3) How many months and how many DRU grades elapse between peak curve progression and plateau?

METHODS

This was a retrospective analysis of a longitudinally maintained dataset of growth and Cobb angle data of patients with AIS who presented with Risser Stages 0 to 3 and were followed to maturity at Risser Stage 5 at a single institute with territory-wide school screening service. From June 2014 to March 2016, a total of 513 patients with AIS fulfilled study inclusion criteria. Of these, 195 were treated with bracing at the initial presentation and were excluded. A total of 318 patients with AIS (74% girls) with a mean age of 12 ± 1.5 years were studied. For analysis, only data from initial presentation to commencement of intervention were recorded. Data for patients during the period of bracing or after surgery were not used for analysis to eliminate potential interventional confounders. Of these 318 patients, 192 were observed, 119 were braced, and seven underwent surgery. Therefore 192 patients (60.4%) who were observed were followed up until skeletal maturity at Risser Stage 5; no patients were lost to followup. The mean curve magnitude at baseline was 21.6 ± 4.8. Mean followup before commencing intervention or skeletal maturity was 4.3 ± 2.3 years. Standing body height, arm span, curve magnitude, Risser stage, and DRU classification were studied. A subgroup analysis of 83 patients inclusive of acceleration, peak, and deceleration progression phases for growth and curve progression was studied to determine any time lag between growth and curve progression. Results were described in mean ± SD.

RESULTS

There was positive correlation between growth rate and curve progression rate for body height (r = 0.26; p < 0.001) and arm span (r = 0.26; p < 0.001). Peak growth for body height occurred at radius grade (R) 6 (0.56 ± 0.29 cm/month) and ulna grade (U) 4 (0.65 ± 0.31 cm/month); peak change in arm span occurred at R5 (0.67 ± 0.33 cm/month) and U3 (0.67 ± 0.22 cm/month); and peak curve progression matched with R7 (0.80 ± 0.89 cm/month) and U5 (0.84 ± 0.78 cm/month). Subgroup analysis confirmed that peak curve progression lagged behind peak growth rate by approximately 7 months or one DRU grade. The mean time elapsed between the peak curve progression rate and the plateau phase at R9 U7 was approximately 16 months, corresponding to two DRU grades.

CONCLUSIONS

By using a standard skeletal maturity parameter in the DRU classification, this study showed that the maximal curve progression occurs after the peak growth spurt, suggesting that the curve should be monitored closely even after peak growth. In addition, the period of potential curve continuing progression extends nearly 1.5 years beyond the peak growth phase until skeletal maturity. Future studies may evaluate whether by observing the trend of growth and curve progression rates, we can improve the outcomes of interventions like bracing for AIS.

LEVEL OF EVIDENCE

Level II, prognostic study.

Vertebral cross-sectional growth: A predictor of vertebral wedging in the immature skeleton

The degree of vertebral wedging, a key structural characteristic of spinal curvatures, has recently been found to be negatively related to vertebral cross-sectional area (CSA). The purpose of this longitudinal study was to examine the relation between vertebral cross-sectional growth and vertebral wedging progression within the immature lumbar spine. Using magnetic resonance imaging (MRI), we analyzed the potential association between increases in lumbar vertebral CSA and changes in L5 vertebral wedging in 27 healthy adolescent girls (ages 9–13 years) twice within a two-year period. Vertebral CSA growth was negatively associated with changes in posteroanterior vertebral wedging (r = -0.61; p = 0.001). Multiple regression analysis showed that this relation was independent of gains in age, height, and weight. When compared to the 14 girls whose vertebral wedging progressed, the 13 subjects whose vertebral wedging decreased had significantly greater vertebral cross-sectional growth (0.39 ± 0.25 vs. 0.75 ± 0.23 cm²; p = 0.001); in contrast, there were no significant differences in increases in age, height, or weight between the two groups. Changes in posteroanterior vertebral wedging and the degree of lumbar lordosis (LL) positively correlated (r = 0.56, p = 0.002)—an association that persisted even after adjusting for gains in age, height, and weight. We concluded that in the immature skeleton, vertebral cross-sectional growth is an important determinant of the plasticity of the vertebral body; regression of L5 vertebral wedging is associated with greater lumbar vertebral cross-sectional growth, while progression is the consequence of lesser cross-sectional growth.

Ontogeny of the Postcranial Axial Skeleton of Melanosuchus niger (Crocodylia, Alligatoridae)

This study proposes the description of the development of the postcranial axial skeleton, including vertebrae, gastralium, ribs, sternum, and interclavicle, in Melanosuchus niger. Six nests were marked and two eggs removed from each nest at 24-hr intervals until hatching. For posthatching evaluation, 30 hatchlings were kept in captivity and one exemplar was euthanized at three-day intervals. Samples were diaphanized using potassium hydroxide (KOH), alizarin red S, and Alcian blue. A routinely generally used method was applied for histological evaluation. It was difficult to define in which vertebrae the development of cartilaginous centers began, but it was possible to observe that this condensation advanced in the craniocaudal direction. The condensation started in the vertebral arches and was visibly stronger in the cervical and dorsal regions, advancing to the lumbar, sacral and, last, to the caudal region. The atlas showed a highly different morphology compared with the other cervical vertebrae, with a short intercenter, two neural arches, and a proatlas. The ossification process began in the body of cervical vertebrae III to VIII and alizarin retention decreased in the last vertebrae, indicating a craniocaudal direction in bone development, similar to cartilage formation. In the histological sections of gastralium and interclavicles of M. niger at several development stages, it was possible to observe that these elements showed intramembranous development. Anat Rec, 301:607-623, 2018. © 2017 Wiley Periodicals, Inc.

Vertebral column regionalisation in Chinook salmon, Oncorhynchus tshawytscha

Teleost vertebral centra are often similar in size and shape, but vertebral-associated elements, i.e. neural arches, haemal arches and ribs, show regional differences. Here we examine how the presence, absence and specific anatomical and histological characters of vertebral centra-associated elements can be used to define vertebral column regions in juvenile Chinook salmon (Oncorhynchus tshawytscha). To investigate if the presence of regions within the vertebral column is independent of temperature, animals raised at 8 and 12 °C were studied at 1400 and 1530 degreedays, in the freshwater phase of the life cycle. Anatomy and composition of the skeletal tissues of the vertebral column were analysed using Alizarin red S whole-mount staining and histological sections. Six regions, termed I-VI, are recognised in the vertebral column of specimens of both temperature groups. Postcranial vertebrae (region I) carry neural arches and parapophyses but lack ribs. Abdominal vertebrae (region II) carry neural arches and ribs that articulate with parapophyses. Elastic- and fibrohyaline cartilage and Sharpey's fibres connect the bone of the parapophyses to the bone of the ribs. In the transitional region (III) vertebrae carry neural arches and parapophyses change stepwise into haemal arches. Ribs decrease in size, anterior to posterior. Vestigial ribs remain attached to the haemal arches with Sharpey's fibres. Caudal vertebrae (region IV) carry neural and haemal arches and spines. Basidorsals and basiventrals are small and surrounded by cancellous bone. Preural vertebrae (region V) carry neural and haemal arches with modified neural and haemal spines to support the caudal fin. Ural vertebrae (region VI) carry hypurals and epurals that represent modified haemal and neural arches and spines, respectively. The postcranial and transitional vertebrae and their respective characters are usually recognised, but should be considered as regions within the vertebral column of teleosts because of their distinctive morphological characters. While the number of vertebrae within each region can vary, each of the six regions is recognised in specimens of both temperature groups. This refined identification of regionalisation in the vertebral column of Chinook salmon can help to address evolutionary developmental and functional questions, and to support applied research into this farmed species.

Skeletal ontogeny of the vertebral column and of the fins in shi drum Umbrina cirrosa (Teleostei: Perciformes: Sciaenidae), a new candidate species for aquaculture

The osteological development of the vertebral column and fins in shi drum Umbrina cirrosa was studied in order to improve knowledge for its introduction in Mediterranean aquaculture. The osteological development was studied in 171 individuals, of total length (L_T ) from 2·7 to 30·2 mm that were reared under the mesocosm technique. Vertebral ontogeny starts at 3·4 and 4·0 mm L_T , with the formation of the first cartilaginous neural and haemal arches, and spines, respectively, and is completed with the full attainment of epicentrals (12·5 mm L_T ). The formation of vertebral centra occurs between 4·1 and 7·4 mm L_T . Pectoral supports are the first fin elements to develop (3·0 mm L_T ), followed by those of the caudal fin (3·8 mm L_T ), pelvic fin (3·9 mm L_T ) and finally by those of the dorsal and anal fins (4·5 mm L_T ). The caudal fin is the first to develop fin rays and attain the full count of principal fin rays (4·5-6·8 mm L_T ), but the last to be fully completed with the formation of procurrent fin rays (6·9-17·5 mm L_T ). The next fins starting to present rays are the dorsal (5·3 mm L_T ) and the pectoral fins (5·6 mm L_T ), while the anal and pelvic fins are the last (5·7 mm L_T ). Following the caudal principal fin rays (6·8 mm L_T ), the dorsal, anal (6·9 mm L_T ), pelvic (7·4 mm L_T ) and pectoral fins (9·8 mm L_T ) are the next with fully completed ray counts. Aggregation of qualitative changes, such as the appearance of cartilages, the beginning and the complement of the ossification process and the full complement of elements in U. cirrosa were measured as cumulative frequency counts. These measurements reveal three ontogenetic intervals: one very developmentally active period during early life stages (from 3 to 5·9 mm L_T ), a second slower developmental period (from 6·0 to 8·9 mm L_T ) and finally a period of ontogeny more focused on structure refinement up to metamorphosis and settlement (>9·0 mm L_T ).

Age and Growth of Elasmobranchs and Applications to Fisheries Management and Conservation in the Northeast Pacific Ocean

In addition to being an academic endeavour, the practical purpose of conducting age and growth studies on fishes is to provide biological data to stock assessment scientists and fisheries managers so they may better understand population demographics and manage exploitation rates. Age and size data are used to build growth models, which are a critical component of stock assessments. Though age determination of elasmobranchs in the northeast Pacific Ocean (NEP) began in the 1930s, the field has evolved substantially in recent years, allowing scientists to incorporate age data into assessments for more species than ever before. Owing to the highly diverse biology of this group of fishes, each species has its own set of challenges with regard to age determination. Age determination methods typically rely on semicalcified hard structures that form regular growth patterns; however, the structure selected and preparation method used is often species specific. New staining techniques have improved the ability to assess age and improve ageing precision for some species, and advances in microchemical methods have allowed for independent means of estimating age and validating age determination accuracy. Here we describe current age determination methods for NEP elasmobranchs. While the library of available techniques is increasing, there are still some NEP species for which reliable ageing methods have yet to be defined; we discuss these challenges and potential avenues of future research. Finally, we conclude by describing how age estimates are used in growth models and subsequently in stock assessments of selected NEP elasmobranchs.

Sequential Magnetic Resonance Imaging Reveals Individual Level Deformities of Vertebrae and Discs in the Growing Scoliotic Spine

STUDY DESIGN

The aim of this study was to measure contributions of individual vertebra and disc wedging to coronal Cobb angle in the growing scoliotic spine using sequential magnetic resonance imaging (MRI). Clinically, the Cobb angle measures the overall curve in the coronal plane but does not measure individual vertebra and disc wedging. It was hypothesized that patients whose deformity progresses will have different patterns of coronal wedging in vertebrae and discs to those of patients whose deformities remain stable.

METHODS

A group of adolescent idiopathic scoliosis (AIS) patients each received two to four MRI scans (spaced 3-12 months apart). The coronal plane wedge angles of each vertebra and disc in the major curve were measured for each scan, and the proportions and patterns of wedging in vertebrae and discs were analyzed for subgroups of patients whose spinal deformity did and did not progress during the study period.

RESULTS

Sixteen patients were included in the study; the mean patient age was 12.9 years (standard deviation 1.7 years). All patients were classified as right-sided major thoracic Lenke Type 1 curves (9 type 1A, 4 type 1B, and 3 type 1C). Cobb angle progression of ≥5° between scans was seen in 56% of patients. Although there were measurable changes in the wedging of individual vertebrae and discs in all patients, there was no consistent pattern of deformity progression between patients who progressed and those who did not. The patterns of progression found in this study did not support the hypothesis of wedging commencing in the discs and then transferring to the vertebrae.

CONCLUSION

Sequential MRI data showed complex patterns of deformity progression. Changes to the wedging of individual vertebrae and discs may occur in patients who have no increase in Cobb angle; therefore, the Cobb method alone may be insufficient to capture the complex mechanisms of deformity progression.

Developmental mechanisms of macroevolutionary change in the tetrapod axis: A case study of Sauropterygia

Understanding how developmental processes change on macroevolutionary timescales to generate body plan disparity is fundamental to the study of vertebrate evolution. Adult morphology of the vertebral column directly reflects the mechanisms that generate vertebral counts (somitogenesis) and their regionalisation (homeotic effects) during embryonic development. Sauropterygians were a group of Mesozoic marine reptiles that exhibited an extremely high disparity of presacral vertebral/somite counts. Using phylogenetic comparative methods, we demonstrate that somitogenesis and homeotic effects evolved in a co-ordinated way among sauropterygians, contrasting with the wider pattern in tetrapods, in which somitogenetic and homeotic shifts are uncorrelated. Changes in sauropterygian body proportions were primarily enabled by homeotic shifts, with a lesser, but important, contribution from differences in postpatterning growth among somites. High body plan plasticity was present in Triassic sauropterygians and was maintained among their Jurassic and Cretaceous descendants. The extreme disparity in the body plan of plesiosaurian sauropterygians did not result from accelerated rates of evolutionary change in neck length, but instead reflect this ancestral versatility of sauropterygian axial development. Our results highlight variation in modes of axial development among tetrapods, and show that heterogeneous statistical models can uncover novel macroevolutionary patterns for animal body plans and the developmental mechanisms that control them.

Life-history traits of the long-nosed skate Dipturus oxyrinchus

This work investigates life-history traits of the long-nosed skate Dipturus oxyrinchus, which is a common by-catch in Sardinian waters. The reproductive variables were analysed from 979 specimens sampled during scientific and commercial hauls. Females (10·4-117·5 cm total length, L_T ) attained larger sizes than males (14·5-99·5 cm L_T ). To evaluate age and growth, a sub-sample of 130 individuals (76 females and 54 males) were used. The age was estimated by annuli counts of sectioned vertebral centra. Four models were used for the length-at-age data: the von Bertalanffy, the exponential, the Gompertz and the logistic functions. According to the Akaike's information criterion, the Gompertz model seemed to provide the best fitting curve (L_∞ mean ± s.e.: 127·55 ± 4·90 cm, k: 0·14 ± 0·09, IP: 3·97 ± 0·90 years). The oldest female and male were aged 17 (115·5 cm L_T ) and 15 years (96·0 cm L_T ), respectively. Lengths at maturity were 103·5 cm for females and 91·0 cm for males, corresponding to 90% of the maximum observed length in both sexes. The monthly distribution of maturity stages highlighted an extended reproductive cycle, with spawning females and active males being present almost throughout the year, as confirmed by the gonado-somatic index. Ovarian fecundity reached a maximum of 26 yolked follicles with a mean ± s.e. size of 19·7 ± 6·5 mm.

IGF1 neuronal response in the absence of MECP2 is dependent on TRalpha 3

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder in which the MECP2 (methyl CpG-binding protein 2) gene is mutated. Recent studies showed that RTT-derived neurons have many cellular deficits when compared to control, such as: less synapses, lower dendritic arborization and reduced spine density. Interestingly, treatment of RTT-derived neurons with Insulin-like Growth Factor 1 (IGF1) could rescue some of these cellular phenotypes. Given the critical role of IGF1 during neurodevelopment, the present study used human induced pluripotent stem cells (iPSCs) from RTT and control individuals to investigate the gene expression profile of IGF1 and IGF1R on different developmental stages of differentiation. We found that the thyroid hormone receptor (TRalpha 3) has a differential expression profile. Thyroid hormone is critical for normal brain development. Our results showed that there is a possible link between IGF1/IGF1R and the TRalpha 3 and that over expression of IGF1R in RTT cells may be the cause of neurites improvement in neural RTT-derived neurons.

Body composition and bone density reference data for Korean children, adolescents, and young adults according to age and sex: results of the 2009-2010 Korean National Health and Nutrition Examination Survey (KNHANES)

We established the timing of peak bone mass acquisition and body composition maturation and provide an age- and sex-specific body composition and bone density reference database using dual-energy X-ray absorptiometry in Korean subjects 10-25 years of age. Reference percentiles and curves were developed for bone mineral content (BMC), bone mineral density (BMD) of the whole body, the lumbar spine, and the femoral neck, and for fat mass (FM) and lean mass (LM) of 1969 healthy participants (982 males) who participated in the 2009-2010 Korean National Health and Nutrition Examination Survey. Additionally, bone mineral apparent density (BMAD), FM index, and LM index were calculated to adjust for body size. BMC and BMD at all skeletal sites as well as LM increased with age, reaching plateaus at 17-20 years of age in females and 20-23 years of age in males. The femoral neck was the first to reach a bone mass plateau, followed by the lumbar spine and then the whole body. Spine BMAD increased with age in both sexes, but femoral and whole-body BMAD remained the same over time. Females displayed a dramatic increase in FM during puberty, but the FM of males decreased until mid-puberty. These findings indicate that bone health and body composition should be monitored using a normal reference database until the late second to early third decade of life, when statural growth and somatic maturation are completed.

Age and growth of the midwater crocodile shark Pseudocarcharias kamoharai

Age and growth were analysed on the basis of 372 vertebrae from specimens of the crocodile shark Pseudocarcharias kamoharai (66·0-122·0 cm, total length, LT ) collected in the south-western Atlantic Ocean. Centrum edge analysis suggested the first four months of the year as the period of band completion, leading to acceptance of free-living bands as annual. A pre-birth ring is formed in embryos >31·0 cm LT , whereas the birthmark is deposited in newborns of 46·1 ± 1·1 cm LT (mean ± s.d.). Growth was parameterized using seven models and the AIC was used for selection of the most plausible model. The von Bertalanffy growth model received the greatest support from the data, providing the following growth parameters for combined sexes: L∞ = 129·2 cm, k = 0·137 year(-1) and t0 = -3·9 years. No significant differences were detected in growth by sex, but significant differences in age composition by sex were found in the sample. Overall age ranged from 2 to >13 years in females and from 1 to 8 years in males. Males achieved first maturity at 3·1 years and females at 5·1 years, with pregnancy appearing at 4·8 years. Similar to other lamnoid species, P. kamoharai is relatively fast growing.

Vertebral Development in Paleozoic and Mesozoic Tetrapods Revealed by Paleohistological Data

Basal tetrapods display a wide spectrum of vertebral centrum morphologies that can be used to distinguish different tetrapod groups. The vertebral types range from multipartite centra in stem-tetrapods, temnospondyls, and seymouriamorphs up to monospondylous centra in lepospondyls and have been drawn upon for reconstructing major evolutionary trends in tetrapods that are now considered textbook knowledge. Two modes of vertebral formation have been postulated: the multipartite vertebrae formed first as cartilaginous elements with subsequent ossification. The monospondylous centrum, in contrast, was formed by direct ossification without a cartilaginous precursor. This study describes centrum morphogenesis in basal tetrapods for the first time, based on bone histology. Our results show that the intercentra of the investigated stem-tetrapods consist of a small band of periosteal bone and a dense network of endochondral bone. In stereospondyl temnospondyls, high amounts of calcified cartilage are preserved in the endochondral trabeculae. Notably, the periosteal region is thickened and highly vascularized in the plagiosaurid stereospondyls. Among “microsaur” lepospondyls, the thickened periosteal region is composed of compact bone and the notochordal canal is surrounded by large cell lacunae. In nectridean lepospondyls, the periosteal region has a spongy structure with large intertrabecular spaces, whereas the endochondral region has a highly cancellous structure. Our observations indicate that regardless of whether multipartite or monospondylous, the centra of basal tetrapods display first endochondral and subsequently periosteal ossification. A high interspecific variability is observed in growth rate, organization, and initiation of periosteal ossification. Moreover, vertebral development and structure reflect different lifestyles. The bottom-dwelling Plagiosauridae increase their skeletal mass by hyperplasy of the periosteal region. In nectrideans, the skeletal mass decreases, as the microstructure is spongy and lightly built. Additionally, we observed that vertebral structure is influenced by miniaturization in some groups. The phylogenetic information that can be drawn from vertebral development, however, is limited.

TGFβ and BMP Dependent Cell Fate Changes Due to Loss of Filamin B Produces Disc Degeneration and Progressive Vertebral Fusions

Spondylocarpotarsal synostosis (SCT) is an autosomal recessive disorder characterized by progressive vertebral fusions and caused by loss of function mutations in Filamin B (FLNB). FLNB acts as a signaling scaffold by linking the actin cytoskleteon to signal transduction systems, yet the disease mechanisms for SCT remain unclear. Employing a Flnb knockout mouse, we found morphologic and molecular evidence that the intervertebral discs (IVDs) of Flnb^–/–mice undergo rapid and progressive degeneration during postnatal development as a result of abnormal cell fate changes in the IVD, particularly the annulus fibrosus (AF). In Flnb^–/–mice, the AF cells lose their typical fibroblast-like characteristics and acquire the molecular and phenotypic signature of hypertrophic chondrocytes. This change is characterized by hallmarks of endochondral-like ossification including alterations in collagen matrix, expression of Collagen X, increased apoptosis, and inappropriate ossification of the disc tissue. We show that conversion of the AF cells into chondrocytes is coincident with upregulated TGFβ signaling via Smad2/3 and BMP induced p38 signaling as well as sustained activation of canonical and noncanonical target genes p21 and Ctgf. These findings indicate that FLNB is involved in attenuation of TGFβ/BMP signaling and influences AF cell fate. Furthermore, we demonstrate that the IVD disruptions in Flnb^–/–mice resemble aging degenerative discs and reveal new insights into the molecular causes of vertebral fusions and disc degeneration.

Whereas there is a large foundation of knowledge concerning skeletal formation and development, identifying the molecular changes behind Intervertebral Disc (IVD) aging and degeneration has been a challenge. The loss of Filamin B, a protein component of the cell’s cytoskeletal structure, gives rise to Spondylocarpotarsal Synostosis, a rare genetic disorder characterized by fusions of the vertebral bodies. Similarly, mice lacking the Filamin B protein show fusions of the vertebral bodies. We found that these fusions are caused by the early degeneration and eventual ossification of the IVDs. Our study demonstrates that this degeneration is caused by the increase in TGFβ and BMP activity, developmental pathways essential in bone and cartilage formation. These findings represent a significant step forward in our understanding of the molecular basis of IVD degeneration. as well as revealing filamin B’s role in TGFβ/BMP signaling regulation. Moreover, we demonstrate that the study of the rare disease spondylocarpotarsal synostosis in a model organism can uncover mechanisms underlying more common diseases. Finally, our findings provide a model system that will facilitate further discoveries regarding disc degeneration, which affects a significant proportion of the population.

Serial elongation derotation flexion (EDF) casting for patients with infantile and juvenile scoliosis

Infantile and juvenile scoliosis, among different types of spinal deformity, is still a challenge for pediatric orthopedic surgeons. The ideal treatment of infantile and juvenile scoliosis has not yet been identified as both clinicians and surgeons still face multiple challenges, including preservation of the thoracic spine, thoracic cage, lung growth and cardiac function without reducing spinal motion. Elongation, derotation, flexion (EDF) casting technique is a custom-made thoracolumbar cast based on a three dimensional correction concept. This cast offers three-dimensional correction and can control the evolution of the deformity in some cases. Spinal growth can be guided by EDF casting as it can influence the initially curved spine to grow straighter. This article aimed to provide a comprehensive review of how infantile and juvenile scoliosis can affect normal spine and thorax and how these deformities can be treated with serial EDF casting technique. A current literature review is mandatory in order to understand the principles of the serial EDF casting technique and the effectiveness of conservative treatment in young and very young patients.

Estimating growth from tagging data: an application to north-east Atlantic tope shark Galeorhinus galeus

This study addresses the inherent uncertainty when estimating growth from limited mark-recapture information. A selection procedure was developed utilizing 18 competing growth estimation methods. The optimal method for a given data set was identified by simulating the length at capture and recapture under different scenarios of measurement error and growth variability while considering the structure of observed data. This selection procedure was applied to mark-recapture data for 37 female and 16 male tope sharks Galeorhinus galeus obtained from tagging studies in the north-east Atlantic Ocean. Parameter estimates differed strongly among methods, showing the need for careful method selection. The selection approach suggested that best estimates for males and females were given by James' weighted least-squares approach with a fixed asymptote. Given an average total length (LT) at birth of 28 cm, the von Bertalanffy growth function of north-east Atlantic G. galeus would be LT = 200·85 - (200·85 - 28)e(-0·076t) for females and LT = 177·30 - (177·30 - 28)e(-0·081t) for males. The resulting age estimates were up to 11 years lower when compared with previous estimates derived from highly uncertain vertebrae readings. More generally, this procedure can help identify optimal estimation methods for a given data set and therefore aid in estimating more reliable growth parameters from mark-recapture information.

Slow growth of the overexploited milk shark Rhizoprionodon acutus affects its sustainability in West Africa

Age and growth of Rhizoprionodon acutus were estimated from vertebrae age bands. From December 2009 to November 2010, 423 R. acutus between 37 and 112 cm total length (LT ) were sampled along the Senegalese coast. Marginal increment ratio was used to check annual band deposition. Three growth models were adjusted to the length at age and compared using Akaike's information criterion. The Gompertz growth model with estimated size at birth appeared to be the best and resulted in growth parameters of L∞ = 139.55 (LT ) and K = 0.17 year(-1) for females and L∞ = 126.52 (LT ) and K = 0.18 year(-1) for males. The largest female and male examined were 8 and 9 years old, but the majority was between 1 and 3 years old. Ages at maturity estimated were 5.8 and 4.8 years for females and males, respectively. These results suggest that R. acutus is a slow-growing species, which render the species particularly vulnerable to heavy fishery exploitation. The growth parameters estimated in this study are crucial for stock assessments and for demographic analyses to evaluate the sustainability of commercial harvests.

Development of the Synarcual in the Elephant Sharks (Holocephali; Chondrichthyes): Implications for Vertebral Formation and Fusion

The synarcual is a structure incorporating multiple elements of two or more anterior vertebrae of the axial skeleton, forming immediately posterior to the cranium. It has been convergently acquired in the fossil group ‘Placodermi’, in Chondrichthyes (Holocephali, Batoidea), within the teleost group Syngnathiformes, and to varying degrees in a range of mammalian taxa. In addition, cervical vertebral fusion presents as an abnormal pathology in a variety of human disorders. Vertebrae develop from axially arranged somites, so that fusion could result from a failure of somite segmentation early in development, or from later heterotopic development of intervertebral bone or cartilage. Examination of early developmental stages indicates that in the Batoidea and the ‘Placodermi’, individual vertebrae developed normally and only later become incorporated into the synarcual, implying regular somite segmentation and vertebral development. Here we show that in the holocephalan Callorhinchus milii, uniform and regular vertebral segmentation also occurs, with anterior individual vertebra developing separately with subsequent fusion into a synarcual. Vertebral elements forming directly behind the synarcual continue to be incorporated into the synarcual through growth. This appears to be a common pattern through the Vertebrata. Research into human disorders, presenting as cervical fusion at birth, focuses on gene misexpression studies in humans and other mammals such as the mouse. However, in chondrichthyans, vertebral fusion represents the normal morphology, moreover, taxa such Leucoraja (Batoidea) and Callorhinchus (Holocephali) are increasingly used as laboratory animals, and the Callorhinchus genome has been sequenced and is available for study. Our observations on synarcual development in three major groups of early jawed vertebrates indicate that fusion involves heterotopic cartilage and perichondral bone/mineralised cartilage developing outside the regular skeleton. We suggest that chondrichthyans have potential as ideal extant models for identifying the genes involved in these processes, for application to human skeletal heterotopic disorders.

The use of non-adult vertebral dimensions as indicators of growth disruption and non-specific health stress in skeletal populations

OBJECTIVE

Traditional methods of detecting growth disruption have focused on deficiencies in the diaphyseal length of the long bones. This study proposes the implementation of vertebral measurements (body height and transverse diameter of the neural canal) from non-adults (0-17 years) as a new methodology for the identification of growth disruption.

METHODS

Measurements of vertebral body height and transverse diameter were taken from 96 non-adult skeletons and 40 adult skeletons from two post-medieval sites in England (Bow Baptist, London and Coronation Street, South Shields). Non-adult measurements were plotted against dental age to construct vertebral growth profiles through which inter-population comparisons could be made.

RESULTS

Results demonstrated that both sites experienced some growth retardation in infancy, evident as deficiencies in transverse diameter. However, analysis of vertebral body height revealed different chronologies of growth disruption between the sites, with a later age of attainment of skeletal maturity recorded in the Bow Baptist sample.

DISCUSSION

These vertebral dimensions undergo cessation of growth at different ages, with transverse diameter being "locked-in" by ∼1-2 years of age, while vertebral body height may continue to grow into early adulthood. These measurements can therefore provide complementary information regarding the timing of growth disruption within archaeological populations. Non-adult vertebral measurements can increase our osteobiographical understanding of the timings of episodes of health stress, and allow for the analysis of growth when other skeletal elements are fragmentary.

Tissue regeneration and biomineralization in sea urchins: role of Notch signaling and presence of stem cell markers

Echinoderms represent a phylum with exceptional regenerative capabilities that can reconstruct both external appendages and internal organs. Mechanistic understanding of the cellular pathways involved in regeneration in these animals has been hampered by the limited genomic tools and limited ability to manipulate regenerative processes. We present a functional assay to investigate mechanisms of tissue regeneration and biomineralization by measuring the regrowth of amputated tube feet (sensory and motor appendages) and spines in the sea urchin, Lytechinus variegatus. The ability to manipulate regeneration was demonstrated by concentration-dependent inhibition of regrowth of spines and tube feet by treatment with the mitotic inhibitor, vincristine. Treatment with the gamma-secretase inhibitor DAPT resulted in a concentration-dependent inhibition of regrowth, indicating that both tube feet and spine regeneration require functional Notch signaling. Stem cell markers (Piwi and Vasa) were expressed in tube feet and spine tissue, and Vasa-positive cells were localized throughout the epidermis of tube feet by immunohistochemistry, suggesting the existence of multipotent progenitor cells in these highly regenerative appendages. The presence of Vasa protein in other somatic tissues (e.g. esophagus, radial nerve, and a sub-population of coelomocytes) suggests that multipotent cells are present throughout adult sea urchins and may contribute to normal homeostasis in addition to regeneration. Mechanistic insight into the cellular pathways governing the tremendous regenerative capacity of echinoderms may reveal processes that can be modulated for regenerative therapies, shed light on the evolution of regeneration, and enable the ability to predict how these processes will respond to changing environmental conditions.

Topography of spinal column and kidney receptors as illustrated by microsystem of the foot

OBJECTIVE

To test the accuracy of the distribution of reflective zones on the feet as proposed by William Fitzgerald using the spine and kidney receptors as reference points.

METHODS

Spine and feet lengths were measured first along straight lines and then again, taking into consideration the anatomical curves. The spinal column was further measured with regard to its individual regions (cervical, thoracic, lumbar, sacrum-coccyx). Straight-line measurements were taken with the help of an anthropometer. Measurements that took into account all of the curves were performed with the opisometer (also known as a "map measurer"). All the measurements were accurate to within 1 mm. The study subjects were a healthy, physically fit 16-year-old female student and a 53-year-old male office employee exposed to an average dose of physical exercise.

RESULTS

The kidney receptor in the foot did not reflect onto the predetermined lumbar section of the spinal column as measured along the straight line or with regard to curves. Instead, in both subjects the kidney receptor reflected onto the thoracic spine.

CONCLUSION

Te particular level of the spinal cord that innervates the given organ controls the distribution of receptors of individual organs in the foot.

Age and growth of the tiger shark Galeocerdo cuvier off the east coast of Australia

Total lengths (L(T)) at age and growth rates for south-west Pacific Galeocerdo cuvier were estimated from vertebral growth-band counts of 202 sagitally sectioned centra from 112 females (71-430 cm L(T)), 79 males (72-351 cm L(T)) and 11 of unknown sex. Captive growth data were also examined to complement vertebral age estimations. The sexes combined modelled growth coefficient (k = 0.08) was smaller than previously reported for G. cuvier populations elsewhere. Split-band and narrow banding patterns were identified as potential sources of age underestimation in this species.

Targeted Deletion of Btg1 and Btg2 Results in Homeotic Transformation of the Axial Skeleton

Btg1 and Btg2 encode highly homologous proteins that are broadly expressed in different cell lineages, and have been implicated in different types of cancer. Btg1 and Btg2 have been shown to modulate the function of different transcriptional regulators, including Hox and Smad transcription factors. In this study, we examined the in vivo role of the mouse Btg1 and Btg2 genes in specifying the regional identity of the axial skeleton. Therefore, we examined the phenotype of Btg1 and Btg2 single knockout mice, as well as novel generated Btg1^-/-;Btg2^-/- double knockout mice, which were viable, but displayed a non-mendelian inheritance and smaller litter size. We observed both unique and overlapping phenotypes reminiscent of homeotic transformation along the anterior-posterior axis in the single and combined Btg1 and Btg2 knockout animals. Both Btg1^-/- and Btg2^-/- mice displayed partial posterior transformation of the seventh cervical vertebra, which was more pronounced in Btg1^-/-;Btg2^-/- mice, demonstrating that Btg1 and Btg2 act in synergy. Loss of Btg2, but not Btg1, was sufficient for complete posterior transformation of the thirteenth thoracic vertebra to the first lumbar vertebra. Moreover, Btg2^-/- animals displayed complete posterior transformation of the sixth lumbar vertebra to the first sacral vertebra, which was only partially present at a low frequency in Btg1^-/- mice. The Btg1^-/-;Btg2^-/- animals showed an even stronger phenotype, with L5 to S1 transformation. Together, these data show that both Btg1 and Btg2 are required for normal vertebral patterning of the axial skeleton, but each gene contributes differently in specifying the identity along the anterior-posterior axis of the skeleton.

Age, growth and maturity of the pelagic thresher Alopias pelagicus and the scalloped hammerhead Sphyrna lewini

Indonesia has the greatest reported chondrichthyan catches worldwide, with c.110,000 t caught annually. The pelagic thresher (Alopias pelagicus) and scalloped hammerhead (Sphryna lewini) together comprise about 25% of the total catches of sharks landed in Indonesia. Age and growth parameters were estimated for A. pelagicus and S. lewini from growth-band counts of thin-cut vertebral sections. Alopias pelagicus (n = 158) and S. lewini (n = 157) vertebrae were collected from three Indonesian fish markets over a 5 year period. A multi-model analysis was used to estimate growth parameters for both species. The models of best fit for males and females for A. pelagicus was the three-parameter logistic (L∞ = 3169 mm LT , k = 0·2) and the two-parameter von Bertalanffy models (L∞ = 3281 mm LT , k = 0·12). Age at maturity was calculated to be 10·4 and 13·2 years for males and females, respectively, and these are the oldest estimated for this species. The samples of S. lewini were heavily biased towards females, and the model of best fit for males and females was the three-parameter Gompertz (L∞ = 2598 mm LT , k = 0·15) and the two-parameter Gompertz (L∞ = 2896 mm LT , k= 0·16). Age at maturity was calculated to be 8·9 and 13·2 years for males and females, respectively. Although numerous age and growth studies have previously been undertaken on S. lewini, few studies have been able to obtain adequate samples from all components of the population because adult females, adult males and juveniles often reside in different areas. For the first time, sex bias in this study was towards sexually mature females, which are commonly lacking in previous biological studies on S. lewini. Additionally, some of the oldest aged specimens and highest age at maturity for both species were observed in this study. Both species exhibit slow rates of growth and late age at maturity, highlighting the need for a re-assessment of the relative resilience of these two globally threatened sharks at current high levels of fishing mortality throughout the eastern Indian Ocean.

Maternal high-fat diet and offspring expression levels of vitamin K-dependent proteins

Studies suggest that bone growth and development and susceptibility to vascular disease in later life are influenced by maternal nutrition during intrauterine and early postnatal life. There is evidence for a role of vitamin K-dependent proteins (VKDPs) including osteocalcin, matrix Gla protein, periostin, and growth-arrest specific- protein 6, in both bone and vascular development. We have examined whether there are alterations in these VKDPs in bone and vascular tissue from offspring of mothers subjected to a nutritional challenge: a high-fat diet during pregnancy and postnatally, using 6-week-old mouse offspring. Bone site-specific and sex-specific differences across femoral and vertebral bone in male and female offspring were observed. Overall a high-fat maternal diet and offspring diet exacerbated the bone changes observed. Sex-specific differences and tissue-specific differences were observed in VKDP levels in aorta tissue from high-fat diet-fed female offspring from high-fat diet-fed mothers displaying increased levels of Gas6 and Ggcx compared with those of female controls. In contrast, differences were seen in VKDP levels in femoral bone of female offspring with lower expression levels of Mgp in offspring of mothers fed a high-fat diet compared with those of controls. We observed a significant correlation in Mgp expression levels within the femur to measures of bone structure of the femur and vertebra, particularly in the male offspring cohort. In summary, the current study has highlighted the importance of maternal nutrition on offspring bone development and the correlation of VKDPs to bone structure.

The MAGEC system for spinal lengthening in children with scoliosis: A NICE Medical Technology Guidance

Scoliosis-structural lateral curvature of the spine-affects around four children per 1,000. The MAGEC system comprises a magnetically distractible spinal rod implant and an external remote controller, which lengthens the rod; this system avoids repeated surgical lengthening. Rod implants brace the spine internally and are lengthened as the child grows, preventing worsening of scoliosis and delaying the need for spinal fusion. The Medical Technologies Advisory Committee at the National Institute for Health and Care Excellence (NICE) selected the MAGEC system for evaluation in a NICE medical technologies guidance. Six studies were identified by the sponsor (Ellipse Technologies Inc.) as being relevant to the decision problem. Meta-analysis was used to compare the clinical evidence results with those of one conventional growth rod study, and equal efficacy of the two devices was concluded. The key weakness was selection of a single comparator study. The External Assessment Centre (EAC) identified 16 conventional growth rod studies and undertook meta-analyses of relevant outcomes. Its critique highlighted limitations around study heterogeneity and variations in baseline characteristics and follow-up duration, precluding the ability to draw firm conclusions. The sponsor constructed a de novo costing model showing that MAGEC rods generated cost savings of £9,946 per patient after 6 years, compared with conventional rods. The EAC critiqued and updated the model structure and inputs, calculating robust cost savings of £12,077 per patient with MAGEC rods compared with conventional rods over 6 years. The year of valuation was 2012. NICE issued a positive recommendation as supported by the evidence (Medical Technologies Guidance 18).

Validated age, growth and maturity of the bonnethead Sphyrna tiburo in the western North Atlantic Ocean

The age, growth and maturity of bonnetheads Sphyrna tiburo inhabiting the estuarine and coastal waters of the western North Atlantic Ocean (WNA) from Onslow Bay, North Carolina, south to West Palm Beach, Florida, were examined. Vertebrae were collected and aged from 329 females and 217 males ranging in size from 262 to 1043 mm and 245 to 825 mm fork length, LF , respectively. Sex-specific von Bertalanffy growth curves were fitted to length-at-age data. Female von Bertalanffy parameters were L∞  = 1036 mm LF , k = 0·18, t0  = -1·64 and L0  = 272 mm LF . Males reached a smaller theoretical asymptotic length and had a higher growth coefficient (L∞  = 782 mm LF , k = 0·29, t0  = -1·43 and L0  = 266 mm LF ). Maximum observed age was 17·9 years for females and 16·0 years for males. Annual deposition of growth increments was verified by marginal increment analysis and validated for age classes 2·5+ to 10·5+ years through recapture of 13 oxytetracycline-injected specimens at liberty in the wild for 1-4 years. Length (LF50 ) and age (A50 ) at 50% maturity were 819 mm and 6·7 years for females, and 618 mm and 3·9 years for males. Both female and male S. tiburo in the WNA had a significantly higher maximum observed age, LF50 , A50 and L∞ , and a significantly lower k and estimated L0 than evident in the Gulf of Mexico (GOM). These significant differences in life-history parameters, as well as evidence from tagging and genetic studies, suggest that S. tiburo in the WNA and GOM should be considered separate stocks.

Dietary supplementation with long chain polyunsaturated fatty acids in pregnant guinea pigs has sex-dependent effects on growth and bone outcomes in offspring

Long chain PUFA enhance bone mass in non-pregnant mammals. We examined the effects of arachidonic (AA; 20:4n-6) and docosahexaenoic (DHA; 22:6n-3) acid on bone mass of mothers and neonates. Guinea pig sows (n=15) were fed control, DHA or AA+DHA diets from mating to weaning. Measurements included: osteocalcin (OC), deoxypyridinoline (DPD), areal bone mineral density (aBMD) in sows and neonates; and volumetric density (vBMD) in neonates. Only vertebral aBMD and OC:DPD ratio declined during reproduction and only DHA reduced OC:DPD. Male pup weight was reduced by DHA and female weight elevated by AA+DHA. Whole body and femur aBMD were reduced by DHA and AA+DHA; whereas tibia vBMD was reduced by DHA in males. Female whole body, tibia and vertebrae aBMD plus tibia vBMD were elevated by AA+DHA; and DHA elevated whole body, tibia and vertebrae aBMD. Dietary AA+DHA and DHA elicit sex-dependent effects on neonatal bone, with minimal impact on mothers.

[Abnormal growth of spine in patients with adolescent idiopathic thoracic scoliosis]

OBJECTIVE

To investigate if the growth patterns of the spine and pelvis are consistent in adolescent idiopathic scoliosis (AIS) patients with single thoracic curves.

METHODS

Forty-eight thoracic adolescent idiopathic scoliosis (T-AIS) female patients and 48 healthy age-matched adolescents were recruited consecutively between December 2011 and October 2012. Radiographic parameters including height of spine (HOS), length of spine (LOS), height of thoracic spine (HOT), length of thoracic spine (LOT), height of pelvis (HOP), width of pelvis (WOP) and width of thorax (WOT) were measured on the long-cassette posteroanterior standing radiographs. In addition, ratios including HOS/HOP, LOS/HOP, HOT/HOP, LOT/HOP, LOS/LOT, WOT/WOP were also calculated. Independent t-test was performed to compare the radiographic parameters and ratios between the two groups.

RESULTS

Compared to the age-matched healthy adolescents, T-AIS patients had a significantly higher LOS and LOT (t = -2.364 and -1.495, P = 0.020 and 0.043) and smaller HOS and HOT (t = 2.060 and 3.359, P = 0.042 and 0.001). Yet, all of HOP, WOP and WOT showed no significant difference between T-AIS patients and healthy adolescents. Similarly, LOS/HOP and LOT/HOP were significantly higher in T-AIS patients as may be expected with an average LOS/HOP of 2.26 ± 0.14 in normal controls.In addition, LOS/LOT in normal controls had a trend of increase with age which was different from the stable LOS/LOT in T-AIS patients, indicating an increased growth of thoracic vertebra compared to lumbar vertebra.

CONCLUSIONS

Compared to the age-matched healthy adolescents, T-AIS patients have an abnormal growth characteristics with longer spine. The growth of pelvis and thorax show no significant differences between T-AIS patients and healthy adolescents.

Surgical aspects of spinal growth modulation in scoliosis correction

Spine growth modulation for scoliosis correction is a technique for slowing growth on the convex side of the curve and enhancing growth on the concave side by using the Heuter-Volkmann principle; this results in gradual deformity correction. The theoretic advantages include speedier recovery because of the minimally invasive approach used, as well as motion preservation. Several devices have been used in humans, including vertebral body stapling, with either a flexible titanium clip or a nitinol staple, and anterior spinal tethering. Prerequisites for the use of these devices are a relatively flexible curve and sufficient remaining growth in the patient. Although vertebral body stapling is effective for moderate curves of less than 40°, anterior spinal tethering can be used for curves greater than 40°. The titanium clip and spinal tethers are used exclusively for thoracic scoliosis, whereas nitinol staples can be used for the thoracic spine or the lumbar spine. The thoracoscopic technique is used for thoracic instrumentation, and the mini-open retroperitoneal technique is used for lumbar staple insertion. The insertion of a titanium clip and an anterior spinal tether requires sacrifice and mobilization of the segmental vessels, whereas nitinol staples can be inserted without such sacrifice. Single lung ventilation and CO2 insufflation are used to improve visualization with the thoracoscope. The curve should be instrumented from an end vertebra to an end vertebra. Postoperative immobilization depends on the type of device used. Most complications are approach related, such as atelectasis caused by a mucus plug, pain at the chest tube site, and pneumothorax. Device-related complications are rare. Overcorrection is a concern. In patients with early onset scoliosis, a hybrid construct with vertebral stapling and growing rods or a vertical expandable prosthetic titanium rib has been suggested. A failure of the spinal growth modulation procedure does not preclude spinal fusion. None of the devices for spine growth modulation have been approved by the FDA for human use and are still investigational. Early results are promising, and continued clinical studies are necessary.