This study addresses a crucial gap in the knowledge of normative spinal growth in children. The objective of this study is to provide detailed and accurate 3D reference values for global and segmental spinal dimensions in healthy children under the age of 11.

Radiographic spine examinations of healthy children conducted to rule out scoliosis were reviewed in four scoliosis referral centers in North America. All consecutive children aged three to eleven years old with EOS biplanar good quality x-rays, but without diagnosed growth-affecting pathologies, were included. Postero-Anterior and Lateral calibrated x-rays were used for spine 3D reconstruction and computation of vertebral body height and spine length. Median and interquartile range were calculated from cross-sectional data. Smooth centiles growth curves for 3D True Spinal Length (3DTSL) between T1 and S1, as well as for mid-vertebral heights of T5, T12 and L3, where fit and calibrated from data using the Lambda-Mu-Sigma method (GAMLSS package for R). This method automatically selects the best performing distribution from a familly of choices. Tables of centiles were then predicted from the computed models for selected ages.

A total of 638 full spine examinations from asymptomatic patients were reconstructed in 3D, 397 in girls and 241 in boys. Medians and interquartile ranges were calculated for 3DTSL (T1-S1): 285 (24) mm, 314 (26) mm and 349 (31) mm, and for selected vertebral heights T5: 10 (1) mm, 11 (1) mm and 12 (1) mm, T12: 13 (2) mm, 14 (1) mm and 16 (2) mm, and L3: 14 (1) mm, 16 (2) mm and 18 (2) mm, respectively for the 3–6, 6–8 and 8–11 age groups. Centile curves ready for clinical use of the 3DTSL (T1-S1) and of the vertebral heights of T5, T12 and L3 as a function of age were derived for the 5, 10, 25, 50, 75, 90 and 95th centiles. In general, boys presented linear relationships between spinal dimensions and age, and girls presented more diverging trends with increased variance for older ages. Accordingly curves for boys follow the Normal distribution whereas those for girls follow the original Box-Cox-Cole-Green distribution. Model diagnostic tests (normally distributed residuals, adequate wormplots and |Z statistics| < 2) confirmed adequacy of the models and the absence of significant misfit.

Accurate reference values were derived for spinal dimensions in healthy children. Spinal dimension charts showed that the spinal lengths and vertebral heights changed relatively constantly across the age groups closely resembling WHO total body height charts. The reference values will help physicians better assess their patients' growth potential. It could also be used to predict expected spinal dimensions at maturity or changes in pathologic conditions as well as to assess the impact of growth friendly interventions in the correction of spinal deformities.

Introduction

Resistant organisms are difficult to eradicate in infected total knee arthroplasty, and treatment of methicillin-resistant Staphylococcus aureus (MRSA) is especially challenging. Whereas most surgeons use antibiotic-impregnated cement during revision to treat infection, the delivery of the drug in adequate doses is limited in penetration and duration. This study presents the 2- to 8-year prospective results of one-stage revision and intraarticular antibiotic infusion protocol used to treat MRSA.

Introduction

Recent clinical studies found no apparent reduction in wear using yttria-stabilized zirconia (Y-TZP) instead of cobalt chromium alloy femoral heads bearing against cross-linked UHMWPE. The purpose of this study was to compare the surface topography of retrieved Y-TZP and magnesia-stabilized zirconia (Mg-PSZ) femoral heads and evaluate the influence of time in vivo. The increase in average roughness (Ra, Sa) of Y-TZP due to phase transformation in vivo is well documented, while Mg-PSZ does not roughen or undergo phase transformation in vivo. However, the effects of phase transformation on the polarity (skewness, Ssk) of the surface of retrieved ZrO₂ heads has not been reported. We hypothesized that phase transformation associated with the increased roughness of Y-TZP would influence skewness and thus the wear potential of the heads.

Purpose: Prediction of progression is actually impossible in adolescent idiopathic scoliosis (AIS). Potential risk factor to consider at first visit might be morphologic parameters of the spine. The objective of this study was to compare 3D morphologic parameters of the spine in a non evolutive an in an evolutive group of AIS.

Method: A retrospective cohort study was done. Two groups were recruited with sample size based on a difference of 5 degrees for rotation parameters. First group were all surgical patients (n=19) and second group non evolutive patient (n=18). Inclusion criteria were

Risser sign of 0 or 1

Exclusion criteria were

limb length discrepancy

All spines were reconstructed in 3D with AP and lateral radiographs of the first visit and measurements were performed on the reconstruction. There were 4 categories of measurements done: Cobb angle, wedging, rotation, slenderness. Student t test were performed.

Results: There was no statistical difference between the two groups for Cobb angle in maximal plane, for lordosis and kyphosis. Differences were found for wedging of the apical disk in 3D plane (S=5,4° vs NE= 0,7° with p=0,04). For coronal orientation of the apex (S=7,8° vs NE=0,1° with p=0,01). For axial orientation of inferior junctional vertebrae (S=1,9° vs 0,1° with p=0,007). For torsion (S=−4,1° vs NE= – 1,2° with p=0,03). For ratio between height and width of T6 (S=51% vs NE=53,6% with p=0,04).

Conclusion: This study give for the first time some 3D morphologic parameters that could be use in the prediction of AIS. Some limitations exist such as the small sample size and the low level of significance. In the future those parameters will be used in the development of a prediction model base on those keys parameters that will confirm the actual findings.

Purpose: In pediatric orthopedics, Risser sign is used to assess skeletal maturity. Two grading system exist for the Risser sign, one US and one European. In adolescent idiopathic scoliosis (AIS) the curve acceleration phase begin at a digital skeletal age (DSA) score between 400 – 425. The objective was to asses the disagreement between both grading system and evaluate the best estimator of the curve acceleration phase.

Method: One hundred twenty-one AIS patients had a PA and lateral X-rays of the spine and a left hand and wrist X-ray. Risser sign was measured according to both grading system and bone age was calculated according to Tanner-Whitehouse III method. Kappa statistics were done to evaluate concordance between US and Euro-pean grading system and 2 multiple linear regression models were performed to find which stage best predicts the beginning of the rapid acceleration phase.

Results: Kappa statistic between the US and European system was 0.517 (moderate agreement). US Risser 1 was the best predictor of the curve acceleration phase. DSA scores predicted with Risser 1 were 425 and 445 for US and European system respectively.

Conclusion: American and European Risser grading system use different criteria to define 6 stages of a same sign. This is reflected in our study with a moderate agreement between both grading systems. US Risser 1 is the stage that best predicts the beginning of the rapid acceleration phase and a close follow up should be made at the beginning of the iliac apophysis ossification.

Introduction: Familial idiopathic scoliosis (FIS) is a complex genetic disorder potentially resulting from multiple genetic interactions and variants. A previous genome wide screen in a large population of families with FIS followed by fine mapping utilizing STRP’s identified and narrowed critical regions on chromosomes 9 and 16. A high density SNP map was then designed across these regions. This array was then assayed within the same population in an effort to link and/or associate specific genetic intervals or candidate genes with the expressed phenotype.

Methods: A sample of families with IS (202 families, 1198 individuals) was recruited with IRB approval and underwent a genomic screen. Results were analysed by model-independent linkage analysis (SIBPAL). Following initial analyses, families were then stratified according to mode of inheritance. 101 families (550 individuals) represented an autosomal dominant mode of heritability and underwent fine mapping in the candidate regions.

Custom SNP pools were designed for the candidate regions at a density of 1 SNP/58Kb. DNA from 550 individuals (AD group) were genotyped using the Illumina platform. A total of 1536 SNP markers were attempted, of which 1324 were released; 519 SNPs were genotyped on 9q32-24 and 805 SNPs genotyped on 16p12-q22. The map was generated using NCBI dbSNP chromosome report on Build 34. Overall missing rate was 0.06%; the overall duplicate error rate was 0.05%.

FIS was analysed both as a qualitative trait with an arbitrary threshold, and as a quantitative trait, or the degree of lateral curvature. Model independent sib-pair linkage analysis was performed on the subsets (SIBPAL, S. A. G. E. v4.5).

Results:

Chromosome 9: Multipoint model-independent qualitative analysis (threshold at ten degrees) did not result in any p values of < 0.05. When the threshold was set at 30 degrees, several regions with p values of < 0.005 were observed. One region spanned 10 Mb, and coincides with the region found to be most suggestive of linkage at the 0.05 level for the quantitative analysis which was 6 Mb in length.

Discussion: The current work has significance in the stepwise confirmation and narrowing of genomic regions which are potentially meaningful in the aetiology of FIS. Stratification of the initial sample into subgroups, initially by heritability and then by threshold of disease resulted in heightened significance at specific markers demonstrating the heterogeneity of this disorder. Ultimately, the independent association of genetic loci and this disorder will enhance the ability to elucidate prognosis, counsel patients, and guide therapeutic plans.