Radiological and clinical assessment of the distraction achieved with remotely expandable growing rods in early onset XXXX .

@entity1 @entity2166 @entity8527 @entity1635
PURPOSES: Magnetically controlled growing rods (MCGR) allow controlled distraction of the immature spine for the treatment of early onset @entity1635 . This study's primary aim was to determine the disparity between 'true' ( @entity8527 ) and 'intended' (ID) distraction. The secondary aim was to assess truncal growth and development during sequential lengthening. METHODS: Twenty-one @entity1 with a maximum follow up of 37  months were included in the study. @entity1 in the study underwent three monthly distractions. The amount of @entity8527 was determined by measuring the expansion gap on dedicated fluoroscopic images of the actuator. The total @entity8527 to date was compared to the ID measurement reported on the @entity2166 ( @entity2166 ). Weight, sitting and standing heights were recorded at each distraction. RESULTS: The average number of three monthly distractions was 8. The true to intended distraction ratio was calculated as 0.33. @entity1 who had undergone previous surgery gained less distraction with a ratio of 0.30 compared to @entity1 undergoing MCGR as a primary procedure with a ratio of 0.35. Weight, sitting and standing heights increased in all @entity1 by an average of 3.1  kg, 2.3 and 5.2  cm per year. The Cobb angle following surgical correction was maintained in 19 of 21 @entity1 at the latest follow-up. CONCLUSIONS: The TI ratio of 0.33 suggests that for every unit of distraction registered on the @entity2166 approximately 33  % of true distraction occurs in vivo. Increases in sitting and standing heights were observed in all @entity1 in the study.
