Vertebral column growth in children with early onset scoliosis treated with magnetically controlled growing rods - Effects of distraction on vertebral and disc morphology.

Objectives: To report changes in vertebral and disc morphology following treatment of early onset scoliosis (EOS) with magnetically controlled growing rods (MCGR).

Methods: 30 Patients, 21 girls and 9 boys, treated with MCGR for EOS were compared to a matched control group of 19 patients (12 girls, 7 boys) treated with bracing or observation. Age at surgery in the MCGR group was 8.75 (range: 4.6-11) years compared to 7.75 (range: 3.5-10.3) years in the control group at the time of onset of treatment. Mean follow-up was 45 (range: 24-65) months in the MCGR group vs 42 (range: 24-65) months in the control group. Calibrated radiographs were used to digitally measure disc height, vertebral body height, depth and width after surgery and at latest follow-up. Height, width and depth of lumbar and thoracic vertebrae and discs under distraction were compared to the control group and to vertebrae below instrumentation. T1-T12, T1-S1 length and Cobb angles were also measured.

Results: (1) There is a significant increase of lumbar vertebral height under distraction. (2) Lumbar disc height as well as lumbar vertebral width within distraction is significantly reduced. (3) Depth of lumbar vertebrae is not significantly affected by distraction. (4) Morphology of thoracic vertebrae and adjacent discs is not significantly changed with distraction. (5) T1-T12 distance did not show any significant changes between surgical and control group, while T1-S1 growth was significantly reduced compared to the control group.

Conclusions: Significant changes of morphology of lumbar vertebra and discs are observed under distraction with MCGR compared to segments below instrumentation and the control group.

Level Of Evidence: Level III - retrospective comparative series.