Introduction: VBT is believed to prevent disc and facet degeneration due to its less rigid nature. While VBT's flexibility may beadvantageous, the potential for compression-induced degeneration needs further research. The aim was toanalyze the changes in the intermediate and adjacent levels, at least 5 years after surgery.
Materials and methods: Demographic, perioperative, clinical and radiographic data were collected. Skeletal maturity and height wereassessed at each follow-up. Curve behavior and mechanical complications were recorded. Whole spine MRI wasobtained preoperatively on a routine basis. Follow-up MRI (between T2-S1) was obtained at a minimum of 5years post-op. Disc and facet scores were compared using McNemar's Test and Related Samples MarginalHomogeneity Test.
Results: Out of the first 49 consecutive patients operated between 2014-2018, 35 (71.4%) were included. 34 (97%) werefemale. Mean age was 12.6 (9.5–16). Median Sanders was 4 (1-7). Mean preop major curve was 49 (40-73) degrees. 28 had a thoracic VBT, while 4 had thoracolumbar and 3 had bilateral. A median of 7 (5-11) levels weretethered. Preop mean height of 155.1 (130-178) was increased to 162.7 (147-189) at the latest f-up. At thetime of the MRI (mean 72.5±14.8 (60−119) months), the median Sanders was 8 (7-8). Analyses of changes inthoracic disc and facet scores revealed no differences (p>0.05). For the lumbar levels, 23 patients were gradedas normal both at preop and postop. 3 patients that already had multilevel facet degeneration did not show anydeterioration. However, 2 patients that had single level disc degeneration had a 1-point increase. Of theremaining 7 patients that were graded normal at preop, 2 experienced disc, 2 experienced facet, while 3experienced both disc and facet degeneration, all of which were mild and located at the lower adjacentsegments.
Conclusion: Intermediate discs and facet joints were preserved after growth modulation with VBT surgery at a mean of 72.5months of follow-up. 6% of the patients experienced deterioration of previously degenerated discs, while loweradjacent facets had a mild degeneration in 20% of the patients. Studies in larger cohorts with longer follow-upare warranted to have more in-depth analyses of the effects of relative stabilization and altered biomechanicalloads.