Vertical expandable prosthetic titanium ribs (VEPTR) in early-onset scoliosis: impact on thoracic compliance and sagittal balance

BACKGROUND Theoretically, dynamic thoracic compliance (DTC) should be reduced by vertical expandable prosthetic titanium ribs (VEPTR) since titanium rods, scar tissue and ossifications increase stiffness of the rib cage. The effect of VEPTR on thoracic compliance has not yet been elucidated. The impact of VEPTR on the development of sagittal balance has not been fully investigated. PATIENTS AND METHODS In a retrospective study, we investigated 21 consecutive children who were treated by VEPTR from 2004 to 2011 and three control groups. We compared the development of thoracic compliance during growth to Nr1. Development of sagittal balance during growth was compared to Nr2 and to Nr3 (which has been instrumented from ileum to rib). Mean follow-up was 60.67 months (standard error of the mean (SE 4.77). RESULTS The difference of change of DTC during growth of VEPTR group versus a control group was not significant (p < 0.05). However, initial DTC and DTC at last follow-up of VEPTR group were lower than DTC of the control group. The difference was significant (p < 0.05). Mean correction of Cobb angle after the first operation was 16.41° (SE 3.01). Until last follow-up, we saw a loss of correction of 8.23° (SE 3.22). The differences between the development of parameters of sagittal balance during growth between the VEPTR group, control group 2 and control group 3 were not significant (p > 0.05). CONCLUSIONS VEPTR treatment should start as early as possible since VEPTR seems to lead to an increased rate of DTC that is similar to healthy controls. Sagittal balance showed a similar development as in healthy children.