Spinal deformity changes in children with long-term VEPTR treatment

This dissertation deals with spinal deformity changes in children and adolescents in the course of long-term treatment with the vertical expandable prosthetic titanium rib (VEPTR) system. The analysis of secondary curves and the sagittal plane as well as possible influencing variables on curve pattern changes were of special interest. The underlying study comprises a collective of 32 children and adolescents, consisting of 24 female (75%) and 8 male (25%) patients. Diagnoses included congenital scoliosis (n=10), neuromuscular scoliosis (n=19) and idiopathic scoliosis (n=3). Further biometric and clinical data, including ability to walk and dislocation of the hip, were obtained. A retrospective analysis of following radiologic parameters was performed for 403 digital and conventional available radiographs: Measurement of the Cobb-angle of main and associated curves in anteroposterior and bending radiographs, extent of pelvic obliquity and horizontal distance in anteroposterior radiographs as wells as measurement of kyphosis, lordosis, spinal length and horizontal distance sagittal in lateral radiographs. For kyphosis and lordosis, the deviation between the measured angle and the standard age dependent value was calculated. All measurements were performed for the whole collective (n=32) in 2-year-intervals during VEPTR treatment for an average of 5.5 years. For a subset of 16 children, further measurements were performed in post VEPTR removal radiographs after an average of 6.1 years. For evaluation of inter-observer errors, all measurements were done by two independent investigators. Analysis of variance (ANOVA) and post-hoc tests with Bonferroni correction were adopted. The results show a significant reduction of the thoracic and the lumbar curve in the frontal plane directly after implantation of the VEPTR system. After an average of 2.8 years, which is half-time of VEPTR treatment, a continuous increase of the kyphosis, exceeding the baseline value, was observed. A significant lengthening of the spinal length could be observed after implantation of the VEPTR system. For congenital scoliosis, spinal length increased steadily in the course of VEPTR treatment, representing a normal growth curve. In contrast, children with neuromuscular scoliosis experienced a sudden increase (32 mm) of spinal length immediately upon VEPTR surgery, but had an unchanged curve thereafter, indicating the flexibility of the neuromuscular scoliosis. Pelvic obliquity showed a significant improvement in the neuromuscular subset, but after explantation of VEPTR instruments the positive effects on pelvic position diminished again. In this dissertation was shown that spinal deformities in children can be effectively controlled by implantation of the VEPTR system. By VEPTR implantation a straightening of the spine can be achieved, resulting in an improvement of the frontal plane. Regarding the sagittal plane, a marked progression of kyphosis after initially good correction was obtained. This implies that the VEPTR system is less applicable for the treatment of kyphosis. The improvement of the scoliosis in the frontal plane was preserved in the congenital subset after explantation of the VEPTR system. This could be shown for the first time. Considering this result, patients with congenital scoliosis could likely be spared from subsequent spinal fusion surgery with the risk of severe complications. However, long-term follow-ups as well as the evaluation of larger collectives have to be performed to support this result. After removal of the VEPTR system, a worsening of the spinal deformities beyond baseline values was obtained in the neuromuscular subset. This shows the flexibility of the deformity as well as the fact, that by usage of the rib-to-pelvis-implant type, commonly used in neuromuscular scoliosis, there is no relevant stiffening of the spine. This implies that the VEPTR system with rib-to-pelvis implant type is an appropriate device for the treatment of neuromuscular scoliosis throughout growth period as the spine remains untouched and mostly flexible for definitive spondylodesis.2017-12-1