Development of a non-fusion scoliosis correction device

Adolescent idiopathic scoliosis is characterised by an S- or C-shaped lateral deviation of the spine, an axial rotation of the vertebrae, and a flattening of the sagittal curvature.
Present surgical therapy brings several disadvantages like fusion of the involved vertebrae and the necessity to wait with surgery until the end of the growth of the patient.
Therefore, a non-fusion scoliosis correction device is being developed in which the disadvantages of present systems are reduced. Furthermore, this device should correct the deformity in all three anatomical planes and should allow growth of the patient.

The focus of this thesis is on providing boundary conditions for adequate testing and application of the non-fusion scoliosis correction device rather than on testing of the device itself. For optimization of the design of the implant, a finite element model of the complete spine is being made and for the validation of this model, extensive in-vitro tests were performed and described in this thesis.

Furthermore, the implant will be tested in a porcine model and therefore part 1 of this thesis aims to answer to question whether the geometrical and biomechanical characteristics of the porcine spine are representative for the human spine.

Part 2 of this thesis focuses on the timing of the surgery. This is highly important and mainly dependent on the timing of the pubertal growth spurt of the adolescent patient. Therefore, part 2 of this thesis presents several methods for prediction of the timing and magnitude of the peak growth velocity in the individual child.