Growing Implant for the Treatment of Early Onset Scoliosis

Abstract

Scoliosis is a spinal deformity characterised by lateral curvatures of the spine. It typically occurs during adolescence, but in rare incidences can occur in young children. In adolescents, if severe or progressive, surgical treatment in the form of spinal fusion using screw and rod constructs may take place. However, in younger patients the spine and lungs are still growing, therefore, fusion is not recommended before the age of eight years.For early onset scoliosis fusionless techniques are used, with the current gold standard being traditional growing rods, incorporating pedicle screws and rods, which are periodically lengthened through frequent surgical interventions. Due to the number surgeries throughout the treatment period, this treatment suffers from high complication rates. As this treatment is far from ideal, alternative treatments are being explored to reduce these issues.This thesis describes the initial development of an alternative implant for the treatment of early onset scoliosis to alleviate the issues of traditional growing rods. The implant was based on a pedicle screw and rod system, but incorporated a bearing component to allow free extension of the construct without the need for further surgery. The development of the implant design was achieved through finite element analysis of individual components and of constructs using contact conditions.It was initially intended to use a UHMWPE bearing component incorporating a crosslink and Ti-6Al-4V sliding rod, with a commercially available pedicle screw. However, issues of the construct size lead to the development of a novel screw design incorporating an alumina bearing, a decoupled crosslink and CoCrMo sliding rod. The results of the finite element analysis show that an implant incorporating an alumina bearing component is a promising area for development, however, additional investigations of the construct are still required.

Date of Award	15 Mar 2016
Original language	English
Awarding Institution	University of Bath
Supervisor	Richie Gill (Supervisor) & Sabina Gheduzzi (Supervisor)