Paediatrics (RCH) - Theses

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    Proximal femoral osteotomy in children and adolescents with cerebral palsy
    Zhou, Leena ( 2018)
    Background Cerebral Palsy (CP) is the most common cause of physical disability affecting children in developed countries. Approximately one third of children with CP may develop hip displacement. Non-ambulant children at Gross Motor Function Classification System (GMFCS) levels IV and V are at highest risk. Without early detection through surveillance programs, hip displacement can progress to hip dislocation, which is frequently painful and negatively impacts health-related quality of life (HRQoL). Injections of Botulinum Neurotoxin A (BoNT-A) have no role, and soft tissue surgery has a limited role in preventing hip displacement in non-ambulant children with CP. Bony hip reconstruction surgery such as a proximal femoral osteotomy (PFO) is effective in stabilising the hip and HRQoL. PFOs include Femoral Derotation Osteotomies (FDO) which aim to improve the gait of an ambulant child (GMFCS I-III), and Varus Derotation Osteotomies (VDRO) which aim to contain the hips in non-ambulant children (GMFCS IV-V). However, PFOs can carry high risks, especially in children with medical co-morbidities such as respiratory disease, nutritional deficiencies, hypertonia and osteopenia. Aim This thesis involved a series of three studies, which aimed to expand our knowledge of the trainee learning curve, outcomes and adverse events relating to PFO in children and adolescents with CP. Method and Results A new implant combining locking and cannulated technology (Locking Cannulated Blade Plate, LCBP) was recently developed for use in PFO. A pilot study was performed on the first 25 patients who had surgery with the LCBP, at the Royal Children’s Hospital (RCH), Melbourne. This study established safety for use in children as young as three, with weights as low as eleven kilograms. A further prospective, parallel cohort study of 90 consecutive children with CP was conducted to compare the LCBP against with existing non-cannulated, non-locking implant (Angled Blade Plate, ABP). Technical and radiological outcomes of surgery were similar between implants. However, the surgical technique was reported by trainees to be easier when using the LCBP, with less technical errors. Approximately 60 percent of the children experienced minor adverse events including: constipation, inadequate pain control, and respiratory compromise. However, a CP specific tool was not available to classify the severity of events. Study three was performed to clarify the Modified Clavien-Dindo (MCD) system for lower limb surgery in children with CP and test its’ reliability for classifying adverse events. Very good reliability was demonstrated amongst members within a multidisciplinary team. Conclusion Novel findings from these studies may help improve the safety and efficacy of the management of hip displacement in children with CP. Further research should address the long-term outcomes of PFO in children with CP, evaluate the validity of the MCD for children in CP and determine if the MCD can be embedded in the electronic medical records (EMR) as a routine tool for audit and clinical research.
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    Minimising complications after surgical repair of coarctation of the aorta
    Lee, Melissa Gar Yan ( 2018)
    Coarctation of the aorta is one of the most common congenital heart defects, often requiring surgery soon after birth. In Australia alone, approximately 150 babies are born with coarctation each year with an estimated 3,000 people living with a coarctation repair. Coarctation can no longer be considered a benign condition cured by surgery. There has been renewed interest into the late outcomes after coarctation repair as rates of late aortic arch reobstruction and late hypertension have recently been demonstrated to be much higher than initially expected. Alarmingly, studies have demonstrated that this late hypertension is directly linked to mortality at a young age. Unfortunately, late hypertension is often resistant to conventional antihypertensive medication and its exact mechanism is unknown. This thesis aimed to (i) determine the long-term outcomes after surgical repair of coarctation with a particular focus on determining the mechanisms leading to the development of late hypertension, (ii) examine the impact of an associated bicuspid aortic valve on patients with previous coarctation repair, and (iii) examine the complication of vocal cord paresis after aortic arch repair via sternotomy approach. A broad range of potential mechanisms for late hypertension including mechanical, arterial wall, neural, and genetic factors were all explored. In this thesis, I present our current understanding of the population, their outcomes and risk factors for early and late complications, and, finally, present initial data serving as a foundation for a prospective aortic arch anomaly biobank and hypothesis-generated research. Through a collaboration with the Royal Brompton Hospital, London, UK, this thesis has also resulted in the largest and longest cohort study in the world comprising 834 coarctation patients spanning seven decades of follow-up. Through this thesis, I have demonstrated that: (i) there is likely a high prevalence of late hypertension after coarctation repair, (ii) there is significant device-dependence of 24-hour blood pressure monitoring devices, making the identification of the hypertensive patient challenging, (iii) the risk of late mortality is three times higher than a healthy matched population, with the majority of deaths attributable to complications related to hypertension, (iv) there is four times increased risk of aortic valve and ascending aortic interventions in those with an associated bicuspid aortic valve, (v) the use of extensive aortic arch repair techniques may reduce long-term complications, and (vi) there is a high incidence of left vocal cord paresis after aortic arch repair via sternotomy approach. This journey began when I was an undergraduate medical student investigating the outcomes of patients with coarctation repaired at The Royal Children’s Hospital. This thesis has refined our understanding and management of complications after coarctation repair and will ultimately improve the long-term outcomes of many patients with coarctation of the aorta.