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(2022)ThesisBackground: Anterior lumbar interbody fusion (ALIF) remains one of the mainstay surgical approaches in treating painful degenerative disc disease with or without segmental instability in the lower spine. The risk factors and complication profile for ALIF differs significantly from other established fusion techniques. Objectives: The goal of the first part of this thesis is to establish the factors associated with long-term clinical outcome (Chapter 2) and short-term perioperative outcomes (Chapter 3) following ALIF. Chapter 4 focuses on the long-term radiographic evidence for biomaterial alternatives for ALIF implants, namely titanium (Ti)-coated PEEK integrated cages. Methods and Results: From a prospective cohort analysis of 147 patients undergoing ALIF, elderly age (≥64 years old) was associated with an increased rate of subsidence but does not affect clinical outcomes. Obesity was not associated with postoperative complications or follow-up patient-reported outcomes. Failed fusion was significantly higher for smokers, and they were significantly more likely than non-smokers to experience postoperative complications such as pseudoarthrosis. To assess risk factors for perioperative complications and readmissions after ALIF, the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was analysed. ALIF was associated with prolonged length of stay and higher rate of return to operating theatre compared to posterior lumbar fusion. Obesity and alcohol intake increased the risk of 30-day readmissions. Discharge to non-home destination following ALIF was independently associated with wound complications and venous thromboembolism. Finally, a prospective follow-up study was performed to determine the long-term radiographic outcome following ALIF using Ti-coated PEEK cages with allograft and INFUSE. Effective fusion was achieved at up to 24-month follow-up for various indications including degenerative spine/disc disease, low grade lumbar isthmic spondylolisthesis, spondylotic radiculopathy and discogenic low back pain. Conclusions: Collectively, this thesis highlights the importance of personalising the care of an ALIF surgery patient, through identification and optimization of individual risk factors for short-term and long-term outcomes, as well as through choice of implant biomaterial and design.
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(2020)ThesisThe "ophthalmohelioses" represent a conglomeration of ocular surface and adnexa disease strongly influenced by increased ultraviolet light B exposure. Despite overlapping pathogenesis pathways, the severity of these differs across the different spectrums. Ocular surface squamous neoplasia (OSSN), pterygium and conjunctival melanocytic lesions represent the three most impacting subtypes of such "ophthalmohelioses" affecting the ocular surface. OSSN represents a broad class of squamous dysplastic lesions ranging from benign papillomas till invasive squamous cell carcinomas. Melanocytic tumours such as primary acquired melanosis have a great propensity to become malignant, especially if cells are atypical. Finally, pterygium is a benign growth commonly treated with surgical excision, but patients often face an endless remitting-relapsing cycle of pterygium recurrence and repeat surgery. If untreated, patients sight limitation secondary to visual axis invasion. The early detection of OSSN, pterygium and melanocytic lesions is non-existent and often disease requires to be excised and subsequently microscopically analysed before a formal conclusion is made. For pterygium, the identification of Fuchs' Flecks at the head of pterygium may serve as satellite cells ahead of the main pterygium body. Handedness may serve a role in the eye in which pterygium is worse or develops. From a therapeutic point of view, these three "ophthalmohelioses" tend to recur consistently despite optimized treatments. This therapeutic dilemma presents themes of concern, including vision disruption, secondary to repeat surgeries given the relapsing-remitting characteristic of all three disease entities. Topical eye drops such as interferon alfa-2b combined with retinoic acid serve as a potential solution which offer superior tumour-free follow-up and rapid tumour resolution of OSSN or primary acquired melanosis lesions. The viral influence of human papilloma virus upon OSSN may be mitigated with the application of topical cidofovir. Additionally, specialized pterygium surgery may be an effective alternative to otherwise other subtypes of pterygium excision, others often being anatomically more destructive. At essence, a focus of novel therapeutic options that target pathways within "ophthalmoheliosis" pathogenesis is being presented within this thesis which may hopefully improve and expand ophthalmologist's arsenal against disease spectrums very relevant to the Australian populace.
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(2021)ThesisThe following thesis examines the implementation of objective methods to measure patient physical capabilities within the spine surgery setting. With a broad aim to introduce accurate and robust assessment tools that are not influenced by subjective patient factors and experiences our methods have been devised after a wide literature search to examine the current state-of-play. Following this literature review two separate arms have been conducted, one in the clinical setting on a large scale using affordable and accurate devices while a second arms aim’s to examine range-of-motion as a potential outcome measure. The latter arm within the scope of the thesis is limited to a validation study with 2 separate emerging technologies; an inertial based sensor system and a digital goniometer. Together these two arms pave way for clinicians not just in the spine surgery setting to employ similar assessment methods in aims to achieve safe, affordable, remote and objective measures of patient outcome. Briefly we have been able to validate the digital goniometer for clinical use, while our accelerometer data is promising for use in the large volume outpatient setting.
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(2022)ThesisAcute kidney injury (AKI) occurs commonly in hospitalised children and carries an increased risk of morbidity and mortality. This thesis investigates the relationship between AKI and baseline kidney function, as this has not been well explored. We studied children exposed to acyclovir, and children with cancer, as these groups both have an increased risk of AKI. Children with cancer have been shown to have high baseline kidney function, known as glomerular hyperfiltration (GH), which is poorly understood. GH is a glomerular filtration rate above normal, which we define as a measured glomerular filtration rate (NMGFR) ³160mL/min/1.73m2. In a retrospective review of 150 children treated with acyclovir, 27 (18%) developed AKI. The only factor associated with AKI on multivariable analysis in this cohort was higher baseline estimated GFR (p=0.013). We reviewed the records of 202 children who underwent allogeneic haematopoietic stem cell transplant (HSCT) for haematological malignancy. In the first 100 days post-HSCT, 173 (85.6%) children developed AKI and stage 3 AKI occurred in 58 (28.7%). Factors significantly associated with stage 3 AKI on multivariable analysis were use of ciclosporin (vs. tacrolimus) (p=0.02), total body irradiation (p=0.01), early AKI on or before day 10 post-HSCT (p=0.001), ³10% creatinine increase 24 hours after AKI onset (p=0.001), and higher pre-HSCT NMGFR (p=0.03). At 1-year, patients with stage 3 AKI had greater reduction in estimated GFR than other children (-53.9 vs -18.8mL/min/1.73m2; p=0.0002). Analysis of the above cohort combined with the records of 91 children who underwent NMGFR at time of solid organ cancer diagnosis revealed that 16% had GH. GH was more common in young children (p=0.0055) and those with acute myeloid leukaemia (p=0.02), and was associated with higher weight gain (a surrogate for fluid accumulation) post-HSCT (p=0.02). Most children with GH pre-HSCT returned to a normal GFR. Development of GH at 1-year post-HSCT was associated with prior acute GVHD. This research is among the first to demonstrate that GH is associated with an increased risk of AKI. Our results suggest that GH occurring before HSCT may have a different underlying cause to hyperfiltration occurring post-HSCT and warrants further investigation.
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(2021)ThesisBackground: Cervical spine degenerative conditions effect up to two-thirds of the population and are the most common cause of acquired disability in patients over the age of 50. These disorders commonly present with axial pain, myelopathy, radiculopathy or a combination of these symptoms. Surgical intervention is generally indicated in with failure of conservative management or with evidence of cord compression or myelopathy. Anterior cervical discectomy and fusion (ACDF) is an effective option. It is not well established what factors contribute to dysphagia and recurrent laryngeal nerve palsy complications following ACDF surgery. Objective: 1. To determine the rates of dysphagia and recurrent laryngeal nerve complications following ACDF reported in the literature and potential associated factors. 2. To determine rates of dysphagia and recurrent laryngeal nerve injuries in a large Australian series of ACDF by a single surgeon. Methods: For the systematic reviews, electronic searches were performed using electronic databases. Relevant studies reporting the rate of dysphagia or recurrent laryngeal nerve injury as an endpoint for patients undergoing ACDF for degenerative disease, myelopathy, cervical canal stenosis or ossification of the posterior longitudinal ligament were identified according to prior inclusion and exclusion criteria. Statistical analysis was performed using odds ratio (OR) as the effective size. I2 was used to explore heterogeneity. For the retrospective chart review, consecutive patients undergoing ACDF from 2015 to 2019 for cervical radiculopathy and/or myelopathy were included. Univariate logistic regression analysis was performed to identify risk factors of RLN palsy, swallowing problems and adjacent-level ossification disease (ALOD). Results and conclusions: We found that based on pooled analysis that there was a higher rate of dysphagia for multiple-level ACDF (6.6%) compared with single-level ACDF (4%). The pooled incidence of recurrent laryngeal nerve palsy from the literature was 1.2%, with no difference between multiple- and single-level ACDF. These rates were similar to analysis of our retrospective series, with 1.8% patients having recurrent laryngeal nerve palsy and 4.0% with clinical dysphagia. We confirm based on our series that multi-level operation was associated with higher rate of RLN palsy, but this was not affected by other factors including age, gender, and the use of plate, internal fixation or number of screws.