Failure of a primary hip arthroplasty is often caused by osteolysis which compromises the patient’s periprosthetic bone stock. Impaction allografting involves the use of morselized allograft bone and cement to stabilize the implant and restore this periprosthetic bone stock. Although clinical results of impaction allografting are favourable, regions of necrotic bone graft have been shown to exist for many years post-operatively and may ultimately lead to implant failure. Previous laboratory research has identified a correlation between mechanical stimuli and bone growth; therefore, the purpose of this study was to develop an in vivo device that would enable the investigation of the effect of mechanical load on bone graft incorporation in impacted allograft hip prostheses. An actuator was developed with a finite volume to enable its subcutaneous implantation along the tibia (20mm x 10mm x 10mm) and spine (35mm x 25mm x 15mm) in a rat bone chamber model. The actuator was designed to deliver a dynamic, (1Hz), compressive, (-6N), load that was controlled telemetrically throughout a 6-week long in vivo study. Independent validations of the mechanical actuator and the electrical control system were performed prior to an electromechanical validation of the integrated system. The responsiveness, quantity and magnitude of the load were investigated. The mechanical actuator was motor-driven and the electrical control system was based on radio frequency signal transmission. The electromechanical actuator conformed to the volumetric restrictions of the rat bone chamber model (tibia: 13mm x 17mm x 10mm; spine: 35mm x 30mm x 11mm). A wide range of operating frequencies (0.5 to 3.0 ± 0.05Hz) was achieved and a telemetrically controlled load was produced for 20 seconds per day throughout a simulated 6 week in vivo study. Due to inefficiencies of the mechanical actuator and voltage limitations of the control system, the magnitude of the compressive load produced by the actuator (-1.67 ± 0.10N) was less than specified by the design criteria. Future work to optimize the actuator design and fabrication is warranted in order to increase the maximum load magnitude; however, the current design provides a novel means to begin the investigation of the role of mechanical load on bone graft incorporation in impaction allografting. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Background: Prolonged recovery after tendon injury has given rise to the need for innovative therapy including tendon engineering and cell based therapies. The role of cells in grafted or engineered tendon is poorly understood. Clarifying the persistence of grafted tissue is fundamentally important to ensure that tissue engineering strategies are fit for clinical application. We have devised a murine model for tendon grafting that allows for cell tracking and the assessment of tendon integration and engineered construct integration. Materials and methods: We studied the macroscopic and microscopic architecture of the mouse Achilles tendon to investigate its properties as a study model. Using microsurgical techniques, transgenic tendon grafting procedures were then carried out between C57B/L6 wild type and GFP (Green Fluorescent Protein) mice Achilles tendon. The temporal and spatial fate of the cells in the graft was assessed using quantitative serial histology and immunohistochemistry with Three Dimensional reconstruction. Markers for proliferation, collagen synthesis, cell death and inflammatory infiltrate were used. The Achilles tendon model was also applied to test its applicability to investigate tissue engineered tendon constructs developed in vitro. Results: GFP positive graft cells were seen at Day 3 and Day 21 but disappeared by Day 90. At Day 21both graft cells and the cells of the recipient tendon showed intense collagen synthetic activity. At the same time both graft and host tendon cells began to show signs of apoptosis which continued till Day 90. Subcutaneous tissue and paratenon maintained a much higher level of cellularity, cell proliferation, collagen synthesis and apoptosis at all time. The interplay between cell activity and cell death appear to play central role in the integration of the tendon graft. The persistence of tissue engineered tendon constructs was far less than syngenic or autografts. The Achilles tendon model proved to be a robust and economically viable model for testing of biomaterials particularly at the early stage of their development. Conclusion: The cells of tendon grafts persist only for a finite time before being repopulated by host cells. Tissue engineered cell-based constructs do not provide sufficient persistence to substitute in place of syngenic or autologous graft options. Future designs of engineered tendon should facilitate tendon integration and aim to persist for longer periods of time in order to participate in the healing process.

Research Report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirement for the Degree of Masters of Medicine in Otorhinolaryngology Johannesburg October 2017 / AIM: This study aimed to assess the anatomical and functional success rate of Butterfly Cartilage Inlay Graft myringoplasties done at Chris Hani Baragwanath Academic Hospital using an oto-endoscope. Size of perforation was assessed as a possible predictor of success. METHODS: The study comprised of a retrospective review of all records from the ENT Department at Chris Hani Baragwanath Academic Hospital of all patients who underwent BCIG myringoplasty from January 2009 to December 2013. 85 of the 160 patients who had BCIG’s at CHBAH met the inclusion criteria for this study. Data was collected on a data collection sheet and analysed using standard statistical methods. RESULTS: 85 patients were included in the study of ages 5 years – 67 years with a mean age (SD) of 19,2 years (16,3). 61% were children (<13 years), 39% adults (14 – 49 years) and only 6% were >50 years. There were 30 (35%) Female patients and 55 (65%) Male patients. The data presented in this study show an anatomical success rate of 90,6% for Butterfly Cartilage Inlay Grafts at Chris Hani Baragwanath Academic Hospital. The anatomical success rate of this study is equal to the success rates reported in the literature for the same procedure. 87% of patients experienced hearing improvement post operatively. The average hearing improvement in this study post Butterfly Cartilage Inlay Graft is 15dB. Finally, perforation size does not influence both anatomical and functional success rates in this study. CONCLUSION: Endoscopic BCIGs performed at Chris Hani Baragwanath Academic Hospital, for small, medium and large perforations, show anatomical and functional success rates similar to those reported in the literature, performed with both microscope and endoscope. Size of perforation is not a predictor of anatomical and functional success for this procedure. / MT2018

Objective – 1) To determine whether a graft of fascia lata and part of the patellar ligament, used in an extracapsular fashion from the tibial crest to the femorofabellar ligament, would eliminate abnormal cranial drawer motion in the cranial cruciate ligament (CrCL) deficient stifle 2) To determine if two new tibial suture anchor points would enhance biomechanical function of the lateral fabellar-tibial suture (FTS). Study Design – Experimental. Animals – 28 canine cadaver hind limbs. Methods – Stifles were mounted in a jig that allowed tibial rotation during loading and were tested between loads of â 65 to 80 N in caudal and cranial drawer respectively. Stifles were tested with the CrCL intact followed by one of four stabilization techniques after CrCL transection: lateral graft technique (LGT) and three FTS with different tibial anchor points. Results – Differences in cranial drawer motion (displacement) and stiffness between the LGT and standard FTS were not significant in two data sets, when compared to the intact CrCL. The FTS with the anchor point in the tibial crest showed the least displacement of all stabilization methods. Differences in stiffness were not significant between the stabilization techniques. Conclusions – Stability provided by the LGT is comparable to that of the standard FTS for the CrCL-deficient stifle in the cadaver. Altering the tibial anchor points for the FTS did not improve stiffness or result in a further decrease in cranial drawer motion. Clinical Relevance – The LGT could be used for the treatment of acute and chronic CrCL ruptures in the dog. A clinical study is recommended. / Master of Science

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A instalação de implantes odontológicos requer a presença de substrato ósseo adequado para garantir estabilidade e equilíbrio biomecânico. A deficiência óssea requer procedimentos de enxertia para adequar o volume para a instalação de implantes, porém a utilização de enxertos autógenos causa aumento de morbidade ao paciente e o uso de material homógeno e xenógeno apresenta dúvidas quanto à reação autoimune, transmissão de doenças e ao grau de reabsorção do enxerto. Com o grande desenvolvimento científico e tecnológico dos biomateriais, os materiais cerâmicos, tornaram-se alternativas promissoras para a recomposição da estrutura óssea perdida. As cerâmicas à base de fosfato de cálcio como a hidroxiapatita (HA) e o beta- fosfato tricálcido (beta-TCP), são materiais que apresentam qualidades desejáveis no processo de neoformação óssea como, por exemplo, a biocompatibilidade, bioatividade e osteocondutividade. A proposta deste trabalho é desenvolver e estudar corpos de prova na forma de cúpula oca de hidroxiapatita preenchidos por coágulo, beta- TCP e composto vitamínico, para estudar a osteogênese supracortical, a partir do potencial osteocondutor da cúpula de HA. As cúpulas foram obtidas por prensagem isostática a 200 MPa e sinterização ao ar a 1100°C por 60 minutos. As caracterizações físico-químicas das matérias-primas e da cúpula de HA foram realizadas por difração de raios X, microscopia eletrônica de varredura e determinação da densidade. Na caracterização biológica, foram realizados o teste de citotoxicidade in vitro e ensaio in vivo. Foram designados 9 coelhos (raça Nova Zelândia), sendo instaladas 18 cúpulas, divididas em três grupos, de acordo com o preenchimento: controle, composto vitamínico e &beta;-TCP em forma de pó. O período de reparação tecidual foi de 8 semanas, no qual foram aplicados marcadores de fluorescência. Após o período de cicatrização e eutanásia, as amostras foram incluídas em resina para a obtenção das lâminas e observadas em microscópio de fluorescência, para avaliar a quantidade de tecido ósseo neoformado, em microscópio de campo claro, para verificar as células presentes no tecido formado e por Espectroscopia de Energia Dispersiva, para análise química, da formação no interior das cúpulas. Como resultados, a cúpula de hidroxiapatita apresenta bom desempenho como arcabouço para neoformação óssea acima da cortical da tíbia de coelhos, pois manteve-se íntegra, com boa estabilidade e boa integração ao tecido ósseo, e principalmente pela neoformação óssea, demonstrando seu potencial osteocondutor. Em relação aos materiais de preenchimento, o beta-TCP apresenta maior valor de área de osso neoformado, em comparação com o coágulo. Nas cúpulas com preenchimento de composto vitamínico, não há formação de tecido ósseo pela não reabsorção do material. / The installation of dental implants requires the presence of adequate bone substrate to ensure stability and biomechanical balance. Deficiency requires bone grafting procedures to adjust the volume for implant placement, but the use of autogenous grafts cause increased morbidity to the patient and the use of homogenous and xenogenous materials has doubts about the autoimmune reaction, transmission of disease and the degree of resorption of the graft. With the great scientific and technological development of biomaterials, ceramic materials, have become promising alternatives for restoration of lost bone structure. The ceramics based on calcium phosphate such as hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) are materials having desirable qualities in the process of bone formation, for example, biocompatibility, bioactivity and osteoconductivity. The purpose of this work is to develop and study the dome-shaped hydroxyapatite filled with blood clot, beta-TCP and vitamin compound, to study osteogenesis supracortical from the osteoconductive potential of the dome of HA. The domes were obtained by isostatic pressing at 200 MPa and sintered in air at 1100 ° C for 60 minutes. The physico-chemical characterization of raw materials and the dome of HA were performed by X-ray diffraction, scanning electron microscopy and density determination. In biological characterization were performed tests for in vitro cytotoxicity and tests in vivo. Were designated 9 rabbits (New Zeland), and installed 18 domes, divided into three groups, according to the filling: control, vitamin compound and &beta;-TCP in powder form. The period of wound healing was 8 weeks, when a fluorescence marker was applied. After the healing period and euthanasia, the samples were embedded in resin to obtain the slides and observed under fluorescence microscope to evaluate the amount of newly formed bone tissue in bright field microscope to check the cells present in the tissue and by Energy Dispersive Spectroscopy for chemical analysis, inside the domes. As a result, the hydroxyapatite dome has good performance as scaffold for bone formation above the cortical tibia of rabbits, it remained intact, with good stability and good integration with bone tissue, especially bone formation, demonstrating osteoconductive potential. Regarding the filling materials, beta-TCP has a higher value of area of new bone formation compared to the clot. In the domes-filled vitamin compound, there is no formation of bone resorption by not material.

Hydroxyapatite (HA) bioceramics are commercially available as bone graft substitute materials. The aim of the current research was to characterise the electrical properties of hydroxyapatite-barium titanate (HABT) composites and to assess in vitro biological responses to the composites in order to investigate their potential use as bone graft substitutes. A range of HABT ceramics of different compositions was manufactured and their electrical properties were measured. The microstructure and piezoelectric properties of the ceramics were both dependent on the proportion of barium titanate (BT) present. Composites containing more than 70% BT displayed piezoelectric charge coefficients (d33) of up to 86.3±7.9pCN-1 (95% BT). The ferroelectric nature of the 90 and 95% BT materials was confirmed by assessment of their ferroelectric hysteresis loops. The highest piezoelectric voltage coefficient (g33) recorded was 14x10-3Vm-1Pa-1 (90% BT). Following the assessment of the electrical properties, the HABT ceramic containing 90% BT was selected for the assessment of biological responses to the composites. The proliferation, viability, activity and morphology of human osteoblast-like cells cultured on HABT were comparable to those cultured on hydroxyapatite (HA) up to 7 days after seeding. The remnant polarisation of poled HABT induced an increase in cell attachment. This influence was independent of the nature (positive or negative) of the polarisation. Poling was not found to influence cell morphology, activity or differentiation in the first 7 days of incubation. At 14 days after seeding, results were inconsistent, indicating some variations in cell population and differentiation depending on the composition and poling of the ceramics respectively. This study has substantially defined the electrical properties of a range of HABT ceramics. It indicates their in vitro biocompatibility and thus their potential for use as bone graft substitutes. These results provide a benchmark against which future work investigating the influence of mechanical loading and longer term studies may be measured.