Browsing by Author "Karadeniz, Emre"

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    Açılı vidalar ile plak tespitinin mekanik ek getirilerinin değerlendirilmesi : biyomekanik çalışma)
    (Başkent Üniversitesi Tıp Fakültesi, 2008) Karadeniz, Emre; Tuncay, İ. Cengiz
    Bu çalısmanın amacı: her iki planda dik, bir planda dik, diğer planda açılı ve her iki planda açılı vidalar ile plak tespitinin, aralık kapatan (gap-close) eğilme ve yan eğilme kuvveti uygulayarak en yüksek moment kuvveti ve olusan deformite yönünden biyomekanik olarak karsılastırılmasıdır. Çalısmada, 2,5-3,5 yaslarında koyun tibiaları, 6 delikli dar dinamik kompresyon plakları ile özel olarak üretilmis bir kılavuz yardımı ile vida gönderilerek tespit edildi. Tespit: 1. Grupta; plağa her iki planda dik açılı vidalar ile, 2. Grupta; bir planda dik, diğer planda 20 derece açılı vidalar ile 3. Grupta; bir planda plağa 20 derece açılı diğer planda 7 derece açılı vidalar ile sağlandı. Bu gruplara; instron cihazında, 3 nokta prensibine uygun olarak, beser adet aralık-kapatan eğilme (A) ve yan eğilme (B ) testleri uygulandı. Vida-plak sistemini gevseten en yüksek moment kuvveti ve bu kuvvet esnasında olusan deformite istatistiksel olarak karsılastırıldı. Deneylerin sonunda; Ortalama en yüksek moment kuvveti A1:51,90 Nm, A2:67,47 Nm, A3:82,05 Nm, B1:34,64 Nm, B2:49,91 Nm, B3:49,29 Nm idi. Aralık kapatan eğilme testinde Grup 1 ile diğer Gruplar karsılastırıldığında; p<0,05 iken, Grup 2 ile 3 arasında p=0,053 idi. Yan eğilme testinde ise yine Grup1 ile Grup 2,3 arasında p<0,05 olup, grup 2 ile 3 arasında anlamlı farklılık tespit edilmemistir. Eğilme testlerinin her ikisinin ortalama sonuçları beraber gruplar arasında değerlendirildiğinde ise: Grup 1 ile Grup 2 arasında p=0,070, Grup 2 ile 3 arasında p=0,552 ve Grup 1 ile 3 arasında ise p=0,006 idi. En yüksek kuvvet esnasında olusan deformite A1:7,3mm A2:5,4mm A3:7,1mm, B1:6,1mm B2:6,9mm B3:6,4mm olarak tespit edildi ve tüm gruplar arası deformite karsılastırmalarında p >0,05 idi. Sonuç olarak, klasik plak vida tespit yöntemi olarak kullanılan her iki planda dik açı ile vida tespitine göre, her iki planda açılı vidalar ile tespit eğilme kuvvetlerine karsı daha sağlam tutunma sağlar. Ancak deformiteye karsı dirençte açılı vida tespiti ile ek getiri yoktur. The aim of this study is to evaluate; plate fixation with screws perpendicular in two plane as in conventional technique, oblique in one plane and angled in two planes, does change the strength of the fixation to bending forces. And is there any correlation between elevated strength and deformity resistance. As the study method; 2,5-3,5 year old sheep rear leg tibias are fixed with the help of a custom made guide to a six hole DCP. Fixation in Group 1: With screws perpendicular in two planes. In Group 2: 20 degree to the shaft axis and perpendicular in the transverse plane. In Group 3: 20 degree to the shaft axis and 7 degree in the transverse plane. We tested these Groups fixation strength with gap-close bending (A) and side bending (B) forces in tree point bending fashion. We statistically analyzed the maximum moment force and deformation at the time of the failure. After the experiments; mean maximum moment force was A1:51.90 Nm, A2:67.47 Nm, A3:82.05 Nm, B1:34.64 Nm, B2:49.91 Nm, B3:49.29 Nm. In gap-close bending tests p value was < 0.05 between Group 1 and the other groups. Between Group 2 and 3 p=0.053. In site bending tests p value was < 0.05 between Group 1 and the other two but not significant between 2 and 3. When two of the bending tests evaluated together p value was significant in only between Group 1 and 3 (p=0.006).The deformity at the time of the maximum moment was not significantly different between any Groups. In consequence, oblique screw placement in two plane increases the strength of the platescrew fixation under bending forces. But there is no degrease of the deformity with elevated strength of the fixation.
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    Effect of pentoxifylline on healing of segmental bone defects and angiogenesis
    (2015) Cakmak, Gokhan; Sahin, Mehmet Sukru; Ozdemir, B. Handan; Karadeniz, Emre; 26511696
    Objective: The aim of this study was to determine the effect of pentoxifylline (PTX) on angiogenesis and the healing of a critical-sized segmental defect of the radius diaphysis in a rat model, using radiological and histological grading systems. Methods: The study included 24 female Sprague-Dawley rats (weight: 300 +/- 20 g) divided into 4 groups. A critical-sized segmental defect was created in the radius diaphysis in all rats. In Group 1, morcellized iliac crest autografts were used to fill the segmental bone defect. In Group 2, segmental bone defects were filled using morcellized iliac crest autografts, and 25 mg/kg/day PTX was applied intraperitoneally. In Group 3, the segmental bone defects were not filled, and in Group 4 the segmental bone defects were left unfilled, and an intraperitoneal (IP) dose of 25 mg/kg/day PTX was applied. Rats were sacrificed at postoperative Week 8, and defects were evaluated using radiographic, histological and immunohistochemical methods. Results: There were significant differences between Group 1 and 2 according to radiological evaluation (p = 0.003) and quality of union at the defect site (p = 0.01). Union quality was higher in Group 4 than Group 3 (p = 0.01). Cluster of differentiation 31 (CD31) and vascular endothelial growth factor (VEGF) levels were higher in Group 2 than in Groups 3 and 4. Conclusion: According to radiological and histological parameters, PTX appears to improve angiogenesis and healing of segmental cortical bone defects of the radius in a rat model.