Salim ERSÖZLÜ, Bartu SARIÖZEN, Reşat ÖZCAN, Özgür ÖZER, Rasim ŞERİFOĞLU

Kemik iliği ablasyonunun sıçan tibiasının bölgesel biyomekanik özellikleri üzerine etkileri

Amaç: Normal sıçan tibiasının bölgesel (metafiz-diyafiz) biyomekanik özellikleri ve bir kırık iyileşme modeli olan kemik iliği ablasyonu sonrası bu özelliklerde ortaya çıkan değişiklikler incelendi. Çalışma planı: Tibialarına kemik iliği ablasyonu uygulanan 24 adet Sprague-Dawley cinsi sıçan deney grubunu, hiçbir cerrahi işlem uygulanmayan sekiz adet sıçan kontrol grubunu oluşturdu. Tüm sıçanlardan proksimal metafiz, proksimal diyafiz, distal diyafiz ve distal metafiz örnekleri hazırlandı. Kontrol grubunda kompresif kuvvetler uygulanarak tibianın bölgesel segmentlerinde sertlik (E), güç (Smaks) ve dayanıklılık (toplam enerji absorbsiyonu, U) parametreleri ölçüldü. Deney grubunda ise ablasyonu takiben 1, 3, 7, 9 ve 15. günlerde kompresyon uygulanarak, ablasyonun tibianın bölgesel mekanik özelliklerinde meydana getirdiği değişiklikler incelendi. Sonuçlar: Normal sıçan tibiasında anatomik bölgeler arasında en düşük E, Smaks ve U ölçümleri proksimal metafiz bölgesinden elde edilirken, en yüksek değerler E ve Smaks ölçümlerinde distal diyafiz, U ölçümlerinde ise proksimal diyafiz bölgelerinden elde edildi. Kemik iliği ablasyonu sonrasında tüm test değerlerinde 1-7. günlerde düşüş, 7-9. günlerde hafif bir artış ve 9-15. günlerde yeniden bir düşüş saptandı. Mekanik ölçüm parametreleri açısından iki grup arasında belirgin istatistiksel fark saptanırken (p0.05). Çıkarımlar: Normal sıçan tibiasında biyomekanik açıdan diyafiz en dirençli, proksimal metafiz ise en zayıf anatomik bölgedir. Kemik iliği ablasyonu sonrası meydana gelen metabolik olaylar, tibianın bölgesel mekanik özelliklerinde değişikliklere neden olmaktadır. Ablasyona bağlı intramedüller hasardan en fazla etki lenen bölgeler tibianın metafizer segmentleridir.

Anahtar Kelimeler:

Sıçan, Sprague-Dawley, Tibia, Kırık iyileşmesi, Modeller, hayvan, Biyomekanik, Tibia kırıkları

The effect of bone marrow ablation on regional biomechanical properties of rat tibia

Objectives: Regional (metaphyseal-diaphyseal) biomechanichal properties of normal rat tibia, and changes on these biomechanichal properties after bone marrow ablation, a model of fracture healing, were examined. Methods: The study included 24 Sprague-Dawley rats that underwent tibial marrow ablation, and eight control rats with no surgical procedure. Proximal metaphyseal, proximal diaphyseal, distal diaphyseal, and distal metaphyseal samples were prepared from the tibias of all rats. In the control group, stiffness (elastic modulus, E), strength (maximum strength, Smax), and toughness (total energy absorption, U) parameters of the regional tibial segments were evaluated under compression loads. In the experimental group, compression was applied following bone marrow ablation on days 1, 3, 7, 9, and 15, and ablation-induced changes in the regional biomechanical properties were studied. Results: The lowest E, Smax, and U values were obtained from the proximal metaphysis. The highest E and Smax values were from the distal diaphyseal, and the highest U values were from the proximal diaphyseal regions. In ablation-induced rats, decreases were observed in all the mechanical test values during days 1 to 7, followed by slight increases on days 7 to 9, and eventual decreases on days 9 to 15. There were significant differences between the two groups with respect to biomechanical parameters (p<0.05), but no significant differences were found between the tibial regions (p>0.05). Conclusion: Biomechanically, the most resistant and the weakest anatomic regions of normal rat tibia are the diaphyseal region and proximal metaphysis, respectively. The metabolic changes occurring after bone marrow ablation lead to changes in the mechanical properties of the tibia. The most affected tibial segments from ablation- induced intramedullary injury are the metaphyseal segments.

Keywords:

Rats, Sprague-Dawley, Tibia, Fracture Healing, Models, Animal, Biomechanics, Tibial Fractures,

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