Ercan OLCAY, TURGUT GÜLMEZ, Zihni MUTLU, CELAL ŞAHİN ERMUTLU, Ertuğrul ALLAHVERDI

The evaluation of pullout tests of an expandable newly designed screw

Ucu açılabilir yeni tasarlanmış kortikal vidaların sıyırma kuvvetlerinin biomekanik olarak değerlendirilmesi genç boğaların tibia kemiğinde yapıldı. Yeni tasarlanmış ucu açılabilir 14 kortikal titanyum vida taze tibia kemiğine yerleştirildi. Bu vidaların 7 tanesi kontrol grubu olarak kullanıldı. Vidalar yerleştirildikten sonra kemikler polimetilmetakrilat ile fikse edildi. Vida başları özel bir alete bağlandı ve sıyırma testi için hazırlandı. Elastik modulus değerleri (Newton/mm2), akma kuvveti (Newton) ve maksimum kuvvet (Newton) değerleri ucu genişleyebilen ve kontrol gruplarında değerlendirildi. Ucu genişleyebilen kortikal vida grubunun ortalama akma değerleri istatistiksel olarak normal gruba göre daha yüksek bulundu (P=0.025). Genişleyebilen kortikal vida grubunun maksimum güçlerinin ortalaması normal gruba nazaran önemli derecede yüksek bulundu (P=0.003). Eşlendirilmiş grupların karşılaştırılmasında genişleyen kortikal vidaların pullout kuvvetlerinin normal kontrol gruplara nazaran önemli derecede yüksek olduğu bulundu. Bu çalışmalarımızın ışığı altında yeni tasarlanmış böyle vidaların vida çapını genişletmeksizin daha fazla kemik kontağına izin vererek gelecekte kırık fiksasyonuna katkıda bulunabileceği tartışıldı.

Ekspanse olabilen yeni tasarım bir vidanın sıyırma (pullout) testlerinin değerlendirilmesi

Biomechanical evaluation of pullout forces of newly designed cortical screws with openable tips was done in the tibia bone of the young bulls. Newly designed expandable titanium 14 cortical screws with openable tips were inserted in fresh tibia bone. Of these screws, 7 were used as controls. The bones were fixed with polymethylmethacrylate after the insertion of the screws. Screw heads were attached to a custom device and prepared for pullout tests. The elastic modulus values (Newton/mm2), yield forces (Newton) and maximum forces (Newton) of expandable and control groups were assessed. The median of yield forces (Newton) of expandable cortical screw group was found to be statistically higher than that of normal group (P=0.025). The median of maximum forces of expandable cortical screw group was found to be significantly higher than that of normal group (P=0.003). In the comparison of paired groups, it was found that the pullout forces of expandable cortical screws were significantly superior to that of normal control group. In the light of these results, it was concluded that such kind of newly designed screws are able to contribute to fracture fixation in the future, allowing more bone contact without enlarging the diameter of the screw.

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