İrfan ESENKAYA, Yurdaer DENİZHAN, MEHMET AKİF KAYGUSUZ, MEHMET YETMEZ, Mehmet Halidun KELEŞTEMUR

Pediküler vida revizyonlarında üç farklı tip vidanın sıyırma kuvvetlerinin karşılaştırılması: Biyomekanik çalışma

Amaç: Pediküler vida revizyon cerrahisinde üç farklı tipte pediküler vida tasarımının aksiyel sıyırma kuvvetini nasıl etkilediği araştırıldı. Çalışma planı: Çalışmada dana lomber vertebralarından iki ayrı deney grubu oluşturuldu. Vertebraların her bir pedikülüne (tepleme uyguladıktan sonra veya tepleme uygulamadan) 6.5 mm dış çaplı Alıcı pediküler vidalar uygulandı. Vidalara aksiyel sıyırma (pull-out) testi uygulanarak pedikül yetersizliği geliştirildi. Tüm vertebraların sol pediküllerine 7 mm dış çaplı Alıcı tipi pediküler vida uygulandı. Sağ pediküllere ise, bir deney grubunda birinci tipte, diğer deney grubunda ikinci tipte uç kısımları genişleyebilen pediküler vida uygulandı. Aksiyel sıyırma testi her iki grupta tekrar edildi ve elde edilen sonuçlarla 6.5 mm Alıcı vidalarla ölçülen sıyırma kuvvetleri karşılaştırıldı. Sonuçlar: Birinci deney grubunda, 7 mm’lik Alıcı tipi revizyon vidalarıyla başlangıçtaki sıyırma kuvvetinin %65’i, birinci tip uç kısımları genişleyebilen pediküler vidalarla da %64’ü elde edildi. İkinci deney grubunda ise 7 mm’lik Alıcı tipi revizyon vidalarıyla başlangıçtaki sıyırma kuvvetinin %70’i, ikinci tip uç kısımları genişleyebilen pediküler vidalarla da %68.5’i elde edildi. Vida giriş yerinin teplenmesi, teplenme uygulanmayan grupla karşılaştırıldığında, sıyırma kuvvetinde ortalama %13’lük bir azalmaya neden oldu. Çıkarımlar: Pediküler vidaların revizyonunda, vida çapında sadece 0.5 mm’lik bir artışla yeterli vida-kemik ara yüzey kuvveti ve pedikül doluluğu elde edilemedi. Genişleyebilen pediküler vida kullanımıyla da yeterli pediküler vida stabilitesi sağlanamadı.

Anahtar Kelimeler:

Biyomekanik, Kemik vidaları, Omurilik hastalıkları

Comparison of the pull-out strengths of three different screws in pedicular screw revisions: a biomechanical study

Objectives: We investigated the possible effects of three pedicular screws on axial pull-out strength in pedicular revision surgery. Methods: Two study groups were formed from calf lumbar vertebrae. Initially, Alıcı pedicular screws with an outer diameter of 6.5 mm were applied (with our without tapping) to all the pedicles. All the pedicles were subjected to axial pull-out testing to induce pedicular insufficiency. Then, Alıcı pedicular screws with an outer diameter of 7 mm were applied to the left pedicles. The right pedicles in the two study groups were assigned to receive two different types of pedicular screws with an expandable (enlargeable) end, respectively. Axial pull-out testing was repeated in both groups and the results were compared with the initial pull-out strength values. Results: In the first group, 65% and 64% of the initial pull-out strengths were obtained with 7-mm Alıcı pedicular screws and with expandable pedicular screws, for the left and right pedicles, respectively. The corresponding pull-out strengths in the other study group were 70% and 68.5% of the initial values, respectively. Tapping of the screw hole entrance resulted in a mean decrease of 13% in the pull-out strength compared to screw applications without tapping. Conclusion: Pedicular screw revisions using a 0.5 mm greater screw in diameter did not provide adequate screw-bone inter-face strength and pedicle filling. Similarly, expandable pedicular screws did not contribute to screw stability.

Keywords:

Biomechanics, Bone Screws, Spinal Diseases,

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