A. Meriç ÜNAL, Önder BARAN, BORA UZUN, Ahmet C. TURAN

Comparison of screw-fixation stabilities of first metatarsal shaft osteotomies: a biomechanical study

Amaç: Orta ve ileri halluks valguslu olguların cerrahi tedavisinde son yıllarda yaygınlaşan metatarsal şaft osteotomilerinin, daha iyi redüksiyon ve stabilite sağlamalarına karşın, açısal düzeltmeyle ters orantılı tespit sorunları bulunmaktadır. Bu çalışmada, günümüzde sıklıkla kullanılan metatarsal şaft osteotomileriyle yeni tanımlamış olduğumuz osteotomi modifikasyonunun ileri açısal düzeltmelerde vidayla tespit yönteminin sağlamlığı üzerindeki etkileri biyomekanik olarak değerlendirildi. Çalışma planı: Şaft osteotomilerinin var olan sorunları irdelenerek, daha fazla açısal düzeltme yapabilirken yeterli temas alanı sağlayan, stabiliteyi artırıcı özelliklere sahip ve osteosentez açısından daha güvenli yeni bir osteotomi tasarlandı. Mau osteotomisinin yeni bir modifikasyonu olarak değerlendirilen bu yöntemde, Sammarco modifikasyonunda temas yüzeyini artırmak amacıyla tanımlanmış olan proksimal plantar çentik, daha proksimalden ve osteotomi ile yaklaşık 50° açı yapacak şekilde uygulandı ve osteotomi distal eklem yüzüne 5 mm kalana kadar uzatıldı. Böylece, temas yüzeyinin ve intrensek stabilitenin artırılması amaçlandı. Biyomekanik çalışma için 30 adet Sawbones metatars kemik modeli beş gruba ayrıldı ve her bir gruba şu osteotomi yöntemlerinden biri uygulandı: Ludloff osteotomisinin Myerson modifikasyonu, Mau, scarf, ofset V osteotomileri ve Mau osteotomisinin yeni modifikasyonu. Bütün osteotomilerde standart olarak intermetatarsal açıda 10 derecelik düzeltme sağlanarak uygun osteosentez iki adet Acutrak vidası ile yapıldı. Osteotomiler ile osteosentez arasındaki stabilite ilişkisi üç nokta eğme testiyle araştırıldı. Sonuçlar: Ludloff grubunun sertlik değeri diğer tüm gruplardan anlamlı derecede düşük bulundu (p

Anahtar Kelimeler:

Kemik vidaları, Kırık tespiti, internal, Rekonstrüktif cerrahi işlemler, Osteotomi, Metatarsal kemikler, Donanım tasarımı, Biyomekanik

Birinci metatars şaft osteotomilerinin vida ile tespit stabilitelerinin karşılaştırılması: Biyomekanik çalışma

Objectives: Although metatarsal shaft osteotomies have become popular in the surgical treatment of moderate or advanced hallux valgus owing to better reduction and stability, they present fixation problems as the angular correction increases. The purpose of this biomechanical study was to evaluate the effects of widely used metatarsal shaft osteotomies and a newly defined osteotomy modification on the stability of screw fixation at greater angular corrections. Methods: Upon evaluation of known problems of shaft osteotomies, a new osteotomy type was designed that might provide an adequate contact area while allowing a greater angular correction, increased stability, and safer osteosynthesis. In our new modification of the Mau osteotomy, the proximal plantar notch that was defined for the Sammarco’s modification to increase the contact area was created more proximally making an angle of about 50 degrees with the osteotomy, and the osteotomy was extended until 5 mm to the distal joint surface, aiming to increase the contact area and intrinsic stability. For biomechanical analysis, 30 standard metatarsal bone models (Sawbones) were divided into five groups equal in number for the following osteotomy methods: Myerson’s modification of the Ludloff osteotomy, Mau osteotomy, scarf osteotomy, offset V osteotomy, and the new modification of the Mau osteotomy. Osteotomies were performed with a standard correction of 10 degrees in the intermetatarsal angle, followed by appropriate osteosynthesis with fixation by two Acutrak compression screws. The relationship between osteotomies and osteosynthesis in terms of stability was assessed by the three-point bending test. Results: The mean stiffness of the Ludloff osteotomy was significantly lower than all the other osteotomy groups (p<0.05). Stiffness of the Mau group was significantly greater than three groups (p<0.05), but the difference from the offset V group did not reach significance. Stiffness of the new Mau modification was significantly greater than the scarf group (p=0.016), but did not differ significantly from the offset V group. Osteotomy groups with and without notching had similar stiffness values (p=0.582), whereas single notching was associated with a significantly greater stiffness compared to double notching (p=0.031). Conclusion: Our findings suggest that the new modification to the proximal shaft osteotomies moves the center of rotation of angulation more proximally and provides sufficient stability of screw fixation.

Keywords:

Bone Screws, Fracture Fixation, Internal, Reconstructive Surgical Procedures, Osteotomy, Metatarsal Bones, Equipment Design, Biomechanics,

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