İnstabil femur boyun kırıklarının internal tespitinde vida sayısı ve yöneliminin stabiliteye etkisi

Öz

Amaç: Bu çalışmada instabil femur boyun kırıklarının tedavisinde 3 farklı kanüllü vida konfigürasyonu kullanılarak yapılan internal tespitin biyomekanik olarak karşılaştırılması amaçlandı.

Çalışma planı: Çalışmada 28 adet sentetik sol femur rastgele olarak 4 eşit gruba ayrıldı. İlk üç gruptaki örnekler Pauwels Tip 3 kırık oluşturacak şekilde bazoservikal bölgeden osteotomize edildi. Tespit kanüllü vidalarla yapıldı. Birinci gruba 4 adet vida, 3’ü boyuna paralel ters üçgen konfigürasyonda, dördüncüsü ise kalkara çapraz şekilde; ikinci gruba 3 adet vida, 2’si boyuna paralel konfigürasyonda, üçüncüsü ise kalkara çapraz şekilde; üçüncü gruba ise 3 adet vida, 3’ü de boyuna paralel ters üçgen konfigürasyonda olacak şekilde kanüle vida ile fiksasyon uygulandı. Dördüncü gruba ise osteotomi veya tespit uygulanmadı. Tüm gruplara yüklenme testi yapıldı ve vida tespitlerinin aksiyel yüklenmeye dayanma gücü ve yer değişimi miktarı ölçüldü.

Bulgular: Grup 1’de ortalama maksimum dayanım 36.1±3.2 N/mm2, Grup 2’de 27.3±4.1 N/mm2 ve Grup 3’te 21.9±3.2 N/mm2 olarak saptandı. Grup 3’teki ortalama maksimum dayanım anındaki (21.9±3.2 N/mm2) osteotomi hattındaki ortalama yer değişimi 11.5±2.1 mm iken, Grup 2’de aynı değerde yer değişimi 6±1.3 mm, Grup 1’de 5.8±1.1 mm olarak bulundu (p<0.05). Ayrıca Grup 2’deki ortalama maksimum dayanım (27.3±4.1 N/mm2) anındaki yer değişimi 9.1±1.7 mm iken, aynı stres değeri altında Grup 1’deki şekil değişiminin 9±1.7 mm olduğu gözlendi (p>0.05).

Çıkarımlar: İnstabil femur boyun kırıklarının tedavisinde boyuna paralel gönderilen kanüllü vidalara ek olarak kalkara gönderilen çapraz vidanın stabiliteye olumlu katkı sağlayacağı görüşündeyiz.

Anahtar Kelimeler

• Femur boyun kırıkları; instabil; kanüllü vida; tespit.

Influence of number and orientation of screws on stability in the internal fixation of unstable femoral neck fractures

Öz

Objective: The aim of this study was to biomechanically compare 3 different cannulated screw configurations used in internal fixation of unstable femoral neck fractures.

Methods: The study included 28 synthetic left femurs randomly divided into 4 equal groups. Samples in the first 3 groups were osteotomized in the basicervical region to create Pauwels Type 3 fractures. Fixation was carried out using cannulated screws. In Group 1, four screws were used including 3 in an inverted triangle configuration in parallel with the neck and the fourth screw transversely into the calcar. In Group 2, three screws were used including 2 in parallel with the neck and the third transversely into the calcar. In Group 3, three screws were used in an inverted triangle configuration in parallel with the neck. No osteotomy or fixation was carried out in Group 4. Load test was performed on all the groups and the strength of the screw fixations against axial load and their amount of relocation were measured.

Results: Average maximum strength was 36.1±3.2 N/mm2 in Group 1, 27.3±4.1 N/mm2 in Group 2 and 21.9±3.2 N/mm2 in Group 3. The average relocation in the line of osteotomy in the moment of average maximum stress (21.9±3.2 N/mm2) was 11.5±2.1 mm in Group 3, 6±1.3 mm in Group 2 and 5.8±1.1 mm in Group 1 (p<0.05). It was also observed that while the relocation in the moment of average maximum stress (27.3±4.1 N/mm2) was 9.1±1.7 mm in Group 2, the deformation under the same stress value was 9±1.7 mm in Group 1 (p>0.05).

Conclusion: The use of a transverse screw in the calcar in addition to cannulated screws parallel to the neck appear to provide stability benefit in the treatment of unstable femoral neck fractures.

Anahtar Kelimeler

• Cannulated screw
• femoral neck fractures
• fixation
• unstable

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