Fixation of femoral neck fractures with three cannulated screws: biomechanical changes at critical fracture angles

Year 2020, Volume: 4 Issue: 8, 660 - 663, 01.08.2020

Kerim Öner , Ahmet Emre Paksoy , Alaettin Özer

https://doi.org/10.28982/josam.780442

Cited By: 1

Abstract

Aim: Increased fracture angle in the coronal plane results in more instability and complications in femoral neck fractures. Our aim in this study was to analyze biomechanical changes at critical fracture angles (30 degrees, 50 degrees, and 70 degrees) as described in Pauwels classification.
Methods: A femur model was obtained by 3D computerized tomography (CT) scanning. The angle of femoral neck fracture in the coronal plane observed on the CT image was created on the model at 30, 50 and 70-degree angles. Three cannulated screws were placed in the inverted triangle position. Screws were named “anterior-superior” (A), “posterior -superior” (B), and “inferior” (C). The obtained three different models were transferred to the ANSYS Workbench program. Von Mises stress distribution on the screws and distal fracture surfaces were recorded.
Results: In the 30-degree fracture model, the maximum stress was 18.062 MPa on the "A" screw. It was 22.13 MPa on screw "B" and 16.21 MPa on screw "C". In the 50-degree fracture model, the maximum stress values were 68.04 MPa, 89.52 MPa and 48.94 MPa in screws "A", "B", and "C", respectively. In the 70-degree fracture model, the maximum stress values were 120.02 MPa, 138.32 MPa and 98.37 MPa in screws "A", "B", and "C", respectively. The stress values on the distal fracture surfaces were 13.54 MPa, 43.80 MPa, and 50.07 MPa in the 30, 50, and 70-degree models, respectively.
Conclusion: Increasing fracture angle from 30 to 50 degrees in femoral neck fractures significantly increases the stress on the distal fracture surface and implants.
However, this increase is minimal at angles higher than 50 degrees.

Keywords

Femoral neck fractures, Pauwels classification, cannulated screw fixation, finite element study

Thanks

We would like to thank Ahmet Çankaya, who made the modelling work for the purposes of this study.

Femur boyun kırıklarında üç kanüllü vida ile tespit: kritik kırık açılarında biyomekanik değişiklikler

Abstract

Amaç: Femur boyun kırıklarında koronal planda kırık açısının artması instabiliteyi ve komplikasyonları arttırmaktadır. Bu çalışmadaki amacımız Pauwels sınıflamasında belirlenmiş olan kritik açılardaki (30 derece, 50 derece, 70 derece) biyomekanik değişiklikleri analiz etmektir.
Yöntemler: 3D bilgisayarlı tomografi taramasından elde edilen femur modelinde koronal plandaki kırık açısına göre 30, 50 ve 70 derece femur boyun kırığı oluşturuldu. Inverted triangle pozisyonunda 3 adet kanüllü vida yerleştirildi. Vidalar anterior-superior (A), posterior –süperior (B) ve inferior (C) olarak isimlendirildi. Üç model Ansys Workbench programına aktarılarak vidalardaki ve distal kırık yüzeyindeki von mises stres dağılımları kaydedildi.
Bulgular: Maximum stres 30 derece kırık modelinde A vidasında 18,06 mpa idi. B vidasında ise 22,13 MPa, C vidasında 16,21 MPa olarak bulundu. 50 derece kırık modeline baktığımızda max stres değerleri A vidasında 68,04 MPa iken B vidasında 89,52 MPa ,C vidasında ise 48,94 MPa olarak bulundu. 70 derece kırık modelinde A vidasında maximum stres 120,02 MPa, B vidasında 138,32 MPa idi. C vidasında ise 98,37 MPa olarak bulundu. Distal kırık yüzeyindeki stres değerleri ise 30, 50, 70 derece modellerde sırası ile 13,54 MPa, 43,80 MPa ve 50,07 MPa idi.
Sonuç: Femur boyun kırıklarında kırık açısının 30 dereceden 50 dereceye yükseltilmesi distal kırık yüzeyi ve implantlar üzerindeki gerilimi önemli ölçüde artırmaktadır. Ancak bu artış 50 derecenin üzerindeki açılarda minimumdur.

Keywords

Femur boyun kırığı, Pauwels sınıflaması, Kanüllü vida ile fiksasyon, Sonlu elemanlar analizi

References

• 1. Grosso MJ, Danoff JR, Murtaugh TS, Trofa DP, Sawires AN, Macaulay WB. Hemiarthroplasty for Displaced Femoral Neck Fractures in the Elderly Has a Low Conversion Rate. J Arthroplasty. 2017 Jan;32(1):150-4. doi: 10.1016/j.arth.2016.06.048.
• 2. Panteli M, Rodham P, Giannoudis PV. Biomechanical rationale for implant choices in femoral neck fracture fixation in the non-elderly. Injury. 2015 Mar;46(3):445-52. doi: 10.1016/j.injury.2014.12.031.
• 3. Collinge CA, Mir H, Reddix R. Fracture morphology of high shear angle "vertical" femoral neck fractures in young adult patients. J Orthop Trauma. 2014 May;28(5):270-5. doi: 10.1097/BOT.0000000000000014.
• 4. Pauyo T, Drager J, Albers A, Harvey EJ. Management of femoral neck fractures in the young patient: A critical analysis review. World J Orthop. 2014 Jul 18;5(3):204-17. doi: 10.5312/wjo.v5.i3.204.
• 5. Li J, Wang M, Li L, Zhang H, Hao M, Li C, Han L, Zhou J, Wang K. Finite element analysis of different configurations of fully threaded cannulated screw in the treatment of unstable femoral neck fractures. J Orthop Surg Res. 2018 Oct 29;13(1):272. doi: 10.1186/s13018-018-0970-3.
• 6. Slobogean GP, Sprague SA, Scott T, McKee M, Bhandari M. Management of young femoral neck fractures: is there a consensus? Injury. 2015 Mar;46(3):435-40. doi: 10.1016/j.injury.2014.11.028.
• 7. Tianye L, Peng Y, Jingli X, QiuShi W, GuangQuan Z, Wei H, Qingwen Z. Finite element analysis of different internal fixation methods for the treatment of Pauwels type III femoral neck fracture. Biomed Pharmacother. 2019 Apr;112:108658. doi: 10.1016/j.biopha.2019.108658.
• 8. Cha YH, Yoo JI, Hwang SY, Kim KJ, Kim HY, Choy WS, Hwang SC. Biomechanical Evaluation of Internal Fixation of Pauwels Type III Femoral Neck Fractures: A Systematic Review of Various Fixation Methods. Clin Orthop Surg. 2019 Mar;11(1):1-14. doi: 10.4055/cios.2019.11.1.1.
• 9. Biz C, Tagliapietra J, Zonta F, Belluzzi E, Bragazzi NL, Ruggieri P. Predictors of early failure of the cannulated screw system in patients, 65 years and older, with non-displaced femoral neck fractures. Aging Clin Exp Res. 2020 Mar;32(3):505-513. doi: 10.1007/s40520-019-01394-1.
• 10. Shen M, Wang C, Chen H, Rui YF, Zhao S. An update on the Pauwels classification. J Orthop Surg Res. 2016 Dec 12;11(1):161. doi: 10.1186/s13018-016-0498-3.
• 11. Mei J, Liu S, Jia G, Cui X, Jiang C, Ou Y. Finite element analysis of the effect of cannulated screw placement and drilling frequency on femoral neck fracture fixation. Injury. 2014 Dec;45(12):2045-50. doi: 10.1016/j.injury.2014.07.014.
• 12. Li J, Wang M, Zhou J, Han L, Zhang H, Li C, Li L, Hao M. Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation. Biomed Res Int. 2018 Dec 9;2018:1271762. doi: 10.1155/2018/1271762.
• 13. Noda M, Saegusa Y, Takahashi M, Tezuka D, Adachi K, Naoi K. Biomechanical Study Using the Finite Element Method of Internal Fixation in Pauwels Type III Vertical Femoral Neck Fractures. Arch Trauma Res. 2015 Aug 26;4(3):e23167. doi: 10.5812/atr.23167.
• 14. Zhang YL, Zhang W, Zhang CQ. A new angle and its relationship with early fixation failure of femoral neck fractures treated with three cannulated compression screws. Orthop Traumatol Surg Res. 2017 Apr;103(2):229-234. doi: 10.1016/j.otsr.2016.11.019.
• 15. Noda M, Nakamura Y, Adachi K, Saegusa Y, Takahashi M. Dynamic finite element analysis of implants for femoral neck fractures simulating walking. J Orthop Surg (Hong Kong). 2018 May-Aug;26(2):2309499018777899. doi: 10.1177/2309499018777899.
• 16. Zhou L, Lin J, Huang A, Gan W, Zhai X, Sun K, Huang S, Li Z. Modified cannulated screw fixation in the treatment of Pauwels type III femoral neck fractures: A biomechanical study. Clin Biomech (Bristol, Avon). 2020 Apr;74:103-110. doi: 10.1016/j.clinbiomech.2020.02.016.
• 17. Zhang B, Liu J, Zhu Y, Zhang W. A new configuration of cannulated screw fixation in the treatment of vertical femoral neck fractures. Int Orthop. 2018 Aug;42(8):1949-1955. doi: 10.1007/s00264-018-3798-x.
• 18. Li J, Wang M, Zhou J, Han L, Zhang H, Li C, Li L, Hao M. Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation. Biomed Res Int. 2018 Dec 9;2018:1271762. doi: 10.1155/2018/1271762.
• 19. Hoshino CM, Christian MW, O'Toole RV, Manson TT. Fixation of displaced femoral neck fractures in young adults: Fixed-angle devices or Pauwel screws? Injury. 2016 Aug;47(8):1676-84. doi: 10.1016/j.injury.2016.03.014.
• 20. Cordeiro M, Caskey S, Frank C, Martin S, Srivastava A, Atkinson T. Hybrid triad provides fracture plane stability in a computational model of a Pauwels Type III hip fracture. Comput Methods Biomech Biomed Engin. 2020 Jul;23(9):476-483. doi: 10.1080/10255842.2020.1738404.
• 21. Kemker B, Magone K, Owen J, Atkinson P, Martin S, Atkinson T. A sliding hip screw augmented with 2 screws is biomechanically similar to an inverted triad of cannulated screws in repair of a Pauwels type-III fracture. Injury. 2017 Aug;48(8):1743-1748. doi: 10.1016/j.injury.2017.05.013.
• 22. Samsami S, Augat P, Rouhi G. Stability of femoral neck fracture fixation: A finite element analysis. Proc Inst Mech Eng H. 2019 Sep;233(9):892-900. doi: 10.1177/0954411919856138.