Ahmet Sinan ÖKTEM, Ahmet Zafer ŞENALP, Can CANPOLAT, Gökçe AKGÜN, Özgür KALBARAN

Design and Optimization of Sinusoidal Formed Femur Prosthesis

Kalça protezi cerrahisindeki en büyük problemlerden birisi kalça protezi gevşemesidir. Kalça protezi gevşemesi operasyon sonrasında zamanla meydana gelir ve kemik çimentosu ve protezin birbirinden ayrılması ile ilişkilidir. Bu durumun oluşmasının altında yatan sebepler kemik çimentosunda oluşan gerilme ve protezin şeklidir. Bu çalışmada, femura ait kortikal ve trabeküler kemik tabakaları, kemik çimentosu ve protez modellenmiştir. Kemik çimentosu ve protez parametrik olarak modellenmiş olup eski protezlerden farklı olarak iki farklı sinusoidal formda protez geliştirilmiştir. Sonlu elemanlar metodu ile bu iki farklı sinusoidal form için analizler yapılmıştır ve optimum protez sap şekli ve kemik çimentosu kalınlığını belirlemek amacıyla sonlu elemanlar analizlerinde parametrik modelleme yardımıyla optimizasyon yapılmıştır. Sonlu elemanlar analizleri ve optimizasyon için Ansys Workbench yazılımı kullanılmış olup analizler 316LS paslanmaz çelik malzemesi için gerçekleştirilmiştir. Son olarak, gerçekleştirilen analiz sonuçları ile optimum protez sap şekli ve kemik çimentosu kalınlığı belirlenmiştir.

Sinüsoidal Formda Kalça Protezi Tasarımı ve Optimizasyonu

One of the major problems in hip replacement surgery is the hip replacement loosening. Hip replacement loosening occurs over time after the surgery and it is related to the discretization between the bone cement and prosthesis. The underlying factors of this situation are the stress occurring in the bone cement and the shape of the prosthesis. In this study, cortical and trabecular layers of the femur, bone cement and prosthesis were modeled. The models of bone cement and prosthesis were constructed parametrically and two different sinusoidal formed prostheses were developed unlike the former prostheses shapes. Analyses were conducted for these two different sinusoidal forms by using finite element method and optimization was conducted to obtain the appropriate prosthesis stem shape and bone cement thickness by using parametric modeling in finite element analyses. For finite element analyses and optimization, Ansys Workbench software was used and analyses were conducted for 316LS stainless steel material. Finally, the optimum prosthesis stem shape and bone cement thickness was determined by using the results of the analyses in the first stage.

PDF

___

ANSYS, 2010. ANSYS theory reference manual, ANSYS Inc.
Bergmann, G., Graichen, F., Rohlmann, A., 1993. Hip joint loading during walking and running, measured in two patients. Journal of Biomechanics. 26 (8): 990.
Canpolat, C., 2010. Sinüzoidal formda kalça protezinin geliştirilmesi ve sonlu elemanlar yöntemi ile analizi. MS Thesis, GYTE.
Delaunay, C.P., Kapandji, A.I., 1996. Primary total hip arthroplasty with the Karl Zweymuller first generation cementless prosthesis: a 5 to 9 year retrospective study. J Arthroplasty
Huiskes, R., Verdonscot, N., 1997. Biomechanics of artificial joints: the hip. In V.C. Mow and W.C. Hayes, Basic Orthopedic Biomechanics Lippincott-raven Publishers. p
Joshi, M.G., Advani, S.G., Miller, F., Santare, M., 2000. Analysis of a femoral hip prosthesis designed to reduce stress shielding. Journal of Biomechanics 33:1655-1662.
Kayabaşı, O., 2004. Kalça protezinin geliştirilmesi ve sonlu elemanlar yöntemi ile analizi. MS Thesis, GYTE.
Marston, R.A., Cobb, A.G., Bentley, G., 1996. Stanmore compared with Charnley total hip replacement: a prospective study of 413 arth Surg. 78-B:178184.
Miljkovic, N.D., Ercegan, G.M., Stulic, R.B., Jandric, Z.B. 1998. Computer aided evaluation of total hip prosthesis stability. Journal Graphics. 2 (2):141-149.
Neumann, L., Freund, K.G., Sørenson, K.H., 1994. Long-term results of Charnley total hip replacement. Review of 92 patients at 15 to 20 years. J Bone Joint Surg. 76-B:245251.
Nuño, N., Avanzolini, G., 2002. Residual stress at the stem-cement interface of an idealized c stem. J Biomech. 35:849-852.
Savilahti, S., Myllyneva, I., Pajamaki, K.J.J., Lindholm, T.S., 1997. Survival of Lubinus straight (IP) and curved (SP) total hip prostheses in 543 patients after 413 years. Arch Orthop Trauma Surg. 116:1013.
Senalp, A.Z., Kayabasi, O., Kurtaran H., 2007. Static, dynamic and fatigue behavior of newly designed stem shapes for hip prosthesis using finite element analysis. Materials and Design. 28:1577-1583.
Viceconti, M., Casali, M., Massari, B., 1996. The standardized femur program. J Biomech. 29:1241.
Yang, D.T., Zhang, D., Arola, D.D., 2010. Fatigue of the bone/cement interface and loosening of total joint replacements. International Journal of Fatigue. 32:1639-1649.