2022, Vol. 26 ›› Issue (6): 843-847
Finite element analysis of stress distribution of acetabular prosthesis in the Lewinnek safety zone
Lewinnek et al. proposed a “safety zone” concept for acetabular cup position [Abduction angle (40±10)°, anteversion angle (15±10)°]. Although this concept has been widely accepted, it has been lack of further biomechanical study regarding influence of acetabular prosthesis on acetabular bone and prosthetic stress distribution in the safety zone.
To investigate the stress distribution of the acetabular bone and cup (ceramic on ceramic versus metal on polyethylene) with regard to the Lewinnek safety zone using the three-dimensional finite element analysis method.
One healthy volunteer received CT scan. The three-dimensional geometric model of the pelvis was established. Eighteen kinds of different cup position model of hip replacement were established with regard to the Lewinnek safety zone. The stress distribution along the acetabular bone and the different implant materials were studied by means of applying 390 N force. The protocol was performed in accordance with the Declaration of Helsinki and the relevant ethical requirements of Sixth Affiliated Hospital of Xinjiang Medical University.
By applying finite element static vertical force, within the Lewinnek zone: (1): if the cup was positioned in 5° anterversion, 50° abduction (whether it was ceramic on ceramic or metal on polyethylene), the peak stress and the stress zone of the cup were smallest. Under the same anterversion and abduction, the peak stress of the cup did not change significantly. (2) With regard to the stress distribution of the head and liner, the peak stress and the stress zone of the head and the liner were smallest in the metal on polyethylene group, in which the stress was not affected by the position of the cup. (3) The results indicated that within the Lewinnek safety zone, if the cup was positioned in 5° anterversion, 50° abduction, the metal on polyethylene group had the advantage of having the smallest peak stress and the stress zone of the cup, head and the liner. Moreover, the stress was not affected by the position of the cup, and was significantly smaller than the ceramic on ceramic scheme, which can provide clinical reference.
Lewinnek safety zone, acetabular implant, finite element analysis, femoral head, liner, acetabular cup, stress peak, stress region, ceramic on ceramic, metal on polyethylene