Wear estimation at the contact surfaces of oval shaped hip implants using finite element analysis

Abstract

AbstractThe hip joint is one of the most essential joints for transmitting weights to the lower abdomen during day-to-day activities. Loosening of hip implants is mostly caused by wear. The wear assessment during the design stage offers a clear sense of the implant’s life expectancy, and modest adjustments in the design may also greatly enhance the implant’s life expectancy, lowering the probability of revision surgery. Linear wear is estimated at the contact surfaces of the femoral head to the acetabular cup and the acetabular cup to the backing cup in this study. In this work, oval-shaped hip implant is considered with a femoral head diameter of 28 mm, an acetabular cup thickness of 4 mm, and a backing cup thickness of 2 mm. The Archard’s law used to estimate the linear wear rate. It is observed that when the acetabular cup is made of UHWMPE and the stem, femoral head, and backing cup are made of CoCr, the least overall deformation is 0.394 mm during walking loads. When the stem is considered Ti−6Al−4 V and the acetabular cup of UHWMPE, the minimum wear between the femoral head and acetabular cup is 0.063 mm/year. During a typical standing posture, an acetabular cup-to-backing cup wear rate of 0.007 mm/year is estimated. Overall, the CoCr material combination had the lowest wear rate in the four activities considered for this work. These implants designs can be 3D-printed and further can be tested in a hip simulator under the same loading conditions.

Keywords

• Hip implants
• finite element analysis
• wear
• material. Optimisation
• Biomaterials