Relation Between Vertical Orientation and Stability of Acetabular Component in the Dysplastic Hip Simulated by Nonlinear Three‐dimensional Finite Element Method

Abstract

In acetabular dysplasia, more vertical orientation of the acetabular component is often used to minimize the superolateral bone grafting. This study was designed to determine the effects of vertical orientation of the cup on the stability and polyethylene wear of the acetabular component in uncemented total hip arthroplasty (THA). Three-dimensional finite element models of the hemipelvis with dysplastic acetabulum were developed. Metal-backed hemispherical cups were placed in the true acetabulum with abduction angles of 35, 45, 55, and 65 degrees. It was found that more vertical orientation of the cup was associated with larger relative motion of the metal shell between the acetabulum and metal shell. Furthermore, tilting and torsional shear stresses in the model of the cup abduction angle of 65 degrees were found to be 1.7 times larger than that in the model with 35 degrees at the bone-metal shell interface. More vertically oriented cups caused larger contact stresses at the articulating surfaces of the polyethylene liners. The results suggest that the abduction angle of the acetabular component significantly influences cup loosening and polyethylene wear in THA.

High Hip Center Technique Using a Biconical Threaded Zweymüller® Cup in Osteoarthritis Secondary to Congenital Hip Disease

“…The lack of difference in linear PE wear rate and variance between the NHC and HHC groups and the wide distribution of PE wear values in both groups are in accordance with the results of studies that found not only the hip center is responsible for PE wear in a hip arthroplasty but also numerous other factors, such as cup inclination, articulating surfaces, femoral head size, and patient age or body weight [16,17,20,23,24,38].…”

Stresses in cement mantles of hip replacements: effect of femoral implant sizes, body mass index and bone quality

“…A diametral clearance of 0.1mm (Kurtz et al 2000;Oki et al 2004) and contact elements were simulated and used at the interface between the femoral head implant and the acetabular component. This contact was assumed to be frictionless (Dalstra 1993).…”

Total Hip Replacement: Tensile Stress in Bone Cement is influenced by Cement Mantle Thickness, Acetabular Size, Bone Quality, and Body Mass Index

“…Contact elements were used at the subchondral bone and cement mantle interface to represent the mechanical interlock between the bone and the cement [40]. A diametral clearance of 0.1 mm [41,42] was modelled and frictionless contact elements [30] were used at the interface between the femoral head implant and the acetabular component. Our sensitivity analyses of the effect of frictional moments on the stress distribution in the reconstructed hemi-pelves showed only a small relative change of 2-3% in the tensile stress level in the cement mantle.…”