Effects of prosthesis surface roughness on the failure process of cemented hip implants after stem-cement debonding

Abstract

Retrieval studies suggest that the loosening process of the cemented femoral components of total hip arthroplasties is initiated by failure of the bond between the prosthesis and the cement mantle. Finite element (FE) analyses have demonstrated that stem-cement debonding has stress-producing effects in the cement mantle. High interface friction, which corresponds to a degree of surface roughness, reduces these stresses. In experiments, however, debonded rough stems produced more cement damage than polished ones; in the Swedish Hip Register polished stems were clinically superior with respect to stems with a mat surface finish. The purpose of the present study was to investigate this contradiction. For this purpose, global and local FE models with debonded stem-cement interfaces were used to study the effects of prosthesis surface roughness on the cement stresses on a global scale and microscale, respectively. Similar to earlier numerical studies, the global FE model predicted that an increased surface roughness of the stem reduced the stresses in the cement mantle. The local model provided insight in the load-transfer mechanism on a microscale and could explain the experimental and clinical findings. The local cement peak stresses around the asperities of the surface roughness profile increased with increasing surface roughness and decreased again beyond a particular roughness value. Cement abrasion is caused by localized stresses in combination with micromotion. From this study it can be concluded that to minimize cement abrasion, debonded stems should either have a polished microstructure to minimize the local cement stresses or have a profiled macrostructure to minimize micromotions at the stem-cement interface.

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

“…However, if friction is increased by increasing the surface roughness the effects of increased friction are overruled by those of the surface roughness itself as shown in this study and global FEA models are less useful to analyze the localized effects around the asperities of the surface profile. In that case, a local FEA model such as presented by Verdonschot et al [23] (1998) would be more appropriate.…”

Cement-Implant Interface Contamination: Possible Reason of Inferior Clinical Outcomes for Rough Surface Cemented Stems

“…However, revisions where the stem appears not to have been fully bonded may be the result of contamination of the stem prior to, or at the time of implantation. Although researchers [9-11] have shown that the rough surfaced cemented stem can achieve higher interface bonding strength, other studies [12-14] indicated that smooth surface finish cemented Titanium stem achieved better clinical survivorship. But no clear explanation of this outcome has been given.…”

Extraosseous Cement Granuloma Associated With Total Hip Replacement in 6 Dogs

“…After debonding, stem surface roughness has a direct influence on mantle fragmentation, with more textured surfaces causing accelerated cement pulverization. 15 In the situation of chronic and severe loosening in this series of dogs, fragmented PMMA and cancellous bone was expelled from the proximal femur to give the characteristic radiographic appearance of ECG.…”