Mechanical Stability of Custom and Anatomical Femoral Stems: An Experimental Study in Human Femora

Abstract

In this study we have compared the mechanical stability of custom (n=8) and anatomical (n=8) uncemented femoral components, following insertion into human cadaveric femurs, during simulated single leg stance and stair climbing. In the custom group two specimens were excluded from the study due to detachment of the greater trochanter during cyclical loading. As a consequence of their mechanical behaviour both types of stems could be divided into subgroups of “unstable” and “stable” implants. In the course of one thousand loading cycles three anatomical stems and one custom stem migrated more than 1 mm, which was interpreted as mechanical loosening. This difference in rate of mechanical loosening was not significant. However, the majority of the stems were remarkably stable and showed micromotion of less than 18 μm and migration of less than 35 μm at the proximal implant-bone interface. The corresponding figures for the tip of the stems were 243 μm and 170 μm, respectively. During torsional loading the custom stems showed less rotatory motion than the anatomical stem (p<0.05). There were no significant differences in the magnitude of cyclical micromotion or migration for the two types of femoral stems.

Uncemented custom femoral components in hip arthroplasty

“…During the following 5 years, several experimental studies were performed to develop customized femoral stems with optimal fit to the proximal femur based on CT information and CAD-CAM technology. Furthermore, studies were carried out to document the stability of the stem and also the strain shielding in the proximal femur following insertion of the stem in human cadaver femurs ( Kvistad et al 1994 , Aamodt et al 1999 , 2001 , 2002 ). The custom femoral stem that was developed has now been in clinical use since 1995.…”

Development and properties of UV‐cured poly (propylene fumarate)/hydroxyapatite composites coatings as potential application for bone adhesive tape

“…Composite of biodegradable polymer with hydroxylapatite are particularly attractive for bone tissue engineering applications. That is because calcium phosphate‐polymer composite materials are biocompatible and osteoconductive 19–23 . Hydroxyapatite can also closely rope to the bony tissue chemically so that the bone and implant are connected 24,25 .…”

“…That is because calcium phosphate-polymer composite materials are biocompatible and osteoconductive. [19][20][21][22][23] Hydroxyapatite can also closely rope to the bony tissue chemically so that the bone and implant are connected. 24,25 Hydroxyapatite has been widely used as the biomaterials for bone replacement due to its excellent bioactivity, biocompatibility, and osteoconductivity.…”