Related Experiment Videos
Modelling the fibrous tissue layer in cemented hip replacements: experimental and finite element methods
V Waide1, L Cristofolini, J Stolk
1Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, Bologna 40136, Italy.
Journal of Biomechanics
|December 16, 2003
Summary
A fibrous tissue layer at the bone-cement interface in cemented hip replacements can affect load transfer. This study found it influences cement strains and causes stress shielding, impacting long-term fixation.
Area of Science:
- Orthopedic biomechanics
- Biomaterials science
- Finite element analysis
Background:
- Long-term success of cemented femoral components depends on stable bone-cement interface fixation.
- A fibrous tissue layer at this interface can compromise implant longevity.
- Understanding load transfer through this layer is crucial for predicting implant performance.
Purpose of the Study:
- To investigate the load transfer characteristics of cemented hip replacements with a fibrous tissue layer.
- To compare experimental and finite element (FE) methods in analyzing this phenomenon.
- To assess the impact of fibrous tissue on bone and cement strains and stress shielding.
Main Methods:
- Experimental implantation of two cemented hip stem types (Lubinus SPII, Müller-Curved) into composite femurs with a silicone elastomer simulating fibrous tissue.
- Simulation of two fibrous tissue conditions: full cement mantle coverage and partial proximal coverage.
- Finite element (FE) modeling of the full fibrous tissue layer condition for both implant types.
- Cross-comparison of experimental and FE findings, with agreement verified within 15%.
Main Results:
- Stress shielding was observed for both stems under both fibrous tissue conditions, most notably around the calcar.
- Cortical bone strains were generally larger than those for well-fixed stems, despite stress shielding.
- The fibrous tissue layer had minimal impact on cortical bone strains but significantly affected cement strains.
- Localized high stress regions were detected within the cement mantle, though the general strain pattern was not increased.
Conclusions:
- The presence of a fibrous tissue layer affects load transfer and can lead to stress shielding in cemented hip replacements.
- FE analysis provides a reliable method for studying these biomechanical effects.
- While not increasing general cement strain, the fibrous layer can create localized stress concentrations, potentially impacting long-term implant fixation.