Thesis Format
Integrated Article
Degree
Master of Science
Program
Surgery
Supervisor
Lanting, Brent
2nd Supervisor
Willing, Ryan
Co-Supervisor
3rd Supervisor
Vasarhelyi, Edward
Co-Supervisor
Abstract
Total hip arthroplasty (THA) is one of the most successful procedures in modern medicine. As the population ages, the number of THAs performed increases as well. With age comes a decrease in bone quality. Cemented femoral stems are known to provide an advantage in older patients. However, there is debate regarding the optimal technique for cementing femoral stems.
In this thesis, we compared the line-to-line cementing technique, also known as the “French Paradox” (FP), with the standard (STD) cementing technique involving a minimum 2 mm cement mantle via a cadaver-based biomechanical model. The relationship between these varying techniques, cement mantle thickness, alignment of the stem and micromotion were examined.
Results demonstrate that both techniques appear to result in well-fixed and well-aligned stems with no statistically significant difference in micromotion or alignment. Cement mantle thickness was, as expected, thinner in the FP technique. Further longer-term clinical studies are necessary to determine whether the differences noted are of any clinical significance.
Summary for Lay Audience
Hip replacement for arthritis is a common and very successful procedure. It replaces both sides of the joint with metal implants. These are connected by a head, or ball, and liner to form the ball and socket joint. The implant on the pelvis side is called an acetabular cup, or shell, and the implant on the femur side is called a femoral stem. Certain types of hip fractures, those that involve the neck of the femur, can also be treated with a full or half hip replacement - where only the femoral stem side is implanted with a bigger metal head and no cup.
Different options exist for how to hold these implants in the bone. The two main methods are with and without cement. Cementless implants use a particular coating that allows the bone to grow into the implant. Cemented implants are held in place by cement that surrounds the implant and fills the bone. Cemented implants in the femur have been shown to perform better in older patients with weaker bones, or osteoporosis. As our population ages, there is increasing interest in cemented stems because of this.
There are different types of cemented stems that work in different ways to hold the implant in the cement. The two main types are stems that the cement bonds to, which are usually bigger and have a rougher coating, and highly polished or smooth stems that use their wedge shape to lodge themselves in the cement. Debate exists about how much cement is needed around these implants to properly hold them in place and whether more or less cement is beneficial for the long-term survival of hip replacements.
This thesis uses a cadaver-based biomechanical model to compare two different and opposing techniques for implanting a polished cemented stem, that use either more or less cement based on the size of the implant inserted. Our results show that both techniques result in stems that are well-fixed in the bone with good alignment and minimal motion despite significant differences in the thickness of the cement.
Recommended Citation
St George, Stefan A., "Biomechanical Analysis of the French Paradox and Standard Cementing Techniques for Femoral Stems in Hip Arthroplasty" (2024). Electronic Thesis and Dissertation Repository. 10669.
https://ir.lib.uwo.ca/etd/10669