The effect of femoral prosthesis design on cement strain in cemented total hip arthroplasty

doi:10.1054/arth.2001.20537

The Journal of Arthroplasty

Volume 16, Issue 2, February 2001, Pages 216-224

https://doi.org/10.1054/arth.2001.20537 Get rights and content

Abstract

Finite element studies show that the highest cement stresses are located at the most proximal and distal ends of the prosthesis. In vitro biomechanical and histologic analyses of autopsy-retrieved cemented femoral components show these areas to be associated with cement—prosthesis debonding. In this study, cement strains were measured in 2 geometrically different femoral stems in paired cadaver femora: A straight, collared, moderately tapered stem (Centralign) was compared with an anatomically curved, collarless, dramatically tapered stem (Scientific Hip Prosthesis [SHP]). Results showed that the maximum strain and the overall strain profile differed between the 2 stems. The Centralign had peak strains located at the most proximal gauge positions, whereas the peak strains of the SHP were located around the middle of the femoral stem. Minimization of cement strain, especially at the crucial proximal and distal areas of the stem, by altering component design may be able to reduce cement—prosthesis debonding and improve clinical results.

Section snippets

Specimen preparation

Six pairs of fresh frozen human cadaver femora with an average age of 63 years were used for this study (Table 1).Radiographs were taken to exclude specimens with pathologic lesions and to size and template the medullary canals. The cadaver specimens were freed of all soft tissue and muscle by sharp dissection using a scalpel and forceps.

Osteometrics, a precision method of measuring the bone in vitro using a custom-made alignment device 15, 16, 17, 18, 19, was performed on the specimens to

Results

In all 6 pairs of cadaver femora, both types of cemented implants remained stable and well fixed throughout the study. Postimplantation radiographs revealed proper femoral stem and strain gauge location as well as an adequate cement mantle for all the femora. One of the femora sustained a nondisplaced, linear fracture during broaching for a Zimmer Centralign prosthesis. This fracture was treated using 5 doubled 16-gauge Luque wires (Zimmer, Inc) around the proximal femur. The Centralign

Discussion

Concerns remain regarding the durability of cemented total hip arthroplasty despite the relatively new improvements in cement application. With modern techniques to maintain an adequate cement mantle and to reduce cement porosity, femoral prosthesis survival rates have improved substantially 7, 22. Jasty et al ^[9] have shown in analysis of autopsy-retrieved, well-functioning cemented femoral components that the cement was well tolerated and that the bone—cement interface remained well

Conclusion

Our objective was to perform an in vitro examination of the effect of femoral prosthesis shape on cement strains adjacent to the cemented femoral component. Our results indicate that prosthesis geometry does influence cement strain because we found that the more anatomically shaped SHP prosthesis was associated with a different cement strain profile than the straight tapered design of the Centralign prosthesis. Specifically, the more anatomically shaped prosthesis showed lower cement strains

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Cited by (19)

Characteristic loosening of the distally straight cylindrical femoral stem
2014, Journal of Orthopaedic Science
The cemented femoral stem with a distally straight cylindrical shape was designed to fill the distal femoral canal to facilitate higher cement pressurization and stability. We examined the mid-term outcomes of a stem made of titanium alloy and the efficacy of this shape.
Four hundred and twenty-nine consecutive patients (505 hips), who underwent a total hip arthroplasty with the distally straight cylindrical stem made of titanium alloy as their primary hip arthroplasty at two institutes, were followed for a minimum 2 years. Loosening was defined as subsidence of over 3 mm, tilting of the femoral component, or fracture of the cement or the stem. A continuous radiolucent line along the entire interface was considered to indicate loosening, too. We examined the interface stresses on the distally straight cylindrical stem compared with a newly manufactured femoral prosthesis with a double-taper design using a finite element model study.
The mean follow-up was 101.3 months after surgery. Thirty patients (30 hips) had aseptic loosening of the stems. Of these 30 hips, 18 had osteolysis, 17 showed subsidence, and 11 had cement fractures at the tip of the stem. These 11 hips had osteolysis and ectasia in the same place: the stem tip. The stem survival rate with stem loosening as the end-point was 94.4 % at 10 years and 66.9 % at 15 years. A finite element model study revealed higher stress around the tip of the cylindrical stem compared with that in the double-taper stem.
The straight cylindrical stem is potentially subject to early failure because of high stress around the tip of the stem, and showed a characteristic loosening with osteolysis and ectasia at the tip of the stem.
Randomized comparison between the cemented scientific hip prosthesis and omnifit: 2-Year DEXA and minimum 10-year clinical follow-up
2013, Journal of Arthroplasty
Radiostereometry (RSA) of the cemented Scientific Hip Prosthesis (SHP) reported excessive migration and predicted high failure rates. In a prospective randomized clinical trial we compared minimum 10 years results of the SHP (n = 38) with the Omnifit-stem (n = 37). Two-year bone remodelling, compared with dual energy x-ray absorptiometry and assessed in regions of interest A-D based on the 7 Gruen zones, showed better periprosthetic bone preservation around the SHP in all but one regions (P < .05). At 10 years Harris Hip Score was better for the SHP (P = .0001) but Oxford Hip Score was the same (P = .79). There were no revisions in either group, but radiographic loosening was definite in 1 SHP and 1 Omnifit. Based on earlier RSA studies, the rough surface finish of the SHP was expected to cause cement abrasion, osteolysis and inferior survival. However our clinical and remodelling results could not confirm these expectations, suggesting that the link of early migration and mid-term clinical results is not sufficiently clear for the SHP.
A finite element method approach to compare the wear of acetabular cups in polyethylene according to their lateral tilt in relation to the coronal plane
2013, Wear
Citation Excerpt :
Moreover, mechanical simulators are costly and the time needed for performing each trial is very long [13,31]. Based on positive results obtained from numerical simulations using the finite element method (FEM) in applications such as analysis of the factors influencing luxation in total hip joint [32], design of the tip of the femoral head in order to reduce the stress peaks in the acrylic cement [33], biomechanics of arthroplasty of “resurfacing” type [34], and effect of the design of the femoral head on the coating of acrylic cement [35], some attempts to predict wear rates from FEM models have been made. Several authors developed hip joint models that reproduce its kinematics and kinetics [26,36–41].
In this work, the finite element method was used to model and simulate the hip joint prosthetic tribosystem. We use an adaptation of the Archard equation to determine the abrasive wear of acetabular cups in UHMWPE as a function of their lateral tilts in relation to the coronal plane. Numerical simulations performed with acetabular cups at tilt angles of 30°, 45°, and 60° presented respectively linear wear of 0.19 mm, 0.17 mm, and 0.26 mm per year, and volumetric wear of 30.85 mm³, 30.97 mm³, and 47.41 mm³, for the same period. The results of the study suggest that acetabular cups assembled at 45° present lower linear wear rates, whereas a significant increase in the volumetric wear rate is obtained for sets positioned at tilts above 45°. This conclusion is corroborated by comparison with clinical results presented in the literature.
In vitro analysis of the cement mantle of femoral hip implants: Development and validation of a CT-scan based measurement tool
2005, Journal of Orthopaedic Research
We developed, validated and assessed inter- and intraobserver reliability of a CT-scan based measurement tool to evaluate morphological characteristics of the bone–cement–stem complex of hip implants in cadaver femurs. Two different models were investigated: the stem-cavity model using a double tapered polished femoral-stem that is removed after cement curing and the plastic-replica model using a stereolithographic stem replica that is left in place during CT-scanning. Software was developed to segment and analyze connective CT-images and identify the contours of bone, cement, and stem based on their respective gray values. Volume parameters (whole specimen, cement, stem, air contents of bone and cement), concentricity parameters (distances between centroids of stem and cement, cement and bone, stem and bone), contact surfaces (bone/air and cement/bone) and bone cement mantle thickness parameters were calculated. A three-dimensional protocol was developed to evaluate the minimal mantle thickness out of the CT-plane. The average accuracy for surfaces within CT-images was 7.47 mm² (1.80%), for bone and cement mantle thickness it was 0.51 mm (9.39%), for distances between centroids it was 0.38 mm (18.5%) and contours: 0.27 mm (2.57%). The intra- and interobserver reliability of air content in bone and cement was sub-optimal (intraclass-correlation coefficient (ICC) as low as 0.54 with an average ICC of 0.85). All other variables were reliable (ICC > 0.81, average ICC: 0.96). This in vitro technique can assess characteristics of cement mantles produced by different cementing techniques, stem types or centralizers.
Fatigue Failure of Hip Implants: A Short Review of Biomechanical Testing
2022, Trends in Biomaterials and Artificial Organs
Optimization of a Cemented Femoral Prosthesis Considering Bone Remodeling
2016, Journal of Biomechanical Engineering

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^*: Benefits and funds were received in partial or total support of the research material described in this article from the Department of Orthopaedics, University of Utah School of Medicine; Biomet, Inc; and the Musculoskeletal Transplant Foundation.

^**: Reprint requests: Christopher L. Peters, MD, Orthopaedic Bioengineering Research Laboratory, 20 North 2030 East, Room 190, University of Utah, Salt Lake City, UT 84112.

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Original ArticlesThe effect of femoral prosthesis design on cement strain in cemented total hip arthroplasty*,**

Abstract

Section snippets

Specimen preparation

Results

Discussion

Conclusion

J Biomech

J Biomech

J Biomech

J Arthroplasty

Long-term results of low-friction arthroplasty of the hip performed as a primary intervention

J Bone Joint Surg Br

The nine and ten year results of the low-friction arthroplasty of the hip

Clin Orthop

A ten-year follow-up study of 170 Charnley total hip arthroplasties

Clin Orthop

Roentgenologic results of total hip arthroplasty: a ten year follow-up study

Clin Orthop

Ten-year follow-up study of total hip replacement with particular reference to roentgenographic loosening of the components

J Bone Joint Surg Am

A ten-year follow-up of one hundred consecutive Müller curved-stem total hip-replacement arthroplasties

J Bone Joint Surg Am

The effect of improved cementing techniques on component loosening in total hip replacement

J Bone Joint Surg Br

The outcome of Charnley total hip arthroplasty with cement after a minimum twenty-year follow-up

J Bone Joint Surg Am

Original Articles
The effect of femoral prosthesis design on cement strain in cemented total hip arthroplasty*,**