Load transfer in the proximal femur and primary stability of a cemented and uncemented femoral stem: An experimental study on cadaver femurs

2017 ◽  
Vol 231 (12) ◽  
pp. 1195-1203 ◽  
Author(s):  
Cathrine H Enoksen ◽  
Tina S Wik ◽  
Jomar Klaksvik ◽  
Astvaldur J Arthursson ◽  
Otto S Husby ◽  
...  
Keyword(s):  
Proximal Femur ◽  
Load Transfer ◽  
Femoral Stem ◽  
Primary Stability ◽  
The Elderly ◽  
Stair Climbing ◽  
Physiological Strain ◽  
Fixation Methods ◽  
Cemented Stem ◽  
Total Point

There are principally two fixation methods in total hip arthroplasty, cemented and uncemented. Both methods have in general good long-time survival. Studies comparing cemented and uncemented femoral stems indicate that the cemented stems perform somewhat better, at least in the elderly population. The aim of this study was to compare load transfer and the initial micromotion pattern for an uncemented and a cemented stem. A total of 12 human cadavers were tested in a hip simulator during single leg and stair climbing. Strain was measured on the proximal femur before and after implantation of the prostheses, and the values were presented as percentage of physiological strain. The micromovements between the stem and bone were measured and a total point motion was calculated. The results showed small statistically significant differences between the fixation methods, the largest difference being 8.1 percentage points. The uncemented stem had somewhat higher micromotion than the cemented stem, but less than 10 µm. Both stems thus had acceptable primary stability. The main finding of this study is the strain and micromotion pattern of a cemented and an uncemented stem of similar geometry is overall equal. There were small statistical significant differences between the two fixation methods regarding strain and micromotion levels. The differences are considered too small to be clinically relevant.

Interface biomechanics of the Anca Dual Fit hip stem: An in vitro experimental study

2001 ◽  
Vol 215 (6) ◽  
pp. 555-564 ◽  
Author(s):  
L Monti ◽  
L Cristofolini ◽  
M Viceconti
Keyword(s):  
Load Transfer ◽  
Bone Ingrowth ◽  
Stress Shielding ◽  
Primary Stability ◽  
Stair Climbing ◽  
Term Stability ◽  
Long Term Stability ◽  
Cemented Stem

The Anca Dual Fit hip stem (Cremascoli Wright, Milan, Italy) is a partially cemented stem developed to overcome the drawbacks of both cemented and uncemented fixations. Its design was based on the hypothesis that partial cementing would ensure the primary stability necessary to allow bone ingrowth on the cement-free stem surfaces. At the same time, the limitation of the cement to the proximal regions would prevent stress-shielding by increasing proximal load transfer. After finite element (FE) simulations and in vitro primary stability assessment, an analysis of the long-term stability of the Anca Dual Fit stem was necessary to conclude the preclinical testing. Three stems were implanted in composite femurs and subjected to testing for 1 × 106 cycles, each cycle reproducing the activity of stair climbing. The simulation was designed so as to replicate the physiological loading in a simplified, yet relevant way for this test. Various measurements were collected before, during and after the test in order to give exhaustive information on the response of the implant to long-term, cyclic loading. The present study confirmed the positive results of previous investigations, and proved that the Anca Dual Fit stem has excellent long-term stability; therefore successful clinical outcomes are predicted.

Patient-specific design process and evaluation of a hip prosthesis femoral stem

2018 ◽  
Vol 42 (6) ◽  
pp. 271-290 ◽  
Author(s):  
Osama Abdelaal ◽  
Saied Darwish ◽  
Hassan El-Hofy ◽  
Yoshio Saito
Keyword(s):  
Load Transfer ◽  
Hip Prosthesis ◽  
Femoral Stem ◽  
Primary Stability ◽  
Patient Specific ◽  
Medical Implants ◽  
Element Analysis ◽  
Cross Sectional ◽  
Custom Implant ◽  
Metaphyseal Region

Introduction: There are several commercially available hip implant systems. However, for some cases, custom implant designed based on patient-specific anatomy can offer the patient the best available implant solution. Currently, there is a growing trend toward personalization of medical implants involving additive manufacturing into orthopedic medical implants’ manufacturing. Methods: This article introduces a systematic design methodology of femoral stem prosthesis based on patient’s computer tomography data. Finite element analysis is used to evaluate and compare the micromotion and stress distribution of the customized femoral component and a conventional stem. Results: The proposed customized femoral stem achieved close geometrical fit and fill between femoral canal and stem surfaces. The customized stem demonstrated lower micromotion (peak: 21 μm) than conventional stem (peak: 34 μm). Stress results indicate up to 89% increase in load transfer by conventional stem than custom stem because the higher stiffness of patient-specific femoral stem proximally increases the custom stem shielding in Gruen’s zone 7. Moreover, patient-specific femoral stem transfers the load widely in metaphyseal region. Conclusion: The customized femoral stem presented satisfactory results related to primary stability, but compromising proximo-medial load transfer due to increased stem cross-sectional area increased stem stiffness.

Biomechanical Robustness of a Contemporary Cementless Stem to Surgical Variation in Stem Size and Position

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Rami M. A. Al-Dirini ◽  
Dermot O'Rourke ◽  
Daniel Huff ◽  
Saulo Martelli ◽  
Mark Taylor
Keyword(s):  
Fibrous Tissue ◽  
Femoral Stem ◽  
Primary Stability ◽  
Bone Adaptation ◽  
Stair Climbing ◽  
Patient Specific ◽  
Fe Model ◽  
Bone Implant ◽  
Stem Size ◽  
Automated Method

Successful designs of total hip replacement (THR) need to be robust to surgical variation in sizing and positioning of the femoral stem. This study presents an automated method for comprehensive evaluation of the potential impact of surgical variability in sizing and positioning on the primary stability of a contemporary cementless femoral stem (Corail®, DePuy Synthes). A patient-specific finite element (FE) model of a femur was generated from computed tomography (CT) images from a female donor. An automated algorithm was developed to span the plausible surgical envelope of implant positions constrained by the inner cortical boundary. The analysis was performed on four stem sizes: oversized, ideal (nominal) sized, and undersized by up to two stem sizes. For each size, Latin hypercube sampling was used to generate models for 100 unique alignment scenarios. For each scenario, peak hip contact and muscle forces published for stair climbing were scaled to the donor's body weight and applied to the model. The risk of implant loosening was assessed by comparing the bone–implant micromotion/strains to thresholds (150 μm and 7000 με) above which fibrous tissue is expected to prevail and the periprosthetic bone to yield, respectively. The risk of long-term loosening due to adverse bone resorption was assessed using bone adaptation theory. The range of implant positions generated effectively spanned the available intracortical space. The Corail stem was found stable and robust to changes in size and position, with the majority of the bone–implant interface undergoing micromotion and interfacial strains that are well below 150 μm and 7000 με, respectively. Nevertheless, the range of implant positions generated caused an increase of up to 50% in peak micromotion and up to 25% in interfacial strains, particularly for retroverted stems placed in a medial position.

Statistical Analysis of Interfacial Gap in a Cementless Stem FE Model

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Youngbae Park ◽  
DonOk Choi ◽  
Deuk Soo Hwang ◽  
Yong-San Yoon
Keyword(s):  
Mechanical Stability ◽  
Femoral Stem ◽  
Primary Stability ◽  
Stair Climbing ◽  
Fe Model ◽  
Contact Ratio ◽  
Cementless Stem ◽  
Noticeable Effect ◽  
Significant Difference ◽  
Interfacial Gap

In cementless total hip arthroplasty, a fair amount of interfacial gap exists between the femoral stem and the bone. However, the effect of these gaps on the mechanical stability of the stem is poorly understood. In this paper, a finite element model with various interfacial gap definitions is used to quantify the effect of interfacial gaps on the primary stability of a Versys Fiber Metal Taper stem under stair climbing loads. In the first part, 500 random interfacial gap definitions were simulated. The resulting micromotion was approximately inversely proportional to the contact ratio, and the variance of the micromotion was greater with a lower contact ratio. Moreover, when the magnitude of the micromotion was compared between the gap definitions that had contact at a specific site and those that had no contact at that site, it was found that gaps located in the proximal-medial region of the stem surface had the most important effect on the micromotion. In a second trial, 17 gap definitions mimicking a gap pattern that has been observed experimentally were simulated. For a given contact ratio, the micromotion observed in the second trial was lower than the average result of those in the first, where the gaps were placed randomly. In either trial, when the contact ratio was higher than 40%, the micromotion showed no significant difference (first trial) or a gentle slope (−0.24μm∕% in the second trial) in relation to the contact ratio. Considering the reported contact ratios for properly implanted stems, variations in the amount of interfacial gap would not likely cause a drastic difference in micromotion, and this effect could be easily overshadowed by other clinical factors. In conclusion, differences in interfacial gaps are not expected to have a noticeable effect on the clinical micromotion of this cementless stem.

scholarly journals The Olympia anatomic polished cemented stem is associated with a high survivorship, excellent hip-specific functional outcome, and high satisfaction levels: follow-up of 239 consecutive patients beyond 15 years

2021 ◽  
Author(s):  
Gareth S. Turnbull ◽  
Claire Marshall ◽  
Jamie A. Nicholson ◽  
Deborah J. MacDonald ◽  
Nicholas D. Clement ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Femoral Stem ◽  
Patient Reported Outcome Measures ◽  
Patient Reported Outcome ◽  
High Satisfaction ◽  
Age At Surgery ◽  
Patient Reported ◽  
Cemented Stem ◽  
Oxford Hip Score

Abstract Introduction The Olympia femoral stem is a stainless steel, anatomically shaped, polished and three-dimensionally tapered implant designed for use in cemented total hip arthroplasty (THA). The primary aim of this study was to determine the long-term survivorship, radiographic outcome, and patient-reported outcome measures (PROMs) of the Olympia stem. Patients and methods Between May 2003 and December 2005, 239 patients (264 THAs) underwent a THA with an Olympia stem in our institution. Patient-reported outcome measures were assessed using the Oxford Hip Score (OHS), EuroQol-5 dimensions (EQ-5D) score, and patient satisfaction at mean 10 years following THA. Patient records and radiographs were then reviewed at a mean of 16.5 years (SD 0.7, 15.3–17.8) following THA to identify occurrence of complications or revision surgery for any cause following surgery. Radiographs were assessed for lucent lines and lysis according to Gruen’s zones Results Mean patient age at surgery was 68.0 years (SD 10.9, 31–93 years). There were 156 women (65%, 176 THAs). Osteoarthritis was the indication for THA in 204 patients (85%). All cause stem survivorship at 10 years was 99.2% (95% confidence interval [CI], 97.9%–100%) and at 15 years was 97.5% (94.6%–100%). The 15-year stem survival for aseptic loosening was 100%. Analysis of all-cause THA failure demonstrated a survivorship of 98.5% (96.3%–100%) at 10 years and 95.9% (92.4%–99.4%) at 15 years. There were 9 THAs with non-progressive lucent lines in a single Gruen zone and 3 had lines in two zones, and no patient demonstrated signs for lysis. At a mean of 10-year (SD 0.8, 8.7–11.3) follow-up, mean OHS was 39 (SD 10.3, range 7–48) and 94% of patients reported being very satisfied or satisfied with their THA. Conclusions The Olympia stem demonstrated excellent 10-year PROMs and very high rates of stem survivorship at final follow-up beyond 15 years.

Does the femoral offset affect replacements? The results from a National Joint Registry

2018 ◽  
Vol 29 (3) ◽  
pp. 289-298 ◽  
Author(s):  
Michael C Wyatt ◽  
David C Kieser ◽  
Mark A Kemp ◽  
Gavin McHugh ◽  
Chris M A Frampton ◽  
...  
Keyword(s):  
Femoral Component ◽  
Revision Rate ◽  
Femoral Stem ◽  
Joint Registry ◽  
Total Hip Replacements ◽  
Significant Difference ◽  
Hip Replacements ◽  
Cemented Stem ◽  
And Gender ◽  
Low Offset

Background: Femoral component offset influences the torque forces exerted on a femoral stem and may therefore adversely affect femoral component survival. This study investigated the influence of femoral component offset on revision rates for primary total hip replacements (THR) registered on the New Zealand Joint Registry (NZJR). Methods: There were 106,139 primary THRs registered, resulting in 4960 revisions for any cause. There were 46,242 THRs performed using the five commonest femoral components listed on the NZJR. A total of 41,100 were done for primary osteoarthritis of which 40,548 had all the offset information available for analysis. We defined low offset as < 42 mm, standard as 42–48 mm and high offset as > 48 mm offset and examined revision rates according to the reasons for revision. We performed survival analyses for both cemented and uncemented femoral components grouped by the different offsets. Results: The all-cause revision rate was 0.54/100 component years (cys). Stems with < 42 mm offset had a revision rate of 0.58/100 cys (mean 0.58; 95% confidence interval (CI) 0.53–0.63), 42–48 mm offset 0.47 (95% CI 0.43–0.52) and > 48 mm offset 0.67 (95% CI 0.57–0.79). There was no significant difference in all-cause revision rates between varying stem offsets in uncemented stems adjusting for age and gender. In cemented stems both high and low offset stems were more likely to be revised. Uncemented stems of all offsets were more likely to undergo revision for femoral fracture. Conclusions: Femoral component offset affects the overall all-cause revision rate of the most commonly used cemented stem, but not uncemented stem designs. In cemented stems offset influences the rate of revision for loosening and periprosthetic fractures.

Association of abductor hip muscle atrophy with fall-related proximal femur fractures in the elderly

Injury ◽  
2020 ◽  
Vol 51 (7) ◽  
pp. 1626-1633
Author(s):  
Samet Erinç ◽  
Mehmet Ali Bozca ◽  
Müjdat Bankaoğlu ◽  
Süleyman Çakırtürk ◽  
Yusuf Yahşi ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Proximal Femur ◽  
The Elderly ◽  
Proximal Femur Fractures ◽  
Femur Fractures ◽  
Hip Muscle

Cement within Cement Revision Hip Arthroplasty a Minimum 5 Year Follow-Up Study

1998 ◽  
Vol 8 (3) ◽  
pp. 129-137 ◽  
Author(s):  
J.P. Holland ◽  
F.A. Weber
Keyword(s):  
Femoral Stem ◽  
Femoral Shaft ◽  
Complete Removal ◽  
Senior Author ◽  
Long Term Results ◽  
Cemented Stem ◽  
Revision Hip Surgery

Complete removal of femoral shaft cement during revision hip surgery is a difficult task prone to complications. If the cement bone interface is intact however, is there a place for its preservation and re-use with a new cemented stem? The results are reported of 51 cement within cement femoral stem revisions carried out between 1984 and 1991 with a minimum of 5 years’ follow-up, and a mean of 7.8 years. Excluding patients lost or deceased, 39 hips in 38 patients were reviewed clinically and radiologically. Eighty-two percent of these were still functioning in situ, 72% were excellent or good using the HSS scoring system and 97% had no radiological evidence of loosening. Femoral stem failure due to aseptic loosening occurred in 4 cases (10%) between 4 and 12 years after revision. Comparing this series to a previous revision hip series by the senior author, there appears to be no deterioration in long term results using this technique, and a better long term radiological outcome.

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