Contact Mechanics Analysis and Initial Stability of Press-Fit Metal-on-Metal Hip Resurfacing Prostheses

2005 ◽  
Author(s):  
I. Udofia ◽  
F. Liu ◽  
Z. Jin ◽  
P. Roberts ◽  
P. Grigoris
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Bone Structure ◽  
Hip Resurfacing ◽  
Implant Stability ◽  
Acetabular Cup ◽  
Press Fit ◽  
Initial Stability ◽  
Metal On Metal

To ensure potential long-term stability and survivorship for metal-on-metal hip resurfacing prostheses, implant migration would need to be minimised to encourage bone in-growth. This study uses the finite element method to investigate the effects of the surgical press-fit procedure on the bearing and interfacial contact mechanics, and on the initial stability of a metal-on-metal (MOM) hip resurfacing prosthesis. The finite element models simulated the press-fit procedure using different amounts of interference between the cup-bone (1–2mm). The resurfacing prosthesis was implanted anatomically into a 3-D bone model. Resultant hip joint loads were applied to the model through muscle and subtrochanteric forces. Results showed that increasing the friction and the interference between the cup and bone resulted in significant reductions in the relative micromotion between the cup and bone. This would ensure the immediate post-operative stability of the acetabular cup and provide adequate conditions for potential long-term bone in-growth and implant stability. The contact mechanics at the bearing surfaces, which has a large effect on tribological performance, was found to be little affected by changes at the cup-bone interface. These findings are consistent with the general satisfactory short and medium-term clinical results of metal-on-metal hip resurfacing prostheses. This study suggests that interference, friction and a mechanically sound bone structure are important parameters to promote implant stability and support.

Effect of Acetabular Cup Design on the Tribology of Metal-on-Metal Hip Resurfacing Replacements: A Contact Mechanics and Elastohydrodynamic Lubrication Study

2005 ◽  
Author(s):  
I. Udofia ◽  
F. Liu ◽  
Z. Jin ◽  
P. Roberts ◽  
P. Grigoris
Keyword(s):  
Contact Mechanics ◽  
Wall Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Hip Resurfacing ◽  
Fluid Film ◽  
Acetabular Cup ◽  
Metal On Metal ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The tribology of metal-on-metal (MOM) hip resurfacing prostheses has been investigated in this study, with particular consideration of the effect of prosthesis design (cup wall thickness and clearance) on the contact mechanics and elastohydrodynamic lubrication (EHL) of these man-made bearings. Two commercially available MOM hip resurfacings, which differ mainly in cup-wall thickness and diametral clearance, were investigated. Finite element contact mechanics and lubrication analyses were carried out on the two MOM hip resurfacing designs. It was found that the thinner acetabular cup with a the relatively smaller clearance resulted in lower contact and hydrodynamic pressure predictions, and a significant increase in the predicted lubricant film thickness at the bearing surfaces. This was attributed to the increase in contact area, conformity between the cup and ball and to the increased influence of the underlying non-metallic structures such as bone and cement, which enhanced the elasticity of the thin acetabular cup. It was shown that full fluid-film lubrication was possible in MOM hip resurfacings during the walking cycle with the small clearance and thin cup-wall thickness model. The importance of the design and manufacturing parameters on the tribological performance of MOM hip resurfacings is highlighted in this study, particularly in promoting fluid film lubrication as a means to further reduce wear at the bearing surfaces.

Comparing the cup deformation following implantation of a novel ceramic-on-ceramic hip resurfacing bearing to a metal standard in a cadaveric model

2019 ◽  
Vol 233 (6) ◽  
pp. 603-610
Author(s):  
Adam James Farrier ◽  
Lauren Moore ◽  
Will Manning ◽  
Carolina Avila ◽  
Simon N Collins ◽  
...  
Keyword(s):  
Femoral Head ◽  
Hip Resurfacing ◽  
Attractive Alternative ◽  
Acetabular Cup ◽  
Metal Implants ◽  
Press Fit ◽  
Metal On Metal ◽  
Fresh Frozen ◽  
Ceramic Implants ◽  
Cadaveric Model

Hip resurfacing is an attractive alternative to total hip replacement preserving bone and reducing dislocation risk. Recent metal-on-metal designs have caused failure due to metal wear debris. Ceramic implants may mitigate this risk. Deformation of the acetabular cup can affect the lubrication, producing high friction torques between the femoral head and the cup that would increase wear and/or lead to cup loosening due to femoral head clamping. Our objective was to quantify the deformation of a novel monobloc ceramic hip resurfacing cup component compared to a metal standard, in a fresh frozen cadaveric model using a press-fit technique representative of standard surgical conditions. For this study eight acetabula were prepared from four fresh frozen cadavers. One surgeon with extensive experience in hip resurfacing surgery (J.H.) prepared the acetabulum by sequential reaming. The implants were then impacted into the acetabulum. Four ceramic and four metal implants were used of equal and varying size. Deformation was measured peri-implantation, and at 30 min, using an optical high-precision deformation sensor (GOM GmbH, Braunschweig, Germany). The maximum inscribed circle and the measurement of radial segment techniques were used. Deformation was greater in the metal implants (mean: 34–22mm) immediately after implantation. At 30 min after implantation, the deformation increased to 36mm in the metal and 26mm in the ceramic cup. Greater diameter changes were observed in larger cups. Metal and ceramic implants did not return to the initial diameter. We conclude the ceramic resurfacing acetabular implants undergo similar deformation to existing metal-on-metal implants. The deformation observed was significantly less in the ceramic component at 30 min on one measure. Less deformation may result in better surface conditions and wear characteristics. Deformation change did not resolve after 30 min for both implants.

Method Development for Determination of Initial Stability of Cementless Femoral Stems

2009 ◽  
Author(s):  
Laura Yanoso Scholl ◽  
Gregg Schmidig ◽  
Mayur Thakore ◽  
Daniel Hayes
Keyword(s):  
Method Development ◽  
Mechanical Stability ◽  
Implant Stability ◽  
Bone Implant ◽  
Cementless Total Hip Arthroplasty ◽  
Press Fit ◽  
Initial Stability ◽  
Femoral Stems

For press-fit (cementless) total hip arthroplasty, area of non-contact (gaps) between the bone and the implant may reduce the mechanical stability of the implant. Stability is essential for osteointegration and ultimately the long-term success of the implant. Therefore, it is necessary to assess the micromotion that occurs at the bone/implant interface and identify whether this micromotion is within an appropriate range to allow for successful osteointegration between the implant and host bone [1].

scholarly journals Effect of interposed tissue and contamination on the initial stability of a highly porous press‐fit acetabular cup

2019 ◽  
Vol 37 (5) ◽  
pp. 1117-1122 ◽  
Author(s):  
Daniel H. Wiznia ◽  
Garrett Joyal ◽  
Gregg Schmidig ◽  
Raga Rajaravivarma ◽  
Raja Lokesh ◽  
...  
Keyword(s):  
Acetabular Cup ◽  
Press Fit ◽  
Initial Stability ◽  
Highly Porous

CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS

2016 ◽  
Vol 16 (05) ◽  
pp. 1650070 ◽  
Author(s):  
DESMOND Y. R. CHONG ◽  
ULRICH N. HANSEN ◽  
ANDREW A. AMIS
Keyword(s):  
Finite Element ◽  
Bone Ingrowth ◽  
Stair Climbing ◽  
Fixation Strength ◽  
Knee Prostheses ◽  
Periprosthetic Bone ◽  
Design Change ◽  
Initial Stability ◽  
Better Than

Fixation strength of the cementless knee prostheses is dependent on the initial stability of the fixation and minimal relative motion across the prosthesis–bone interface. Broad mini-keels have been developed for tibial components to allow minimally invasive knee arthroplasty, but the effect of the change in fixation design is unknown. In this study, bone–prosthesis interface micromotions of the mini-keel tibial components (consisting of two designs; one is stemless and another with a stem extension of 45[Formula: see text]mm) induced by walking and stair climbing were investigated by finite element modeling and compared with standard stemmed design. The prosthesis surface area amenable for bone ingrowth for the mini-keel tibial components (both stemmed and unstemmed) was predicted to be at least 67% larger than the standard stemmed implant, thereby reducing the risk of long-term aseptic loosening. It was also found that while different load patterns may have led to diverse predictions of the magnitude of the interface micromotions and the extent of osseointegration onto the prosthesis, the outcome of design change evaluation in cementless tibial fixations remains unchanged. The mini-keel tibial components were predicted to anchor onto the periprosthetic bone better than the standard stemmed design under all loading conditions investigated.

scholarly journals A hierarchy of computationally derived surgical and patient influences on metal on metal press-fit acetabular cup failure

2012 ◽  
Vol 45 (9) ◽  
pp. 1698-1704 ◽  
Author(s):  
S.G. Clarke ◽  
A.T.M. Phillips ◽  
A.M.J. Bull ◽  
J.P. Cobb
Keyword(s):  
Acetabular Cup ◽  
Press Fit ◽  
Metal On Metal

scholarly journals Do Ion Levels in Metal-on-metal Hip Resurfacing Differ From Those in Metal-on-metal THA at Long-term Followup?

2013 ◽  
Vol 471 (9) ◽  
pp. 2964-2971 ◽  
Author(s):  
Lucia Savarino ◽  
Matteo Cadossi ◽  
Eugenio Chiarello ◽  
Nicola Baldini ◽  
Sandro Giannini
Keyword(s):  
Hip Resurfacing ◽  
Metal On Metal

Characterization of Acetabular Cup Insertion Forces in Cancellous Bone Proxy for Validation of an Invasive Sensing Model and Development of Automatic Prosthesis Installation Device: A Preliminary Study

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Kambiz Behzadi ◽  
Jesse Rusk
Keyword(s):  
Force Feedback ◽  
Primary Stability ◽  
The United States ◽  
Assistive Technologies ◽  
Medical Procedure ◽  
Implant Stability ◽  
Acetabular Cup ◽  
Total Hip ◽  
Press Fit ◽  
Preliminary Study

Abstract Total hip replacement is a widespread medical procedure, with over 300,000 surgeries performed each year in the United States alone. The vast majority of total hip replacements utilize press fit fixation. Successful seating of the implant requires a delicate balance between inserting the implant deep enough to obtain sufficient primary stability, while avoiding fracture of bone. To improve patient outcomes, surgeons need assistive technologies that can guide them as to how much force to apply and when to stop impacting. The development of such technology, however, requires a greater understanding of the forces experienced in bone and the resulting cup insertion and implant stability. Here, we present a preliminary study of acetabular cup insertion into bone proxy samples. We find that as the magnitude of force on the acetabular cup increases, cup insertion and axial extraction force increase linearly, then nonlinearly, and finally plateau with full insertion. Within the small nonlinear zone, approximately 90% of both cup insertion and extraction force are achieved with only 50% total energy required for full seating, posing the question as to whether full seating is an appropriate goal in press-fit arthroplasty. For repeated impacts of a given energy, cup displacement and force experienced in bone (measured force profile—MFP) increase correspondingly and reach a plateau over a certain number of impacts (number of impacts to seating—NOITS), which represents the rate of insertion. The relationship between MFP and NOITS can be exploited to develop a force feedback mechanism to quantitatively infer optimal primary implant stability.

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