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.

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

2020 ◽  
Author(s):  
Kambiz Behzadi
Keyword(s):  
Primary Stability ◽  
Feedback Mechanism ◽  
Assistive Technologies ◽  
Medical Procedure ◽  
Implant Stability ◽  
Acetabular Cup ◽  
Total Hip ◽  
Press Fit ◽  
Hip Replacements ◽  
Sensing Model

Abstract Total hip replacement is a widespread medical procedure, with over 300,000 surgeries performed each year in the US alone. The vast majority of total hip replacements utilize press fit fixation, where the implant cup is physically impacted into the patient’s acetabular cavity. 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, which causes pain, complications during recovery, and revision surgery. To improve patient outcomes, this surgical field needs assistive technologies that can measure the forces applied during press fit fixation, and provide real-time feedback to guide how much force to apply, and when to stop applying additional forces. The development of such technology, however, requires a greater understanding of the forces experienced at the implant-acetabular cup interface, 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, the cup displacement and axial extraction force increase linearly and then plateau. For repeated impacts of a given force, cup insertion and force experienced in bone increase correspondingly and reach a plateaued value over certain number of impacts, which represents rate of insertion. These finding suggest the plausibility of a feedback mechanism that utilizes measured force patterns in bone, implant/bone interface, and impaction tool in relation to rate of insertion to infer optimal primary implant stability in arthroplasty.

scholarly journals Is Restoration of Hip Center Mandatory for Total Hip Arthroplasty of Protrusio Acetabuli?

2021 ◽  
Author(s):  
Beom Seok Lee ◽  
Hong Seok Kim ◽  
Jung Wee Park ◽  
O Sang Kwon ◽  
Young-Kyun Lee ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Successful Outcome ◽  
Harris Hip Score ◽  
Implant Stability ◽  
Acetabular Cup ◽  
Total Hip ◽  
Protrusio Acetabuli ◽  
Press Fit ◽  
Initial Fixation

Abstract Background: While initial fixation by a press-fit of the acetabular cup is essential for the durability of the component, restoration of the hip center has been known as an attributable factor for implant survival and successful outcome. In protrusio acetabuli (PA), it might be difficult to obtain both restoration of the hip center and the press-fit of the acetabular cup simultaneously during total hip arthroplasty (THA). We tested a hypothesis that medialized cup, if press-fitted, does not compromise the implant stability and outcome after cementless THA of PA. Methods: We reviewed 27 cementless THAs of 23 patients with PA. During THA, we prioritized press-fit of the cup than the hip center restoration. A press-fit was obtained in 24 hips. In the remaining 3 hips, a press-fit could not be obtained, and reinforcement acetabular components were used. The hip center was restored in 18 cups; 15 primary cups and 3 reinforcement components, while it was medialized in 9 cups. We compared implant stability and modified Harris hip score (mHHS) between the 2 groups at a mean of 5.2 (2-16) year follow-up. Results: One restored reinforcement cup was loose. The remaining 26 cups; 17 restored cups and 9 medialized press-fitted cups, remained stable. The final mHHS was similar between the restored group and the medialized group (81.8 ± 10.8 vs 83.6 ± 12.1, p = 0.498). Conclusions: Press-fitted cups, irrespective of hip center restoration, rendered implant stability and favorable results. Initial fixation of the cup is more important than the restoration of hip center.

Double-Modular Hip Device Design Susceptible to Stress Corrosion Failure

2009 ◽  
Author(s):  
Sara A. Atwood ◽  
Eli W. Patten ◽  
Kevin J. Bozic ◽  
Lisa A. Pruitt ◽  
Michael D. Ries
Keyword(s):  
Femoral Head ◽  
Femoral Anteversion ◽  
Metal Alloy ◽  
Leg Length ◽  
Acetabular Cup ◽  
Corrosion Failure ◽  
Total Hip ◽  
Press Fit ◽  
Free Mobility ◽  
Hip Replacements

Total hip replacements restore pain-free mobility to approximately 200,000 patients in the U.S. each year [1]. A typical hip system comprises a metal alloy stem, a femoral head (ceramic or metal alloy), and a polyethylene acetabular cup fit into a metal alloy backing. A modular press-fit Morse taper is commonly used to attach the femoral head to the stem. There are also more recent designs that incorporate a second interface at the neck-stem junction (Figure 1). Increased modularity in total hip replacement design allows the surgeon to intraoperatively preserve patient anatomy such as leg length and femoral anteversion and better balance the surrounding soft tissue for optimal biomechanics. However, modularity also increases the number of mechanical junctions and interfaces in the device which may lead to complications such as corrosion, wear, and fracture.

Failure of an Uncemented Press-Fit Acetabular Cup in Primary Total Hip Arthroplasty

2002 ◽  
Vol 12 (4) ◽  
pp. 371-377 ◽  
Author(s):  
N. Rama Mohan ◽  
P. Grigoris ◽  
D.L. Hamblen
Keyword(s):  
Femoral Stem ◽  
Acetabular Cup ◽  
Total Hip ◽  
Press Fit ◽  
Total Hip Replacements ◽  
Locking Mechanism ◽  
Hip Replacements ◽  
The Mean ◽  
Open Position ◽  
Primary Total Hip Arthroplasty

We reviewed fifteen primary total hip replacements performed using the uncemented, non-porous coated press-fit AcSys Shearer Cup. A modular titanium straight femoral stem with a 32mm head was used in all cases. The mean age of the group containing five males and 10 females was 66 years. Eight cups have been revised for aseptic loosening at a mean of seven years and the remaining four cups are radiologically loose. At revision surgery none of the cups showed any evidence of bony ingrowth. Our 10-year results with this cup indicate an unacceptably high failure rate of 80%. Absence of bony ingrowth and the lack of a secure locking mechanism between the polyethylene liner and the metal shell are the most important causes of failure. The use of a 32mm diameter head and implantation of the cup in an open position contributed to this failure. Even though this cup is no longer manufactured, our experience suggests that all non-porous coated cups should be closely followed up.

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.

scholarly journals Biomechanical evaluation of the primary stability of three different types of femoral stem fixations for canine total hip replacement

2020 ◽  
Author(s):  
Charles Saban ◽  
Eric Viguier ◽  
Mathieu Taroni ◽  
Arnaud Baldinger ◽  
Margaux Blondel ◽  
...  
Keyword(s):  
Femoral Stem ◽  
Primary Stability ◽  
Longitudinal Axis ◽  
Transverse Displacement ◽  
Salvage Procedure ◽  
Total Hip ◽  
Press Fit ◽  
Femoral Stems ◽  
Mean Strain

Abstract Background: Total hip arthroplasty is the main salvage procedure performed for hip osteoarthritis in dogs. Two main types of femoral stems are available: cemented stems, which offer excellent primary stability but are subject to aseptic loosening in the long term, and cementless stems, which have good long-term outcomes but lack primary stability. The adjunction of a neutral rod through the neck of the cementless stem to the lateral cortex of the femur could offer better primary stability before osteointegration. The aim of this study was to compare the primary stability of three different femoral stems, cemented (cFS), press-fit cementless (pfFS), and rod-press-fit cementless stems (r-pfFS), by measuring their transverse displacement on cyclic assays and resistance to subsidence with unidirectional load compression parallel to the longitudinal axis of the femur.Results: The force-displacement and stress-strain curves were assessed. The work necessary for subsidence, strain to failure, and mean strain of the cyclic assays were calculated. No significant differences were observed in transverse displacement (p=0.263) or mean strain (p=0.244) during the cyclic tests or in work necessary for subsidence (p=0.079) or strain to failure (p=0.075). The cFS and r-pfFS were significantly more resistant to subsidence than was the pfFS (p<0,05). No significant differences were observed between the cFS and r-pfFS groups (p=0.48).Conclusions: Cementless femoral stems with transfixing rods offer significantly higher stability to compressive load parallel to the longitudinal axis of the femur than do standard cementless stems and a level of stability comparable to that of cemented stems. r-pfFSs may be valuable in limiting the subsidence and micro-motion of press-fit femoral stems and thus improving the state of osteointegration of the prosthesis during the short-term postoperative period.

scholarly journals Total Hip Replacement: Exchange of a Loose Perforated Press-Fit Cup with a Porous-Coated Press-Fit Cup in a Dog

VCOT Open ◽  
2020 ◽  
Vol 03 (02) ◽  
pp. e129-e133
Author(s):  
Stephanie M.M. Colthurst ◽  
James O. Simcock ◽  
Ricky G. Cashmore
Keyword(s):  
Total Hip Replacement ◽  
Hip Replacement ◽  
Internal Diameter ◽  
Acetabular Cup ◽  
Total Hip ◽  
Press Fit ◽  
Long Term Follow Up ◽  
Excellent Functional Outcome ◽  
Head Neck

Abstract Objective The aim of this study was to report the successful revision of a loose perforated press-fit cup by exchange with a porous-coated press-fit cup while maintaining the original locking stem and head–neck unit. Methods Cup revision was performed in a dog with a loose acetabular cup that had undergone total hip replacement with a perforated press-fit cup and locking stem 29 months previously. The original locking stem was well integrated. A single session cup exchange was performed by implantation of a 28-mm porous-coated press-fit cup with 16 mm internal diameter to allow the original locking stem and head–neck unit to be preserved. Results Revision total hip arthroplasty by cup exchange resulted in excellent functional outcome with long-term follow-up 18 months postoperatively. There were no intraoperative or postoperative complications. Conclusion A loose perforated press-fit cup was successfully revised with a porous press-fit cup while allowing preservation of the initial locking stem and head–neck unit.

scholarly journals Two Different Methods to Measure the Stability of Acetabular Implants: A Comparison Using Artificial Acetabular Models

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 254
Author(s):  
Quentin Goossens ◽  
Leonard Cezar Pastrav ◽  
Michiel Mulier ◽  
Wim Desmet ◽  
Jos Vander Sloten ◽  
...  
Keyword(s):  
Surgical Techniques ◽  
Primary Stability ◽  
Test Methods ◽  
Implant Design ◽  
Implant Stability ◽  
Press Fit ◽  
Initial Stability ◽  
Custom Made ◽  
Golden Standard ◽  
Load To Failure

The total number of total hip arthroplasties is increasing every year, and approximately 10% of these surgeries are revisions. New implant design and surgical techniques are evolving quickly and demand accurate preclinical evaluation. The initial stability of cementless implants is one of the main concerns of these preclinical evaluations. A broad range of initial stability test methods is currently used, which can be categorized into two main groups: Load-to-failure tests and relative micromotion measurements. Measuring relative micromotion between implant and bone is recognized as the golden standard for implant stability testing as this micromotion is directly linked to the long-term fixation of cementless implants. However, specific custom-made set-ups are required to measure this micromotion, with the result that numerous studies opt to perform more straightforward load-to-failure tests. A custom-made micromotion test set-up for artificial acetabular bone models was developed and used to compare load-to-failure (implant push-out test) with micromotion and to assess the influence of bone material properties and press-fit on the implant stability. The results showed a high degree of correlation between micromotion and load-to-failure stability metrics, which indicates that load-to-failure stability tests can be an appropriate estimator of the primary stability of acetabular implants. Nevertheless, micromotions still apply as the golden standard and are preferred when high accuracy is necessary. Higher bone density resulted in an increase in implant stability. An increase of press-fit from 0.7 mm to 1.2 mm did not significantly increase implant stability.

scholarly journals ELEVATION OF THE CENTER OF ROTATION WITH THE USE OF JUMBO CUPS IN REVISION TOTAL HIP ARTHROPLASTY – A RADIOGRAPHIC STUDY

2021 ◽  
Vol 27 (1) ◽  
pp. 3518-3522
Author(s):  
Maksim Zagorov ◽  
◽  
Kalin Mihov ◽  
Svetoslav Dobrilov ◽  
Gergana Nenova ◽  
...  
Keyword(s):  
Hip Arthroplasty ◽  
Revision Arthroplasty ◽  
Leg Length ◽  
Acetabular Cup ◽  
Hip Revision ◽  
Total Hip ◽  
Rotation Center ◽  
Press Fit ◽  
Cementless Cup ◽  
Jumbo Cup

Background: Acetabular revision with extra-large (jumbo) cementless cups is an effective treatment for many cavitary and segmental peripheral bone defects. However, hip center elevation may occur with the use of a jumbo cup owing to the superior direction of reaming and the increased diameter of the component compared with the native acetabulum. Purposes: The primary goal of this study was to evaluate the radiographically observed hip center elevation with the use of jumbo cups in acetabular and total hip revision at our institution. Materials and methods: We retrospectively reviewed control radiographic images of 43 consecutive patients treated with acetabular and total hip revision arthroplasty with a press-fit cementless cup. The difference between the height of the rotation center of the acetabular cup and the height of the rotation center of the contralateral native hip relative to the inter teardrop line was radiographically measured. Results: The radiographically measured mean elevation of the rotation center of the jumbo cup was 8,75 mm, which yielded an average increase in the height of the rotation centre of 83,6. A mean vertical shift of the rotation center of 0,72 mm was estimated for every 1 mm increase in the size of the jumbo cup. Conclusions: Our results indicate that the use of jumbo cups in revision hip arthroplasty leads to elevation of the rotation center of the hip with an average of 9 mm. This could be considered by the surgeon in an attempt to restore leg length, stability and biomechanics of the prosthetic hip.

scholarly journals Influence of Synthetic Bone Substitutes on the Anchorage Behavior of Open-Porous Acetabular Cup

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1052 ◽  
Author(s):  
Volker Weißmann ◽  
Tim Ramskogler ◽  
Christian Schulze ◽  
Rainer Bader ◽  
Harald Hansmann
Keyword(s):  
Primary Stability ◽  
Bone Substitutes ◽  
Fixation Strength ◽  
Bone Stock ◽  
Structural Elements ◽  
Acetabular Cup ◽  
Load Bearing ◽  
Synthetic Bone ◽  
Press Fit ◽  
Pull Out

Background: The development in implants such as acetabular cups using additive manufacturing techniques is playing an increasingly important role in the healthcare industry. Method: This study compared the primary stability of four selectively laser-melted press-fit cups (Ti6Al4V) with open-porous, load-bearing structural elements on the surface. The aim was to assess whether the material of the artificial bone stock affects the primary stability of the acetabular cup. The surface structures consist of repeated open-porous, load-bearing elements orthogonal to the acetabular surface. Experimental pull-out and lever-out tests were performed on exact-fit and press-fit cups to evaluate the primary stability of the cups in different synthetic bone substitutes. The acetabular components were placed in three different commercially available synthetic materials (ROHACELL-IGF 110, SikaBlock M330, Sawbones Solid Rigid). Results & conclusions: Within the scope of the study, it was possible to show the differences in fixation strength between the tested acetabular cups depending on their design, the structural elements used, and the different bone substitute material. In addition, functional correlations could be found which provide a qualitative reference to the material density of the bone stock and the press-fit volume of the acetabular cups.

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