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Edge loading inclination

Allahyar Gerami, Sepideh Dadgar, Vahid Rakhshan, Puya Jannati, Farhad Sobouti
BACKGROUND: Fixed orthodontic retainers have numerous advantages, but it is not known whether they can exert pathological forces on supporting tissues around the splinted teeth. The purpose of this study was to investigate how the inclination of the lower anterior teeth can affect dental displacement and also change the direction of occlusal loads exerted to dental and its supporting tissues. METHODS: Four three-dimensional finite element models of the anterior part of the mandible were designed...
December 2016: Progress in Orthodontics
Xijin Hua, Junyan Li, Zhongmin Jin, John Fisher
The occurrence of edge loading in hip joint replacement has been associated with many factors such as prosthetic design, component malposition and activities of daily living. The present study aimed to quantify the occurrence of edge loading/contact at the articulating surface and to evaluate the effect of cup angles and edge loading on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR) during different daily activities. A three-dimensional finite element model was developed based on a modular MoP bearing system...
June 2016: Medical Engineering & Physics
Willem B Hiddema, Johan F van der Merwe, Werner van der Merwe
BACKGROUND: The success of a total hip arthroplasty relies on optimal acetabular cup placement to ensure mating of the femoral head and acetabular cup throughout all positions of the hip joint. Poor cup placement is associated with dislocation, impingement, microseparation, component loosening, and accelerated wear due to rim loading. This study examined a novel method of using the transverse acetabular ligament (TAL) to guide cup inclination during primary total hip arthroplasty. METHODS: A descriptive study using 16 hips from 9 cadavers...
July 2016: Journal of Arthroplasty
Li Liu, Timo Michael Ecker, Steffen Schumann, Klaus-Arno Siebenrock, Guoyan Zheng
Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter relies on estimation of peak contact pressures and contact areas using either patient specific or constant thickness cartilage models. We performed a finite element analysis investigating the optimal reorientation of the acetabulum in PAO surgery based on simulated joint contact pressures and contact areas using patient specific cartilage model. Furthermore we investigated the influences of using patient specific cartilage model or constant thickness cartilage model on the biomechanical simulation results...
2016: PloS One
Hiroaki Suzuki, Yoshiaki Hata, Fumihiko Watanabe
The purpose of this study was to investigate the relationship between implant fracture under cyclic-fatigue loading at different embedding angles, embedding depths, and loading forces. Twenty-four cylinder-type implants 3.3 mm in diameter and 10 mm in length were used. Test specimens were 30 mm(3) resin blocks with one surfaces inclined at angles of either 5°, 10°, 15° and 20° and embedded vertically with implants at depths of either 5 or 10 mm to the these surfaces. A straight abutment was connected to the implant and cut to 5 mm in length, and a hemispherical crown 5 mm in diameter and 7 mm in length was cast with a 12 % gold-silver-palladium alloy and cemented onto the abutment...
September 2016: Odontology
Fei Li, Hejuan Chen, Ken Mao
Stripe wear occurs when the components of hip prostheses move a sufficient distance laterally to contact the edge of the acetabular cup, causing abnormally high contact stresses. In this research, edge loading contact of prosthetic hip is analyzed in the most commonly used material pairs. The contact dimensions and maximal contact pressure are investigated in mutative normal edge loading with 3 different inclination angles (15°, 20°, 25°) and in alterable edge torus radius with edge loading of 2500 N and inclination of 20°...
2015: Acta of Bioengineering and Biomechanics
Mariska Wesseling, Christophe Meyer, Friedl De Groote, Kristoff Corten, Jean-Pierre Simon, Kaat Desloovere, Ilse Jonkers
Following metal-on-metal hip arthroplasty, edge loading (i.e., loading near the edge of a prosthesis cup) can increase wear and lead to early revision. The position and coverage angle of the prosthesis cup influence the risk of edge loading. This study investigates the effect of altered gait patterns, more specific hip, and pelvis kinematics, on the orientation of hip contact force and the consequent risk of antero-superior edge loading using muscle driven simulations of gait. With a cup orientation of 25° anteversion and 50° inclination and a coverage angle of 168°, many gait patterns presented risk of edge loading...
June 2016: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Asheesh Gupta, Sivashankar Chandrasekaran, John M Redmond, Jon E Hammarstedt, T Luke Cramer, Yuan Liu, Benjamin G Domb
BACKGROUND: Hip dysplasia has been shown to be a cause of early arthritis. The decrease in bony coverage has shown increased stress on the acetabular labrum as it shares an increased load. PURPOSE/HYPOTHESIS: The purpose of this study was to divide a cohort of patients by radiographic measures of dysplastic and nondysplastic hips for comparison with regard to labral size at 4 anatomic locations. The hypothesis was that dysplastic hips will have significantly larger labral size compared with nondysplastic hips...
February 2015: Orthopaedic Journal of Sports Medicine
Li-hui Han, Xiao-xia Qiu, Xu-na Xing, Liu-yi Cai
PURPOSE: To provide theoretical reference for maxillary anterior restoration designment in clinics by observing the masticatory stress distribution of the implant-bone interface and the displacement of implant. METHODS: This study built simplified 3 dimensional finite models with different angles, which included partial implant (4.3 mm×11.5 mm), abutment and all ceramic crown (Zirconia) and combined with angle of implant A between the long axis of ideal implant and factual implant (0°, 5°, 10°, 15°, 20°, 25°), as well as angle of abutment B between the long axis of abutment and implant (0°, 5°,10°,15°,20°,25°)...
April 2015: Shanghai Kou Qiang Yi Xue, Shanghai Journal of Stomatology
Herzl Chai
Extracted human molar teeth are indented by hard balls laid at the central fossa, sectioned, and their interior examined for damage. Contact on the fissured enamel coat generally occurs on three distinct spots. The main forms of damage are radial cracks growing from the DEJ to the occlusal surface and median radial and cylindrical cracks growing from a contact spot to the DEJ. For large balls failure by edge chipping near a cusp apex may occur. The median cracks tend to run unstably to the DEJ upon reaching the middle part of the enamel coat...
April 2015: Journal of the Mechanical Behavior of Biomedical Materials
Stephen J Mellon, George Grammatopoulos, Michael S Andersen, Hemant G Pandit, Harinderjit S Gill, David W Murray
Edge-loading in patients with metal-on-metal resurfaced hips can cause high serum metal ion levels, the development of soft-tissue reactions local to the joint called pseudotumours and ultimately, failure of the implant. Primary edge-loading is where contact between the femoral and acetabular components occurs at the edge/rim of the acetabular component whereas impingement of the femoral neck on the acetabular component's edge causes secondary or contrecoup edge-loading. Although the relationship between the orientation of the acetabular component and primary edge-loading has been identified, the contribution of acetabular component orientation to impingement and secondary edge-loading is less clear...
January 21, 2015: Journal of Biomechanics
LaQuawn Loving, Lizeth Herrera, Samik Banerjee, Christopher Heffernan, Jim Nevelos, David C Markel, Michael A Mont
Steep cup abduction angles with adverse joint loading may increase traditional polyethylene bearing wear in total hip arthroplasties. However, there have been few reports evaluating the effect of cup inclination on the wear of dual-mobility devices. In a hip joint simulation, we compared the short-term wear of two-sizes of modular highly cross-linked dual-mobility bearings (28 mm femoral head diameter/42 mm polyethylene insert outer diameter/54 mm acetabular shell diameter; 22.2 mm femoral head diameter/36 mm polyethylene insert outer diameter/48 mm acetabular shell diameter) at 50 and 65° of cup inclination with modular 28 mm femoral head on 54 mm cup diameter metal-on-highly cross-linked polyethylene bearings...
March 2015: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Feng Liu, Sophie Williams, John Fisher
Some early failures of metal-on-metal (MoM) hip replacements associated with elevated wear have caused concerns for the use of this bearing combination. Simulator studies have shown that microseparation and its associated rim contact and edge loading may produce the most severe wear in MoM bearings. It is generally recognized that this high wear can be attributed to the high contact stress of the head on the rim of the cup. In this study, an improved finite element contact model that incorporates an elastic-perfectly plastic material property for cobalt-chrome alloy of the metal bearing was developed in an attempt to provide an accurate prediction of the stress and strain for the rim contact...
August 2015: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Laryssa A Korduba, Aaron Essner, Robert Pivec, Perry Lancin, Michael A Mont, Aiguo Wang, Ronald E Delanois
The effect of acetabular component positioning on the wear rates of metal-on-polyethylene articulations has not been extensively studied. Placement of acetabular cups at abduction angles of more than 40° has been noted as a possible reason for early failure caused by increased wear. We conducted a study to evaluate the effects of different acetabular cup abduction angles on polyethylene wear rate, wear area, contact pressure, and contact area. Our in vitro study used a hip joint simulator and finite element analysis to assess the effects of cup orientation at 4 angles (0°, 40°, 50°, 70°) on wear and contact properties...
October 2014: American Journal of Orthopedics
Xijin Hua, Junyan Li, Ling Wang, Zhongmin Jin, Ruth Wilcox, John Fisher
Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined...
October 17, 2014: Journal of Biomechanics
Vaibhav Kanawade, Lawrence D Dorr, Zhinian Wan
The angles of the acetabular component of a total hip replacement change with body postural changes, and this change can affect stability and wear. We sought to correlate the intraoperative angles of inclination and anteversion of the cup with the changes in these angles when patients moved from standing to sitting and determine if these changes were predictable.METHODS: Eighty-five patients (eighty-five hips) had sagittal (lateral) spinopelvic radiographs made while they were standing and while they were sitting before and after undergoing total hip replacement...
June 18, 2014: Journal of Bone and Joint Surgery. American Volume
Jelle J Halma, Jose Señaris, Daniel Delfosse, Reto Lerf, Thomas Oberbach, Steven M van Gaalen, Arthur de Gast
The mal-positioning of total hip arthroplasty components can result in edge loading conditions. Purpose of this study was to determine if the wear rate of ceramic-on-ceramic and metal-on-polyethylene increases under edge loading conditions. The literature was reviewed to determine which of the commonly used hip bearings is the most forgiving to implant mal-orientation. Two 28-mm ceramic-on-ceramic articulations were tested in vitro: pure alumina (PAL) ceramic versus the new alumina-toughened zirconia (ATZ)...
November 2014: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Ashley K Matthies, Johann Henckel, Suzie Cro, Alexander Suarez, Philip C Noble, John Skinner, Alister J Hart
Suboptimal component position and design are thought to lead to edge wear and raised blood metal ion levels in metal-on-metal hip resurfacing (MOM-HR). These factors are thought to influence the "contact patch to rim distance" (CPRD), and calculation of this distance may improve prediction of wear and blood metal ion levels. We measured blood cobalt and chromium ion levels and the wear rates of the bearing surfaces in 165 MOM-HR retrieval cases. We then determined the contribution and effect sizes of cup inclination and version angles, component size and design, and CPRD (calculated from case-specific data) on blood metal ion levels and component wear rates...
January 2014: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Brian Derbyshire, Peter J Diggle, Christopher J Ingham, Rory Macnair, James Wimhurst, Henry Wynn Jones
Accurate radiographic measurement of acetabular cup orientation is required in order to assess susceptibility to impingement, dislocation, and edge loading wear. In this study, the accuracy and precision of a new radiographic cup orientation measurement system were assessed and compared to those of two commercially available systems. Two types of resurfacing hip prostheses and an uncemented prosthesis were assessed. Radiographic images of each prosthesis were created with the cup set at different, known angles of version and inclination in a measurement jig...
February 2014: Journal of Arthroplasty
Takayuki Kyo, Ichiro Nakahara, Hidenobu Miki
In total hip arthroplasty, steep cup inclination should be avoided because it increases the risk of edge loading. Pelvic posterior tilt should be carefully monitored because it increases cup inclination and anteversion, leading to edge loading or impingement. The authors evaluated how much the pelvic tilt angle changes from the supine position referenced in planning for cup orientation preoperatively to the standing position 1 year after total hip arthroplasty (Δref). The pelvic tilt angle was measured in 124 patients who underwent total hip arthroplasty due to osteoarthritis, and the mean Δref was -9...
June 2013: Orthopedics
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