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Desmond Y R Chong - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of bone Prosthesis interface micromotion for cementless talar component Fixation through critical loading conditions
International Journal for Numerical Methods in Biomedical Engineering, 2020Co-Authors: Irwan Shah Bin Mohd Moideen, Chin Tat Lim, Raye Chen Hua Yeow, Desmond Y R ChongAbstract:The total ankle replacement (TAR) survivability rate is still suboptimal, and this leads to many orthopaedic surgeons opting arthrodesis as a better option for the ankle arthritis patients. One of the fundamental reasons is due to the lack of primary stability of the Prosthesis Fixation at the bone-Prosthesis interface hence leading to long-term aseptic loosening of the talar component. The commercially available Scandinavian Total Ankle Replacement (STAR) Ankle design and several additional design features (including trabecular metal, side fin, double fin, and polka-dot designs) were studied using finite element analysis, and the bone-Prosthesis interface relative micromotion (BPIRM) and talar bone minimum principal stresses were examined and analysed. Three loading conditions at a gait cycle of heel strike, midstance, and toe off with different meniscal bearing displacement were also included as part of the study parameters. The results were correlated to in vitro cadaveric measurements and reported clinical studies. Simulated results showed that the de-bonding relative distance between the bone and Prosthesis upon loading (COPEN defined by the simulation software) was the main reason constituting to the high interface micromotion between the talar component and talus bone (which could lead to long-term aseptic loosening). The polka-dot design was shown to induce the lowest BPIRM among all the designs studied.
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the influence of tibial Prosthesis design features on stresses related to aseptic loosening and stress shielding
Journal of Mechanics in Medicine and Biology, 2011Co-Authors: Desmond Y R Chong, Ulrich Hansen, Andrew A. AmisAbstract:Aseptic loosening caused by mechanical factors is a recognized failure mode for tibial components of knee prostheses. This parametric study investigated the effects of Prosthesis Fixation design changes, which included the presence, length and diameter of a central stem, the use of Fixation pegs beneath the tray, all-polyethylene versus metal-backed tray, Prosthesis material stiffness, and cement mantle thickness. The cancellous bone compressive stresses and bone–cement interfacial shear stresses, plus the reduction of strain energy density in the epiphyseal cancellous bone, an indication of the likelihood of component loosening, and bone resorption secondary to stress shielding, were examined. Design features such as longer stems reduced bone and bone–cement interfacial stresses thus the risk of loosening is potentially minimized, but at the expense of an increased tendency for bone resorption. The conflicting trend suggested that bone quality and Fixation stability have to be considered mutually for the optimization of Prosthesis designs. By comparing the bone stresses and bone–cement shear stresses to reported fatigue strength, it was noted that fatigue of both the cancellous bone and bone–cement interface could be the driving factor for long-term aseptic loosening for metal-backed tibial trays.
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analysis of bone Prosthesis interface micromotion for cementless tibial Prosthesis Fixation and the influence of loading conditions
Journal of Biomechanics, 2010Co-Authors: Desmond Y R Chong, Ulrich Hansen, Andrew A. AmisAbstract:Abstract A lack of initial stability of the Fixation is associated with aseptic loosening of the tibial components of cementless knee prostheses. With sufficient stability after surgery, minimal relative motion between the Prosthesis and bone interfaces allows osseointegation to occur thereby providing a strong Prosthesis-to-bone biological attachment. Finite element modelling was used to investigate the bone–Prosthesis interface micromotion and the relative risk of aseptic loosening. It was anticipated that by prescribing different joint loads representing gait and other activities, and the consideration of varying tibial–femoral contact points during knee flexion, it would influence the computational prediction of the interface micromotion. In this study, three-dimensional finite element models were set up with applied loads representing walking and stair climbing, and the relative micromotions were predicted. These results were correlated to in-vitro measurements and to the results of prior retrieval studies. Two load conditions, (i) a generic vertical joint load of 3×body weight with 70%/30% M/L load share and antero-posterior/medial-lateral shear forces, acted at the centres of the medial and lateral compartments of the tibial tray, and (ii) a peak vertical joint load at 25% of the stair climbing cycle with corresponding antero-posterior shear force applied at the tibial–femoral contact points of the specific knee flexion angle, were found to generate interface micromotion responses which corresponded to in-vivo observations. The study also found that different loads altered the interface micromotion predicted, so caution is needed when comparing the Fixation performance of various reported cementless tibial prosthetic designs if each design was evaluated with a different loading condition.
Min Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of baseplate positioning on Fixation of reverse total shoulder arthroplasty
Clinical Biomechanics, 2019Co-Authors: Ulrich Hansen, Min Zhang, Sarah Junaid, Thomas Gregory, Chengkung ChengAbstract:Background: The glenoid component in reverse total shoulder arthroplasty is recommended to be positioned inferiorly or with a downward tilt with the intention of reducing scapular notching. However, it is still unclear whether modifying the position of the glenoid Prosthesis affects implant stability. The aim of this study was to determine the association between implant positioning and glenoid Prosthesis Fixation using Grammont reverse total shoulder arthroplasty. Methods: Four positions for the glenoid Prosthesis were studied using the finite element method. The glenosphere was positioned as follows: 1) in the middle of the glenoid fossa, 2) flush with the inferior glenoid rim, 3) with an inferior overhang, 4) with a 15° inferior inclination. Bone-Prosthesis micromotions and strain-induced bone adaptations were quantified during five daily activities. Findings: When the glenoid component was tilted inferiorly, the activities producing anterior-posterior shear forces (e.g. standing up from an armchair) caused an increase in peak micromotions. In the lateral-middle glenoid, inferior positioning caused a 64.6% reduction in bone apparent density. In the lateral-inferior glenoid, central positioning led to the most severe bone resorption, reaching 43.9%. Interpretation: Reducing activities which generate anterior-posterior shear forces on the shoulder joint will increase bone formation and may improve the primary stability of the implant when fixed in the position with an inferior tilt. Postoperative bone resorption is highly dependent on implant positioning. Understanding the relationship between bone resorption and implant positioning will help surgeons improve the long-term stability of reverse total shoulder arthroplasty.
Chengkung Cheng - One of the best experts on this subject based on the ideXlab platform.
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effect of baseplate positioning on Fixation of reverse total shoulder arthroplasty
Clinical Biomechanics, 2019Co-Authors: Ulrich Hansen, Min Zhang, Sarah Junaid, Thomas Gregory, Chengkung ChengAbstract:Background: The glenoid component in reverse total shoulder arthroplasty is recommended to be positioned inferiorly or with a downward tilt with the intention of reducing scapular notching. However, it is still unclear whether modifying the position of the glenoid Prosthesis affects implant stability. The aim of this study was to determine the association between implant positioning and glenoid Prosthesis Fixation using Grammont reverse total shoulder arthroplasty. Methods: Four positions for the glenoid Prosthesis were studied using the finite element method. The glenosphere was positioned as follows: 1) in the middle of the glenoid fossa, 2) flush with the inferior glenoid rim, 3) with an inferior overhang, 4) with a 15° inferior inclination. Bone-Prosthesis micromotions and strain-induced bone adaptations were quantified during five daily activities. Findings: When the glenoid component was tilted inferiorly, the activities producing anterior-posterior shear forces (e.g. standing up from an armchair) caused an increase in peak micromotions. In the lateral-middle glenoid, inferior positioning caused a 64.6% reduction in bone apparent density. In the lateral-inferior glenoid, central positioning led to the most severe bone resorption, reaching 43.9%. Interpretation: Reducing activities which generate anterior-posterior shear forces on the shoulder joint will increase bone formation and may improve the primary stability of the implant when fixed in the position with an inferior tilt. Postoperative bone resorption is highly dependent on implant positioning. Understanding the relationship between bone resorption and implant positioning will help surgeons improve the long-term stability of reverse total shoulder arthroplasty.
Lars Good - One of the best experts on this subject based on the ideXlab platform.
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tourniquet use in total knee replacement does not improve Fixation but appears to reduce final range of motion a randomized rsa study involving 50 patients
Acta Orthopaedica, 2012Co-Authors: Hakan Ledin, Per Aspenberg, Lars GoodAbstract:Background and purpose Although a tourniquet may reduce bleeding during total knee replacement (TKA), and thereby possibly improve Fixation, it might also cause complications. Migration as measured by radiostereometric analysis (RSA) can predict future loosening. We investigated whether the use of a tourniquet influences Prosthesis Fixation measured with RSA. This has not been investigated previously to our knowledge. less thanbrgreater than less thanbrgreater thanMethods 50 patients with osteoarthritis of the knee were randomized to cemented TKA with or without tourniquet. RSA was performed postoperatively and at 6 months, 1 year, and 2 years. Pain during hospital stay was registered with a visual analog scale (VAS) and morphine consumption was measured. Overt bleeding and blood transfusions were registered, and total bleeding was estimated by the hemoglobin dilution method. Range of motion was measured up to 2 years. less thanbrgreater than less thanbrgreater thanResults RSA maximal total point motion (MTPM) differed by 0.01 mm (95% CI-0.13 to 0.15). Patients in the tourniquet group had less overt bleeding (317 mL vs. 615 mL), but the total bleeding estimated by hemoglobin dilution at day 4 was only slightly less (1,184 mL vs. 1,236 mL) with a mean difference of -54 mL (95% CI-256 to 152). Pain VAS measurements were lower in the non-tourniquet group (p = 0.01). There was no significant difference in morphine consumption. Range of motion was 11 more in the non-tourniquet group (p = 0.001 at 2 years). less thanbrgreater than less thanbrgreater thanInterpretation Tourniquet use did not improve Fixation but it may cause more postoperative pain and less range of motion.
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celecoxib does not appear to affect Prosthesis Fixation in total knee replacement a randomized study using radiostereometry in 50 patients
Acta Orthopaedica, 2009Co-Authors: Andreas Meunier, Per Aspenberg, Lars GoodAbstract:Background and purpose After joint replacement, a repair process starts at the interface between bone and cement. If this process is disturbed, the Prosthesis may never become rigidly fixed to the bone, leading to migration—and with time, loosening. Cox-2 inhibitors are widely used as postoperative analgesics, and have adverse effects on bone healing. This could tamper Prosthesis Fixation. We investigated whether celecoxib, a selective Cox-2 inhibitor, increases Prosthesis migration in total knee replacement (TKR).Methods 50 patients were randomized to either placebo or celecoxib treatment, 200 mg twice daily, for 3 weeks after TKR (NexGen; Zimmer). Maximum total point motion (MTPM) of the tibial component was measured after 2 years using radiostereometric analysis (RSA). In addition, range of motion, pain, and, subjective outcome were evaluated.Results No differences in Prosthesis migration, pain scores, range of motion, and subjective outcome were found after 2 years. Confidence intervals were narrow.In...
Arlen D Hanssen - One of the best experts on this subject based on the ideXlab platform.
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mid term to long term followup of two stage reimplantation for infected total knee arthroplasty
Clinical Orthopaedics and Related Research, 2004Co-Authors: Abdul A Haleem, Daniel J Berry, Arlen D HanssenAbstract:Between January 1989 and December 1994, 94 patients (96 knees) had a two-stage reimplantation for treatment of an infected total knee arthroplasty. All patients were treated with an interval antibiotic-loaded static cement spacer and had antibiotic-loaded bone cement for Prosthesis Fixation at the time of reimplantation. The purpose of this study was to assess the long-term risk of reinfection and the mechanical durability of these reimplantation arthroplasties. Patients were followed up for a median of 7.2 years (range, 2.5-13.2 years). At final followup, 15 knees (16%) had required reoperation. Nine knees (9%) had component removal for reinfection and six knees (6%) were revised for aseptic loosening. The median time to reoperation for reinfection was 1 year (range, 0.1-9.8 years). The risk of recurrent infection was not correlated with the type of organism, patient demographics, or method of Prosthesis Fixation at reimplantation. The survivorship free of implant removal for any reason was 90% (confidence intervals, 83.9-96.4%) at 5 years and 77.3% (confidence intervals, 65.5-89.6%) at 10 years. The survivorship free of implant removal for reinfection was 93.5% (confidence intervals, 88.5-98.7%) at 5 years and 85% (confidence intervals, 73.8-96.3%) at 10 years. Survival free of revision for mechanical failure (aseptic loosening or radiographic loosening) was 96.2% (confidence intervals, 92-100%) at 5 years and 91% (confidence intervals, 80.8-98.3%) at 10 years. These results suggest that the high likelihood of early success after two-stage reimplantation of an infected TKA is well maintained throughout long-term followup, with a modest rate of late recurrent infection or mechanical implant failure.
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treatment of the infected total knee arthroplasty with insertion of another Prosthesis the effect of antibiotic impregnated bone cement
Clinical Orthopaedics and Related Research, 1994Co-Authors: Arlen D Hanssen, James A Rand, Douglas R OsmonAbstract:Eighty-six patients with 89 infected total knee arthroplasties were treated with insertion of another Prosthesis. Treatment was not according to an established protocol for parameters, such as delay between removal of the infected Prosthesis and insertion of the new Prosthesis, duration of antibiotics, use of antibiotic-impregnated cement spacers or beads, and use of antibiotic-impregnated cement for prosthetic Fixation at revision surgery. Final followup averaged 52 months (range, 6-126 months). Complications occurred in 30 (33.7%) knees, with recurrent deep infection developing in 10 (11.24%) knees. Patient age, medical diagnosis, type of microorganism, duration of parenteral antibiotics, delay between the resection and revision surgery, and use of antibiotic-impregnated cement spacers or beads were not correlated with the cure rate of infection. Use of antibiotic-impregnated bone cement for Prosthesis Fixation at revision surgery was the only variable that correlated with the cure rate of deep infection. Seven (28%) of the 25 knees without antibiotic-impregnated cement for Prosthesis Fixation developed recurrent infection compared with 3 (4.7%) of 64 knees with antibiotic-impregnated cement for Prosthesis Fixation. This difference was statistically significant (p = 0.0025, log-rank test).
