MyMedR

Interface stress in socket/residual limb with transtibial prosthetic suspension systems during locomotion on slopes and stairs

Eshraghi A, Abu Osman NA, Gholizadeh H, Ali S, Abas WA

Am J Phys Med Rehabil, 2015 Jan;94(1):1-10.

PMID: 24919079 DOI: 10.1097/PHM.0000000000000134

This study aimed to compare the effects of different suspension methods on the interface stress inside the prosthetic sockets of transtibial amputees when negotiating ramps and stairs.

Matched MeSH terms: Prosthesis Design

Fulltext Interface pressure in transtibial socket during ascent and descent on stairs and its effect on patient satisfaction

Ali S, Abu Osman NA, Eshraghi A, Gholizadeh H, Abd Razak NA, Wan Abas WA

Clin Biomech (Bristol, Avon), 2013 Nov-Dec;28(9-10):994-9.

PMID: 24161521 DOI: 10.1016/j.clinbiomech.2013.09.004

Transtibial amputees encounter stairs and steps during their daily activities. The excessive pressure between residual limb/socket may reduce the walking capability of transtibial prosthetic users during ascent and descent on stairs. The purposes of the research were to evaluate the interface pressure between Dermo (shuttle lock) and Seal-In X5 (prosthetic valve) interface systems during stair ascent and descent, and to determine their satisfaction effects on users.

Matched MeSH terms: Prosthesis Design

Infolding of the Venus P-Valve After Transcatheter Pulmonary Valve Implantation

Riahi M, Ang HL, Jones M, Prachasilchai P, Baruteau AE, Promphan W, et al.

Circ Cardiovasc Interv, 2018 04;11(4):e005923.

PMID: 29618579 DOI: 10.1161/CIRCINTERVENTIONS.117.005923

Matched MeSH terms: Prosthesis Design

In-stent restenosis: the gold standard has changed

Chin K

EuroIntervention, 2011 May;7 Suppl K:K43-6.

PMID: 22027726 DOI: 10.4244/EIJV7SKA7

In-stent restenosis remains an important issue even in the drug-eluting stent (DES) era today. In recent years, drug-eluting balloons (DEB) have emerged as a potential alternative to the treatment of in-stent restenosis. Paclitaxel was identified as the primary drug for DEB because of its rapid uptake and prolonged retention. Non-stent-based local drug delivery using DEB maintains the antiproliferation properties of DES, but without the limitations of DES such as subacute stent thrombosis, stent fractures, prolonged antiplatelet therapy and more importantly, avoiding a "stent-in-a-stent" approach. The first major impact of drug-eluting balloon (DEB) in the management of bare metal instent restenosis was the "PACCOCATH ISR I" randomised trial, comparing the efficacy of drug-eluting balloon versus uncoated balloon. The six months angiographic results showed a binary restenosis of 5% and 4% MACE in the drug-eluting balloon group, compared with 43% binary restenosis and 31% MACE, in the uncoated balloon group (p=0.002 and 0.02). The second major DEB trial is the "PEPCAD II Trial", comparing the efficacy of the SeQuent Please DEB with the Taxus drug-eluting stent in the treatment of bare-metal stent instent restenosis. At 6-month follow-up, in-segment late lumen loss was 0.38 ± 0.61 mm in the DES group versus 0.17 ± 0.42 mm (p=0.03) in the DEB group, resulting in a binary restenosis rate of 12/59 (20%) versus 4/57 (7%; p=0.06). At 12 months, MACE rates were 22% in the Taxus group and 9% in the DEB group (P=0.08). The TLR at 12 months was 15% in the Taxus group and 6% in the DEB group (p=0.15). Based on these two pivotal trials, the European Society of Cardiology Guidelines for Percutaneous Coronary Intervention (2010) recommended that DEB should be considered for the treatment of in-stent restenosis after prior bare-metal stent. This was accorded a class 2 IIa indication, with a level B evidence.

Matched MeSH terms: Prosthesis Design

In silico study of glenoid perforation during total shoulder arthroplasty: the effects on stress & micromotion

Wahab AHA, Saad APM, Syahrom A, Kadir MRA

Comput Methods Biomech Biomed Engin, 2020 Apr;23(5):182-190.

PMID: 31910663 DOI: 10.1080/10255842.2019.1709828

Glenoid perforation is not the intended consequence of the surgery and must be avoided. The analysis on biomechanical aspect of glenoid vault perforation remains unknown. The purpose of this study is to determine the impact of glenoid perforation towards stress distribution and micromotion at the interfaces. Eight glenoid implant models had been constructed with various size, number and type of fixation. A load of 750 N was applied to centre, superior-anterior and superior-posterior area. Implant perforation had minimal impact on stress distribution and micromotion at the interfaces. However, cement survival rate for implant without perforation was the highest with a difference of up to 37% compared to other perforated models. Besides that, implant fixation and high stresses at the implant had more of an impact on implant instability than implant perforation. As a conclusion, glenoid perforation did not influence the stress distribution and micromotion, but, it reduced cement survival rate and increase the stress critical volume.

Matched MeSH terms: Prosthesis Design

Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions

Choudhury D, Lackner JM, Major L, Morita T, Sawae Y, Bin Mamat A, et al.

J Mech Behav Biomed Mater, 2016 06;59:586-595.

PMID: 27085502 DOI: 10.1016/j.jmbbm.2016.04.004

This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading.

Matched MeSH terms: Prosthesis Design

Fulltext Immediate placement and loading of implants in anterior maxilla using an altered screw-retained implant fixed prosthesis

Baig MR, Rajan G

Indian J Dent Res, 2010 Apr-Jun;21(2):311-3.

PMID: 20657109 DOI: 10.4103/0970-9290.66635

This article describes the immediate placement and loading of implants in the aesthetic zone using an implant-retained, fixed prosthesis with a modified design. One section of the implant prosthesis has cemented crowns and the other section is the conventional screw-retained. This combined approach significantly offsets the unsuitable implant position, alignment or angulation, while ensuring the easy retrievability, repair and maintenance of the prosthesis at the same time.

Matched MeSH terms: Dental Prosthesis Design

Hybrid ABSORB bioresorbable vascular scaffold and drug eluting stent or hybrid BVS-DES percutaneous coronary intervention: Method and rationale for hybrid overlapping PCI

Yew KL

Int J Cardiol, 2015;186:74-6.

PMID: 25814348 DOI: 10.1016/j.ijcard.2015.02.092

Matched MeSH terms: Prosthesis Design

Histomorphometric profile of the corneal response to short-term reverse-geometry orthokeratology lens wear in primate corneas: a pilot study

Cheah PS, Norhani M, Bariah MA, Myint M, Lye MS, Azian AL

Cornea, 2008 May;27(4):461-70.

PMID: 18434851 DOI: 10.1097/ICO.0b013e318165642c

To investigate the histological changes in primate cornea induced by short-term overnight orthokeratology (OK).

Matched MeSH terms: Prosthesis Design

Fulltext Growing endoprosthesis in management of bone tumours in Malaysia

Saravanan S, Vivek AS

Med J Malaysia, 2007 Dec;62(5):418-9.

PMID: 18705481 MyJurnal

This is to report on the use of growing endoprosthesis, also known as lengthening prosthesis in the management of four patients in the paedriatic age group in the Orthopaedic Oncolgy Unit at University Malaya Medical Centre. These are custom made prosthesis, designed and made in India based on measured roentrograms. The ages of these patients vary from 6 to 13 years old. These are cases of Osteosarcoma and Ewing's sarcoma around the knee. This is the first time these custom made prosthesis have ever been used in Malaysia. We feel that this is a feasible option for limb salvage in the treatment of primary bone tumours in growing children.

Matched MeSH terms: Prosthesis Design

Geometric variable designs of cam/post mechanisms influence the kinematics of knee implants

Fallahiarezoodar A, Abdul Kadir MR, Alizadeh M, Naveen SV, Kamarul T

Knee Surg Sports Traumatol Arthrosc, 2014 Dec;22(12):3019-27.

PMID: 25149643 DOI: 10.1007/s00167-014-3227-7

PURPOSE: Reproducing the femoral rollback through specially designed mechanism in knee implants is required to achieve full knee function in total knee arthroplasty. Most contemporary implants use cam/post mechanism to replace the function of Posterior Cruciate Ligament. This study was aimed to determine the most appropriate cam and post designs to produce normal femoral rollback of the knee.

METHODS: Three different cams (triangle, ellipse, and circle) and three different posts (straight, convex, concave) geometries were considered in this study and were analysed using kinematic analyses. Femoral rollback did not occur until reaching 50° of knee flexion. Beyond this angle, two of the nine combinations demonstrate poor knee flexion and were eliminated from the study.

RESULTS: The combination of circle cam with concave post, straight post and convex post showed 15.6, 15.9 and 16.1 mm posterior translation of the femur, respectively. The use of ellipse cam with convex post and straight post demonstrated a 15.3 and 14.9 mm femoral rollback, whilst the combination of triangle cam with convex post and straight post showed 16.1 and 15.8 mm femoral rollback, respectively.

CONCLUSION: The present study demonstrates that the use of circle cam and convex post created the best femoral rollback effect which in turn produces the highest amount of knee flexion. The findings of the study suggest that if the design is applied for knee implants, superior knee flexion may be possible for future patients.

LEVEL OF EVIDENCE: IV.

Matched MeSH terms: Prosthesis Design*

Fulltext Gait biomechanics of individuals with transtibial amputation: effect of suspension system

Eshraghi A, Abu Osman NA, Karimi M, Gholizadeh H, Soodmand E, Wan Abas WA

PLoS One, 2014;9(5):e96988.

PMID: 24865351 DOI: 10.1371/journal.pone.0096988

Prosthetic suspension system is an important component of lower limb prostheses. Suspension efficiency can be best evaluated during one of the vital activities of daily living, i.e. walking. A new magnetic prosthetic suspension system has been developed, but its effects on gait biomechanics have not been studied. This study aimed to explore the effect of suspension type on kinetic and kinematic gait parameters during level walking with the new suspension system as well as two other commonly used systems (the Seal-In and pin/lock). Thirteen persons with transtibial amputation participated in this study. A Vicon motion system (six cameras, two force platforms) was utilized to obtain gait kinetic and kinematic variables, as well as pistoning within the prosthetic socket. The gait deviation index was also calculated based on the kinematic data. The findings indicated significant difference in the pistoning values among the three suspension systems. The Seal-In system resulted in the least pistoning compared with the other two systems. Several kinetic and kinematic variables were also affected by the suspension type. The ground reaction force data showed that lower load was applied to the limb joints with the magnetic suspension system compared with the pin/lock suspension. The gait deviation index showed significant deviation from the normal with all the systems, but the systems did not differ significantly. Main significant effects of the suspension type were seen in the GRF (vertical and fore-aft), knee and ankle angles. The new magnetic suspension system showed comparable effects in the remaining kinetic and kinematic gait parameters to the other studied systems. This study may have implications on the selection of suspension systems for transtibial prostheses. Trial registration: Iranian Registry of Clinical Trials IRCT2013061813706N1.

Matched MeSH terms: Prosthesis Design

Full-arch metal-resin cement- and screw-retained provisional restoration for immediately loaded implants

Baig MR, Rajan G

J Oral Implantol, 2010;36(3):219-23.

PMID: 20553176 DOI: 10.1563/AAID-JOI-D-09-00048

Abstract This article describes the clinical and laboratory procedures involved in the fabrication of laboratory-processed, provisional, screw-retained, implant-supported maxillary and mandibular fixed complete dentures incorporating a cast metal reinforcement for immediate loading of implants. Precise fit is achieved by intraoral luting of the cast frame to milled abutments. Effective splinting of all implants is attained by the metal substructure and retrievability is provided by the screw-retention of the prosthesis.

Matched MeSH terms: Dental Prosthesis Design

From concept to patient--biomaterials solutions to medical problems

Bonfield W

Med J Malaysia, 2004 May;59 Suppl B:1.

PMID: 15468788

Matched MeSH terms: Prosthesis Design

Fulltext Fluid Structure Interaction on Paravalvular Leakage of Transcatheter Aortic Valve Implantation Related to Aortic Stenosis: A Patient-Specific Case

Basri AA, Zuber M, Basri EI, Zakaria MS, Aziz AFA, Tamagawa M, et al.

Comput Math Methods Med, 2020;2020:9163085.

PMID: 32454886 DOI: 10.1155/2020/9163085

This study investigated the impact of paravalvular leakage (PVL) in relation to the different valve openings of the transcatheter aortic valve implantation (TAVI) valve using the fluid structure interaction (FSI) approach. Limited studies were found on the subject of FSI with regards to TAVI-PVL condition, which involves both fluid and structural responses in coupling interaction. Hence, further FSI simulation with the two-way coupling method is implemented to investigate the effects of hemodynamics blood flow along the patient-specific aorta model subjected to the interrelationship between PVL and the different valve openings using the established FSI software ANSYS 16.1. A 3D patient-specific aorta model is constructed using MIMICS software. The TAVI valve identical to Edward SAPIEN XT 26 (Edwards Lifesciences, Irvine, California), at different Geometrical Orifice Areas (GOAs), is implanted into the patient's aortic annulus. The leaflet opening of the TAVI valve is drawn according to severity of GOA opening represented in terms of 100%, 80%, 60%, and 40% opening, respectively. The result proved that the smallest percentage of GOA opening produced the highest possibility of PVL, increased the recirculatory flow proximally to the inner wall of the ascending aorta, and produced lower backflow velocity streamlines through the side area of PVL region. Overall, 40% GOA produced 89.17% increment of maximum velocity magnitude, 19.97% of pressure drop, 65.70% of maximum WSS magnitude, and a decrement of 33.62% total displacement magnitude with respect to the 100% GOA.

Matched MeSH terms: Prosthesis Design

Fulltext Fixed rehabilitation of patient with aggressive periodontitis using zygoma implants

Rajan G, Baig MR, Nesan J, Subramanian J

Indian J Dent Res, 2010 Jan-Mar;21(1):125-8.

PMID: 20427922 DOI: 10.4103/0970-9290.62801

Treatment of patients with aggressive periodontitis has always been a challenge to the clinician. Both young and old are known to be affected by this progressive destructive condition of the supporting dental structures. Although dental implants have been offered as a viable treatment alternative for such patients, additional procedures (like bone grafting) and delayed protocols have limited their usage. This case report describes the treatment of a young patient with aggressive periodontitis using a graftless implant solution. Zygoma implants in conjunction with conventional implants were used with immediate loading.

Matched MeSH terms: Dental Prosthesis Design

Five- to 12-year follow-up of a hydroxyapatite-coated, cementless total knee replacement in young, active patients

Tai CC, Cross MJ

J Bone Joint Surg Br, 2006 Sep;88(9):1158-63.

PMID: 16943464

We carried out a prospective study of 118 hydroxyapatite-coated, cementless total knee replacements in patients who were = 55 years of age and who had primary (92; 78%) or post-traumatic (26; 22%) osteoarthritis. The mean period of follow-up was 7.9 years (5 to 12.5). The Knee Society clinical scores improved from a pre-operative mean of 98 (0 to 137) to a mean of 185 (135 to 200) at five years, and 173 (137 to 200) at ten years. There were two revisions of the tibial component because of aseptic loosening, and one case of polyethylene wear requiring further surgery. There was no osteolysis or progressive radiological loosening of any other component. At 12 years, the overall rate of implant survival was 97.5% (excluding exchange of spacer) and 92.1% (including exchange of spacer). Cementless total knee replacement can achieve excellent long-term results in young, active patients with osteoarthritis. In contrast to total hip replacement, polyethylene wear, osteolysis and loosening of the prosthesis were not major problems for these patients, although it is possible that this observation could change with longer periods of follow-up.

Matched MeSH terms: Prosthesis Design

Finite element study of functionally graded porous femoral stems incorporating body-centered cubic structure

Alkhatib SE, Tarlochan F, Mehboob H, Singh R, Kadirgama K, Harun WSBW

Artif Organs, 2019 Jul;43(7):E152-E164.

PMID: 30805945 DOI: 10.1111/aor.13444

The mismatch between stiffness of the femoral dense stem and host bone causes complications to patients, such as aseptic loosening and bone resorption. Three-dimensional finite-element models of homogeneous porous (HGP) and functionally graded porous (FGP) stems incorporating body-centered cubic (BCC) structures are proposed in this article as an alternative to the dense stems. The relationship between the porosity and strut thickness of the BCC structure was developed to construct the finite-element models. Three levels of porosities (20%, 50%, and 80%) were modeled in HGP and FGP stems. The porosity of the stems was decreased distally according to the sigmoid function (n = 0.1, n = 1 and n = 10) with 3 grading exponents. The results showed that FGP stems transferred 120%-170% higher stresses to the femur (Gruen zone 7) as compared to the solid stem. Conversely, the stresses in HGP and FGP stems were 12%-34% lower than the dense stem. The highest micromotions (105-147 µm) were observed for stems of 80% overall porosity, and the lowest (42-46 µm) was for stems of 20% overall porosity. Finally, FGP stems with a grading exponent of n = 10 resulted in an 11%-28% reduction in micromotions.

Matched MeSH terms: Prosthesis Design

Finite element analysis on longitudinal and radial functionally graded femoral prosthesis

Oshkour AA, Abu Osman NA, Davoodi MM, Yau YH, Tarlochan F, Wan Abas WA, et al.

Int J Numer Method Biomed Eng, 2013 Dec;29(12):1412-27.

PMID: 23922316 DOI: 10.1002/cnm.2583

This study focused on developing a 3D finite element model of functionally graded femoral prostheses to decrease stress shielding and to improve total hip replacement performance. The mechanical properties of the modeled functionally graded femoral prostheses were adjusted in the sagittal and transverse planes by changing the volume fraction gradient exponent. Prostheses with material changes in the sagittal and transverse planes were considered longitudinal and radial prostheses, respectively. The effects of cemented and noncemented implantation methods were also considered in this study. Strain energy and von Mises stresses were determined at the femoral proximal metaphysis and interfaces of the implanted femur components, respectively. Results demonstrated that the strain energy increased proportionally with increasing volume fraction gradient exponent, whereas the interface stresses decreased on the prostheses surfaces. A limited increase was also observed at the surfaces of the bone and cement. The periprosthetic femur with a noncemented prosthesis exhibited higher strain energy than with a cemented prosthesis. Radial prostheses implantation displayed more strain energy than longitudinal prostheses implantation in the femoral proximal part. Functionally graded materials also increased strain energy and exhibited promising potentials as substitutes of conventional materials to decrease stress shielding and to enhance total hip replacement lifespan.

Matched MeSH terms: Prosthesis Design

Finite element analysis of zygomatic implants in intrasinus and extramaxillary approaches for prosthetic rehabilitation in severely atrophic maxillae

Ishak MI, Kadir MR, Sulaiman E, Kasim NH

Int J Oral Maxillofac Implants, 2013 May-Jun;28(3):e151-60.

PMID: 23748334 DOI: 10.11607/jomi.2304

To compare the extramaxillary approach with the widely used intrasinus approach via finite element method.

Matched MeSH terms: Dental Prosthesis Design/methods*

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