scholarly journals Morphological Study of the Newly Designed Cementless Femoral Stem

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Mohd Yusof Baharuddin ◽  
Sh-Hussain Salleh ◽  
Ahmad Hafiz Zulkifly ◽  
Muhammad Hisyam Lee ◽  
Alias Mohd Noor
Keyword(s):  
Three Dimensional ◽  
Stress Shielding ◽  
Femoral Stem ◽  
Medullary Canal ◽  
Stem Design ◽  
Asian Patients ◽  
Cementless Femoral Stem ◽  
Fixation Stability ◽  
Flare Index ◽  
Metaphyseal Region

A morphology study was essential to the development of the cementless femoral stem because accurate dimensions for both the periosteal and endosteal canal ensure primary fixation stability for the stem, bone interface, and prevent stress shielding at the calcar region. This paper focused on a three-dimensional femoral model for Asian patients that applied preoperative planning and femoral stem design. We measured various femoral parameters such as the femoral head offset, collodiaphyseal angle, bowing angle, anteversion, and medullary canal diameters from the osteotomy level to 150 mm below the osteotomy level to determine the position of the isthmus. Other indices and ratios for the endosteal canal, metaphyseal, and flares were computed and examined. The results showed that Asian femurs are smaller than Western femurs, except in the metaphyseal region. The canal flare index (CFI) was poorly correlated (r<0.50) to the metaphyseal canal flare index (MCFI), but correlated well (r=0.66) with the corticomedullary index (CMI). The diversity of the femoral size, particularly in the metaphyseal region, allows for proper femoral stem design for Asian patients, improves osseointegration, and prolongs the life of the implant.

scholarly journals Distal Femoral Cortical Hypertrophy after Hip Arthroplasty Using a Cementless Double-Tapered Femoral Stem

2016 ◽  
Vol 24 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Yoon Je Cho ◽  
Young Soo Chun ◽  
Kee Hyung Rhyu ◽  
Jong Hun Baek ◽  
Hu Liang
Keyword(s):  
Clinical Outcome ◽  
Hip Arthroplasty ◽  
Stress Shielding ◽  
Femoral Stem ◽  
Visual Analogue Score ◽  
Thigh Pain ◽  
Harris Hip Score ◽  
Cortical Hypertrophy ◽  
Flare Index ◽  
The Mean

Purpose To review 437 hips in 404 patients who underwent total hip arthroplasty (THA) or hemiarthroplasty using the Accolade TMZF stem to determine the incidence and risk factors of distal femoral cortical hypertrophy (DFCH). Methods Records of 437 hips in 169 men and 235 women aged 26 to 100 (mean, 65.7) years who underwent THA (n=293) or hemiarthroplasty (n=144) using the Accolade TMZF femoral stem by 2 senior surgeons and were followed up for a mean of 54.7 months were reviewed. Clinical outcome was assessed using the modified Harris Hip Score and visual analogue score for pain. Proximal femoral geometry and canal flare index were assessed on preoperative radiographs, and DFCH, stem position, subsidence, loosening, and stress shielding were assessed on postoperative radiographs according to the Gruen zone. Results Of 437 hips, 27 (6.2%) developed DFCH and 410 did not. Hips with DFCH had a higher incidence of thigh pain (18.5% vs. 2.2%, p<0.001) and earlier onset of thigh pain (12.3 vs. 20.8 months, p=0.015), compared with those without. Nonetheless, all femoral stems were well-fixed, and no osteolysis or loosening was detected. The 2 groups achieved comparable clinical outcome in terms of Harris Hip Score and pain. The mean canal flare index was higher in hips with than without DFCH (3.706 vs. 3.294, p=0.002). The mean vertical subsidence of the femoral stem was lower in hips with than without DFCH (1.5 vs. 3.4 mm p<0.001). Subsidence negatively correlated with the canal flare index (correlation coefficient= −0.110, p=0.022). The incidence of the DFCH increased with each unit of increment in canal flare index (odds ratio [OR]=1.828, p=0.043) and each year younger in age (OR=0.968, p=0.015). Conclusion The incidence of DFCH in hips with the Accolade TMZF stem was 6.2%. Patients with a higher canal flare index and younger age had a higher incidence of DFCH. Nonetheless, DFCH did not affect clinical outcome or femoral stem stability.

Mechanics of the canine femur with two types of hip replacement stems

2003 ◽  
Vol 16 (03) ◽  
pp. 145-52 ◽  
Author(s):  
L. Banks-Sills ◽  
R. Eliasy ◽  
R. Shahar
Keyword(s):  
Finite Element ◽  
Hip Replacement ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Femoral Stem ◽  
Cementless Stem ◽  
Entire Cross Section ◽  
Element Analysis ◽  
Periprosthetic Bone Loss ◽  
Intact Femur

SummaryThe long-term performance of total hip replacement is of concern to veterinary surgeons. Two of the main complications associated with this procedure are implant loosening and stress shielding. Designs of the femoral stem which will avoid loosening and achieve maximum endurance while reducing stress shielding and periprosthetic bone loss are sought.In the intact femur the stress is distributed over the entire cross section of the bone. After hip replacement this pattern of stress distribution is altered because of the manner in which the load is transferred from the prosthesis to the bone.The objective of this study was to examine the stresses that develop in the femur and implant components of two different methods of hip replacement used clinically in dogs. Anatomic, three-dimensional finite element models of the canine femur with a cemented femoral stem and a Zurich cementless stem were constructed. The stresses and displacements were calculated by the finite element analysis method, under physiologic loads that included muscle forces and joint reaction forces. The results were compared to results obtained by a similar analysis of an intact femur.This study demonstrates that the Zurich cementless method causes less stress shielding in the proximal femoral cortex than does the cemented method. Implant stresses are higher in the Zurich cementless stem, but still within an acceptable range.

scholarly journals Design process of cementless femoral stem using a nonlinear three dimensional finite element analysis

2014 ◽  
Vol 15 (1) ◽  
Author(s):  
Mohd Yusof Baharuddin ◽  
Sh-Hussain Salleh ◽  
Ahmad Hafiz Zulkifly ◽  
Muhammad Hisyam Lee ◽  
Alias Mohd Noor ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Process ◽  
Three Dimensional ◽  
Femoral Stem ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Cementless Femoral Stem ◽  
Three Dimensional Finite Element

Effect of chewing and cutting condition for V-shape three-dimensional titanium miniplate for fixation of mandibular angle fractures (MAFs)

2020 ◽  
Vol 11 (4) ◽  
pp. 625-631
Author(s):  
Ruslizam Daud ◽  
Xu Wenzhao ◽  
Ishak Ibrahim ◽  
Nur Saifullah Kamarrudin ◽  
Khairul Salleh Basaruddin ◽  
...  
Keyword(s):  
Bone Structure ◽  
Three Dimensional ◽  
Stress Shielding ◽  
Stress Transfer ◽  
Bite Force ◽  
Von Mises Stress ◽  
Cutting Condition ◽  
Content Type ◽  
Force Condition ◽  
Fixation Stability

PurposeMiniplate shapes determine the fixation stability to promote best healing and osseointegration process of mandibular fracture. In clinical treatment, the common method used two straight-type miniplate or I-shape miniplate; sometimes this method is not stable enough or limited by the fracture geometry and caused high risk of failure due to screw loosening. This paper aims to investigate a new type of miniplate called V-shape miniplate design as an alternative to the standard straight plate based on total displacement, von Mises stress, stress transfer parameter (STP) and strain energy density transfer parameters (SEDPTs) for two types of bite force condition, which is cutting and chewing condition.Design/methodology/approachThe 3D fixation models were constructed and the finite element (FE) simulation is based on the two-bite force load that ranges from 50 to 700 N based on cutting and chewing bite force condition using ANSYS Workbench 19.2.FindingsIn result comparison, the maximum loading of the V-shape miniplate can reduce deformation by 5.9%, reduce stress by 0.58% reduce strain by 8.1% in cutting condition while reducing deformation by 6.43%, reduce stress by 15.25%, reduce strain by 10.1% in chewing condition. To assess the stress transfer behavior of miniplates fixations to the mandibular bone, the STP and SEDPT were evaluated at the normal cortex screw and the locking head screw. In the simulation, the locking head screw is vertical to the bone structure while the cortex screw is 95 degrees to the bone structure, as a result, the STP value for locking head screw is 1.0073 while in cortex screw is 0.7408.Research limitations/implicationsMeanwhile, the SEDPT value for locking head screw is 2.7574 and 1.8412 for cortex screw.Practical implicationsClinically, V-shape miniplate has shown factual data that can be used for prototyping. STP and SEDTP values provide evidence of how fixation stability is better than I-shape miniplate.Originality/valueIn conclusion, the newly designed V-shape miniplate has overall better stability than the standard I-shape miniplate, and the locking head screw has the STP value closer to 1 than the standard cortex screw; it means the locking screw is better in reducing the stress shielding.

scholarly journals The Three-Dimensional Morphology of Femoral Medullary Cavity in the Developmental Dysplasia of the Hip

2021 ◽  
Vol 9 ◽  
Author(s):  
Min Zhang ◽  
Bo-Lun Liu ◽  
Xin-Zheng Qi ◽  
Qing-Qing Yang ◽  
Jing-Yang Sun ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Femoral Stem ◽  
Developmental Dysplasia ◽  
Medullary Canal ◽  
Medullary Cavity ◽  
Cylindrical Shape ◽  
Lesser Trochanter ◽  
Computed Tomography Images ◽  
Canal Diameter ◽  
Dysplasia Of The Hip

ObjectiveThis study aimed to assess the morphology of the femoral medullary canal in subjects with developmental dysplasia of the hip (DDH) with the intent of improving the design of femoral stems in total hip arthroplasty.MethodsComputed tomography images of 56 DDH hips, which were classified into Crowe I to Crowe IV, and 30 normal hips were collected and used to reconstruct three-dimensional morphology of the femoral medullary cavity. Images of twenty-one cross sections were taken from 20 mm above the apex of the lesser trochanter to the isthmus. The morphology of femoral cavity was evaluated on each cross section for the longest canal diameter, the femoral medullary torsion angle (FMTA), and the femoral medullary roundness index (FMRI).ResultsThe Crowe IV group displayed the narrowest medullary canal in the region superior to the end of the lesser trochanter, but then gradually aligned with the medullary diameter of the other groups down to the isthmus. The FMTA along the femoral cavity increased with the severity of DDH, but the rate of variation of FMTA along the femoral canal was consistent in the DDH groups. The DDH hips generally showed a larger FMRI than the normal hips, indicating more elliptical shapes.ConclusionA femoral stem with a cone shape in the proximal femur and a cylindrical shape for the remainder down to the isthmus may benefit the subjects with severe DDH. This design could protect bone, recover excessive femoral anteversion and facilitate the implantation in the narrow medullary canal.

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