A dynamic model of simulating stress distribution in the distal femur after total knee replacement

Author(s):  
J F Shi ◽  
C J Wang ◽  
T Laoui ◽  
W Hart ◽  
R Hall

The aim of this study has been to develop a dynamic model of the knee joint after total knee replacement (TKR) to analyse the stress distribution in the distal femur during daily activities. Using MSC/ADAMS and MSC/MARC software, a dynamic model of an implanted knee joint has been developed. This model consists of the components of the knee prosthesis as well as the bones and ligaments of the knee. The femur, tibia, fibula, and patella have been modelled as mixed cortico-cancellous bone. The distal part of femur has been modelled as a flexible body with springs used to simulate the ligaments positioned at their anatomical insertion points. With this dynamic model a gait cycle was simulated. Stress shielding was identified in the distal femur after TKR, which is consistent with other investigators' results. Interestingly, higher stresses were found in the bone adjacent to the femoral component peg. This dynamic model can now be used to analyse the stress distribution in the distal femur with different load conditions. This will help to improve implant designs and will allow comparison of prostheses from different manufacturers.

2014 ◽  
Vol 931-932 ◽  
pp. 1122-1128
Author(s):  
Surasith Piyasin ◽  
Kriengkrai Nabudda ◽  
Suwipong Hemathulin

Nowadays, patients with osteoarthritis in Thailand are likely to increase in number every year. There are approximately 462,000 people and most are females than males. The treatment is surgery knee replacement implants which must be imported from abroad and cost is expensive.Total knee prosthesis used in Thailand would not fit with the body of the Thai women because of the design total knee prosthesis use anatomical data of Europe and designed for both male and female, which is different in the knee structure. This research aims to study the size and shape of knee for Thai women and design total knee replacement. The using of finite elements is to assist in the analysis which focuses on the influence of the force active on and the effects of stress distribution on the part of the knee at different stages of gait cycle. The results of the study can measure the average size of Thai knee women base on analytical data. Anthropometric data on the proximal tibia and distal femur of 55 female knees were obtained using three dimensional computer tomographic measurements. The parametric studies are dimension analysis of the femoral mediolateral (fML) and femoral anteroposterior (fAP) dimension on distal femur surface and tibial mediolateral (tML), tibial anteroposterior (tAP) on proximal tibia surface. The measuring average values are 65, 60, 67 and 45 mm respectively. All parameters were compared to the size of the total knee prosthesis which currently used in Thailand. It is found that values are 70, 62, 68 and 48 mm respectively which is larger than the average Thai woman.The study of finite elements can be made aware of the stress distribution and stress in the area of artificial knee while walking and leading to the design of artificial knee joint to have size and shape suitable for Thai women.


2010 ◽  
Vol 450 ◽  
pp. 111-114 ◽  
Author(s):  
Chang J. Wang ◽  
Jun F. Shi ◽  
Colin Morgan ◽  
Diane J. Mynors

Aseptic loosening of the femoral component is one cause of failure in total knee replacement (TKR). Inadequate bone stock in the distal femur after TKR, due to the stress shielding, was often found in revision of the femoral component. The pegs in the femoral component are used as an aid to the correct placement of the component but they also help to transfer the load to the diaphyseal part of the bone and improve stability. This paper investigates the influence of femoral component peg design on stress distribution and bone remodelling in the distal femur after TKR. Eight different peg designs were investigated and reported in this paper. The bone remodelling parameters in the distal femur are presented, compared and analysed. Results show that a slender peg is advantageous in TKR.


Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 36
Author(s):  
Matúš Ranuša ◽  
Markus A. Wimmer ◽  
Spencer Fullam ◽  
Martin Vrbka ◽  
Ivan Křupka

Total knee arthroplasty is on the rise worldwide. Despite its success, revision surgeries are also increasing. According to the American Joint Replacement Registry 2020, 3.3% of revision surgeries are due to wear, and 24.2% are due to mechanical loosening. The combination of shear stresses and wear particles occurring at the bone/implant interface can lead to local osteolysis. Although the shear stresses are partially driven by joint friction, relatively little is known about the evolution of the coefficient of friction (CoF) during a gait cycle in total knee replacement. Here we describe the CoF during a gait cycle and investigate its association with kinematics (slide–roll-ratio), applied load, and relative velocity. The artificial knee was simulated by cobalt–chromium condyle on a flat ultra-high-molecular-weight polyethylene (UHMWPE) tibial plateau, lubricated by either water or proteinaceous solution. We found that the CoF is not a constant but fluctuates between the values close to 0 and 0.15. Cross-correlation suggested that this is primarily an effect of the slide–roll ratio and the contact pressure. There was no difference in the CoF between water and proteinaceous solution. Knowledge about the CoF behavior during a gait cycle will help to increase the accuracy of future computational models of total knee replacement.


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