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Category Archives: Knee

High Flexion in Contemporary Total Knee Design: A Precursor of UHMWPE Damage? A Finite Element Study

The success of total knee arthroplasty has contributed to its widening application to a younger, more active patient population who daily regimen includes more demanding high flexion activities. Worldwide expansion to Middle Eastern and Asian populations, where the attainment of high knee joint flexion is often a cultural requirement, has been steadily increasing in recent years. This study reveals the contact areas and stresses that are associated with polymer insert abrasion in four total knee designs during the most highly loaded portions of three different high flexion activities, and suggests their efficacy in clinical use.

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Patello-Femoral Replacement Polymer Stress During Daily Activities: A Finite Element Study

Isolated, patello-femoral arthritis, although uncommon, has been reported to affect 8% of women and 2% of men over the age of 55. Both conservative and surgical non-arthroplasty interventions have been advocated, however, their reports suggest limited success. Patello-femoral replacement designs as a solution alternative are beginning to re-emerge largely through an appreciation of design requirements and the importance of component placement, which have been major factors in earlier clinical disappointments. This study reveals the influence that three different patello-femoral implant design geometries have on stresses that are associated with polymer abrasion and delamination and suggests their efficacy in clinical use.

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Polymer Insert Stress in Total Knee Designs During High Flexion Activities: A Finite Element Study

The success of total knee arthroplasty has contributed to its widening application to a younger, more active patient population who daily regimen includes more demanding high flexion activities. Worldwide expansion to Middle Eastern and Asian populations, where the attainment of high knee joint flexion is often a cultural requirement, has been steadily increasing in recent years. This study reveals the contact areas and stresses that are associated with polymer insert abrasion in four total knee designs during the most highly loaded portions of three different high flexion activities, and suggests their efficacy in clinical use.

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Tibial Plateau Abrasion in Mobile Bearing Knee Systems During Walking Gait III: A Finite Element Study

The abrasion observed in ultrahigh molecular weight polyethylene (UHMWPE) total knee arthroplasty component retrievals is the result of high cyclical loads, which act on the tibial plateau during daily ambulation. This dynamic process influences in vivo component longevity and is dependent on the magnitude and distribution of contact stresses on the tibial plateau. Mobile bearing knee systems offer increased component conformity over their fixed plateau counterparts and thus diminish the magnitudes of these contact stresses. This study reveals the contact areas and stresses that are associated with tibial insert abrasion in four mobile bearing knee designs during three highly loaded points in the walking gait cycle, and suggests their efficacy in clinical use.

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The Effects of Walking Gait on UHMWPE Damage in Unicompartmental Knee Systems: A Finite Element Study

There is increasing re-interest in the use of unicompartmental knee replacement as a remedy of choice for isolated compartment disease, although there is debate regarding its role as a temporizing or definitive procedure. The popularization of mini-incision surgery with claims of reduced pain, shorter hospitalization, more rapid rehabilitation, more normal knee function and decreased cost are positive arguments for the procedure. However, the damage observed in ultra-high molecular weight polyethylene (UHMWPE) component retrievals is the result of high cycle fatigue loads, which act on the polymer insert during daily ambulation and suggests a material limitation in their use. The study reveals the influence that four different modular unicompartmental knee design geometries have on stresses that are associated with abrasion and delamination of the polymer insert and suggests their efficacy in clinical use..

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Tibial Plateau Abrasion in Mobile Bearing Knee Systems During Walking Gait II: A Finite Element Study

The abrasion observed in ultrahigh molecular weight polyethylene (UHMWPE) total knee arthroplasty component retrievals is the result of high cyclical loads, which act on the tibial plateau during daily ambulation. This dynamic process influences in vivo component longevity and is dependent on the magnitude and distribution of contact stresses on the tibial plateau. Mobile bearing knee systems offer increased component conformity over their fixed plateau counterparts and thus diminish the magnitudes of these contact stresses. This study reveals the contact areas and stresses that are associated with tibial plateau abrasion in four mobile bearing knee designs during three highly loaded points in the walking gait cycle, and suggests their efficacy in clinical use.

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Classification of Mobile Bearing Knee Design: Mobility and Constraint

Restoration of normal knee joint function through surgical reconstruction is dependent upon load sharing between the implant and surrounding soft tissue structures. Mobile bearing knee designs offer the advantage of maximum conformal geometry while diminishing constraint forces to fixation interfaces through plateau mobility. The degree of mobility afforded by these designs in the anterior-posterior, medial-lateral and rotational directions defines the required interaction between soft tissue and design geometry to maintain a stable articulation. This study characterizes nine, contemporary mobile bearing knee designs in terms of the force generated during a prescribed displacement.

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Tibial Plateau Abrasion in Mobile Bearing Knee Systems During Walking Gait: A Finite Element Study

The abrasion observed in ultrahigh molecular weight polyethylene (UHMWPE) total knee arthroplasty component retrievals is the result of high cyclical loads, which act on the tibial plateau during daily ambulation. This dynamic process influences in vivo component longevity and is dependent on the magnitude and distribution of contact stresses on the tibial plateau. Mobile bearing knee systems offer increased component conformity over their fixed plateau counterparts and thus diminish the magnitudes of these contact stresses. This study reveals the contact areas and stresses that are associated with tibial insert abrasion in four mobile bearing knee designs during three highly loaded points in the walking gait cycle, and suggests their efficacy in clinical use.

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