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Tag Archives: Link/Waldemar Link

The High Performance Modular Hip: What a Surgeon Should Know

Modularity in total hip arthroplasty design has received increased citation in the clinical literature. The advantages of these systems include off-the-shelf flexibility for customizing proximal and distal canal filling, preservation of soft tissue structures, biomechanical restoration of offset, version and leg length, as well as accommodating difficult situations of femoral deformity and bone loss. Both mid-stem and distal neck modular femoral systems have been successfully employed for a variety of patient skeletal pathology. However, they are not without clinical concerns. The maintenance of anatomical stability within the femoral canal, structural compromise at metal-metal interconnections due to cyclic microdisplacements defined as fretting, decoupling of components in vivo, and increased potential for metallic wear debris generation and corrosion have all been reported. This handout describes a laboratory basis for the evaluation of modular femoral stem designs and suggests a thought process when considering their employ.

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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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Posted in Knee| Tagged , , |

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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