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Tag Archives: Zimmer

The Influence of Contemporary Knee Design on High Flexion IV: A Kinematic Comparison with the Healthy Intact Knee

Although Total Knee Arthroplasty (TKA) surgery enjoys 90% of outcomes with good to excellent results, some patients are uncomfortable adjusting their gait to accommodate the new articulations inherent in many contemporary implant designs. Paradoxical motions, inclusive of anterior sliding and lateral pivot of the femur relative to the tibia are examples of aberrant TKA kinematics that are opposite of those observed in healthy intact knees. A computational kinematic simulator is employed in this study to quantify the motion of six posterior stabilized TKA designs during high flexion activity, allowing comparison to the motion of healthy intact knees.

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The Influence of Contemporary Knee Design on High Flexion III: A Kinematic Comparison with the Healthy Intact Knee

Although Total Knee Arthroplasty (TKA) surgery enjoys 90% of outcomes with good to excellent results, some patients are uncomfortable adjusting their gait to accommodate the new articulations inherent in many contemporary implant designs. Paradoxical motions, inclusive of anterior sliding and lateral pivot of the femur relative to the tibia are examples of aberrant TKA kinematics that are opposite of those observed in healthy intact knees. A computational kinematic simulator is employed in this study to quantify the motion of six posterior stabilized TKA designs during high flexion activity, allowing comparison to the motion of healthy intact knees.

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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 whose 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 in turn has led to design changes in contemporary polyethylene tibial inserts which accommodate these increased flexion ranges. This study reveals the contact areas and stresses that are associated with polymer insert abrasion and subsurface delamination for four contemporary 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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Preclinical Computational Models: Promise and Progress in Total Knee Arthroplasty Design

Clinicians, manufacturers and regulatory agencies share a common goal of having safe and effective total knee arthroplasty (TKA) products available in the global marketplace. Preclinical computational modeling of new, innovative knee designs allows dynamic visualization of anticipated in vivo performance during activities of daily living. Comparison is possible with established, clinically successful designs determining relative performance differences. This handout presents fluoroscopic and clinical range of motion evidence for a variety of fixed bearing knee designs, suggesting computational modeling can be predictive of in vivo performance. The modeling environment is extended to include mobile bearing designs and smaller patients, validated through comparison with an Asian clinical report. What emerges from these studies is the promise that preclinical computational modeling offers a first line tool for contemporary knee design.

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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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The Evolving Role of Bone-Graft Substitutes

It is estimated that more than 500,000 bone-grafting procedures are performed annually in the United States, with approximately half of these procedures related to spine fusion. These numbers easily double on a global basis and indicate a shortage in the availability of musculoskeletal donor tissue traditionally used in these reconstructions. This reality has stimulated a proliferation of corporate interest in supplying what is seen as a growing market in bone replacement materials. These graft alternatives are subjected to varying degrees of regulatory scrutiny, and thus their true safety and effectiveness in patients may not be know prior to their use by orthopaedic surgeons. It is thus important to gain insight into this emerging class of bone-substitute alternatives.

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Bone Graft Substitutes: Facts, Fictions & Applications

It is estimated that more than 500,000 bone-grafting procedures are performed annually in the United States, with approximately half of these procedures related to spine fusion. These numbers easily double on a global basis and indicate a shortage in the availability of musculoskeletal donor tissue traditionally used in these reconstructions. This reality has stimulated a proliferation of corporate interest in supplying what is seen as a growing market in bone replacement materials. These graft alternatives are subjected to varying degrees of regulatory scrutiny, and thus their true safety and effectiveness in patients may not be know prior to their use by orthopaedic surgeons. It is thus important to gain insight into this emerging class of bone-substitute alternatives.

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The Influence of Contemporary Knee Design on High Flexion II: A Kinematic Comparison with the Normal Knee

Although Total Knee Arthroplasty (TKA) surgery enjoys 90% of outcomes with good to excellent results, some patients have difficulty adjusting their gait to accommodate the new articulations inherent in contemporary implant designs. Paradoxical motions inclusive of anterior sliding and lateral pivot are examples of aberrant TKA kinematics. This paper compares the motion of six contemporary TKA designs with recent in-vivo kinematic data of the health un-operated knee through deep flexion by employing a computational kinematic simulator.

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Bone Graft Substitutes: Facts, Fictions & Applications

It is estimated that more than 500,000 bone-grafting procedures are performed annually in the United States, with approximately half of these procedures related to spine fusion. These numbers easily double on a global basis and indicate a shortage in the availability of musculoskeletal donor tissue traditionally used in these reconstructions. This reality has stimulated a proliferation of corporate interest in supplying what is seen as a growing market in bone replacement materials. These graft alternatives are subjected to varying degrees of regulatory scrutiny, and thus their true safety and effectiveness in patients may not be know prior to their use by orthopaedic surgeons. It is thus important to gain insight into this emerging class of bone-substitute alternatives.

View PDF

Return to Library

The Influence of Contemporary Knee Design on High Flexion: A Kinematic Comparison with the Normal Knee

Although Total Knee Arthroplasty (TKA) surgery enjoys 90% of outcomes with good to excellent results, some patients have difficulty adjusting their gait to accommodate the new articulations inherent in contemporary implant designs. Paradoxical motions inclusive of anterior sliding and lateral pivot are examples of aberrant TKA kinematics. This handout describes the utilization of a computational kinematic simulator to compare the motion of six contemporary TKA designs with recent in-vivo kinematic data of the healthy unoperated knee through deep flexion.

View PDF

Return to Library

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