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Tag Archives: Smith + Nephew

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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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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Preclinical Computational Models: Predictors of Tibial Insert Damage Patterns in TKA

Manufacturers and regulatory agencies share a common goal of having safe and effective total knee arthroplasty (TKA) products available in the global marketplace. Several preclinical methods of testing TKA designs, inclusive of virtual computational models and physical laboratory wear simulations, are employed to predict polymer tibial insert damage patterns. However, the latter is criticized for poor clinical correlation, long testing times, large expense and the difficulty in providing meaningful comparisons with other clinically successful designs. This handout describes a computational modeling experience dating back 16 years for over 45 TKA designs where predicted polymer insert damage patterns have correlated well with physical contact area and stress measurements, laboratory wear simulation and clinical retrievals, suggesting an alternative pre-clinical pathway of evaluating these systems.

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Posted in Knee| Tagged , |

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.

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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.

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Posted in Knee| Tagged , , , , |

Fracture of Highly Crosslinked UHMWPE Acetabular Liners

Four well-placed crosslinked UHMPWE acetabular liners of distinct design were retrieved subsequent to fracture failure of the rim. In each case, electron microscopy of the fracture surface revealed fatigue initiation markings associated with a stress concentrating feature in the rim. Fracture surface investigation demonstrated that crack propagation in all cases followed contours of tensile stresses. FEA simulations were performed to examine whether direct rim loading could be the cause of the observed failures.

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Posted in Hip| Tagged , , |