They also noted evidence of backside wear in rotating-platform knees, similar to what is seen with fixed-bearing knees. They proposed that the reduced wear was a result of less cross-shear forces during flexion, allowing anteroposterior (AP) translation to more readily align with the ultra-high-molecular-weight molecules. In a similar study, Fisher et al7 confirmed less wear with rotating-platform designs.
McEwen et al6 performed a laboratory study comparing two different rotatingplatform systems with a fixed-bearing system under both “intermediate” and “high kinetic conditions.” They noted that both rotating-platform systems resulted in significantly less wear compared with a similar fixed-bearing design. The popularity of rotating platforms stems largely from the results of early in-vitro wear studies. Highly dependent on polyethylene wear.5 One of the proposed benefits of rotating platforms is decreased polyethylene wear as a result of better force distribution. Received Februaccepted Februpublished online May 5, 2015 Wear Durability and high survivorship rates are important factors to determine the success of TKA.4 Currently, aseptic loosening remains the primary mechanical cause of revision TKA and is Furthermore, we will highlight our institution’s indications for using rotating platform in TKA. This article outlines our institution’s experience, as well as the latest clinical research on (1) wear, (2) kinematics, (3) clinical outcomes, and (4) survivorship of fixed bearings versus rotating platforms in TKA. Two types of mobile bearings exist: meniscal bearings that translate in a multitude of directions and rotating platforms that rotate based on a centralized pivot (►Fig. The principle behind mobile bearings is to create a rotational articulating surface, thereby uncoupling the translational and rotational forces about the knee. 1) and mobile bearing when the polyethylene freely articulates on the tibial tray. Implants are considered fixed bearing when the polyethylene is locked onto the tibial tray (►Fig. While many implant designs are available, most can be classified as either fixed or mobile bearing. The goal of total knee arthroplasty (TKA) is to reduce pain and restore function in patients with advanced arthritis.1–3 As restoration of function and motion is highly dependent on joint kinematics, it is widely believed that optimal kinematics after TKA should best approximate that of a native, nonarthritic knee. This article reviews our institution’s experience, as well as the latest clinical research on wear, kinematics, clinical outcomes, and survivorship of fixed-bearing and rotating-platform knees. However, these benefits have failed to translate into improved clinical outcomes or survivorship. Kinematic follow-up studies showed significantly improved axial rotation with rotating-platform knees. In-vitro wear studies showed significantly less wear with rotating platforms as opposed to fixedbearing designs. Rotating platforms were introduced as an alternative to fixed bearings in hopes of providing more natural kinematics and improved clinical outcomes. fixed bearing rotating platform total knee TKA White, BA, Department of Orthopaedics, Hospital for Special Surgery, 535 E 70th st, 6th floor, New York, NY 10021 (e-mail: ). White, BA1ġ Department of Othopedics, Hospital for Special Surgery, New York,Īddress for correspondence Peter B.
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The bee takes it upon itself to destroy the massive bird from the inside out, and free all the enslaved critters within.Fixed Bearings versus Rotating Platforms in Total Knee Arthroplasty Peter B. Inside the bird, all of the bugs that it eats are brainwashed and put to work in fantastical, mechanical factories that exist in the place of its organs, except for the outcast bee, whose very disability prevents them from being brainwashed. That is, until a bird attacks and eats it.īut that's only the beginning. Born different from the others, the bee is exiled from the hive and forced to survive the world on its own. About This Game BirdGut is a hand-drawn 2d puzzle-platformer set inside the internal organs of a bird.Ī bee hatches in the hive, but something's wrong.
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