40º aniversario de una publicación introduciendo un implante aún vigente: "ENDO model" / 40th anniversary of a publication presenting an implant that is still in use: "ENDO model"

En 2021, se cumplen 40 años de la publicación original que describió al implante "intracondilar con capacidad rotatoria Endo-Model", evolución del diseño precedente St. George, ahora capaz de proveer doble grado de libertad de movimiento y reducir la tensión en la interfase cemento-hueso. Condición singular es que dicha publicación no es referida en estudios bibliométricos, a pesar de lo cual su indicación electiva está aún vigente tras cuatro décadas. Un trabajo merece la calificación de "clásico" no exclusivamente por el volumen de citaciones, sino fundamentalmente por la confianza que inspira la aplicación de su contenido en el largo plazo. Contemporáneamente, todas las compañías de la industria de implantes que lideran el mercado internacional han incorporado en sus catálogos un modelo propio de implante a bisagra rotacional. La magnitud de constricción comparativa es un dilema y, por ende, materia de discusión. Contemporáneamente aplicando la tecnología de sensores inerciales se ha logrado resolver la cuestión: la bisagra rotacional ofrece menor constricción que el implante de constricción condilar. Nivel de Evidencia: V

The year 2021 marks the 40th anniversary of the original publication describing the "Endo-model intracondylar rotational" implant, the evolution of the previous St Georg design, now providing two-degree-of-freedom motion and reducing stress on the cement-bone interface. A unique condition is that the publication is not reported in bibliometric studies, although its elective indication still exists after four decades. A work deserves the qualification of "classic" not only for the volume of citations but fundamentally for the confidence that the application of its content inspires in the long term. Currently all the leading international companies in the implant industry have included in their catalogs their own rotating hinge implants. The scale of comparative constriction is a dilemma and thus a topic for discussion. Currently, the matter has been solved applying inertial sensors technology: the rotating hinge provides less constriction than the condylar constriction implant. Level of Evidence: V

Biographical sketch: William Russell MacAusland, MD 1882-1965.

This biographical sketch on William Russell MacAusland corresponds to the historic text, The Classic: Total Replacement of the Knee Joint by a Prosthesis, available at DOI 10.1007/s11999-010-1305-9 .

The history of mobile-bearing total knee replacement systems.

The use of a mobile-bearing knee system is routine in modern total knee arthroplasty (TKA). There are indications for use of a mobile-bearing TKA for a growing number of patients. The design, however, was not always well appreciated. Fears of perioperative difficulties and lack of understanding of the design principles limited the acceptance of mobile-bearing technology. Recent evidence has shown that use of mobile-bearing prostheses in TKA has increased, and today, nearly three decades after its introduction, the mobile-bearing design remains relavent and important. The theories behind the design of mobile-bearing prostheses have shown in clinical practice what many already believed to be true: mobile-bearing TKA, when performed correctly, is reliable, and capable of providing substantial benefit for patients.

The early innovators of today's resurfacing condylar knees.

The 1970s saw an explosion of ideas in the field of prosthetic knee arthroplasty. This paper is an effort to identify the innovators who contributed to the development of today's condylar total knee prostheses and the surgical techniques used to insert them. The 1970s were selected because most innovations occurred during those years. Two different design approaches were undertaken simultaneously. One was a functional approach whereas the other was a strictly anatomical approach. Initially, these 2 approaches led to very different designs. But the common goal of recreating human knee function eventually led to more similarities than differences. The author describes how, when, and why these dedicated individuals came to their ideas. The work is largely based on interviews and correspondence with those involved as well as on reviews of patents and papers pertaining to their work.

History of total knee replacement.

In the early 1970s, the condylar knee was developed independently in the United States and overseas. The concept of replacing the tibiofemoral condylar surfaces with cemented fixation, along with preservation of the cruciate ligaments, was developed and refined. To correct severe knee deformities, the condylar knee with posterior cruciate-sacrificing design was introduced, also in the early 1970s. By 1974, replacing the patellofemoral joint and either preserving or sacrificing the cruciate ligaments had become standard practice. Subsequently, condylar knee designs were improved to include modularity and noncemented fixation, with use of universal instrumentation. Today, over 19 companies in the United States distribute total knee implants of three different types: cruciate-preserving, cruciate-substituting, and TC-III. Six major companies are actively involved in designing mobile-bearing knees. Future developments, such as navigation-guided surgery, enhanced kinematics, and wear-resistant bearing surfaces with better fixation, promise a consistent evolution for the total knee replacement.

The Insall legacy in total knee arthroplasty.

John N. Insall was a pioneer in the field of knee surgery. He was a rare individual who accomplished unparalleled levels of success as a surgeon, designer, and teacher. During the past 4 decades, he was instrumental in evolving total knee arthroplasty to its current state of excellence. Insall's impact on orthopaedics is felt by all who have come in contact with him.