When is a Doubled Semitendinosus Tendon Autograft after ACL Reconstruction "Normal"?

http://sportsmedresearch.blogspot.com/2012/03/when-is-doubled-semitendinosus-tendon.html

Wednesday, March 7, 2012

When is a Doubled Semitendinosus Tendon Autograft after ACL Reconstruction "Normal"?

Biomechanical and histological evaluation of the doubled semitendinosus tendon autograft after anterior cruciate ligament reconstruction in sheep

Kondo E, Yasuda K, Katsura T, Hayashi R, Kotani Y, & Tohyama H. The American Journal of Sports Medicine 2012. 40(2):315-324.

http://www.ncbi.nlm.nih.gov/pubmed/22088579

Anterior cruciate ligament (ACL) reconstruction often involves the use of a graft to help restore the knee to a point of normalcy.  However, the graft may not actually be “normal” either mechanically or histologically.  Animal reconstruction models allow us to closely evaluate the reconstructed graft but few have investigated the semitendinosus graft.  The purpose of this study was to evaluate the biomechanical and histological properties of semitendinosus ACL autografts in a sheep model.  The surgically reconstructed semitendinosus ACL autograft of 36 sheep were used for biomechanical (i.e., translation, tensile strength; 20 sheep) and histological (looking for cell structure and fiber alignment; 16 sheep) evaluation in comparison to contralateral control ACLs.  Five sheep were biomechanically evaluated at each of the 4 time points, 0, 12, 24, and 52 weeks post-surgery.  For histological evaluation, 3 sheep were evaluated at 4 time points: 0, 2, 24, and 52 weeks post-surgery, and 2 were evaluated at 6 and 12 weeks post-surgery.  Anterior-posterior translation was significantly greater in the ACL reconstruction knee than the contralateral control knees at all time points (0, 12, 24, & 52 weeks post-surgery), and translation was significantly less at 52 weeks than at 12 weeks post-surgery.  All ACL autografts failed tensile strength tests with 3 out of 5 being midsubstance tears at 12 weeks, and all 5 samples at 24 as well as 52 weeks post-surgery being midsubstance tears.  Maximum load at failure was significantly greater at 52 weeks than 12 weeks post-surgical.  In contrast, the contralateral control ACLs failed by avulsing from the bone. Histological observation was near normal by 24 weeks with abnormalities at earlier time points (0 and 12 weeks post-surgery); including the presence of necrotic (dead) tissue at 12 weeks.  Cell density was significantly lower at 2 weeks than all other time points.

Clinically, it appears that up to 1-year post-injury the semitendinosus autograft may not fully reach “normal” ACL biomechanical properties, despite histological similarities around this time point.  The authors note that these findings are similar to other autografts (e.g., bone-patellar tendon-bone).  Abnormalities that exist up to 1 year post-surgery have major implications regarding rehabilitation and return-to-play expectations.  There may be activity modifications or changes in rehabilitation programs that are necessary to promote the long-term health of the knee.  Based on the data, the authors suggest that vigorous activity should be limited in earlier periods when the graft is necrotized and weakened.  Even later in the process, the autografts are failing with midsubstance tears indicating that they are not as strong as the contralateral ACL.  As clinicians, we may need to think about acting more conservatively.  Research has demonstrated within humans (Beynnon et al. 2005) that there are biochemical abnormalities in the knee still present at 1-year post ACL reconstruction regardless of ACL rehabilitation program (conservative versus accelerated programs).  Within our current treatment approaches, it appears that the surgery (or the injury) itself may immediately alter the biomechanics and biochemistry of the knee and it is unclear when the graft returns to normal (if it ever does).  So the question remains, does the knee ever fully return to “normal” or do we need to establish a newly accepted “normal?”  Also, thinking long-term knee health, do we think it is healthy to return someone to activity with abnormalities or are we are returning athletes to activity prematurely after ACL reconstruction?

Written by: Nicole Cattano

Reviewed by: Jeffrey Driban
Related Post:
Patellar Tendon versus Hamstring Autografts: 11-year Follow-Up of a Randomized Clinical Trial

Kondo E, Yasuda K, Katsura T, Hayashi R, Kotani Y, & Tohyama H (2012). Biomechanical and histological evaluations of the doubled semitendinosus tendon autograft after anterior cruciate ligament reconstruction in sheep. The American Journal of Sports Medicine, 40 (2), 315-24 PMID: 22088579

A través de videojuego chileno gratuito niños y jóvenes aprenden sobre biología celular

http://www.mascienciaparachile.cl/?p=1895 

06 de marzo de 2012 | Ciencia y Tecnología en Chile

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A través de videojuego chileno gratuito niños y jóvenes aprenden sobre biología celular

Kokori se llama este videojuego en 3D donde nano-robots combaten virus y bacterias en un viaje al centro de la biología celular humana. Proyecto financiado por CONICYT y desarrollado por la Universidad Santo Tomás conecta el mundo de las TICs con la comunidad educativa. En el desarrollo de la iniciativa, participaron docentes y biólogos, quienes adaptaron los contenidos del programa de enseñanza media, junto a un grupo de expertos en diseño de videojuegos, quienes dieron vida a esta lúdica herramienta educativa, financiada por el Programa TIC-EDU de CONICYT.

La directora de este proyecto, Virginia Garretón, es una gran fan de los videojuegos, a los cuales considera una fuente de entretención, aprendizaje y entrenamiento. “Impartiendo cursos de biología para educación media percibí que las herramientas para el desarrollo de esas clases están muy lejos del lenguaje más visual, interactivo y de colaboración virtual que caracteriza a los jóvenes de hoy. Así nació la idea hacer Kokori”, cuenta.

Kokori se divide en varias misiones cortas con diferentes niveles de complejidad en donde los jugadores deberán recorrer una célula usando diminutos “Nanobots”. Este personaje irá adquiriendo cualidades que le ayudarán a los jugadores a solucionar problemas que han puesto a dicha célula en peligro (ej: infección de un virus, mala nutrición, intoxicación, etc). Al cumplir con las etapas, además de entretenerse, se logrará el objetivo de que el jugador explore una célula, reconozca sus componentes y entienda diferentes procesos biológicos o funciones de sus estructuras.

Para el equipo de investigadores tan importante como los jugadores (alumnos), son los profesores, por lo que se está trabajando en el desarrollo de ejercicios que muestren de qué manera se puede insertar el videojuego al interior del aula. De éste modo, el docente accederá a una metodología de enseñanza en un lenguaje familiar a los jóvenes, favoreciendo la motivación y el trabajo en equipo de sus alumnos. Ya está disponible la guía 1 y además una versión “soft” que permite a los docentes navegar por el mundo celular sin la presión propia de un videojuego.

El videojuego ha sido descargado 8.703 veces por usuarios diferentes, a octubre de 2011 (12% docentes). Sin embargo, los desarrolladores del proyecto calculan que circulan muchas más copias, puesto que ellos mismos recomiendan distribuirlo por otros medios una vez que ya ha sido descargado.

“Kokori no solo está en inglés sino también en mapudungún, rapanui, inglés e italiano. Nuestra decisión de incluir los idiomas originarios mayoritarios del país es porque nuestro objetivo es llegar a todos los jóvenes del país y extender la idea de ofrecer a cada comunidad docente herramientas que los acerquen a su realidad y la de sus niños”, puntualiza Virginia Garretón

Premios

Kokori obtuvo el segundo lugar en la categoría de desarrollo de herramientas TIC del concurso Conectar-Igualdad del Mineduc de Argentina y por medio de la visibilidad que obtuvo Kokori por este premio, el ministerio Argentino incluirá Kokori en la oferta de herramientas a la que tienen acceso los 3 millones de computadores que se están distribuyendo en Argentina bajo su programa “un computador por niño”.

Además, Kokori será convertida en serie animada a transmitirse en 2012 con fondos del CNTV, gracias a un proyecto de la Prodcutora Cábala, basada en la idea original del proyecto.

Kokori

Kokori es una palabra rapa nui que significa “juego colectivo” y que da nombre al laboratorio desde donde se inician las misiones del videojuego, cuyos objetivos son combatir virus y bacterias, restablecer la energía de las células y reparar organelos.

Mas información en el sitio www.kokori.cl

FUENTE: CONICYT – MARZO 2012

Extubación y ventilación comprometidas

Extubación de pacientes con debilidad neuromuscular. Un manejo nuevo de manejo Extubation of Patients With Neuromuscular Weakness A New Management Paradigm John Robert Bach, MD, Miguel R. Gonçalves, PT, Irram Hamdani, MD and Joao Carlos Winck, MD, PhD Chest 2010;137;1033-1039; Abstract Background: Successful extubation conventionally necessitates the passing of spontaneous breathing trials (SBTs) and ventilator weaning parameters. We report successful extubation of patients with neuromuscular disease (NMD) and weakness who could not pass them. Methods: NMD-specific extubation criteria and a new extubation protocol were developed. Data were collected on 157 consecutive "unweanable" patients, including 83 transferred from other hospitals who refused tracheostomies. They could not pass the SBTs before or after extubation. Once the pulse oxyhemoglobin saturation (SpO 2) was maintained at ≥ 95% in ambient air, patients were extubated to full noninvasive mechanical ventilation (NIV) support and aggressive mechanically assisted coughing (MAC). Rather than oxygen, NIV and MAC were used to maintain or return the SpO 2 to ≥ 95%. Extubation success was defined as not requiring reintubation during the hospitalization and was considered as a function of diagnosis, preintubation NIV experience, and vital capacity and assisted cough peak flows (CPF) at extubation. Results: Before hospitalization 96 (61%) patients had no experience with NIV, 41 (26%) used it < 24 h per day, and 20 (13%) were continuously NIV dependent. The first-attempt protocol extubation success rate was 95% (149 patients). All 98 extubation attempts on patients with assisted CPF ≥ 160 L/m were successful. The dependence on continuous NIV and the duration of dependence prior to intubation correlated with extubation success (P < .005). Six of eight patients who initially failed extubation succeeded on subsequent attempts, so only two with no measurable assisted CPF underwent tracheotomy. Conclusions: Continuous volume-cycled NIV via oral interfaces and masks and MAC with oximetry feedback in ambient air can permit safe extubation of unweanable patients with NMD. http://chestjournal.chestpubs.org/content/137/5/1033.full.pdf+html   Falla respiratoria hipoxémica severa: parte 2- estrategias no ventilatorias Severe hypoxemic respiratory failure: part 2--nonventilatory strategies. Raoof S, Goulet K, Esan A, Hess DR, Sessler CN. Division of Pulmonary and Critical Care Medicine, New York Methodist Hospital, 506 Sixth St, Brooklyn, NY 11215, USA. sur9016@nyp.org Chest. 2010 Jun;137(6):1437-48. Abstract ARDS is characterized by hypoxemic respiratory failure, which can be refractory and life-threatening. Modifications to traditional mechanical ventilation and nontraditional modes of ventilation are discussed in Part 1 of this two-part series. In this second article, we examine nonventilatory strategies that can influence oxygenation, with particular emphasis on their role in rescue from severe hypoxemia. A literature search was conducted and a narrative review written to summarize the use of adjunctive, nonventilatory interventions intended to improve oxygenation in ARDS. Several adjunctive interventions have been demonstrated to rapidly ameliorate severe hypoxemia in many patients with severe ARDS and therefore may be suitable as rescue therapy for hypoxemia that is refractory to prior optimization of mechanical ventilation. These include neuromuscular blockade, inhaled vasoactive agents, prone positioning, and extracorporeal life support. Although these interventions have been linked to physiologic improvement, including relief from severe hypoxemia, and some are associated with outcome benefits, such as shorter duration of mechanical ventilation, demonstration of survival benefit has been rare in clinical trials. Furthermore, some of these nonventilatory interventions carry additional risks and/or high cost; thus, when used as rescue therapy for hypoxemia, it is important that they be demonstrated to yield clinically significant improvement in gas exchange, which should be periodically reassessed. Additionally, various management strategies can produce a more gradual improvement in oxygenation in ARDS, such as conservative fluid management, intravenous corticosteroids, and nutritional modification. Although improvement in oxygenation has been reported with such strategies, demonstration of additional beneficial outcomes, such as reduced duration of mechanical ventilation or ICU length of stay, or improved survival in randomized controlled trials, as well as consideration of potential adverse effects should guide decisions on their use. Various nonventilatory interventions can positively impact oxygenation as well as outcomes of ARDS. These interventions may be considered for use, particularly for cases of refractory severe hypoxemia, with proper appreciation of potential costs and adverse effects. http://chestjournal.chestpubs.org/content/137/6/1437.full.pdf+html

Atentamente Anestesiología y Medicina del Dolor www.anestesia-dolor.org

Colegio Mexicano de Ortopedia y Traumatología A.C.

Transmisión en vivo vía internet por el siguiente canal: http://www.livestream.com/bibliomanazteca_platicas_medicas			SESIÓN REGLAMENTARIA 02/2012
El Consejo Directivo del Colegio Mexicano de Ortopedia y Traumatología A.C., atentamente le invita y convoca a su segunda Sesión Reglamentaria, que tendrá verificativo el miércoles 7 de marzo de 2012, a las 20:30 horas, en el auditorio de nuestra sede, ubicado en el WTC México, Montecito No. 38, piso 25, Oficinas 23 a 27, Col. Nápoles, 03810 México, D.F., bajo la siguiente:
ORDEN DEL DÍA
1.      Lectura del acta de la sesión anterior, celebrada el 1° de febrero de 2012.
2.      Asuntos generales
3.      Presentación de seis trabajos de ingreso en la modalidad de oral.
		Coordinador: Dr. Rubén Torres González Titular del Capítulo de Investigación en Ortopedia
		a)       Introducción (5’) Dr. Rubén Torres González
		b)       Resultados y complicaciones de la cadera flotante (8’) Dr. Julio César Pérez Alavez Hospital General Xoco
		Comentarista oficial Dra. Fryda Medina Rodríguez (2’)
		c)       Tipo y número de factores de riesgo en pacientes con pie diabético reamputados (8’) Dr. Diego Eduardo Buendía Valdez Hospital General Dr. Manuel Gea González
		Comentarista oficial Dr. Jesús Vázquez Escamilla (2’)
		d)       Manejo de fracturas del cuello de la escápula (8’) Dr. Oliver Paul Pineda Castro Hospital General Xoco
		Comentarista oficial Dr. Michell Ruiz Suárez (2’)
		e)       Evolución clínica y radiográfica de los pacientes con Hallux Valgus tratados con cirugía percutánea (8’) Dr. Luis Enrique García Anaya Hospital General Dr. Manuel Gea González
		Comentarista oficial Dr. Eduardo G. López Gavito (2’)
		f)         Complicaciones de fracturas de tobillo en pacientes diabéticos (8’) Dr. Juan Nájera Nevarez Hospital General Xoco
		Comentarista oficial Dr. Sergio Rodríguez Rodríguez (2’)
		g)       Tratamiento de las lesiones sindesmales con gancho (8’) Dr. Ray Durán Jesús Hospital General Xoco
		Comentarista oficial Dr. Eduardo G. López Gavito (2’)
		h)       Sesión de preguntas y comentarios (10’) Dr. Rubén Torres González
4.      Convivio ofrecido por el CMO
Nota: durante el presente año, se va a adjudicar una beca semestral entre los miembros al corriente en sus cuotas, que tengan el mayor número de asistencias a las sesiones reglamentarias, las becas incluyen traslado aéreo en clase turista, inscripción al evento y hospedaje, para acudir al 49° Congreso Nacional 2012 de la Sociedad Española de Cirugía Ortopédica y Traumatología - SECOT en Málaga, España, los días del 3 al 5 de octubre, y al Congreso Anual 2013 de la  American Academy of Orthopaedic Surgeons – AAOS a realizarse en Chicago, Illinois, del 19 al 23 de marzo.
Sigue nuestra transmisión en vivo por internet en: http://www.livestream.com/bibliomanazteca_platicas_medicas