Sebastián Irarrázaval

The Anterolateral Capsule of the Knee Behaves Like a Sheet of Fibrous Tissue

Background: The function of the anterolateral capsule of the knee has not been clearly defined. However, the contribution of this region of the capsule to knee stability in comparison with other anterolateral structures can be determined by the relative force that each structure carries during loading of the knee. Purpose/Hypothesis: The purpose of this study was to determine the forces in the anterolateral structures of the intact and anterior cruciate ligament (ACL)–deficient knee in response to an anterior tibial load and internal tibial torque. It was hypothesized that the anterolateral capsule would not function like a traditional ligament (ie, transmitting forces only along its longitudinal axis). Study Design: Controlled laboratory study. Methods: Loads (134-N anterior tibial load and 7-N·m internal tibial torque) were applied continuously during flexion to 7 fresh-frozen cadaveric knees in the intact and ACL-deficient state using a robotic testing system. The lateral collateral ligament (LCL) and the anterolateral capsule were separated from the surrounding tissue and from each other. This was done by performing 3 vertical incisions: lateral to the LCL, medial to the LCL, and lateral to the Gerdy tubercle. Attachments of the LCL and anterolateral capsule were detached from the underlying tissue (ie, meniscus), leaving the insertions and origins intact. The force distribution in the anterolateral capsule, ACL, and LCL was then determined at 30°, 60°, and 90° of knee flexion using the principle of superposition. Results: In the intact knee, the force in the ACL in response to an anterior tibial load was greater than that in the other structures (P < .001). However, in response to an internal tibial torque, no significant differences were found between the ACL, LCL, and forces transmitted between each region of the anterolateral capsule after capsule separation. The anterolateral capsule experienced smaller forces (~50% less) compared with the other structures (P = .048). For the ACL-deficient knee in response to an anterior tibial load, the force transmitted between each region of the anterolateral capsule was 434% greater than was the force in the anterolateral capsule (P < .001) and 54% greater than the force in the LCL (P = .036) at 30° of flexion. In response to an internal tibial torque at 30°, 60°, or 90° of knee flexion, no significant differences were found between the force transmitted between each region of the anterolateral capsule and the LCL. The force in the anterolateral capsule was significantly smaller than that in the other structures at all knee flexion angles for both loading conditions (P = .004 for anterior tibial load and P = .04 for internal tibial torque). Conclusion: The anterolateral capsule carries negligible forces in the longitudinal direction, and the forces transmitted between regions of the capsule were similar to the forces carried by the other structures at the knee, suggesting that it does not function as a traditional ligament. Thus, the anterolateral capsule should be considered a sheet of tissue. Clinical Relevance: Surgical repair techniques for the anterolateral capsule should restore the ability of the tissue to transmit forces between adjacent regions of the capsule rather than along its longitudinal axis.

Anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) reconstruction is a common procedure performed by orthopaedic surgeons, particularly in association with sports-related injuries. Over the past 10 years, a renewed interest in the native anatomy of the ACL has facilitated a progression from non-anatomic to more anatomic reconstruction techniques. The anatomic and individualised ACL reconstruction concept attempts to closely reproduce the patients individual anatomy with the goal of reproducing the native ACL characteristics and improving patient outcomes. Measurements of the patients anatomy help determine graft choice and whether anatomic reconstruction should be performed with an single-bundle or double-bundle technique. The bony landmarks and insertions of the ACL are preserved to assist with anatomic placement of both tibial and femoral tunnels. Long-term outcomes for anatomic ACL reconstruction are unknown and future research, considering biomechanics and clinical outcomes, should be focused on this area. Future studies may yield important information with regard to the potential progression to osteoarthritis after ACL reconstruction, including factors affecting or preventing it. In this State of the art review, we have attempted to summarise the best available evidence addressing ACL injury diagnostics, treatment, surgical techniques, complications, tips, pitfalls and geographical differences, following our primary goal of improving medical care and outcomes for patients who suffer an ACL injury.

Gross, Arthroscopic, and Radiographic Anatomies of the Anterior Cruciate Ligament: Foundations for Anterior Cruciate Ligament Surgery

The anterior cruciate ligament (ACL) is one of the more studied structures in the knee joint. It is not a tubular structure, but is much narrower in its midsubstance and broader at its ends, producing an hourglass shape. The ACL is composed of 2 functional bundles, the anteromedial and posterolateral bundles, that are named for their location of insertion on the anterior surface of the tibial plateau. Although the relative contribution in terms of total cross-sectional area of the ACL has been noted to be equal in regards to each bundle, dynamically these bundles demonstrate different properties for knee function.

In situ force in the anterior cruciate ligament, the lateral collateral ligament, and the anterolateral capsule complex during a simulated pivot shift test

The role of the anterolateral capsule complex in knee rotatory stability remains controversial. Therefore, the objective of this study was to determine the in situ forces in the anterior cruciate ligament (ACL), the anterolateral capsule, the lateral collateral ligament (LCL), and the forces transmitted between each region of the anterolateral capsule in response to a simulated pivot shift test. A robotic testing system applied a simulated pivot shift test continuously from full extension to 90° of flexion to intact cadaveric knees (n = 7). To determine the magnitude of the in situ forces, kinematics of the intact knee were replayed in position control mode after the following procedures were performed: (i) ACL transection; (ii) capsule separation; (iii) anterolateral capsule transection; and (iii) LCL transection. A repeated measures ANOVA was performed to compare in situ forces between each knee state (*p < 0.05). The in situ force in the ACL was significantly greater than the forces transmitted between each region of the anterolateral capsule at 5° and 15° of flexion but significantly lower at 60°, 75°, and 90° of flexion. This study demonstrated that the ACL is the primary rotatory stabilizer at low flexion angles during a simulated pivot shift test in the intact knee, but the anterolateral capsule plays an important secondary role at flexion angles greater than 60°. Furthermore, the contribution of the “anterolateral ligament” to rotatory knee stability in this study was negligible during a simulated pivot shift test.

Plaza cubierta en República Dominicana

La realidad climatica de Republica Dominicana hace necesario dar cabida a un sinnumero de situaciones cotidianas bajo la sombra. Una gran plaza cubierta no debiera, entonces, provocar extraneza frente a la idea que tenemos de espacio publico exterior. Este proyecto forma parte de un conjunto de propuestas de oficinas de todo el mundo, convocadas por el gobierno municipal para dar una nueva cara a la ciudad de Santo Domingo.

Case Report of Frostbite with Delay in Evacuation: Field Use of Iloprost Might Have Improved the Outcome

Frostbite is a common injury in high altitude medicine. Intravenous vasodilators have a proven efficacy and, recently, have been proposed as a safe outpatient treatment. Nevertheless, the lack of availability and consequently delayed application of this treatment option can result in poor clinical outcomes for patients. We present the case of a 60-year-old Chilean man with severe frostbite injuries suffered while climbing Mount Everest. The patient was initially given field treatment to the extent permitted by conditions and consensus guidelines. Unfortunately, advanced management was delayed, with iloprost administered 75 hours after the initial injury. The patient also underwent 5 days of hyperbaric and analgesic/antibiotic therapies. An early bone scan predicted a poor clinical outcome, and five of the patients fingers, between both hands, were incompletely amputated. We present this case to exemplify the importance of advanced in-field management of frostbite injuries.

Anatomy and Function of the Anterolateral Capsule Structures

The overall goal when treating athletes with high-grade rotatory knee laxity is to restore normal knee kinematics and joint function in order to facilitate a safe return to sports. Isolated ACL injuries do not require additional extra-articular tenodesis procedures. However, the current literature is unclear with regard to the more complex situation of chronic ACL tears, combined injuries, athletes with generalized joint hyperlaxity, and revision surgery.

Clinical Management of Ligament Injuries of the Knee and Postoperative Rehabilitation

Ligament injuries of the knee are common and occur via a variety of mechanisms. The medial collateral ligament is most commonly injured but injury to the anterior cruciate ligament is most often highlighted in the media due to its prevalence in sports. However, there are other less common but important ligamentous injuries that can also occur. The long term impact on overall function of the knee depends on the injury pattern and severity. Each ligament is distinct with respect to anatomy. Therefore, mechanism of injury, diagnosis and treatment are based on physical exam as well as imaging. Treatment and overall outcome depends on type of injury and time from the lesion. Surgical management involves restoring specific anatomy and biomechanical properties of these ligaments. Rehabilitation is tailored to the specific injury pattern and should be individualized for each patient with the hope to provide a stable functional knee.

Pabellón 120/Valparaíso

espanolUn pabellon que debia ser lo suficientemente iconico comopara transformarse en el simbolo de una celebracion, y a lavez lo suficientemente ductil como para ser desmontado ytrasladado con facilidad. Una esfera inflable y un basamentoen base a la repeticion circular de un elemento plegable demadera resuelven el problema de proyecto, permitiendo que este pabellon fuese montado en Santiago y Valparaiso, cambiando su nombre pero no sus cualidades arquitectonica.s EnglishA pavilion that needed to be iconic enough in order tobecome the symbol of a celebration, while remainingadequately ductile to be easily dismantled and relocated.An inflatable sphere and a foundation based on the circular repetition of a folding wooden element solve the project�s problem, allowing this pavilion to be assembled in Santiago and Valparaiso, changing its name but not its architectural features.

CASA ORUGA, SANTIAGO, CHILE

Resumen es: La asociacion de un conjunto de contenedores navieros y una estructura metalica de vigas y pilares, que los suspende sobre el terreno, genera una planta ...