Three-Dimensional Printing in Orthopedics: from the Basics to Surgical Applications.

PURPOSE OF REVIEW: Additive manufacturing (AM) is a rapidly evolving field traditionally utilized in non-medical industries. Recently, the medical use of AM is expanding, especially in orthopedics. The goal of this article is presenting the principles of AM and its main applications in orthopedics. RECENT FINDINGS: The main indications for AM in orthopedics are education, orthotics, surgical planning, surgical guides, and custom-made implants. Three-dimensional (3D) digital models can be obtained from tomographic scans using available free software. Then, it can be used to create a physical model, plan surgeries, or develop surgical guides which can aid the orthopedic surgeon during complex cases. Recent studies demonstrated the benefits of using printed models in educating patients and medical residents. Custom-made implants also have been evaluated with promising clinical outcomes. Using 3D technology has become a reality in orthopedics. Surgeons should expect exponential growth of its applications in the upcoming years. It is paramount that orthopedists get familiar with this disruptive technology.

The herbal drug Catuama reverts and prevents ventricular fibrillation in the isolated rabbit heart.

INTRODUCTION: Catuama, an herbal drug very popular in Brazil, was tested on the reversion and prevention of ventricular fibrillation (VF) in the isolated rabbit heart. MATERIALS AND METHODS: Catuama (a mixture of Trichilia catigua, Paullinia cupana, Ptychopetalum olacoides, and Zinziber officinalis) was perfused in the isolated perfused rabbit heart. Its effects on intraventricular conduction, heart rate, and monophasic action potential (MAP) duration were evaluated, and sustained VF was induced. The effects on reversion and reinduction of arrhythmia were observed, and new measures were taken in the hearts that reverted. RESULTS: Catuama and T catigua reverted VF in all hearts, prevented reinduction, and prolonged intraventricular conduction. Catuama prolonged MAP phase 2. On the other hand, P cupana reverted VF in 3 of 5 hearts, but depressed automatism, prolonged MAP phase 3, and did not prevent reinduction. DISCUSSION: Catuama reverted and prevented VF in this model. T catigua extract is probably the main agent responsible for the beneficial actions observed. Further studies are now in progress to clarify these actions.

New model of ventricular fibrillation.

The purpose of this study was to develop a more efficient and stable model of ventricular fibrillation (VF) in the isolated rabbit heart, because there is not a satisfactory model with this animal. We also observed the effects of increasing extracellular calcium in the stability and reversibility of the arrhythmia. After suspending the hearts in a classical Langendorff preparation, VF was induced by burst stimulation (current = 2.0 mA, pulse duration = 3 milliseconds, frequency = 50 Hz, voltage = 10 V, duration of stimulation = 5 minutes). The hearts were then divided into 2 groups, A and B. The hearts in group B were perfused with a modified Krebs-Henseleit solution, which contained twice as much calcium as the solution used in the other group. The rate of success with this model was 100% for both groups. The hearts fibrillated up to 30 minutes in group A and more than 40 minutes in group B, longer then all studies ever published in rabbit hearts. Ventricular fibrillation reverted to sinus rhythm in 100% of the hearts of group A when treated with an antifibrillatory drug, whereas no reversion at all was observed in the hearts of group B. We conclude that high extracellular calcium makes the reversion to sinus rhythm more difficult in this model. Our high rate of success and the exceptionally stable and long-lasting VF turn our model very effective for the study of antiarrhythmic interventions in the isolated rabbit heart.