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Orthopedics

2010;():1-2. doi:10.1115/BioMed2010-32018.

The use of modern technology in knee arthroplasty, like minimally invasive surgery and computer assisted systems, can help in standardization of surgical procedures and improve patient recovery. However, such procedures can affect the surgeon’s ability to properly place and orient the prosthetic components on the bones. In the present study, the effects of surgical placement of components on mechanics of the joint are evaluated. A sagittal plane mathematical model of the knee with unicompartmental replacement is developed.

Anatomical data and geometries of the prosthetic components were taken similar to those in literature. Ligaments were represented as bundles of elastic fibers. Net muscle forces were represented along straight lines.

The prosthetic components were placed on the bones such that selected fibers in the cruciate ligaments remained nearly isometric and no ligament stretched during flexion. This defined the passive motion of the joint. The effects of external load, muscle activity and variations in component placement or size were superimposed.

Component mal-placement or in-appropriate size resulted in stretched/slackened ligaments, influenced the relative positions of bones, and affected joint laxity. The model calculations show general agreement with and explain the experimental/clinical observations reported in literature.

Topics: Surgery , Knee , Arthroplasty
Commentary by Dr. Valentin Fuster
2010;():3-4. doi:10.1115/BioMed2010-32041.

Posterolateral corner (PLC) injury of the knee causes varus and posterolateral rotatory instability. The anatomy of the PLC has been reported in the literature but the importance of PLC reconstruction has only recently been established and ideal reconstruction techniques are still in development. The native function of the PLC is to restrain varus and external rotation. Reconstruction methods should properly restore these functions without overconstraining the joint. Several reconstructions for PLC injury have been reported but with concerns of iatrogenic neurovascular injury, fibular head cutout, and restoration of the knee kinematics. To address these concerns, a new cross fibula tunnel method was developed that may have lower risk of iatrogenic nerve injury and fibula head cutout. The purpose of this study was to verify the stability of this technique using a PLC deficient knee.

Commentary by Dr. Valentin Fuster
2010;():5-6. doi:10.1115/BioMed2010-32049.

The development of new instruments and surgical techniques has improved the outcome of rotator cuff repair even with massive tears. Based on cuff integrity or amount of retraction with massive cuff tears a complete repair may not be possible allowing for only partial repair. The ability to mobilize the cuff to the footprint can affect the degree of partial repair that can be performed. Partial repair may lead to abnormal biomechanics that may predispose patients to limited function and subsequent pathology following rotator cuff repair. Therefore, the purpose of this study is to compare the biomechanical characteristics of massive rotator cuff repair according to the degree of repair completion and to determine a minimum degree of repair required to restore normal biomechanics.

Commentary by Dr. Valentin Fuster
2010;():7-8. doi:10.1115/BioMed2010-32050.

Articular cartilage damage is a common source of knee pain that can be treated with autologous chondrocyte implantation (ACI). Fixation of the scaffolds can be accomplished by various means with bone sutures being the most effective. The purpose of this study was to evaluate the fixation of a new scaffold with three bone sutures after cycling with continuous passive motion (CPM). Two defects, each of 20mm diameter and 5mm depth, were created per knee and the scaffold was fixed with three bone sutures at the 12 o’clock, 4 o’clock and 8 o’clock positions. Knees were then cycled from 0 degrees to 74 degrees to 0 degrees on a CPM machine for a total of 210 cycles and the scaffolds were then evaluated for fixation, fraying and delaminations. All scaffolds were noted to have remained fixed inside the defect. Fraying occurred in 16 out of the 20 scaffolds and delaminations occurred in 12 out of the 20. Only two scaffolds were completely free of both fraying and delaminations. Fraying occurred in 32.5% of the circumference of medial scaffolds while only 15.0% in lateral scaffolds. Fraying occurred mostly over flush areas and the least over recessed areas. Overall, three bone sutures provided excellent fixation of this scaffold. If at all possible, the scaffold should be recessed into the defect to minimize the amount of fraying that occurs.

Topics: Knee
Commentary by Dr. Valentin Fuster
2010;():9-10. doi:10.1115/BioMed2010-32052.

Overhead throwing athletes have been shown to develop adaptive changes in humeral rotation to allow for higher throwing velocities. This manifests as an increase in humeral external rotation and a decrease in internal rotation, which is called glenohumeral internal rotation deficit (GIRD). The percentage of GIRD that significantly affects glenohumeral joint kinematics is not known. The objective of the study was to create a throwers shoulder model with fixed percentages of GIRD to determine at which point kinematic changes start occurring.

The results showed that there was a significant decrease in posterior translation starting at 10% GIRD. With inferior translational loads, significantly less inferior translation starts occurring at 20% GIRD. The humeral head apex position at maximum external rotation moves superiorly, posteriorly and laterally, with significant changes in the superior direction occurring with 10% GIRD onwards. Overall, significant kinematic changes begin at 10% GIRD and this should be taken into account for clinical decision-making as to when intervention is necessary.

Commentary by Dr. Valentin Fuster
2010;():11-12. doi:10.1115/BioMed2010-32056.

The properties of implant materials used in humans may have important influences on the outcomes of clinical treatments. Recently, titanium and titanium alloys have been extensively employed as in-vivo implant materials, due to their generally favorable biocompatibility, high resistance to corrosion, and relatively low cost. On the other hand, even when using chemically identical materials, the biocompatibility of an implant or its stability depends heavily on its surface structure, as well as the thickness and properties of the surface oxide film. As the characteristics of the implant surface have been reported to play an important role in the in-vivo reactions of implants, a great deal of interest has recently been focused on different surface treatment methods. Currently, there are a variety of methods with which titanium implant surfaces are treated. The anodizing method is an electrochemical technique, which forms a rough, thick oxidized capsule with nanotubular structures on the implant surface. To increase the biocompatibility and bone regeneration and to improve the current shortcomings of Ti and Ti alloy (Ti6Al4V)implants, we applied a uniquely fabricated nanotubular coating over the surface of such implants.

Commentary by Dr. Valentin Fuster
2010;():13-14. doi:10.1115/BioMed2010-32059.

The development of biomimetic materials for osteochondral tissue substitution and repair can be the start for a revolution in the classical procedures of orthopaedic surgery. The persisting problems, linked to the absence of a complete functional recovery of the articulation and to the stabilization and protraction of the half-life of an articular prosthesis can be overcome by the new class of osteochondral substitutes. The characteristics of the artificial bone tissue are drastically different from those of the natural one and this is mainly due to the absence of the peculiar self-organizing interaction between apatite crystals and proteic matrix. At this purpose a biomimetic approach was used in which apatitic phases are directly nucleated on different macromolecular matrices, which act as template and induce peculiar physico-chemical features in the mineral phase to create a substitute for osteochondral lesions. In particular a biologically inspired approach was applied to nucleate bone-like hydroxyapatite (HA) nanocrystals on self-assembling collagen fibers. Biohybrid composite materials were obtained mimicking composition, structure and morphology of human osteochondral interfaces. [1–4]

Commentary by Dr. Valentin Fuster
2010;():15-16. doi:10.1115/BioMed2010-32062.

Biodegradable magnesium-calcium (Mg-Ca) implants have the ability to gradually dissolve and absorb into the human body after implantation. The critical issue that hinders the application of Mg-Ca implants is its poor corrosion resistance to human body fluids. A promising approach to tackle this issue is tailoring the surface integrity characteristics of the orthopedic implants to get an appropriate corrosion kinetic. High speed face milling of biodegradable Mg-Ca alloy is used in this study as a possible way to achieve that goal. Polycrystalline diamond inserts are used to avoid material adhesion and likely fire hazards. All the cutting tests are performed without using coolant to keep the manufacturing process ecological. High cutting speed of 40 m/s and 200 μm depth of cut are applied in a broad range of feed values to cover finish and rough cutting regimes. The effect of feed as a key machining parameter which defines the amount and duration of thermo-mechanical load and ultimately provides higher chances for surface integrity changes are investigated.

Commentary by Dr. Valentin Fuster
2010;():17-18. doi:10.1115/BioMed2010-32064.

Objective: Long term clinical data showed that lumbar fusion for Lumbar spinal stenosis (LSS) and lumbar disc degeneration (LDD) therapy could change the loads of disc and articular facet and increase the motion of adjacent segments which lead to facet arthropathy and adjacent level degeneration. This study is to design and analyze an interspinous process device (IPD) that could prevent adjacent level degeneration in the LSS and LDD therapy. Method: The IPD was designed based on anatomical parameters measured from 3D CT images directly. The IPD was inserted at the validated finite element model of the mono-segmental L3/L4. The biomechanical performance of a pair of interbody fusion cages and a paired pedicel screws were studied to compare with the IPD. The model was loaded with the upper body weight and muscle forces to simulate five loading cases including standing, compression, flexion, extension, lateral bending and axial rotation. Results: The interbody fusion cage induced serious stress concentration on the surface of vertebral body, has the worst biomechanical performance among the three systems. Pedicle screws and interbody fusion cage could induce stress concentration within vertebral body which leads to vertebral compression fracture or screw loosening. Regarding to disc protection, the IPD had higher percentage to share the load of posterior lumbar structure than the pedicel screws and interbody fusion cage. Conclusion: IPD has the same loads as pedicle screw-rod which suggests it has a good function in the posterior stability. While the IPD had much less influence on vertebral body. Furthermore, IPD could share the load of intervertebral discs and facet joints to maintain the stability of lumbar spine.

Topics: Design
Commentary by Dr. Valentin Fuster
2010;():19-20. doi:10.1115/BioMed2010-32067.

The implementation of a wireless accelerometer application for the quantification of gait may enable an autonomous strategy for the quantification of gait. A wireless accelerometer application may potentially enable the remote, autonomous, and quantified evaluation of gait beyond the confines of a clinical facility. The accuracy and reliability for the application of accelerometers for gait evaluation has been established through the selection of specific mounting positions based on the anatomy of the subject. Wireless accelerometer systems have been successfully demonstrated for establishing a quantified gait disparity for hemiparetic subjects. For example, the quantification of hemiparetic gait has been conducted using the lateral epicondyle of the femur as a mounting position [1].

Topics: Accelerometers
Commentary by Dr. Valentin Fuster
2010;():21-22. doi:10.1115/BioMed2010-32080.

A successful spinal implant design requires that it perform consistently under a known set of loading conditions. Specifically, the loading conditions experienced in the activities of everyday living must be accounted for in both the design and testing of spinal arthrodesis implants. Knowledge of these loading conditions and, in particular, those which produce implant failure, must be addressed continuously during the design, testing and even during the actual clinical use of the implant. The goals of this presentation are: 1) to provide an understanding of typical spinal implant test procedures and, 2) to understand how to utilize real world failure data to optimize the test loading conditions which would predict failure of a spinal implant. For the first goal, ASTM standards for testing of spinal implants will be described and, for the second goal, data from a clinical case with failure of a pedicle screw connector will be utilized. This will include data from the patient’s medical records, structural and material properties of the implant material, and accident reconstruction analyses. The combined data will provide a most probable cause of implant failure and failure load.

Topics: Spinal fusion
Commentary by Dr. Valentin Fuster
2010;():23-24. doi:10.1115/BioMed2010-32081.

Patents are granted as a way to spur innovation yet profiting from that innovation can be a challenge. Many patents never make it to market and, of those that do, there are those that are infringed and others that face product liability issues. Standing at the head of all these issues is the value of the patent. The more valuable the patent is the more likely it will be that capital can be raised and the idea/product will be brought to market. However, the flip side of the valuable patent coin is the increased probability that someone will infringe the patent; and, in the event of product liability allegations, a valuable patent sends a signal that there are deep pockets for a law suit. In this presentation, economic factors will be considered that affect valuing, protecting, and defending a patent.

Commentary by Dr. Valentin Fuster

Cardiovascular

2010;():25-26. doi:10.1115/BioMed2010-32022.

A polymer based percutaneous access device (PAD) has been developed to allow for a physical interconnection between an implant and the outer world during chronic animal experiments. The PAD consists of a skin-piercing conduit connected to a flat base that is typically implanted. The skin-piercing conduit has one or more circumferential notches in its walls. The stress resulting from external forces acting on the PAD conduit is concentrated at the root of the notch. This permits the conduit to bend more easily at the notch rather than at the PAD-skin interface, thereby reducing the deleterious effect of forces on the PAD-skin interface and extending the useful life of the PAD.

Topics: Stress
Commentary by Dr. Valentin Fuster
2010;():27-28. doi:10.1115/BioMed2010-32025.

Transcatheter aortic valve implantation (TAVI) has emerged as a new intervention for high surgical risk patients with severe symptomatic aortic stenosis [1]. The outcomes of the early experiences have been promising and the treatment modality is evolving very rapidly. However, mild to moderate paravalvular leaks occur commonly, over 50% of the time, after TAVI. While mild to moderate aortic regurgitation after TAVI may not have significant clinical impact in high surgical risk elderly patients, this degree of regurgitation may have considerable consequences long-term if TAV are implanted in younger and healthier patients.

Commentary by Dr. Valentin Fuster
2010;():29-30. doi:10.1115/BioMed2010-32026.

If a small, simple heartbeat recorder, (i.e., a wearable monitoring device that is not as sophisticated or as expensive as a Holter heart monitor) could be attached to an individual, and the heartbeat timing information sent to a health center via the Internet, a significant public health benefit could be achieved. At the health center, sophisticated nonlinear computation could be performed for all the data derived from people connected to the center by such a device. This idea is important because more than 4 in 10 heart attacks (43%) go undiagnosed at the time they occur [1]. Such incidents often take people by surprise. Hence, continuous heartbeat monitoring would be an important technology.

Topics: Computation , Internet
Commentary by Dr. Valentin Fuster
2010;():31-32. doi:10.1115/BioMed2010-32039.

Detection of harder tissues within softer tissues has great advantages in both surgical and clinical applications. In surgical applications, surgeons need to precisely identify the location of potential arteries within softer surrounding tissues to either avoid damage to them or fix them. In addition, surgeons might need to detect the shape, and the location of abnormal tissues such as tumorous lumps within normal ones. In clinical applications, for more reliable detection of the breast cancer, physicists also need a tactile system more accurate than human fingers. Therefore, many challenges in surgical and clinical applications can be met by developing an accurate and a reliable tactile system.

Commentary by Dr. Valentin Fuster
2010;():33-35. doi:10.1115/BioMed2010-32068.

Understanding the characteristic of airflow, and the amount of particle deposition in different sections of respiratory system provides information for treatment procedures and processes. Results of preliminary numerical investigations for development of a system of image transfer and simulation to identify patient specific respiratory problem are presented. The system is a non-intrusive approach for evaluation of central airway diseases which could also be used for development of methods for reviving and recovery of damaged lung, especially at the onset of respiratory problems.

Commentary by Dr. Valentin Fuster
2010;():37-38. doi:10.1115/BioMed2010-32070.

Synthetic vascular grafts are an integral tool in vascular surgery. However, the consistent failure of small diameter grafts is one of the main limitations of these devices. For this reason electrospun polyurethane has been investigated for its suitability as a vascular substitute material in this present study. Aligned and random mesh electrospun polyurethane materials were produced and analysed in vitro by investigating the effect of using both materials as a substrate for the culture of human aortic smooth muscle cells. Immunofluorescence analysis showed that cells cultured on electrospun polyurethane maintained a contractile phenotype to a much greater extent than those cultured on cast polyurethane membranes. This contractile phenotype is associated with the state in which a cell would normally reside in a healthy vessel, suggesting that electrospun polyurethane may provide a suitable vascular substitute material.

Commentary by Dr. Valentin Fuster
2010;():39-40. doi:10.1115/BioMed2010-32072.

Ischemic stroke affects nearly 690,000 patients a year in the United States and is the leading cause of long-term disability and the third leading cause of death [1, 2]. Acute ischemic stroke occurs when a clot becomes lodged in a cerebral vessel, cutting off blood supply to areas of the brain. There are two treatment options for acute ischemic stroke: tissue plasminogen activator (beneficial within the first 4 hours of stroke onset), and mechanical removal (beneficial from 4 to 8 hours after stroke onset). The two FDA approved clot removal devices (MERCI and Penumbra) for ischemic stroke are capable of achieving revascularization rates between 48% and 80% [3, 4].

Commentary by Dr. Valentin Fuster
2010;():41-42. doi:10.1115/BioMed2010-32074.

We report on the development of a polymeric layer consisting of an embedded channel network. The channels are filled with a thermally responsive polymer. The embedded thermally responsive polymer is in solid phase in room ambient, but changes to liquid at physiological body temperature (∼37 °C). This phase change results in the polymer structure changing to a more flexible state. An important application of this polymer layer is its use as a thermally regulated support structure for a gastric pacing electrode, to give some rigidity to the electrode body preferable during implantation surgery, while changing to a more flexible state inside the body as the embedded polymer subsequently melts at physiological temperature. The latter is expected to reduce complications caused by a rigid device.

Commentary by Dr. Valentin Fuster

Advanced Technology

2010;():43-44. doi:10.1115/BioMed2010-32009.

Optical microscopy is an essential tool for many biomedical applications. Although commonly-used in laboratory settings, conventional optical microscopes are bulky and relatively costly to use in resource-limited settings which partially limit their use in point-of-care applications.

Commentary by Dr. Valentin Fuster
2010;():45-46. doi:10.1115/BioMed2010-32011.

Industry-physician relationships have been widely reported throughout the medical device community. However, there is limited research that describes how device developers effectively interact with physicians throughout the development of new medical products. There is also limited research regarding how the process of physician-developer interaction influences the clinical and financial outcomes of early stage companies. Knowledge of such interaction is particularly relevant to the large and growing number of complex and high-risk medical devices, in which physicians are the primary end users and patients are the recipients of care.

Commentary by Dr. Valentin Fuster
2010;():47-49. doi:10.1115/BioMed2010-32014.

This paper describes the capabilities of a miniature multi-functional in vivo robot designed and developed for Laparoendoscopic Single-Site Surgery (LESS). The paper outlines several competing design criteria including robot size, workspace volume, endpoint speeds, and endpoint forces. In this paper, the robot is evaluated according to these criteria. The workspace is described and the maximum no-load endpoint speeds and maximum attainable endpoint forces are presented. Finally, the robot capabilities are discussed, related to medical applications, and demonstrated in an animal surgery.

Topics: Robots , Surgery
Commentary by Dr. Valentin Fuster
2010;():51-52. doi:10.1115/BioMed2010-32016.

We introduce a lensless high-throughput fluorescent detection modality that can simultaneously image micro-objects and labeled cells over an ultra-wide field-of-view (FOV) of ∼8cm2 without the use of any lenses, thin-film filters and mechanical scanners. This lensfree platform utilizes total-internal-reflection (TIR) to block the excitation light, and an inexpensive absorption filter to remove the weakly scattered light that does not obey TIR. The emitted fluorescent light from the objects is then detected on the same chip without the use of any lenses. A digital deconvolution algorithm is used to resolve overlapping fluorescent spots, enabling a resolution of ∼40–50 μm over the entire field-of-view. Such an ultra wide field-of-view lensfree fluorescent imaging modality might be very valuable for high-throughput screening applications as well as quantification of rare cells such as circulating tumor cells using ultra-large microfluidic devices.

Topics: Imaging
Commentary by Dr. Valentin Fuster
2010;():53-54. doi:10.1115/BioMed2010-32024.

The continuing need for enhanced efficacy, safety, and/or functionality in in vivo therapeutics provides immense opportunity for microelectromechanical systems (MEMS). However, continuing reliance upon materials adopted from the semiconductor industry may ultimately limit the scope of what can be achieved. Many such materials suffer from poor mechanical reliability due to low fracture toughness, which results in extreme sensitivity to stress concentration and predisposition to catastrophic failure by fracture. Although mitigation via robust design and packaging is sometimes possible, this invariably increases complexity and cost. Moreover, in many emerging applications, these avenues are not available, due to design constraint and/or performance restriction, thus underscoring need for development of viable alternatives. Herein, we present an overview of high-aspect-ratio titanium micromachining techniques we have developed to address this need. We then follow with a brief summary of recent results from several applications currently under development. In each, Ti micromachining provides a means for leveraging a host of advantageous properties that yield potential for enhanced safety, reliability, and/or performance. As such, Ti micromachining shows considerable promise for extending the utility of MEMS for in vivo therapeutics.

Commentary by Dr. Valentin Fuster
2010;():55-56. doi:10.1115/BioMed2010-32028.

Field Programmable Gate Arrays (FPGAs) have dramatically changed the design of medical devices in the past decade. FPGAs offer the flexibility of writing software on a standard microprocessor and the reliability and performance of dedicated hardware. In the design of medical devices that previously required the rigorous design of custom circuits or ASIC design, FPGAs are providing a good alternative at a much lower cost for low to mid-volume medical device design. In this session, we will explore how FPGAs relate to medical device technology including real-time processing of data, high performance image processing, precise control, and code reuse from prototype to deployed device. We will explore how this technology was applied to two devices that improve the success of high-risk surgeries. In the first, FPGA technology is used to monitor blood glucose levels in patients during open-heart surgery. The second example is a device that simulates electrical signals from the human nervous system to train neurophysiologists for events that may happen during surgery. We will explore the impact FPGAs have on design cycles, briefly explore the design process, and compare different programming methodologies including C, VHDL, and LabVIEW. Finally, we will discuss the impact of FPGAs with respect to the 510k process.

Commentary by Dr. Valentin Fuster
2010;():57-58. doi:10.1115/BioMed2010-32032.

Colon cancer is estimated to be the third leading cause of cancer-related death in the US [1], with the cost of colorectal cancer treatment reaching $8.4 billion annually [2]. Though colonoscopy is the current standard for colon cancer screening and diagnosis, the procedure has disadvantages due from the near-blind navigation process used. During the procedure, endoscopists frequently lose sight of landmarks in the colon, losing track of their locations within the colon and becoming disoriented.

Commentary by Dr. Valentin Fuster
2010;():59-60. doi:10.1115/BioMed2010-32034.

The increasing appreciation of tissue cellular heterogeneity and recent identification of rare cell populations within tissues that are associated with specific biological behaviors, e.g., progenitor cells, has illuminated a limitation of current technologies to study such adherent cells directly from primary tissues. The micropallet array is a recently-developed technology designed to address this limitation by virtue of its capacity to isolate and recover single adherent cells on individual micropallets [1]. Micropallet arrays consist of hundreds of thousands of microscale polymer pedestals (“micropallets”) uniformly arrayed on a glass microscope slide. The micropallets are made from a high aspect photopolymerizable polymer using photolithographic methods. Cells are applied to the arrays and fall stochastically upon its surface, with single cells adhering to individual micropallets. Cells are then analyzed in situ and single, unperturbed cells can be selected and collected from the array by releasing the underlying micropallets using a focused pulsed laser.

Commentary by Dr. Valentin Fuster
2010;():61-62. doi:10.1115/BioMed2010-32045.

Microelectromechanical systems (MEMS) technologies are ideal for use in sub-millimeter scale actuatable transcatheter optical devices. Such technologies enable precise light path control in very small packages for applications such as optical coherence tomography (OCT) and photodynamic therapies. Indeed, there have been numerous published reports of such devices that utilize silicon-based MEMS technologies and actuation methods including piezoelectric, electrostatic, thermal expansive, and electromagnetic [1–4]. We report a novel, dual axis, magnetically actuated micromirror for endoscopic applications that is fabricated from a photopatternable polymer using photolithographic techniques. Our approach provides improvements over other actuation methods and silicon-based devices.

Commentary by Dr. Valentin Fuster
2010;():63-64. doi:10.1115/BioMed2010-32075.

Video capsule endoscopy (VCE) is a non-invasive method of visually examining the internal lumen of small intestine for inflammation and bleeding through a wireless camera contained in a small capsule. Currently, VCE technology is limited because it cannot map images to their specific locations in the small bowel. Furthermore, approximately 40% of identified problem areas are false positives, making bleeding difficult to find. Therefore, physicians can only estimate the location of inflammation and bleeding areas based on the elapsed time before performing a wired endoscopy.

Our pill camera offers an innovative wireless imaging GPS-like location system, in an easy to swallow pill that accurately identifies and displays bleeding areas within the small intestine through an intuitive user interface, which results in a 50% reduction in clinical times, as well as improved diagnosis for potential investors and providers, thus resulting in a $500 cost reduction in physician fees per patient.

Commentary by Dr. Valentin Fuster
2010;():65-66. doi:10.1115/BioMed2010-32076.

Due to the nature of the interfaces used by microfluidic devices — syringes, syringe pumps, and tubing, delivering cells into microfluidic devices faces some practical challenges. Specifically, the unwanted settling and adhesion of cells onto various surfaces can significantly impact the effective transport of cells into the device.[1] One particular challenge is the cell settling that occurs inside devices and especially at the inlet connection port. As most tubing connections are vertical, the cell suspension moves downwards into the device before making a 90° turn into the fluidic channels. This orientation causes cells to settle, clump and adhere to surfaces around the inlet port and eventually causes clogging that prevent more cells from entering the microfluidic channels.

Topics: Microfluidics
Commentary by Dr. Valentin Fuster
2010;():67-68. doi:10.1115/BioMed2010-32077.

Microassays can take on the order of 1 to 72 hours due to complete the lack of mixing [1]. Various micromixers have been developed to quicken assay times, but they require bulky external equipment, difficult to fabrication and implementation, or are expensive. Robin Liu et al developed a low cost micromixer based on cavitation microstreaming which is easy to implement and has low power consumption. The device consists of small cavities or vertical cavity acoustic transducers (VCAT) located above a microfluidic chamber such that these small cavities trap air when a solution is injected into the chamber. A piezoelectric transducer (PZT) is then placed above the air cavities and is used to vibrate the air-liquid membrane to produce cavitation microstreaming within the chamber to cause mixing [2].

Commentary by Dr. Valentin Fuster

Posters

2010;():69-70. doi:10.1115/BioMed2010-32006.

Medical equipment that is used in the MRI room, such as infusion pumps, contrast injectors, patient monitors, anesthesia machines may malfunction and potentially injure the patient if not kept outside of a specific magnetic field strength. In addition, some equipment can degrade the MR image quality because of electromagnetic interference if this equipment is brought too close to the magnet.

Commentary by Dr. Valentin Fuster
2010;():71-77. doi:10.1115/BioMed2010-32008.

This research purpose is to develop minimal medical units applying heated actuations of the Shape Memory Alloy (SMA) transducers using the medical Ti-Ni material, in order to enable minimal hypodermic invasive microvolume either blood suction or drug delivery by equipping nontoxic and minimal edged microneedle to be created in my laboratory. I have focused on lymphocytes for immunotoxin and erythrocytes for glucose level in blood. This paper has reported double-action mechanisms of the compact unit in originally developing and its actions by low DC inputs. The Joule’s heating of the SMA coil spring transducer might be useful for indenting blood vessels whose diameter was larger than the microneedle because of generating indentation stroke of 2 mm and recovery force of 0.25 N 0.6 s later from heating when applied DC 2 V and 0.5 A. When applied DC 1.5 V and 2 A, the octagonal-pyramidal foil transducer for blood suction recovered as plane condition as before octagonal-pyramidal forming 8 s later from heating.

Commentary by Dr. Valentin Fuster
2010;():79-80. doi:10.1115/BioMed2010-32012.

Manipulation of large internal organs, e.g., spleen, kidney, and liver, is a demanding but challenging task during laparoscopic surgery using conventional miniature instruments. Recently fingered hand instruments have been proposed for doing this task which are assembled/disassemble inside the patient’s abdomen [1–3]. They are not, however, feasible for use in real surgeries considering the substantial time needed for their setting up process. This paper describes the conceptual design of an effective laparoscopic instrument for manipulation of large human organs. A novel mechanism is presented which enables the instrument to pass through a 10 mm trocar to enter the abdominal cavity when it is closed, and grasp body organs, as large as 80 mm diameter, when it is opened. It is shown that the instrument can be used effectively for laparoscopic surgery operations without the need to an assembling/disassembling procedure.

Commentary by Dr. Valentin Fuster
2010;():81-82. doi:10.1115/BioMed2010-32020.

Recent developments in device technology and widespread use of cell phone and wireless technology globally have provided an unprecedented opportunity for enhanced healthcare delivery. This study presents development of a cell phone based electronic healthcare system for remote monitoring and control of patients. The system comprises of two modules, each connected to a cell phone for communication of data or instructions. The first module allows real-time data acquisition and analysis from several devices that may be connected to the patient. By calling the cell phone for this module, data can be accessed or any of the connected devices be controlled remotely. Any observed abnormality is reported in real-time by calling a pre-set cell phone. This module allows interactive communication utilizing machine generated voice. Also, this module calls the second module at regular time intervals to transfer the patient’s data over phone. The second module thus receives the data for storage in a central location. All of these features of the system were tested successfully on simulated patient devices. For data and device security, ID and password verifications are required.

Topics: Health care
Commentary by Dr. Valentin Fuster
2010;():83-84. doi:10.1115/BioMed2010-32033.

Compliant mechanisms are flexible devices that transform an input force to a displacement through elastic deformation. Advantages of using compliant mechanisms are that they are monolithic devices that contain flexible members that can undergo large deflection, have fewer joints, have increased reliability, increased precision and have fewer components compared to rigid-body mechanisms.

Commentary by Dr. Valentin Fuster
2010;():85-86. doi:10.1115/BioMed2010-32042.

Programmers creating mission-critical applications — embedded control applications, industrial monitoring applications, and high-performance test systems — cannot afford to introduce errors or uncertainty into the system. The stakes are especially high in medical applications, where failure can often lead to patient injury and costly product recalls.

Commentary by Dr. Valentin Fuster
2010;():87-88. doi:10.1115/BioMed2010-32043.

The capacity to quantify gait in autonomous scenarios may substantially alleviate the rampant strain on limited, scarce, and highly specialized medical resources. A strategy for enabling application autonomy, for which the subject may reside at a remote distant from the clinical resources, has been demonstrated through the research, development, test, and evaluation of wireless accelerometers for gait analysis. An approach for maximizing accuracy and reliability has been demonstrated through the selection of a predetermined anatomical mounting position relative to the human anatomy. Wireless accelerometer systems have presented quantified disparity for the gait of hemiparetic subjects. For the quantification of hemiparetic gait, the selected mounting positions were the lateral epicondyle of the femur and also the lateral malleolus [1].

Topics: Accelerometers
Commentary by Dr. Valentin Fuster
2010;():89-90. doi:10.1115/BioMed2010-32044.

Combined injuries of the posterior cruciate ligament (PCL) and the posterolateral corner (PLC) of the knee results in posterolateral rotatory instability. The detailed anatomy and kinematics of the PCL is well described in the literature as well as the anatomy of the PLC; however, the detailed kinematics of the posterolateral corner ligaments and tendons are not well understood. This information on the posterolateral corner is important for developing a strategy for accurate anatomical reconstructions. Therefore, the purpose of this study was to quantify the detailed kinematics of the posterolateral corner of the knee ligaments and tendons.

Commentary by Dr. Valentin Fuster
2010;():91-92. doi:10.1115/BioMed2010-32047.

Glenohumeral joint stability is provided by complex interaction between the passive (bony geometry, capsule, and ligaments) and active (muscles) stabilizers [1]. The functional roles of geometry, capsule, ligaments, and muscles have been evaluated by sequential cutting studies [2–4] or direct measurements [5–7]. However these isolated function of individual stabilizer does not replicate in vivo glenohumeral joint biomechanics where the joint stability is controlled by interaction between passive and active stabilizers. Direct measurement device instrumentation on the soft tissue do not allow entire capsular strain measurement during rotational range of motion. Sequential cutting of the soft tissue can result in alteration in the synergy of passive and active stabilizers. To replicate in vivo interaction between passive and active stabilizers it is required to minimize the measurement device instrumentation on the glenohumeral joint capsule while the joint stability is provided by both passive and active stabilizers. Therefore, the objective of this study was to quantify the simultaneous contribution of the capsule and muscles using a geometry-driven biomechanical analysis.

Commentary by Dr. Valentin Fuster
2010;():93-94. doi:10.1115/BioMed2010-32057.

Surface registration is a necessary step and widely used in medical image-aided surgery. It’s relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points (651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This transformation contains [0,−9.5, 1] degrees for yaw, pitch and roll rotation and [−3, 14,−13] translation. The related results shows [0, 9.3, 0.95] degrees for rotation and [−2.85, 14.11,−13.07] translation.

Commentary by Dr. Valentin Fuster
2010;():95-97. doi:10.1115/BioMed2010-32060.

In the relatively young field of cardiac tissue engineering, different biomaterials, methods and techniques have been tested for cardiac repair. In this study we examined the validity of a series of new preformed membrane scaffolds, based on collagen type I, for the transplantation of cardiac cells. One type of membrane, cross-linked with 1,4-butanediol diglycidyl ether (BDDGE) and fibronectin-enriched, gave rise to spontaneously beating heart cell constructs 5–9 days after seeding with neonatal rat cardiac cells. This membrane was then grafted, with and without beating cardiac cells, onto the infarcted area of rat models of heart failure. Seriate echocardiography, performed on rats before transplantation and at 4 and 8 weeks after transplantation, showed that rats that received collagen membranes with beating cells showed an improvement in cardiac function after 8 weeks. These results suggest that this new type of collagen membrane can be used as vector for the transplantation of beating heart cells to the injured myocardium, hence representing an important potential tool for cardiac tissue repair technologies.

Topics: Membranes
Commentary by Dr. Valentin Fuster
2010;():99-100. doi:10.1115/BioMed2010-32061.

The development of biodegradable implants has had a beneficial effect on in-vivo treatment of patients with various bone ailments. Currently, biodegradable implants are mainly made of polymers, such as PLA or PMMA. However, these polymer based implants usually have unsatisfactory mechanical strength and are prone to considerable amounts of wear [1]. An alternative to polymers is a biodegradable magnesium-calcium (Mg-Ca) alloy which has the ability to gradually dissolve and absorb into the human body after implantation. The similar properties of Mg to bone indicate it is an ideal implant material to minimize the damaging effects of stress shielding. The critical issue that hinders the application of Mg implants is poor corrosion resistance to human body fluids. Sequential laser shock peening (LSP) of a biodegradable Mg-Ca alloy was initiated to create a superior surface integrity for improving implant performance. LSP is an innovative surface treatment method to impart deep compressive residual stresses across a broad area of an implant. The high compressive residual stress has great potential to slow corrosion rates and improve wear and fatigue performance. Also, LSP produces a unique surface topography. Structural surface modifications are an effective way to alter the implant/tissue interface in order to improve biocompatibility.

Commentary by Dr. Valentin Fuster
2010;():101-102. doi:10.1115/BioMed2010-32073.

We describe the development of devices that utilize the dynamics of laminar microflows for time-resolved emission measurements with steady-state excitation and detection used solely in DC modes of operation. Our current setup allows for measurements of emission lifetimes as short as tens of microseconds. We demonstrated the function of the devices on determining the lifetimes of chelates of lanthanide (III) ions.

Commentary by Dr. Valentin Fuster
2010;():103-104. doi:10.1115/BioMed2010-32078.

Many trauma related surgical procedures cannot ethically be practiced by medical students or inexperienced doctors. Therefore, medical simulators that provide high anatomical and procedural fidelity are used. One of the most important things to monitor during such a procedure is the vital signs of the patient. One procedure for which this is important is a cricothyroidotomy, in which an incision through the skin and cricothyroid membrane is made to secure a patient’s airway during certain emergency situations in which an airway obstruction is present. The amount of cases per doctor is further amplified in many developing countries, with many of these clinicians not being able to practice before being in the real-life situation, partially due to the high cost of current simulators. Therefore, a low-cost cricothyroidotomy simulator with a live feedback system that tells the clinician the vital signs of the patient that they would be monitoring in such a situation that includes heart rate, blood pressure, respiratory rate, oxygen content, and ECG was developed.

Topics: Feedback
Commentary by Dr. Valentin Fuster

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