Subrata Saha

THE NEED OF BIOMEDICAL ETHICS TRAINING IN BIOENGINEERING

ABSTRACT The need for biomedical ethics training for bioengineers is discussed. Such training will be helpful to: 1) guide conducting human and animal experimentation; 2) meet the legal responsibilities associated with device or implant design; 3) reduce burnout of clinical engineers and 4) decide priorities in research and development. The need for adopting a Code of Ethics for the biomedical engineering profession is also pointed out.

The effect of drill hole location on load bearing capacity of long bones

We investigated how load bearing capacity (LBC) of long bone differs with a bicortical drill hole in a compressive/tensile location vs. a neutral location. Group I had a hole drilled through 0°/180° ([compressive at 0°/maximum tensile at 180°]), Group II at 90°/270° ([neutral]), and Group III at 135°/315° ([tensile at 135°/compressive at 315°]). Maximum load at failure and stiffness was measured. A significant ([pu202f<u202f0.05]) decrease in LBC of all Group I and Group III bones was observed. Loss of strength for Group II was statistically insignificant ([pu202f>u202f0.05]). Changes in stiffness for both tibias and fibulas was not statistically significant ([pu202f>u202f0.05]).

Artificial Intervertebral Disc Replacement to Provide Dynamic Stability to the Lumbar Spine: A Finite Element Study

Currently, intervertebral disc prostheses that are designed to restore mobility to a vertebral segment are possible for the lumbar spine. The ball-and-socket joint is a constrained design, wherein the rotational axis of the intervertebral joint is forced to pass through the center of the spherical surfaces that form the joint. One advantage of ball-and-socket joints versus unconstrained designs includes better shear stability, which results in sufficient flexibility. In this study, finite element analyses were performed in preimplanted and implanted (intervertebral disc replacement [IDR]) lumbar spine (L1-S) models to examine range of motion (ROM) and the resulting mechanical responses in the implant and the adjacent bones. Four physiological loading conditions including flexion, extension, and left and right lateral bending were analyzed to observe the effect on ROM under a 10-Newton meter moment. In terms of mechanical response, this study shows that disc replacement is an viable alternative to fusion surgery. The added advantage of IDR over fusion for degenerative discs is the reduced chance of disc degeneration at the adjacent segment of spinal vertebral column; with fusion surgery, chances of degeneration are increased.

Electromagnetic Response of Bones Adjacent to the Dental Root Before and After Dental Implantation

The aim of this study was relative variation quantification of the total electric field (EF) sum in a region very close to a dental root of the first molar tooth for two different materials: dentine (before implantation) and titanium (present in a screw after implantation), due to development of electrical charges generated by chewing force on the tooth. Because bone is a piezoelectric material, mechanical strain that is generated by chewing force on bone adjacent to the dental root produces electrical charges. Relative variations in the EF sum values with distance of nodes from the centerline of the root was observed for both cases and studied for two different boundary voltage conditions. Simulation and analysis were performed using the commercial finite-element analysis package ANSYS14. The detailed convergence analysis validated the effectiveness and accuracy of finite-element simulations. Before and after implantation, a significant variation in generation of electric charges at adjacent bone of the dental root was observed. We found that the differences in stress generation at the adjacent bone for those cases were just 5%, on average.

A Biomechanical Comparison of Different Tendon Repair Techniques

Previous studies have examined multiple suture techniques for the repair of ruptured tendons. In this study, we investigated how the two- and four-stranded Krackow suture weave techniques compared with a novel Krackow/Bunnell suture technique. Our hypothesis was that the Krackow/Bunnell suture would have greater strength compared with the two- and four-stranded Krackow suture in terms of resistance to pullout from the muscle tendon. Thirty fresh bovine Achilles tendons were assigned randomly to three groups: (1) two-stranded Krackow, (2) fourstranded Krackow, and (3) the Krackow/Bunnell combination. After suture placement, all specimens were subjected to initial cyclic loading (0-200 N for 200 cycles) and then the tension to failure force defined as the pullout through the muscle tendon was evaluated. Significantly greater deformation before suture failure was seen in the Krackow/Bunnell group compared with the four-stranded Krackow construct (36.2 vs. 28.7 mm, p = 0.009), as well as greater energy required to rupture the suture (4635 vs. 3346 N/mm; p = 0.016). There was no significant difference with regard to the force to failure between the two groups (four-stranded Krackow vs. Krackow/Bunnell). The two-stranded Krackow was found to be inferior to both the four-stranded Krakow and the Krakow/Bunnell techniques with regard to load to failure. We have found that the Krackow/Bunnell suture technique is at least comparable to, if not superior to, the four-stranded Krackow technique with regard to deformation before suture failure and energy required to rupture the tendon. Therefore, the Krackow/Bunnell technique may be an optimal construct if the surgeon is concerned about suture pullout through the tendon; however, future studies evaluating this technique in the clinical setting are required before making any final conclusions for patient use.

Strength of Syndesmosis Fixation: Two TightRope versus One TightRope with Plate-and-Screw Construct

Injuries involving the distal tibiofibular syndesmosis can lead to critical destabilization of the ankle mortise. Although specific indications for operative fixation remain unclear, accurate reduction of the syndesmosis has been correlated with the best functional outcomes. The purpose of this study was to evaluate the maximum torque and rotation to failure after fixation with a novel construct. Seven pairs (14 ankles) of embalmed cadaveric lower legs, disarticulated at the knee, were obtained. Each pair was randomly assigned to receive either two TightRopes (Arthrex) or a plate-and-screw construct with one TightRope. All samples were mechanically tested in torsion to determine peak torque, torsional stiffness, and the maximum rotation angle at which failure occurred. Differences between the groups were compared using paired Students t test. The maximum torque to failure after fixation was not significantly different between the two TightRopes (28.8 N*m; range, 7.3-49.7 N*m) and the one TightRope group (29.5 N*m; range, 9.2-44.9 N*m; p = 0.92). The maximum rotation to fracture after fixation was not significantly different between the two TightRopes (33.3 degrees; range, 21.6-57.0 degrees) and one TightRope group (38.6 degrees; range, 23.0-73.9 degrees). All specimens failed with the fracture of the fibula at the level of the inferior syndesmotic screw. The similar load to failure of the two TightRope and the one TightRope and plate-and-screw plate suggested similar stiffness between the two constructs. The addition of the plate may improve distribution of forces at the level of syndesmosis, reducing stress risers and decreasing the risk of failure, as demonstrated by a lower rotation to failure of the one TightRope with plate-and-screw construct. In addition, this construct is not likely to not be associated with any substantial cost increase. Further clinical studies may further elucidate the role of plate and/or TightRope augmentation to syndesmosis fixation.

The Need for Ethics in a Bioengineer's Life

Technology has solutions to almost every health problem and if it doesnt have one yet, it will. We are fast approaching the possibility of replacing every part of our body including parts of our brain. Ground breaking technology is helping the blind to see with an interface between artificial vision systems and the retina. We may even be able to alter our personality. We are looking at the possibility of correcting disease states at the genetic level. Eventually, we will not only have the ability to conquer deficits and illness but we will be able to transform ourselves genetically to improve capacity intellectually and physically, thus changing the trajectory of our evolution. We may even be able to extend human life indefinitely. Bioengineers along with society are at a crossroads of possibilities, some of which are exciting and some of which may even be dangerous. How will limits on undesirable technology be imposed in a world that fails to unite around climate change or weapons of mass destruction? As bioengineers get appropriate training in ethics, they will be better prepared to address the ethical challenges that they might face during their professional life. In the end, its our values, principles, and beliefs that make us human.

Biomechanical Properties of Osteophytes and Non-Osteophytic Cortical Bone: A Preliminary Study

Introduction: Several studies have associated the development of spinal osteophytes with disc degeneration. Others have characterized them as adaptive bone remodeling in response to unusual stress/strain. No recent study examined the microstructure and mechanical properties of osteophytes. Materials and methods: Bone tissues were harvested from eight different human cadavers. Beams (length: 24mm, width: 4mm, thickness: 2mm) from lumbar osteophytes, lumbar anterior cortices (non-osteophytic), and femoral diaphyseal cortices were tested for three-point bending and micro-hardness. The specimens were subsequently divided into two parts for material density, ash density, and histological analyses. Results: Hardness values (HV) decreased by 39% from femoral cortical to spinal osteophytic samples. The maximum load to failure for osteophytic and non-osteophytic vertebral beams was 64 and 4 Newtons (N), respectively. Material density ranged from 1.40 to 2.0g/cm3 and 1.18 to 1.70g/cm3 for cortical bone and osteophyte, respectively. Undecalcified histology showed a disorganized structure of the osteophytic osteons as compared with the regular pattern observed in femoral diaphyseal cortical bones. Conclusion: Vertebral osteophytes have higher load carrying capacity than vertebral cortical bone. However, cortical bone presents a more mature and organized microstructure than osteophytes.

Current Concepts in Sports-Related Concussion

Traumatic brain injury, specifically concussion, is prevalent in contact sports. In the United States (US) each year, 170 million adults participate in physical recreational activities, and 38 million children and adolescents participate in organized sports. The Centers for Disease Control estimate that in this group ~1.6 to 3.8 million concussions occur annually. Recent class-action lawsuits in the US filed by professional athletes against their respective leagues allege negligence in protecting them from concussions, and this has contributed to the attention received in the popular media. In response, concussion-related publications have increased exponentially during the past several years. Recent studies have challenged earlier assumptions that the effects of concussion are transient. Stronger links between concussion and neurodegenerative processes such as Alzheimers disease-like conditions, depression, and heightened risk for suicide are being elucidated. In this article, we explore the current knowledge on concussion, including pathophysiology, management, and long-term effects. We conclude that more evidence-based results regarding guidelines for diagnosis, treatment, and return to play (RTP) are needed and should be the focus of future investigations. Attributing the etiology of certain neurodegenerative conditions to a history of concussion has been suggested in the current literature, but additional quantitative data regarding the pathophysiology and causality are needed as well. Bioengineers can have an important role in measuring the dynamic forces encountered during head impacts and their effects on the brain. These results can be effective in designing better helmets as well as improved playing surfaces to reduce the impact of such injuries. At this time, we believe that groups of people with heightened risk for concussion should be followed closely during longer periods of time and compared to matched controls. Such long-term studies are urgently needed to develop appropriate guidelines for safety and protect our young and adult athletes in the future.

Guiding patients toward prudent use of technologies.

A physician with a patient who demands a diagnostic test should focus on the patient-physician relationship and appropriate use of resources. Virtual Mentor is a monthly bioethics journal published by the American Medical Association.