Clinical treatment of Glioblastoma Multiforme (GBM) is generally ineffective in increasing patient survival. Convection-enhanced delivery (CED) is an alternative, investigative therapy in which a small caliber catheter is placed directly into the brain parenchyma. However, standard CED drug delivery techniques are unable to reach the entirety of the brain tumor, attributing to the failure of Phase III clinical trials. Fiber optic microneedle devices (FMDs), capable of simultaneous fluid and laser energy delivery, have shown potential to increase the drug dispersal volume when compared to fluid only devices. Previously described FMDs have had low laser transmission efficiency. In this work, we present two FMD manufacturing methods, a solid fiber inside capillary (SFIC) FMD and a modified fusion spliced (FS) FMD. Transmission efficiency of the two proposed FMDs were measured using a 1064 nm laser and an integrating sphere detector with air, deionized water, and black ink inside of the bore of the FMDs. The transmission efficiency of the FS FMD was between 45 and 127% larger than that of previously reported FS FMDs. Additionally, the transmission efficiency of the SFIC was significantly higher than the FS FMD (p ≤ 0.04 for all groups). However, the SFIC FMDs suffered catastrophic fracture failure at bend radii smaller than the manufacture specification, likely due to scribing of the capillary during the FMD fabrication process. Modifying FS FMDs appears to be the preferred fabrication method providing improved light transmission efficiency and mechanical strength on par with the capillary manufacturer’s specifications.

Trainees in orthopedic surgery are required to receive dedicated laboratory-based surgical skills training in their first year of residency. Simulators are often used in this training. Our group previously developed a hip fracture wire navigation simulator to train and assess skill in placing a K-wire within a femur bone surrogate using synthetic fluoroscopic images to aid in navigation. In this paper, we describe design considerations and challenges in modifying the existing simulator to enable the training of multi-wire pinning of a pediatric supracondylar humerus fracture. The design involves changing the bone of interest from the adult femur to the pediatric humerus, while using the same platform technology. Considerations include ease of use, minimizing motion of the fixed bone, and minimizing materials used. The robustness of the bone mounting was tested by running an experiment using 3D scans and surface deviation analysis to test repeatability of bone placement and its resistance to rotational motion after being placed in the fixture. After the new design was shown to hold the bone rigidly, a pilot study of the new simulator was conducted to confirm that the surgeons and residents consider the simulator experience as being a valid representation of the actual surgical skill.

Open Reduction and Internal Fixation (ORIF) of scapula fractures have increased in numbers recently. This is due to better functional outcomes achieved post-ORIF than non-operative management techniques. In South Africa, there is only one available supplier for anatomical contoured scapula plates used in the ORIF. This study examines the fit of these plates on the bony topology of fifty healthy scapula. It was observed that the short medial body plate performed the best in adhering to the bone topology followed by the short acromion plate. The glenoid plate and the long acromion and body plates were not adequately designed to fit their intended regions on the scapula. In conclusion, this study highlights the drawbacks in design of current commercial plates available for ORIF of scapula. Further studies are needed in order to evaluate the quantitative-fit performance of these plates on fracture scapula surfaces.

The study aims to design and develop an Adaptive Bone Fracture Fixation System for the purpose of enhancing the control over fracture fixation as well as to permit quick device installation. The external ring fixator was designed to employ the use of bolted-nut hinges and rapid-gradual lengthening longitudinal elements to allow for full assembly expansion and progressive or immediate shape adjustment. The ring fixator was stress tested via direct loading (compression and tension) to determine if it can support the average human body weight [max 3.5 kN]. The study had verified that the device possesses intricate designs that would enhance the functionality of the external ring fixator, however these designs would limit the structural integrity of the bone fracture fixation system.

The American Board of Orthopaedic Surgery has mandated dedicated skills training for first-year orthopedic surgical residents. 1 Most residency programs address this requirement with training exercises with cadavers and plastic foam bones. Some programs incorporate one or more simulators in their skills training, including several sophisticated virtual reality simulators and a variety of low-tech simulators. Simulators are helpful because they can provide repeatable educational experiences and quantitative performance assessment. Unfortunately, few simulators have been developed for orthopedic trauma skills training. Even fewer simulators have been developed and validated with more advanced students, such as residents in their 3 rd or 4 th year of training, and for more complex surgeries. In contrast to the completely virtual surgical simulation using haptic feedback devices and sophisticated renderings of soft tissue deformation, our group has chosen to use physical models, real surgical instruments and position tracking in conjunction with virtual reality. 2–4 The physical models provide experience with the surgical tools, and enable more realistic hand movements and haptic cue feedback.

Fracture toughness is an important mechanical property of materials that describes the failure of material by cracking. Yet, characterizing fracture toughness in soft tissue cutting is still a challenging task as the behavior of the soft tissue may vary under different tissue, cutting and pre-crack conditions [1]. Predicting cutting force has been important to needle biopsy design, surgical planning/training, and other surgical operations. However, in order to obtain accurate predictions, understanding the fracture toughness is crucial. In this study, we present an approach to characterize the fracture toughness directly from cutting experiments of hollow needle cutting soft tissue mimicking materials. Cutting tests are carried out to obtain the dynamic force response of gelatin samples when being cut by non-rotational and rotational hollow needles. The data is used to establish a mixed-mode fracture behavior which is then used to implement a cohesive surface based finite element model. Nearly 1% difference of the axial cutting force between the simulation and experimental results showed that the approach is capable of predicting accurate cutting force in rotational needle biopsy. The approach also has the potential to be used to predict the cutting force in various types of needle biopsy.

Stent implantation is widely used to treat blocked lumen. Stents were meshed structure made of polymers and metal alloys, including stainless steel, cobalt chrome and nitinol [1]. Clinical studies had demonstrated that stents helped to scaffold the diseased lesion up to one year when tissue adapted to the stented environment [2]. However, the permanently implanted stents inside artery were associated with complications such as stent fracture, tissue inflammation, in-stent restenosis and thrombosis [3]. Currently, biodegradable stents are attracting more attention due to its potential long-term efficacy in treating blocked lumens. The detailed characterizations of biodegradable stents are essential for the desired clinical outcomes.

The physical impairment caused by OA of a single lower extremity joint is comparable to that reported for major life-altering disorders such as end-stage kidney disease and heart failure. (Buckwalter, et al) [1] Ankle distraction arthroplasty has been shown to greatly decrease pain due to end-stage ankle arthritis. Unlike arthrodesis (fusion of the joint), distraction arthroplasty maintains the joint’s natural movement, and it is far less complicated than total joint replacement surgery. There is a considerable body of research supporting the idea that distraction of an end-stage arthritic joint (most of the work thus far has been done on ankles, although there has also been some investigation of the efficacy of the treatment for knee arthritis) for a period of weeks allows the growth of new tissue in the joint. Although this tissue is not true articular cartilage, distraction arthroplasty has been shown to significantly decrease pain and, in the majority of cases, to be a long lasting remedy for a condition that would otherwise commonly be treated with arthrodesis. [2] Devices currently available for this procedure are generally quite complicated because they are designed for a wide range of functions related to bone fixation. This versatility also tends to make those systems larger and more expensive, and their aggressively mechanical appearance makes potential joint distraction patients hesitant to select the procedure. While fracture patients may not have a choice about being treated with such devices, elective patients are instinctively resistant to their use, even when assured that the end result will most likely significantly improve in the quality of their lives.

According to National Institute of Neurological Disorders and Stroke (NINDS), a division of National Institutes of Health (NIH), about 80% adults suffer from low back pain at some point in time and about 2 out of 10 people who are affected by acute low back pain develop chronic low back pain with persistent symptoms at one year [1] . Though in some cases, treatment does relieve chronic low back pain, but in other cases, pain persists despite treatment. Mostly, the lower back pain is of mechanical nature, i.e., disruption in the way the components of the back (the spine, muscle, intervertebral discs, and nerves) fit together and move. The causes of lower back pain can be imputed to various conditions such as sprains and strains, osteoarthritis, herniated discs, whiplash, compression fracture, scoliosis, stenosis, inflammation of joints, osteoporosis. It not only causes pain, but also severs the economy of a nation. It is a major contributor to missed workdays [1] . Research indicates that the total indirect costs due to back pain accrue to more than $100 billion annually [2] . Not many people can afford traveling by car or taxi to office, especially in developing countries and in cities with high traffic, where people prefer to travel by two-wheelers for their access to work and other amenities. However, people with lumbar problems are recommended not to use two-wheelers as the movement of the body on uneven roads or while braking/accelerating may increase the pain and discomfort. This reduces the productivity of not only the individual and the firm but also the productivity of the country as a whole.

Lower limb length discrepancy (LLD), defined by unequal length of paired lower limbs, contributes to lower back pain, osteoarthritis of the hip, and stress fractures [1–3]. The Center for Disease Control and Prevention estimated that there were approximately 700 children born with LLD each year in US [4]. Patients may receive distraction osteogenesis treatment, in which an osteotomy is performed on the shorter limb, and mechanical force is applied to gradually distract the two halves of the bone during the healing process. This stretches the bone callus during healing to achieve desired limb length upon callus consolidation [5]. The current correction devices are external fixators that leave unsightly scars and are prone to infection [6]. While recently developed intramedullary devices address many of the persistent issues with external lengthening devices, size limitations and potential damage to the bone growth plates make them impractical for use in children [7, 8]. The proposed research addresses an unmet need by developing a novel implantable extramedullary device for LLD correction that is targeted for pediatric use. The device will be implantable, submuscular, and fixed to the outside surface of the bone (extramedullary), thus allowing for use in children without concern for injury to the growth plates. The device’s function will be similar to an external fixator; however, it will not require exposed hardware, which increases risk of infection, or muscle penetration from the pins, which causes pain. Additionally, the device incorporates real-time control of the distraction rate, reducing the risk of complications arising from fixed rate distraction such as premature consolidation and non-union of the callus. [9–11]. The investigators of this study have previously designed and constructed a distraction mechanism prototype and test frame [10]. The current study aims to validate the real-time controller of the prototype.

Seligson [1] describes how Hoffmann and Jaquet, a medical doctor and an engineer, respectively, developed the original Hoffmann fixator as a tool to stabilize human fractures with minimal invasiveness. Whether being utilized in mass trauma injury situations such as the 2010 Haitian earthquake, within our emerging geriatric population, or in veterinary applications, external fixation is widely used [1–4]. In this investigation, a rod-to-wire coupling, shown in Figure 1, and hereafter referred to as the R2W clamp, has been designed and validation tested for Stryker Orthopaedic’s Hoffmann II (HII) External Fixation System. As the name implies, this clamp has the purpose of connecting 8mm rods to 1.5mm or 2mm Kirschner (k-) wires or olive wires to stabilize bony fragments in the lower extremity, thus expediting healing in a trauma case. This paper summarizes the results of the validation tests conducted on prototype clamps. This clamp effectively allows placement of a wire to further stabilize a frame [3] by allowing wire placement without the addition of an intermediate ring, as shown in Figure 2. The wire could be added to any configuration with two parallel rods extending in plane with the bone. As shown in Figure 3, the R2W clamp can be positioned “outboard” with the rod between it and the bone, or “inboard” between the rod and the bone, allowing the surgeon geometric flexibility. The use of two k-wires is recommended to stabilize each bone fragment [5]. One of the goals of the validation testing was to determine the effectiveness and functional safety of the clamp as related to surgically applied k-wire tensions of either 50 kg or 100 kg. Since it is feasible that surgeons may tighten, loosen, then retighten the clamp while positioning it during surgery, the effects of clamp retightenings on the performance of the R2W clamp were also evaluated [4].

This research presents a virtual reality simulator for total hip replacement surgery. The simulator supports a library of 3D hip stem models for different sizes and manufacturers. The 3D hip stems can be adjusted in size and shape by parametric software and sent for 3D printing. Biocompatible materials such as titanium enable the 3D printed stems to be directly implanted on patients. Currently surgical simulation for orthopaedic procedures is not as advanced as other surgical disciplines. As a result there are only limited training simulators available for orthopaedic surgery such as total hip replacement, hip resurfacing or knee replacement. This is demanding since 66,000 hip replacements are performed annually in the UK. One area which is neglected in VR orthopaedic simulation is the digital library generation of implants. Currently orthopaedic surgeons have limited choice in terms of an exact identification of implant specific to patient requirements. We conducted a literature review of orthopaedic training simulators which found no simulators catering for this [9]. Orthopaedic surgeons generally have a positive opinion for the use of virtual reality (VR) training systems. A survey amongst all orthopaedic surgeons in New Zealand found that 77% of qualified surgeons believe simulation is effective for practicing and learning surgical procedures [1]. A separate review from the American Academy of Orthopaedic Surgeons (AAOS) showed that over 80% agreed that surgical skills simulations should become a required part of orthopaedic training, based on views from 185 program directors and 4549 residents. There was a strong agreement that simulation technology should be a required component of orthopaedic resident training [2]. The hip replacement procedure has been considered as the most successful and influential orthopaedic surgery of the twentieth century. Currently over 66,000 total hip replacements (THR) are performed each year in England and Wales by the National Health Service (NHS) and around 75,000 hip fractures are treated each year in the UK. Knee arthroscopy has increased 49% from 1996–2006 and now over 1 million are performed each year [3]. Each year there are an increasing number of orthopaedic procedures due to the aging population. Currently 247,000 hip fractures occur yearly in the United States, with the majority occurring in the population over 45 years old [4]. The incidence of hip fracture is also on the rise, partly due to the aging population, with over half a million hip fractures annually expected by 2040. The cost of these fractures is also expected to rise from $7 billion per year [4], to nearly $16 billion per year by 2040 [5]. Each hip fracture is estimated at costing between $39,555 and $40,600 in the first year after surgery [6]. Hip fractures have the highest cost of any orthopaedic procedure after surgery, and also incur $11,241 each year following surgery in extra health costs. Due to increased life expectancy, worldwide by 2050, it is projected that 6.26 million hip fractures will occur annually [7]. A paradigm shift is underway toward use of surgical training simulations [8]. The conventional master-apprentice learning model for surgical training of ‘see one, do one, teach one’ has recently been seen as inefficient. Due to orthopaedics being heavily dependent on technical skill, orthopaedic VR simulation holds potential to have great impact for improving surgical skill. The transition to VR simulation is relatively new compared to cadaver training which has been the gold standard for several centuries.

The Edwards SAPIEN transcatheter heart valve (Figure 1) is designed for heart valve replacement in patients with severe aortic stenosis without open-heart surgery. Physiological FEA analyses have been performed to provide an assessment of the fracture and fatigue resistance of the device during deployment and operation. The present study validates FEA frame models by comparing the crimping behavior of the FEA models with the results of crimping experiments.

Contemporary drug eluting stents (DES) are designed and tested such that they will endure under in vivo fatigue loading after implantation. However, DES fractures have occasionally been reported in the literature and are often associated with restenosis and/or thrombosis events long after DES deployment. This observation indicates a need for fatigue test methods which appropriately compare the fatigue resistance of various DES platforms at loading levels beyond clinical relevance.

Stents are most commonly used in the relief of coronary artery stenosis, but in the last decade have found increasing applications in the treatment of other cardiovascular disease and in particular in heart valve replacement [1]. In transcatheter valve implantation, acquisition of high temporal and spatial resolution images during stenting procedure and patients’ follow-up is required to help the correct positioning of the device and to assess the mechanical performance over time. The imaging techniques routinely used for this purpose are 2D X-ray fluoroscopy and 3D computed tomography (CT), and recent studies have demonstrated their value as diagnostic tools [1–3]. However, these image modalities carry errors and the resulting information might not be accurate enough to be employed in engineering analyses of stent deformations, mechanics, dynamics and fracture. In this study, we aim to evaluate the errors of conventionally used clinical images (fluoroscopy and CT) and post-processing by comparison with ultra-high resolution micro-CT (μCT) as gold standard. Additionally, an optical image acquisition method and a high-radiation CT scan were evaluated as potential techniques to acquire geometrical data that could be used for computational and in-vitro engineering experiments.

A novel Bayesian Network methodology has been developed to enable the prediction of fatigue fracture of cardiac lead medical devices. The methodology integrates in-vivo measurements of device loading, patient demographics, patient activity level, in-vitro measurements of fatigue strength, and cumulative damage modeling techniques. Many plausible combinations of these variables can be simulated within a Bayesian Network framework to generate a family of fatigue fracture survival curves, enabling sensitivity analyses and the construction of confidence bounds on survival.

The design of self-expanding nitinol stents to treat peripheral arterial disease offers a number of unique challenges. Primary among these is the potentially complex loading environment that these stents must endure, without fracture, for an extended period. As an example, for the superficial femoral artery (SFA), the loading environment on a stent can consist of axial, bending, torsional and pulsatile loads. These loads induce alternating strain that must be accommodated in the device design to ensure suitable fatigue life. Other stent design criteria relate to satisfactory radial force, as well as the ability to achieve delivery system requirements (i.e., volumetric constraints, good compression and deployment characteristics).

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.

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.

Vertically unstable fractures of the pelvis are uncommon high-energy injuries. There exist various methods of fixation for posterior pelvic ring injuries such as anterior plating, tension band-plating, trans-iliac bars, spinopelvic fixation, and iliosacral (IS) screws. Recent literature supports that triangular osteosynthesis (spinopelvic fixation) provides superior fixation strength compared to traditionally placed IS screw fixation. The theoretical advantage of triangular osteosynthesis fixation is that this technique combines unilateral spinopelvic distraction osteosynthesis for vertical stabilization with ipsilateral iliosacral screw fixation for horizontal stabilization, thereby providing biplanar stability. While spinopelvic fixation provides biplanar biomechanical stability there are inherent risks of spinal instrumentation, including neurologic injury from malpositioned pedicle screws, hardware loosening or breakage, local infection, wound dehiscence, hardware prominence requiring removal, and predisposition of spinal arthritis. Iliosacral screws are thought to be advantageous in that they can be applied percutaneously or as an open procedure, potentially limit soft tissue dissection, and minimize blood loss. However, IS screw fixation alone has been associated with fixation failure in unstable vertical shear pelvic fractures. There exists a vertical shear repair technique that has been used in revisional and non-union cases, which utilizes trans-sacral screws to stabilize vertical shear fractures. This trans-sacral technique provides biplanar stability and can be implemented without spinal instrumentation. The purpose of this study was to compare the structural integrity of trans-sacral (TS) versus triangular osteosynthesis (TO) in an unstable sacral fracture model.