Journal of Medical Devices
ISSN / EISSN : 1932-6181 / 1932-619X
Published by: ASME International (10.1115)
Total articles ≅ 1,675
Latest articles in this journal
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052518
In individuals with transtibial limb loss, a contributing factor to mobility-related challenges is the disruption of biological calf muscle function due to transection of the soleus and gastrocnemius. Powered prosthetic ankles can restore primary function of the mono-articular soleus muscle, which contributes to ankle plantarflexion. In effect, a powered ankle acts like an artificial soleus (AS). However, the biarticular gastrocnemius connection that simultaneously contributes to ankle plantarflexion and knee flexion torques remains missing, and there are currently no commercially available prosthetic ankles that incorporate an artificial gastrocnemius (AG). The goal of this work is to describe the design of a novel emulator capable of independently controlling artificial soleus and gastrocnemius behaviors for transtibial prosthesis users during walking. To evaluate the emulator's efficacy in controlling the artificial gastrocnemius behaviors, a case series walking study was conducted with four transtibial prosthesis users. Data from this case series showed that the emulator exhibits low resistance to the user's leg swing, low hysteresis during passive spring emulation, and accurate force tracking for a range of artificial soleus and gastrocnemius behaviors. The emulator presented in this paper is versatile and can facilitate experiments studying the effects of various artificial soleus and gastrocnemius dynamics on gait or other movement tasks. Using this system, it is possible to address existing knowledge gaps and explore a wide range of artificial soleus and gastrocnemius behaviors during gait and potentially other activities of daily living.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052587
The advantage of handheld type surgical microscope is that the size of the probe is small and light, and that both the working distance (15–30 cm) and field of view (30 deg) can be adjusted. The shortness working distance will minimize the loss of light source energy. However, the currently developed handheld type surgical microscope is still large, heavy, and uses relatively high energy (600 mW/cm2). To address the aforementioned problems, this study aimed to develop a pen-type surgical fluorescence microscope that is compact, portable, and has an adjustable beam angle and working distance. These features enable real-time diagnosis. The pen-type probe consists of a laser diode, CMOS camera, light source brightness control device, filter, and power switch. The IR-cut filter inside the CMOS camera was removed to facilitate transmission of the fluorescence emission wavelength. In addition, a long-pass filter was attached to the camera so that the external light source was blocked and only the fluorescence emission wavelength was allowed to pass through. The performance of the pen-type probe was tested through a large animal experiment. Indocyanine green (2.5 mg/kg) was injected into a pig's vein. Fluorescence emission of 805-830 nm was achieved by irradiating an external light source (785 nm and 4 mW/cm2), and liver-uptake occurred after 2.4 min. The designed pen-type probe was capable of sufficiently fluorescence expression through low-energy irradiation, and the pen-type probe is small and light and easy to handle by hand because both the pen-based laser device and the camera device are integrated. In addition, it is easy to adjust the working distance and field of view.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052516
In otolaryngologic surgery, endoscopy is increasingly used to provide a better view of hard-to-reach areas and to promote minimally invasive surgery. However, the need to manipulate the endoscope limits the surgeon's ability to operate with only one instrument at a time. Currently, several robotic systems are being developed, demonstrating the value of robotic assistance in microsurgery. The aim of this literature review is to present and classify current robotic systems that are used for otological and endonasal applications. For these solutions, an analysis of the functionalities in relation to the surgeon's needs will be carried out to produce a set of specifications for the creation of new robots.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052609
Degenerative cervical myelopathy (DCM) is characterized by a progressive deterioration in spinal cord function. Its evaluation requires subjective clinical examination with wide interobserver variability. Objective quantification of spinal cord function remains imprecise, even though validated myelopathy-grading scales have emerged and are now widely used. We created a Smartphone Application, the N-Outcome App, with the aim of quantifying accurately and reliably spinal cord dysfunction using a 5-minute Test. A patient suffering from DCM was clinically evaluated before surgery, at 3 and 6 months follow-up after surgical decompression of the cervical spinal cord. Standard scores (Nurick grade, modified Japanese Orthopedic Association (mJOA) score) were documented at these time points. A 5-minute motor and proprioceptive performance test aided by a smartphone with the N-outcome App was also performed. Motor performance in rapid alternating movements and finger tapping improved in correlation with improvements in standard grading scale scores. Clinical improvements were seen in maximum reflex acceleration and in Romberg testing which showed less closed/open eyes variation, suggesting pyramidal and proprioceptive function recovery. We demonstrate that using the N-Outcome App as an adjunct to clinical evaluation of compressive myelopathy is feasible and potentially useful. The results correlate with the results of clinical assessment obtained by standard validated myelopathy scores.
Journal of Medical Devices; https://doi.org/10.1115/1.4052786
Background: Recently presented minimally invasive endoscopic surgical techniques demonstrated the feasibility of implanting standard osteosynthesis plates for pelvic fractures. The reconstruction and internal fixation of complex acetabular fractures is still challenging. The goal of this study is to introduce a divisible implant, with a positive-locking in situ linking mechanism for plate osteosynthesis, making it possible to stabilize large and complex acetabular fractures with involvement of the quadrilateral surface. Method: Standard implants were used to recreate a base design. Using computer aided design (CAD), a three-dimensional standard implant was divided into two parts, so they could be re-allocated in situ. A critical objective was to reduce the cross-section of each part (clearance gauge). To connect the separated parts in situ, a new linking mechanism (cone in cone) was created. The new construct also features self-stabilization, self-centering, reinforced positional movement and preloading effects. Results: A linking system for plate osteosynthesis was developed entitled PEGASOS ("Percutaneous Endoscopic Guided Acetabulum-Stabilizing Osteosynthesis System"). Endoscopic implantation and in-situ-linking could be performed in a human cadaver. Therefore, we could demonstrate, that buttressing the quadrilateral surface of the acetabulum could be performed minimally invasive using a divisible suprapectineal buttress plate. Conclusion: We created a linking mechanism to couple two plates in situ. This mechanism enables an extremely strong, positive-locking connection, whereas its geometric shape allows for different relative movements during the locking procedure, with a single screw.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052517
This paper proposes a new test method based on the toggle effect under transverse loads (cranial–caudal) to investigate the loosening potential of pedicle screw designs. A three-step in vitro testing procedure was developed to mimic the loosening mechanism of pedicle screws. First, the pedicle screw of a certain design is inserted into a bone substitute model specifically designed for the test. Second, a controlled cyclic cranial–caudal loading is applied transversally to the longitudinal axis of the screw for three ascendent load levels (staircase) by a predetermined number of load cycles. Lastly, each pedicle screw is adjusted and subjected to axial pull-out quasi-static testing. The results are used to calculate a loosening index that, together with statistical analysis, indicates the potential for loosening of the specific design evaluated. The proposed testing method effectively provides a simulated environment to evaluate the loosening potential of pedicle screw designs. The proposed loosening index calculation may be used to compare different pedicle screw designs. The proposed methodology was verified as a valuable tool to investigate the influence of the cranial–caudal loads on pedicle screw behavior. It offers a new alternative for use in preclinical studies on the loosening potential of pedicle screw designs.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052122
Breast augmentation is a common esthetic surgery, and there are two major surgical methods for breast implant delivery: the finger method and the plastic film method. Each method has its advantages and disadvantages, and we have developed a prelubricated polypropylene (PP) injector that might be the most suitable device for delivering breast implants. By covering the interior surface of the injector with a hydrophilic coating, the friction coefficient was significantly reduced when a silicone sled was slid against the prelubricated PP injector. To confirm if the prelubricated PP injector would not damage the breast implant, fatigue testing was performed, and the results showed that the injector did not cause rupture or microleakage of the breast implant. In addition, the cell viability result demonstrated that the prelubricated PP injector was biocompatible. In addition, the prelubricated PP injector provides a small incision site and stability during breast implant delivery. Our results provided evidence that the prelubricated PP injector is a smooth and safe method for breast implant delivery.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052305
Objective: During shoulder arthroplasty, surgeons must select the optimal implant for each patient. The metaphyseal bone properties affect this decision; however, the typical resection “thumb test” lacks objectivity. This investigation's purposes were to determine the correlation strength between the indentation depth of a handheld mechanism and the density, compressive strength, and modulus of a bone surrogate; as well as to assess how changing the indenter tip shape and impact energy may affect the correlation strengths. Methods: A spring-loaded indenter was developed. Four tip shapes (needle, tapered, flat, and radiused cylinders) and four spring energies (0.13 J–0.76J) were assessed by indenting five cellular foam bone surrogates of varying density, every five times. After each indentation, the indentation depth was measured with a separate probe and correlated with manufacturer specifications of the apparent density, compressive strength, and modulus. Results: indentation depth plateaued as the bone surrogate's material properties increased, particularly for indentation tips with larger footprints and the 0.13 J spring. All tip shapes produced strong (R2≥0.7) power-law relationships between the indentation depth metric and the bone surrogate's material properties (density: 0.70 ≤ R2 ≤ 0.95, strength: 0.75 ≤ R2 ≤ 0.97, modulus: 0.70 ≤ R2 ≤ 0.93); though the use of the needle tip yielded the widest indentation depth scale. Interpretation: these strong correlations suggest that a handheld indenter may provide objective intra-operative evidence of cancellous material properties. Further investigations are warranted to study indenter tip shape and spring energy in human tissue; though the needle tip with spring energy between 0.30 J and 0.76 J seems the most promising.
Journal of Medical Devices, Volume 15; https://doi.org/10.1115/1.4052448
Finger extensor muscle weakness and flexor hypertonia are the most commonly reported issues among patients suffering from amyotrophic lateral sclerosis (ALS). Moreover, the relative hyperflexion of the wrist and fingers has limited their ability to voluntarily open the hand and interact with the external environment. In this work, a hybrid hand exoskeleton is developed to prevent the relative hyperflexion of the fingers and wrist and facilitate the users in their functional hand opening by compensating the flexor hypertonia. This exoskeleton, combining a passive device with the soft extra muscle (SEM) glove, assists users in normal hand opening/closing required for some basic activities of daily living. The paper presents kinematic and static models of passive hand exoskeleton design. Moreover, the proposed design is tested and evaluated by comparing the volunteer hand opening with the exoskeleton assistance using the flex sensors attached on the dorsal side of the middle finger, ring finger, and thumb with both healthy subjects and patients. The results show the effectiveness of using the hybrid exoskeleton in improving anatomical hand opening/closing capabilities.
Journal of Medical Devices; https://doi.org/10.1115/1.4052515
The COVID-19 pandemic left an unprecedented impact on the general public health, resulting in hundreds of thousands of deaths in the US alone. Nationwide testing plans were initiated, with drive-through being the currently dominant testing approach, which, however, exhausts personal protective equipment supplies, and is unfriendly to individuals not owning a vehicle. Walk-up positive pressure testing booths are a safe alternative, whereby a health care provider situated on the inside of an enclosed and positively pressurized booth swabs a patient on the outside through chemical resistant gloves. The booths, however, are too prohibitively priced on the market to allow for nationwide deployment. To mitigate this, we present in this paper a safe, accessible, mobile and affordable design of positive-pressure COVID-19 testing booths. The booths have successfully passed the CDC and HICPAC pressure, air exchange, and air quality requirements for positive-pressure rooms, following the guidelines for environmental infection control in health care facilities. The booths are manufactured using primarily off-the-shelf components from US vendors with minimized customization, and the final bill of materials does not surpass USD 3,900. Since August 2019, five booths were deployed and used at the Johns Hopkins University School of Nursing, Baltimore City Health Department, and two community health centers in Baltimore. No health care provider was infected when using our booths, which have shown to facilitate walk-up testing with decreased PPE consumption, reduced risk of infection, and enhanced accessibility to lower-income communities and non-drivers.