Medical Devices and Surgical Tools

Applied Bionics and Biomechanics (2017): Positioning Performance of Power and Manual Drivers in Posterior Spinal Fusion Procedures

Anonymous — Fri, 04 Aug 2017 21:08:55 +0000

Applied Bionics and Biomechanics (2017): Positioning Performance of Power and Manual Drivers in Posterior Spinal Fusion Procedures Anonymous (not verified) Fri, 08/04/2017 - 15:08

[video:https://www.youtube.com/watch?v=kIBVcEbyCgc]

Abstract: This work presents an analysis and comparison of the efficacy of two methods for pedicle screw placement during posterior spinal fusion surgery. A total of 100 screws (64 manual and 36 power driven), all placed utilizing a surgical navigation system, were analyzed and compared. Final screw placement was compared to initial surgical plans using the navigation system, and the final screw locations were analyzed on the basis of angular deviation from these planned trajectories as well as screw translation within a critical reference plane. The power driver was found to insignificantly decrease the resulting angular deviation of these pedicle screws with a mean deviation of 3.35 degrees compared to 3.44 degrees with the manual driver (p=0.853). Conversely, the power driver was found to increase the translational distance in the critical region, with mean deviations of 2.45 mm for the power driver compared to 1.54 mm with the manual driver. The increase in translational deviation was significant (p=0.002) indicating that there may be some loss in performance from the adoption of the power driver.

Prendergast, J.M., Perry, A., Patel, V., Lindley, E., Rentschler, M.E., "Positioning Performance of Power and Manual Drivers in Posterior Spinal Fusion Procedures," Applied Bionics and Biomechanics. 2017: 7262841 (9 pages), 2017.

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European Spine Journal (2016): A New 3-Dimensional Method for Measuring Precision in Surgical Navigation and Methods to Optimize Navigation Accuracy

Anonymous — Fri, 21 Apr 2017 22:43:42 +0000

European Spine Journal (2016): A New 3-Dimensional Method for Measuring Precision in Surgical Navigation and Methods to Optimize Navigation Accuracy Anonymous (not verified) Fri, 04/21/2017 - 16:43

Abstract: Description of a novel method for evaluation of pedicle screws in 3 dimensions utilizing O-arm^® and StealthStation^® navigation; identifying sources of error, and pearls for more precise screw placement. O-arm and StealthStation navigation were utilized to place pedicle screws. Initial and final O-arm scans were performed, and the projected pedicle probe track, projected pedicle screw track, and final screw position were saved for evaluation. They were compared to evaluate the precision of the system as well as overall accuracy of final screw placement. Thoracolumbar deformity patients were analyzed, with 153 of 158 screws in adequate position. Only 5 screws were malpositioned, requiring replacement or removal. All 5 were breached laterally and no neurologic or other complications were noted in any of these patients. This resulted in 97 % accuracy using the navigation system, and no neurological injuries or deficits. The average distance of the screw tip and angle of separation for the predicted path versus the final pedicle screw position were analyzed for precision. The mean screw tip distance from the projected tip was 6.43 mm, with a standard deviation of 3.49 mm when utilizing a navigated probe alone and 5.92 mm with a standard deviation of 3.50 mm using a navigated probe and navigated screwdriver (p = 0.23). Mean angle differences were 4.02° and 3.09° respectively (p < 0.01), with standard deviations of 2.63° and 2.12°. This new technique evaluating precision of screw placement in 3 dimensions improves the ability to define screw placement. Pedicle screw position at final imaging showed the use of StealthStation navigation to be accurate and safe. As this is a preliminary evaluation, we have identified several factors affecting the precision of pedicle screw final position relative to that predicted with navigation.

Kleck, C.J., Cullimore, I., LaFleur, M., Lindley, E., Rentschler, M.E., Burger, E.L., Cain, C.M.J., Patel, V.V., "A New 3-Dimensional Method for Measuring Precision in Surgical Navigation and Methods to Optimize Navigation Accuracy," European Spine Journal. 25(6): 1764-1774, 2016.

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IEEE Transactions on Biomedical Engineering (2014): Wireless Tissue Palpation for Intraoperative Detection of Lumps in Soft Tissue

Anonymous — Fri, 21 Apr 2017 22:42:16 +0000

IEEE Transactions on Biomedical Engineering (2014): Wireless Tissue Palpation for Intraoperative Detection of Lumps in Soft Tissue Anonymous (not verified) Fri, 04/21/2017 - 16:42

Abstract: In an open surgery, identification of precise margins for curative tissue resection is performed by manual palpation. This is not the case for minimally invasive and robotic procedures, where tactile feedback is either distorted or not available. In this paper, we introduce the concept of intraoperative wireless tissue palpation. The wireless palpation probe (WPP) is a cylindrical device (15 mm in diameter, 60 mm in length) that can be deployed through a trocar incision and directly controlled by the surgeon to create a volumetric stiffness distribution map of the region of interest. This map can then be used to guide the tissue resection to minimize healthy tissue loss. The wireless operation prevents the need for a dedicated port and reduces the chance of instrument clashing in the operating field. The WPP is able to measure in real time the indentation pressure with a sensitivity of 34 Pa, the indentation depth with an accuracy of 0.68 mm, and the probe position with a maximum error of 11.3 mm in a tridimensional workspace. The WPP was assessed on the benchtop in detecting the local stiffness of two different silicone tissue simulators (elastic modulus ranging from 45 to 220 kPa), showing a maximum relative error below 5%. Then, in vivo trials were aimed to identify an agar-gel lump injected into a porcine liver and to assess the device usability within the frame of a laparoscopic procedure. The stiffness map created intraoperatively by the WPP was compared with a map generated ex vivo by a standard uniaxial material tester, showing less than 8% local stiffness error at the site of the lump.

Beccani, M., Di Natali, C., Sliker, L.J., Schoen, J., Rentschler, M.E., Valdastri, P. “Wireless Tissue Palpation for Intraoperative Detection of Lumps in Soft Tissue,” IEEE Transactions on Biomedical Engineering. 61(2): 353-361, 2014. *Cover Article

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Journal of Pain (2012): Pain Sensitivity Testing Using a Novel Computer-Controlled Pressure Algometer that Simultaneously Records Sympathetic Nervoous System Responses to Pain Stimuli

Anonymous — Fri, 21 Apr 2017 22:40:26 +0000

Journal of Pain (2012): Pain Sensitivity Testing Using a Novel Computer-Controlled Pressure Algometer that Simultaneously Records Sympathetic Nervoous System Responses to Pain Stimuli Anonymous (not verified) Fri, 04/21/2017 - 16:40

Abstract: Quantitative sensory testing is a popular tool for studying pain in the laboratory setting. Hand-held pressure algometers are commonly used to evaluate pain sensitivity in both healthy subjects and chronic pain patients. However, these hand-held algometers have innate limitations, including human error in manually applying a constant ramp of increasing pressure. The goal of this study was to develop and test a new computer-controlled pressure algometer (CCPA) that applies precisely controlled stimuli and records responses in real-time. Furthermore, we designed the CCPA to simultaneously record changes in heart rate, skin impedance, and blood pressure during pain testing. After collaboration with bioengineers to construct the new computerized algometer, we tested the CCPA and a hand-held algometer in 36 healthy subjects (14 females, 22 males; mean age 23 years) with no history of chronic or acute pain. Pressure pain thresholds and tolerance were recorded over the tibialis anterior muscle across two sessions separated by one week. Subjects indicated threshold and tolerance during CCPA testing by pressing two buttons on a remote control. The rate for CCPA output was 10 kPa/sec; the test administrator also attempted to achieve this rate with the hand-held algometer. For both algometers, females had significantly lower pressure pain thresholds and tolerance than males. When comparing the two algometers, pain thresholds were significantly lower when measured by the CCPA. In females, pain tolerance was also significantly lower when measured by the CCPA. Interestingly, we found a significant reduction in the variability of pain threshold responses when using the CCPA to test pain sensitivity. We are currently analyzing the physiologic data and will determine whether sympathetic nervous system responses to pressure pain stimuli are correlated with pain sensitivity measured with the CCPA. These preliminary results are encouraging and may suggest that the CCPA allows for more precise pain sensitivity measurements.

Lindley, E., Zimkowski, M., Patel, V., Rentschler, M., "Pain Sensitivity Testing Using a Novel Computer-Controlled Pressure Algometer that Simultaneously Records Sympathetic Nervoous System Responses to Pain Stimuli," Journal of Pain. 13(4): S9, 2012.

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ASME Journal of Medical Devices (2012): Initial Design and Evaluation of a Pediatric Intra-Cardiac Camera System for Ventricular Septal Defects

Anonymous — Fri, 21 Apr 2017 22:39:15 +0000

ASME Journal of Medical Devices (2012): Initial Design and Evaluation of a Pediatric Intra-Cardiac Camera System for Ventricular Septal Defects Anonymous (not verified) Fri, 04/21/2017 - 16:39

Abstract: The primary objective of this project is to design, fabricate, and test a small, integrated camera system for aiding in the visualization and surgical repair of certain types of ventricular septal defects (VSD), in pediatric patients. Currently, no purpose-designed commercial device to view VSDs from the left ventricle of the heart exists. The left ventricular perspective is ideal for obtaining an unobstructed view of the VSD. This VSD camera device would also provide a platform for passing a suture through the hole in the ventricular septum, with future work implementing additional tools capable of more advanced tasks. This camera device will help solve some of the major issues currently associated with cardiac imaging and surgical closure of VSDs in newborns and young children This paper examines the design development and preliminary evaluation of a proof of concept device. Included are preliminary results of image quality comparisons, design details of a pediatric-specific VSD camera device, and initial outcomes from in vitro testing.

Rentschler, M.E., Hart, K.D., Mitchell, M.B., "Initial Design and Evaluation of a Pediatric Intra-Cardiac Camera System for Ventricular Septal Defects," ASME Journal of Medical Devices. 6(1): 011001-1-011001-9, 2012.

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IEEE Transactions on Biomedical Engineering (2012): Single Port Access Surgery with a Novel Magnet Camera System

Anonymous — Fri, 21 Apr 2017 22:38:11 +0000

IEEE Transactions on Biomedical Engineering (2012): Single Port Access Surgery with a Novel Magnet Camera System Anonymous (not verified) Fri, 04/21/2017 - 16:38

Abstract: In this paper, we designed, built, and tested a novel single-port access laparoscopic surgery (SPA) specific camera system. This device (magnet camera) integrates a light source and video camera into a small, inexpensive, portable package that does not compete for space with the surgical tools during SPA. The device is inserted through a 26-mm incision in the umbilicus, followed by the SPA port, which is used to maintain an insufflation seal and support the insertion of additional tools. The camera, now in vivo, remains separate from the SPA port, thereby removing the need for a dedicated laparoscope, and, thus, allowing for an overall reduction in SPA port size or the use of a third tool through the insertion port regularly reserved for the traditional laparoscope. The SPA camera is mounted to the abdominal ceiling using one of the two methods: fixation to the SPA port through the use of a rigid ring and cantilever bar, or by an external magnetic handle. The purpose of the magnet camera system is to improve SPA by: 1) eliminating the laparoscope SPA channel; 2) increasing the field of view through enhanced camera system mobility; and 3) reducing interference between the camera system and the surgical tools at the port, both in vivo and ex vivo.

Terry, B.S., Mills, Z., Schoen, J.A., Rentschler, M.E., "Single Port Access Surgery with a Novel Magnet Camera System," IEEE Transactions on Biomedical Engineering. 59(4): 1187-1193, 2012.

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Surgical Innovation (2012): Single Port Access Surgery with a Novel Port Camera System

Anonymous — Fri, 21 Apr 2017 22:37:05 +0000

Surgical Innovation (2012): Single Port Access Surgery with a Novel Port Camera System Anonymous (not verified) Fri, 04/21/2017 - 16:37

Abstract: In this work, the authors designed, built, and tested a novel port camera system for single port access (SPA) laparoscopic surgery. This SPA Port Camera device integrates the monitor, laparoscopic camera, and light source into an inexpensive, portable cannula port. The device uses a 2-channel SPA port inserted through an umbilical incision, similar to traditional SPA. After insertion into a channel, the device deploys a small camera module and LED lamp in vivo. An integrated, on-patient LCD provides the view of the surgical site. The design intent of the port camera is to enhance SPA by (a) reducing the size of the SPA port through the elimination of the dedicated laparoscope channel; (b) reducing equipment cost by integrating an inexpensive CMOS sensor and LED lamp at the port tip; (c) eliminating the need for an assistant who operates the laparoscope; and (d) mechanically coupling the camera, tool port, and on-patient LCD screen. The effectiveness of the device was evaluated by comparing the video performance with a leading industry laparoscope and by performing a user evaluation study and live porcine surgery with the device. Effectiveness of the device was mixed. Overall video system performance of the device is better than an industry standard high-definition laparoscope, implying that significant cost savings over a traditional system are possible. Participant study results suggest that simulated laparoscopic tasks are as efficient with the SPA Port Camera as they are with a typical SPA configuration. However, live surgery revealed several shortcomings of the SPA Port Camera.

Terry, B.S., Schoen, J.A., Mills, Z., Rentschler, M.E., “Single Port Access Surgery with a Novel Port Camera System,” Surgical Innovation. 19(2): 123-129, 2012.

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ASME Journal of Medical Devices (2011): Design and Evaluation of a Computer-Controlled Pressure Algometer

Anonymous — Fri, 21 Apr 2017 22:35:26 +0000

ASME Journal of Medical Devices (2011): Design and Evaluation of a Computer-Controlled Pressure Algometer Anonymous (not verified) Fri, 04/21/2017 - 16:35

Abstract: A challenge is always presented when attempting to measure the pain an individual patient experiences. Unfortunately, present technologies rely nearly exclusively on subjective techniques. Using these current techniques, a physician may use a manually operated algometer and a series of questionnaires to gauge an individual patient’s pain scale. Unfortunately these devices and test methods have been suggested to introduce error due to variability and inconsistent testing methods. Some studies have shown large variability, while others have shown minimal variability, both between patients and within the same patient during multiple testing sessions. Recent studies have also shown a lack of correlation between pain threshold and pain tolerance in pain sensitivity tests. Hand-held algometer devices can be difficult to maintain consistent application rates over multiple test periods, possibly adding to widespread variability. Furthermore, there are limited test results that correlate pain ratings with biological measures in real time. The computer-controlled pressure algometer described is not hand-held or dependent on significant examiner input. This new device is capable of recording electrocardiograph (ECG), blood pressure (BP), pressure pain threshold (PPT), and pressure pain tolerance (PPTol) in real time. One major goal is the capability of correlating pain stimuli with algometer pressure, heart rate, and blood pressure. If a predictable correlation between vital signs and pain could be established, significant gains in the understanding of pain could result. Better understanding of pain will ultimately lead to improvements in treatment and diagnosis of pain conditions, helping patients and physicians alike.

Zimkowski, M., Lindley, E., Patel, V., Rentschler, M.E., "Design and Evaluation of a Computer-Controlled Pressure Algometer," ASME Journal of Medical Devices. 5(3): 031002-1-031002-6, 2011.

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IEEE Transactions on Biomedical Engineering (2010): An Integrated Port Camera and Display System for Laparoscopy

Anonymous — Fri, 21 Apr 2017 22:34:16 +0000

IEEE Transactions on Biomedical Engineering (2010): An Integrated Port Camera and Display System for Laparoscopy Anonymous (not verified) Fri, 04/21/2017 - 16:34

Abstract: In this paper, we built and tested the port camera, a novel, inexpensive, portable, and battery-powered laparoscopic tool that integrates the components of a vision system with a cannula port. This new device 1) minimizes the invasiveness of laparoscopic surgery by combining a camera port and tool port; 2) reduces the cost of laparoscopic vision systems by integrating an inexpensive CMOS sensor and LED light source; and 3) enhances laparoscopic surgical procedures by mechanically coupling the camera, tool port, and liquid crystal display (LCD) screen to provide an on-patient visual display. The port camera video system was compared to two laparoscopic video systems: a standard resolution unit from Karl Storz (model 22220130) and a high definition unit from Stryker (model 1188HD). Brightness, contrast, hue, colorfulness, and sharpness were compared. The port camera video is superior to the Storz scope and approximately equivalent to the Stryker scope. An ex vivo study was conducted to measure the operative performance of the port camera. The results suggest that simulated tissue identification and biopsy acquisition with the port camera is as efficient as with a traditional laparoscopic system. The port camera was successfully used by a laparoscopic surgeon for exploratory surgery and liver biopsy during a porcine surgery, demonstrating initial surgical feasibility.

Terry, B.S., Ruppert, A.D., Steinhaus, K.R., Schoen, J.A., Rentschler, M.E., “An Integrated Port Camera and Display System for Laparoscopy,” IEEE Transactions on Biomedical Engineering. 57(5): 1191-1197, 2010.

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ASME Journal of Medical Devices (2010): An Improved Brace Design for Boutonniere Deformity

Anonymous — Fri, 21 Apr 2017 22:33:10 +0000

ASME Journal of Medical Devices (2010): An Improved Brace Design for Boutonniere Deformity Anonymous (not verified) Fri, 04/21/2017 - 16:33

Abstract: Boutonniere deformities are a common injury to the extensor mechanism of the finger. The deformity results in fixed contraction in the middle finger joint and is severely debilitating to functionality. Due to the complexity of the extensor mechanism, surgical repair is difficult, which usually requires multiple procedures, and in some cases is unsuccessful. Nonsurgical treatment of the deformity has not dramatically improved in many years and usually requires long-term use of braces and physical therapy. This work is focused on design and preliminary evaluation of an improved boutonniere brace to correct the deformity with emphasis on lower costs, integrating therapeutic techniques such as heat and motion to increase blood flow and patient comfort. A review of the current state of the art is presented along with the design approach used to develop an improved device. Experimental test results are also presented. This work demonstrates a new device and approach for treatment of boutonniere deformities that may translate to treatment of other conditions such as arthritis.

Rentschler, M.E., Macdonald, S.A., “An Improved Brace Design for Boutonniere Deformity,” ASME Journal of Medical Devices. 4(2): 021002-1-021002-7, 2010.

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