Strains to go: interactions of the skin microbiome beyond its species.

An extraordinary biodiversity of bacteria, fungi, viruses, and even small multicellular eukaryota inhabit the human skin. Genomic innovations have accelerated characterization of this biodiversity both at a species as well as the subspecies, or strain level, which further imparts a tremendous genetic diversity to an individual's skin microbiome. In turn, these advances portend significant species- and strain-specificity in the skin microbiome's functional impact on cutaneous immunity, barrier integrity, aging, and other skin physiologic processes. Future advances in defining strain diversity, spatial distribution, and metabolic diversity for major skin species will be foundational for understanding the microbiome's essentiality to the skin ecosystem and for designing topical therapeutics that leverage or target the skin microbiome.

Comparison of Ischial Containment and Subischial Sockets Effect on Gait Biomechanics in People With Transfemoral Amputation: A Randomized Crossover Trial.

OBJECTIVE: To compare gait biomechanics of the Northwestern University Flexible Sub-Ischial Vacuum (NU-FlexSIV) Socket to the ischial containment (IC) socket. DESIGN: Randomized crossover trial with 2, 7-week periods. SETTING: Private prosthetic clinics and university research laboratory. PARTICIPANTS: A total of 30 enrolled (n=30); 25 participants completed the study with full (n=18) or partial data (n=7). INTERVENTIONS: Two custom-fabricated sockets (IC and NU-FlexSIV), worn full-time for 7 weeks, with testing at 1, 4, and 7 weeks after socket delivery. MAIN OUTCOME MEASURES: Gait analyses were conducted at 1, 4, and 7 weeks post socket delivery. Differences between sockets in selected gait variables related to hip motion and coronal plane socket stability were assessed. RESULTS: For participants with data for both sockets at week 7 (n=19), there were no significant differences in any gait variables between sockets at self-selected normal walking speed. However, when all participants and all study time points were assessed (n=25), there was a significant main effect of socket (P=.013), with prosthetic side sagittal plane hip range of motion being significantly greater for the NU-FlexSIV Socket at self-selected normal walking speed. There were no other significant effects. CONCLUSIONS: The results suggest that, compared to the IC socket, the NU-FlexSIV Socket did not alter gait biomechanics related to hip motion and coronal plane socket stability in people with unilateral transfemoral amputation.

A 40-year Study of the Factors Associated with Diaphyseal Forearm Fractures in Skiers and Snowboarders.

BACKGROUND: Skiing and snowboarding are popular sports that are associated with a high number of orthopaedic injuries. Diaphyseal forearm fractures are an important subset of these injuries. To our knowledge, factors associated with these injuries, the mechanisms that cause them, and their relative frequencies in skiers and snowboarders have not been described. In addition, it has been proposed that the use of wrist guards may increase the risk of sustaining a diaphyseal forearm fracture; therefore, we sought to explore the relationship between wrist guard use and diaphyseal forearm fractures. QUESTIONS/PURPOSES: (1) What are the relative frequencies and types of diaphyseal forearm fractures in skiers and snowboarders? (2) What factors are associated with these injuries? (3) Is the use of wrist guards associated with an increased risk of forearm fractures? METHODS: This was an unmatched case-control study performed with an injury database from a university-run clinic at the base lodge of a major ski resort. Cases were injured skiers and snowboarders; controls were randomly selected uninjured skiers and snowboarders. Data were collected on the mechanism of injury; experience level; equipment; radiographs; skiing or snowboarding habits; and trail type, defined as green circle (easiest), blue square (intermediate), black diamond (difficult), and double black diamond (most difficult). From this database, we identified 84 patients with diaphyseal forearm fractures, one of which was a Monteggia fracture and was excluded. A logistic regression analysis was used to compare the injured and control groups to identify factors associated with diaphyseal forearm fractures, including wrist guard use. RESULTS: When adjusted for participant days, diaphyseal forearm fractures were more common in snowboarders than skiers (0.03 injuries per 1000 person-days versus 0.004 per 1000 person-days). On multivariable analysis, factors associated with forearm fractures in skiers were younger age (odds ratio 1.08 [95% CI 1.05 to 1.14]; p < 0.01), being a man or boy (OR 11.9 [95% CI 2.5 to 57.2]; p < 0.01), lack of movement at the time of falling (OR 18.2 [95% CI 3.2 to 102.5]; p < 0.01), and skiing on green circle trails compared with black diamond trails (OR 3.6 [95% CI 1.4 to 12.5]; p = 0.04). Factors associated with forearm fractures in snowboarders were younger age (OR 1.08 [95% CI 1.02 to 1.15]; p = 0.01), decreased weight (OR 1.02 [95% CI 1.00 to 1.02]; p < 0.01), snowboarding on gentle terrain (OR 8.4 [95% CI 1.6 to 45.0]; p = 0.01), and snowboarding on groomed terrain compared with other (OR 7.2 [95% CI 1.9 to 28.0]; p < 0.01) or wet, heavy snow (OR 24.8 [95% CI 2.5 to 246.7]; p = 0.01). Wrist guard use was not associated with an increased odds of diaphyseal forearm fracture in skiers or snowboarders. CONCLUSION: Diaphyseal forearm fractures occur more frequently in snowboarders than in skiers. Despite speculation in prior evidence that wrist guards may paradoxically increase the risk of sustaining these injuries, our study suggests that this is not the case and wrist guards are not unsafe to wear. LEVEL OF EVIDENCE: Level III, prognostic study.

Comparison of Ischial Containment and Subischial Sockets on Comfort, Function, Quality of Life, and Satisfaction With Device in Persons With Unilateral Transfemoral Amputation: A Randomized Crossover Trial.

OBJECTIVE: To compare comfort and functional performance of the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket with the ischial containment (IC) socket in persons with unilateral transfemoral amputation. DESIGN: Randomized crossover trial with two 7-week periods. SETTING: Private prosthetic clinics and university research laboratory. PARTICIPANTS: A total of 30 enrolled (N=30); 25 participants completed the study with full (n=18) or partial data (n=7). INTERVENTIONS: Two custom-fabricated sockets (IC and NU-FlexSIV), worn full-time for 7 weeks, with testing at 1, 4, and 7 weeks after socket delivery. MAIN OUTCOME MEASURES: The primary outcome was change in Socket Comfort Score (SCS) at 7 weeks. Secondary outcomes at 7 weeks included the Orthotic and Prosthetic Users' Survey (OPUS) to assess lower extremity functional status, health-related quality of life, and satisfaction with device, as well as the 5-Times Rapid Sit-to-Stand Test, Four Square Step Test, and T-Test of Agility to assess functional performance. RESULTS: At 7 weeks, the mean SCS for IC (7.0±1.7) and NU-FlexSIV (8.4±1.1) Sockets were significantly different (P<.001; 95% confidence interval, 0.8-2.3). Results from a linear mixed-effects model, accounting for data from all time points, indicated that the SCS was 1.7 (SE=0.45) points higher for the NU-FlexSIV Socket (P<.001). For the secondary outcomes, only OPUS satisfaction with device was significantly better in the NU-FlexSIV Socket after accounting for all data points. CONCLUSIONS: The results suggest that after 7 weeks' accommodation, the NU-FlexSIV Socket was more comfortable and led to greater satisfaction with device than the IC socket in persons with unilateral transfemoral amputation and K3/K4 mobility. Other patient-reported outcomes and function were no different between sockets.

MRI-only occult geriatric hip fractures: is displacement common with nonoperative treatment?

INTRODUCTION: Although surgical fixation is routinely recommended for geriatric hip fractures, nonoperative treatment may be an option for certain stable fracture patterns. Occult hip fractures are nondisplaced fractures not evident on radiographs, but display intraosseous edema on MRI. Our aim is to report the rate of nonoperative treatment failure in patients with occult geriatric hip fractures. METHODS: All nonoperatively treated femoral neck or intertrochanteric femur fractures (AO/OTA 31A and 31B) from 2003 to 2018 were identified. Patients older than 65 years with negative radiographs but a hip fracture evident on MRI were included. Patients who died prior to fracture displacement or union were excluded. Charts and imaging were reviewed for demographic data, fracture type, clinical course, displacement, and whether corrective surgery was performed. RESULTS: Of 15 final study patients, there were 6 femoral neck and 9 intertrochanteric fractures. Two fractures displaced, both requiring surgery (2/15; 13.3%). Both displacements occurred in the femoral neck group (2/6; 33%) compared to none in the intertrochanteric cohort (0/9; 0%). This trend did not reach statistical significance (p = 0.14). CONCLUSION: Thirty-three percent (2/6, 33%) of femoral neck fractures displaced and required surgery. The remainder of the cohort (13/15, 87%) healed without complication, including all of the intertrochanteric fractures (9/9, 100%). Although this difference did not reach statistical significance, the results may better inform treatment discussions for geriatric patients with occult hip fractures diagnosed by MRI. LEVEL OF EVIDENCE: Level III.

Wireless sensors for continuous, multimodal measurements at the skin interface with lower limb prostheses.

Precise form-fitting of prosthetic sockets is important for the comfort and well-being of persons with limb amputations. Capabilities for continuous monitoring of pressure and temperature at the skin-prosthesis interface can be valuable in the fitting process and in monitoring for the development of dangerous regions of increased pressure and temperature as limb volume changes during daily activities. Conventional pressure transducers and temperature sensors cannot provide comfortable, irritation-free measurements because of their relatively rigid construction and requirements for wired interfaces to external data acquisition hardware. Here, we introduce a millimeter-scale pressure sensor that adopts a soft, three-dimensional design that integrates into a thin, flexible battery-free, wireless platform with a built-in temperature sensor to allow operation in a noninvasive, imperceptible fashion directly at the skin-prosthesis interface. The sensor system mounts on the surface of the skin of the residual limb, in single or multiple locations of interest. A wireless reader module attached to the outside of the prosthetic socket wirelessly provides power to the sensor and wirelessly receives data from it, for continuous long-range transmission to a standard consumer electronic device such as a smartphone or tablet computer. Characterization of both the sensor and the system, together with theoretical analysis of the key responses, illustrates linear, accurate responses and the ability to address the entire range of relevant pressures and to capture skin temperature accurately, both in a continuous mode. Clinical application in two prosthesis users demonstrates the functionality and feasibility of this soft, wireless system.

Characterization of Parylene-C degradation mechanisms: In vitro reactive accelerated aging model compared to multiyear in vivo implantation.

Implantable neural microelectrodes are integral components of neuroprosthetic technologies and can transform treatments for many neural-mediated disorders. However, dielectric material degradation during long-term (>1 year) indwelling periods restricts device functional lifetimes to a few years. This comprehensive work carefully investigates in vivo material degradation and also explores the ability of in vitro Reactive Accelerated Aging (RAA) to evaluate implant stability. Parylene C-coated Utah electrode arrays (UEAs) implanted in feline peripheral nerve for 3.25 years were explanted and compared to RAA-processed devices, aged in phosphate buffered saline (PBS) + 20 mM H2O2 at either 67 or 87 °C (28 or 7 days, respectively). Electron microscopy revealed similar physical damage characteristics between explants and RAA (87 °C) devices. Parylene C degradation was overwhelmingly apparent for UEAs from both RAA cohorts. Controls aged in PBS alone displayed almost no damage. Spectroscopic characterization (EDX, XPS, FTIR) found clear indications of oxidation and chlorine abstraction for Parylene C aged in vivo. While in vitro aging was also accompanied by signs of oxidation, changes in the chemistry in vivo and in vitro were statistically different. Analysis of RAA-aged devices identified UEA fabrication approaches that may greatly improve device resistance to degradation. This work underscores the need for an improved understanding of in vivo damage mechanisms, to facilitate the critical need for representative in vitro accelerated testing paradigms for long-term implants.

Stakeholder perspectives for possible residual limb monitoring system for persons with lower-limb amputation.

Purpose: To gather ideas from lower-limb prosthesis users and certified prosthetists regarding possible residual limb monitoring system features and data presentation. We also gathered information on the type of residual limb problems typically encountered, how they currently manage those problems, and their ideas for methods to better manage them.Materials and methods: Two focus groups were held; one with certified prosthetists and another with lower-limb prosthesis users. Open-ended questions were used in a moderated discussion that was audio recorded, transcribed, and assessed using applied thematic analysis.Results and conclusions: Seven individuals participated in each focus group. Prosthetists came from a mix of practice settings, while prosthesis users were diverse in level of amputation, aetiology, and years of experience using lower-limb prostheses. Residual limb problems reported by participants were consistent with those in the literature. Participants suggested better managing residual limb problems through improved education, better detection of residual limb problems, and using sensor-based information to improve prosthetic technology. Participants favoured short-term use of a possible residual limb monitoring systems to troubleshoot residual limb problems, with temperature and pressure the most frequently mentioned measurements. Participants described that an ideal residual limb monitoring system would be lightweight, not interfere with prosthesis function, and result in benefits with regard to prosthetic care and socket function that outweighed inconveniences or concerns regarding system use. A potential positive of system use included having objective data for reimbursement justification, although it was pointed out that the residual limb monitoring system itself also needed to be reimbursable.Implications for RehabilitationStakeholders suggested better managing residual limb problems through improved education, better detection of residual limb problems, and using sensor-based information to improve prosthetic technology.Stakeholders favored short-term use of a possible system to troubleshoot residual limb problems, with temperature and pressure the most frequently mentioned measurements.Stakeholders described that an ideal residual limb monitoring system would be lightweight, not interfere with prosthesis function, and result in benefits with regard to prosthetic care and socket function that outweighs any inconveniences or concerns regarding system use.Stakeholders indicated that a potential positive of system use included having objective data for reimbursement justification, although it was pointed out that the residual limb monitoring system itself also needed to be reimbursable.

Risk Factors Associated With a Noncontact Anterior Cruciate Ligament Injury to the Contralateral Knee After Unilateral Anterior Cruciate Ligament Injury in High School and College Female Athletes: A Prospective Study.

BACKGROUND: The incidence of contralateral anterior cruciate ligament (CACL) injuries after recovery from a first-time anterior cruciate ligament (ACL) disruption is high in women; however, little is known about the risk factors associated with this trauma. HYPOTHESIS: Patient characteristics, strength, anatomic alignment, and neuromuscular characteristics of the contralateral uninjured leg at the time of the first ACL trauma are associated with risk of subsequent CACL injury, and these risk factors are distinct from those for a first-time ACL injury. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Sixty-one women who suffered a first-time noncontact ACL injury while participating in high school or college sports and underwent measurement of potential risk factors on their contralateral limb soon after the initial ACL injury and before reconstruction were followed until either a CACL injury or an ACL graft injury occurred, or until the last date of contact. RESULTS: Follow-up information was available for 55 (90.0%) of the 61 athletes and 11 (20.0%) suffered a CACL injury. Younger age, decreased participation in sport before the first ACL disruption, decreased anterior stiffness of the contralateral knee, and increased hip anteversion were associated with increases in the risk of suffering a CACL injury. CONCLUSION: A portion of CACL injury risk factors were modifiable (time spent participating in sport and increasing anterior knee stiffness with bracing), while others were nonmodifiable (younger age and increased hip anteversion). The relationship between younger age at the time of an initial ACL injury and increased risk of subsequent CACL trauma may be explained by younger athletes having more years available to be exposed to at-risk activities compared with older athletes. A decrease of anterior stiffness of the knee is linked to decreased material properties and width of the ACL, and this may explain why some women are predisposed to bilateral ACL trauma while others only suffer the index injury. The risk factors for CACL injury are unique to women who suffer bilateral ACL trauma compared with those who suffer unilateral ACL trauma. This information is important for the identification of athletes who may benefit from risk reduction interventions.

Technique modifications for a suction suspension version of the Northwestern University Flexible Sub-Ischial Vacuum socket: The Northwestern University Flexible Sub-Ischial Suction socket.

BACKGROUND AND AIM:: Development of a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket would expand application of sub-ischial sockets to a larger proportion of persons with transfemoral amputation. While active vacuum suspension provides more positive coupling of the residual limb to the prosthetic socket, there are circumstances when use of active vacuum is not appropriate or feasible. Therefore, this technical note describes the technique modifications required to cast, fabricate, and fit a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket (i.e. the Northwestern University Flexible Sub-Ischial Suction socket). TECHNIQUE:: Most technique modifications stem from the use of an internal seal with the Northwestern University Flexible Sub-Ischial Suction socket and the need to account for the greater relative motion occurring between the residual limb and socket with passive suction compared to active vacuum suspension. DISCUSSION:: Between January 2015 and March 2018, 266 Northwestern University Flexible Sub-Ischial Suction sockets were fit successfully using the described technique modifications. CLINICAL RELEVANCE: A passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket-the Northwestern University Flexible Sub-Ischial Suction socket-broadens the application of sub-ischial sockets to a larger proportion of the population with transfemoral amputation.

Common Upper Extremity Fracture Eponyms: A Look Into What They Really Mean.

Eponyms, whereas commonly used in hand surgery, are perhaps misused as often as they are used correctly. Many commonly used eponyms, such as Colles fracture, Barton fracture, Smith fracture, and Bennett fracture, were actually described decades before the development of radiographs. The goal of this article is to revisit the original descriptions of commonly used eponymous terms for distal radius and first metacarpal base fractures to provide clarity and enhance understanding of what these eponyms actually mean.

Change in residual limb size over time in the NU-FlexSIV socket: A case study.

BACKGROUND:: This case study represented a unique opportunity wherein a long-time user of sub-ischial sockets had kept nearly every socket he wore for a decade. This individual let us borrow these sockets so we could digitize them and indirectly assess change in residual limb size over time by calculating changes in socket volume and circumferences over time. CASE DESCRIPTION AND METHODS:: Over a decade, the subject maintained a relatively stable body weight of 84-88 kg and received nine sub-ischial sockets. The internal surface of each socket was scanned using a mechanical digitizer and volume and circumferences calculated. FINDINGS AND OUTCOMES:: Socket volume increased 31.3%, from a low of 2659.2 cm3 for the oldest socket to a high of 3490.6 cm3 for the most recent socket. Proximal circumferences increased more than distal circumferences with a 15.9% total increase proximally versus 8.9% total increase distally. DISCUSSION AND CONCLUSION:: The results suggest that this individual's residual limb increased in size over time despite the compressive effect of the socket and liner. In addition, the increase in circumference was greater proximally than distally, which is where the remaining muscle bellies are located. CLINICAL RELEVANCE: This case study provides insight into the long-term effect of the sub-ischial socket on residual limb volume given compression of the soft tissues by the socket system.

Neural electrode resilience against dielectric damage may be improved by use of highly doped silicon as a conductive material.

BACKGROUND: Dielectric damage occurring in vivo to neural electrodes, leading to conductive material exposure and impedance reduction over time, limits the functional lifetime and clinical viability of neuroprosthetics. We used silicon micromachined Utah Electrode Arrays (UEAs) with iridium oxide (IrOx) tip metallization and parylene C dielectric encapsulation to understand the factors affecting device resilience and drive improvements. NEW METHOD: In vitro impedance measurements and finite element analyses were conducted to evaluate how exposed surface area of silicon and IrOx affect UEA properties. Through an aggressive in vitro reactive accelerated aging (RAA) protocol, in vivo parylene degradation was simulated on UEAs to explore agreement with our models. Electrochemical properties of silicon and other common electrode materials were compared to help inform material choice in future neural electrode designs. RESULTS: Exposure of silicon on UEAs was found to primarily affect impedance at frequencies >1kHz, while characteristics at 1 kHz and below were largely unchanged. Post-RAA impedance reduction of UEAs was mitigated in cases where dielectric damage was more likely to expose silicon instead of IrOx. Silicon was found to have a per-area electrochemical impedance >10×higher than many common electrode materials regardless of doping level and resistivity, making it best suited for use as a low-shunting conductor. COMPARISON WITH EXISTING METHODS: Non-semiconductor electrode materials commonly used in neural electrode design are more susceptible to shunting neural interface signals through dielectric defects, compared to highly doped silicon. CONCLUSION: Strategic use of silicon and similar materials may increase neural electrode robustness against encapsulation failures.

Analysis of Al2O3-parylene C bilayer coatings and impact of microelectrode topography on long term stability of implantable neural arrays.

OBJECTIVE: Performance of many dielectric coatings for neural electrodes degrades over time, contributing to loss of neural signals and evoked percepts. Studies using planar test substrates have found that a novel bilayer coating of atomic-layer deposited (ALD) Al2O3 and parylene C is a promising candidate for neural electrode applications, exhibiting superior stability to parylene C alone. However, initial results from bilayer encapsulation testing on non-planar devices have been less positive. Our aim was to evaluate ALD Al2O3-parylene C coatings using novel test paradigms, to rigorously evaluate dielectric coatings for neural electrode applications by incorporating neural electrode topography into test structure design. APPROACH: Five test devices incorporated three distinct topographical features common to neural electrodes, derived from the utah electrode array (UEA). Devices with bilayer (52 nm Al2O3 + 6 µm parylene C) were evaluated against parylene C controls (N ⩾ 6 per device type). Devices were aged in phosphate buffered saline at 67 °C for up to 311 d, and monitored through: (1) leakage current to evaluate encapsulation lifetimes (>1 nA during 5VDC bias indicated failure), and (2) wideband (1-105 Hz) impedance. MAIN RESULTS: Mean-times-to-failure (MTTFs) ranged from 12 to 506 d for bilayer-coated devices, versus 10 to >2310 d for controls. Statistical testing (log-rank test, α = 0.05) of failure rates gave mixed results but favored the control condition. After failure, impedance loss for bilayer devices continued for months and manifested across the entire spectrum, whereas the effect was self-limiting after several days, and restricted to frequencies <100 Hz for controls. These results correlated well with observations of UEAs encapsulated with bilayer and control films. SIGNIFICANCE: We observed encapsulation failure modes and behaviors comparable to neural electrode performance which were undetected in studies with planar test devices. We found the impact of parylene C defects to be exacerbated by ALD Al2O3, and conclude that inferior bilayer performance arises from degradation of ALD Al2O3 when directly exposed to saline. This is an important consideration, given that neural electrodes with bilayer coatings are expected to have ALD Al2O3 exposed at dielectric boundaries that delineate electrode sites. Process improvements and use of different inorganic coatings to decrease dissolution in physiological fluids may improve performance. Testing frameworks which take neural electrode complexities into account will be well suited to reliably evaluate such encapsulation schemes.

Northwestern University Flexible Subischial Vacuum Socket for persons with transfemoral amputation-Part 1: Description of technique.

BACKGROUND: Current transfemoral prosthetic sockets restrict function, lack comfort, and cause residual limb problems. Lower proximal trim lines are an appealing way to address this problem. Development of a more comfortable and possibly functional subischial socket may contribute to improving quality of life of persons with transfemoral amputation. OBJECTIVES: The purpose of this study was to (1) describe the design and fabrication of a new subischial socket and (2) describe efforts to teach this technique. STUDY DESIGN: Development project. METHODS: Socket development involved defining the following: subject and liner selection, residual limb evaluation, casting, positive mold rectification, check socket fitting, definitive socket fabrication, and troubleshooting of socket fit. Three hands-on workshops to teach the socket were piloted and attended by 30 certified prosthetists and their patient models. RESULTS: Patient models responded positively to the comfort, range of motion, and stability of the new socket while prosthetists described the technique as "straight forward, reproducible." CONCLUSION: To our knowledge, this is the first attempt to create a teachable subischial socket, and while it appears promising, more definitive evaluation is needed. Clinical relevance We developed the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket as a more comfortable alternative to current transfemoral sockets and demonstrated that it could be taught successfully to prosthetists.

Quantification of rectifications for the Northwestern University Flexible Sub-Ischial Vacuum Socket.

BACKGROUND: The fit and function of a prosthetic socket depend on the prosthetist's ability to design the socket's shape to distribute load comfortably over the residual limb. We recently developed a sub-ischial socket for persons with transfemoral amputation: the Northwestern University Flexible Sub-Ischial Vacuum Socket. OBJECTIVE: This study aimed to quantify the rectifications required to fit the Northwestern University Flexible Sub-Ischial Vacuum Socket to teach the technique to prosthetists as well as provide a computer-aided design-computer-aided manufacturing option. STUDY DESIGN: Development project. METHODS: A program was used to align scans of unrectified and rectified negative molds and calculate shape change as a result of rectification. Averaged rectifications were used to create a socket template, which was shared with a central fabrication facility engaged in provision of Northwestern University Flexible Sub-Ischial Vacuum Sockets to early clinical adopters. Feedback regarding quality of fitting was obtained. RESULTS: Rectification maps created from 30 cast pairs of successfully fit Northwestern University Flexible Sub-Ischial Vacuum Sockets confirmed that material was primarily removed from the positive mold in the proximal-lateral and posterior regions. The template was used to fabricate check sockets for 15 persons with transfemoral amputation. Feedback suggested that the template provided a reasonable initial fit with only minor adjustments. CONCLUSION: Rectification maps and template were used to facilitate teaching and central fabrication of the Northwestern University Flexible Sub-Ischial Vacuum Socket. Minor issues with quality of initial fit achieved with the template may be due to inability to adjust the template to patient characteristics (e.g. tissue type, limb shape) and/or the degree to which it represented a fully mature version of the technique. Clinical relevance Rectification maps help communicate an important step in the fabrication of the Northwestern University Flexible Sub-Ischial Vacuum Socket facilitating dissemination of the technique, while the average template provides an alternative fabrication option via computer-aided design-computer-aided manufacturing and central fabrication.

Northwestern University Flexible Subischial Vacuum Socket for persons with transfemoral amputation: Part 2 Description and Preliminary evaluation.

BACKGROUND: Current transfemoral prosthetic sockets are problematic as they restrict function, lack comfort, and cause residual limb problems. Development of a subischial socket with lower proximal trim lines is an appealing way to address this problem and may contribute to improving quality of life of persons with transfemoral amputation. OBJECTIVES: The purpose of this study was to illustrate the use of a new subischial socket in two subjects. STUDY DESIGN: Case series. METHODS: Two unilateral transfemoral prosthesis users participated in preliminary socket evaluations comparing functional performance of the new subischial socket to ischial containment sockets. Testing included gait analysis, socket comfort score, and performance-based clinical outcome measures (Rapid-Sit-To-Stand, Four-Square-Step-Test, and Agility T-Test). RESULTS: For both subjects, comfort was better in the subischial socket, while gait and clinical outcomes were generally comparable between sockets. CONCLUSION: While these evaluations are promising regarding the ability to function in this new socket design, more definitive evaluation is needed. Clinical relevance Using gait analysis, socket comfort score and performance-based outcome measures, use of the Northwestern University Flexible Subischial Vaccum Socket was evaluated in two transfemoral prosthesis users. Socket comfort improved for both subjects with comparable function compared to ischial containment sockets.

Effect of bias voltage and temperature on lifetime of wireless neural interfaces with Al 2O3 and parylene bilayer encapsulation.

The lifetime of neural interfaces is a critical challenge for chronic implantations, as therapeutic devices (e.g., neural prosthetics) will require decades of lifetime. We evaluated the lifetime of wireless Utah electrode array (UEA) based neural interfaces with a bilayer encapsulation scheme utilizing a combination of alumina deposited by Atomic Layer Deposition (ALD) and parylene C. Wireless integrated neural interfaces (INIs), equipped with recording version 9 (INI-R9) ASIC chips, were used to monitor the encapsulation performance through radio-frequency (RF) power and telemetry. The wireless devices were encapsulated with 52 nm of ALD Al2O3 and 6 µm of parylene C, and tested by soaking in phosphate buffered solution (PBS) at 57 °C for 4× accelerated lifetime testing. The INIs were also powered continuously through 2.765 MHz inductive power and forward telemetry link at unregulated 5 V. The bilayer encapsulated INIs were fully functional for ∼35 days (140 days at 37 °C equivalent) with consistent power-up frequencies (∼910 MHz), stable RF signal (∼-75 dBm), and 100 % command reception rate. This is ∼10 times of equivalent lifetime of INIs with parylene-only encapsulation (13 days) under same power condition at 37 °C. The bilayer coated INIs without continuous powering lasted over 1860 equivalent days (still working) at 37 °C. Those results suggest that bias stress is a significant factor to accelerate the failure of the encapsulated devices. The INIs failed completely within 5 days of the initial frequency shift of RF signal at 57 °C, which implied that the RF frequency shift is an early indicator of encapsulation/device failure.

Evaluation of a Prototype Hybrid Vacuum Pump to Provide Vacuum-Assisted Suspension for Above-Knee Prostheses.

Vacuum-assisted suspension (VAS) of prosthetic sockets utilizes a pump to evacuate air from between the prosthetic liner and socket, and are available as mechanical or electric systems. This technical note describes a hybrid pump that benefits from the advantages of mechanical and electric systems, and evaluates a prototype as proof-of-concept. Cyclical bench testing of the hybrid pump mechanical system was performed using a materials testing system to assess the relationship between compression cycles and vacuum pressure. Phase 1 in vivo testing of the hybrid pump was performed by an able-bodied individual using prosthesis simulator boots walking on a treadmill, and phase 2 involved an above-knee prosthesis user walking with the hybrid pump and a commercial electric pump for comparison. Bench testing of 300 compression cycles produced a maximum vacuum of 24 in-Hg. In vivo testing demonstrated that the hybrid pump continued to pull vacuum during walking, and as opposed to the commercial electric pump, did not require reactivation of the electric system during phase 2 testing. The novelty of the hybrid pump is that while the electric system provides rapid, initial vacuum suspension, the mechanical system provides continuous air evacuation while walking to maintain suspension without reactivation of the electric system, thereby allowing battery power to be reserved for monitoring vacuum levels.