Use of the Independent Medical Spotter in Identifying Head Injuries in Division I Football Players.

OBJECTIVE: Sport-related concussion (SRC) is a known risk of contact sports and strategies to minimize risk have been used. We aimed to determine if an independent medical spotter (IMS) identified more SRCs than would otherwise be detected by trained sideline medical staff (SMS). DESIGN: Prospective review of SRCs during competition in the 2019 season and retrospective review of SRCs in the 2015 to 2018 seasons, which also used an IMS. SETTING: Division I football games (home and away) of a Big 10 Conference institution. PARTICIPANTS: All football team members who participated in competition. INDEPENDENT VARIABLES: Occurrence of SRC during competition and whether the IMS or SMS directly visualized the injury. MAIN OUTCOME MEASURES: The total number of SRCs that occurred during competition in the 2015 to 2019 football seasons and whom observed the SRC-SMS or IMS-or if a student athlete reported symptoms after competition. RESULTS: Over the 5-year study period, 24 SRCs occurred during competition. Of those, 19 (79.2%) were observed by SMS, 2 (8.3%) by the IMS, and 3 (12.5%) were reported to SMS after competition ended. CONCLUSIONS: Most SRCs are accurately identified by SMS, but a small number were apparent only to the IMS who seemed to add sensitivity in detecting a SRC. Instances remain in which SRC recognition and diagnosis were delayed despite trained SMS and IMS. CLINICAL RELEVANCE: An IMS allows for a small-added player protection benefit using different vantage points to identify potential SRCs during competition.

Characterizing the Effects of Explosive Ordnance Disposal Operations on the Human Body While Wearing Heavy Personal Protective Equipment.

OBJECTIVE: To provide a comprehensive characterization of explosive ordnance disposal (EOD) personal protective equipment (PPE) by evaluating its effects on the human body, specifically the poses, tasks, and conditions under which EOD operations are performed. BACKGROUND: EOD PPE is designed to protect technicians from a blast. The required features of protection make EOD PPE heavy, bulky, poorly ventilated, and difficult to maneuver in. It is not clear how the EOD PPE wearer physiologically adapts to maintain physical and cognitive performance during EOD operations. METHOD: Fourteen participants performed EOD operations including mobility and inspection tasks with and without EOD PPE. Physiological measurement and kinematic data recording were used to record human physiological responses and performance. RESULTS: All physiological measures were significantly higher during the mobility and the inspection tasks when EOD PPE was worn. Participants spent significantly more time to complete the mobility tasks, whereas mixed results were found in the inspection tasks. Higher back muscle activations were seen in participants who performed object manipulation while wearing EOD PPE. CONCLUSION: EOD operations while wearing EOD PPE pose significant physical stress on the human body. The wearer's mobility is impacted by EOD PPE, resulting in decreased speed and higher muscle activations. APPLICATION: The testing and evaluation methodology in this study can be used to benchmark future EOD PPE designs. Identifying hazards posed by EOD PPE lays the groundwork for developing mitigation plans, such as exoskeletons, to reduce physical and cognitive stress caused by EOD PPE on the wearers without compromising their operational performance.

Physical and Cognitive Load Effects Due to a Powered Lower-Body Exoskeleton.

OBJECTIVE: The aim of this study is to determine the effects of a powered exoskeleton on measures of physical and cognitive performance. BACKGROUND: US warfighters carry heavy equipment into battle, and exoskeletons may reduce that burden. While exoskeletons are currently evaluated for their effects on physical performance, their cognitive effects are not currently considered. METHOD: Twelve military members participated in a simulated patrol task under three conditions: wearing a powered exoskeleton (PWR), an unpowered exoskeleton (UNP), and without wearing an exoskeleton (OFF). While following a confederate over obstacles at a constant pace, participants performed additional audio and visual tasks. Dependent measures included visual misses, visual reaction time, audio misses, audio reaction time, incremental lag time, and NASA-TLX scores. RESULTS: The variability in the follow-task lag time was lowest with OFF and highest with UNP, highlighting reduced ability to maintain pace with the exoskeleton. Visual reaction time was significantly slower with PWR compared to OFF for 5 of 12 subjects. The NASA-TLX overall workload scores were lower for OFF compared to PWR and UNP. CONCLUSION: Efforts to understand individual variability are warranted such that exoskeleton designs can be used for a wider set of the population. While not all subjects had measurable differences in the selected performance tasks, the perception of increased workload was present across subjects. It remains to be determined what difference in reaction time would be operationally relevant for task-specific settings. APPLICATION: Findings draw attention to the need to consider "cognitive fit" and subject differences in the design and implementation of exoskeletons.

Correlation of knee and hindfoot deformities in advanced knee OA: compensatory hindfoot alignment and where it occurs.

BACKGROUND: Many patients undergoing TKA have both knee and ankle pathology, and it seems likely that some compensatory changes occur at each joint in response to deformity at the other. However, it is not fully understood how the foot and ankle compensate for a given varus or valgus deformity of the knee. QUESTIONS/PURPOSES: (1) What is the compensatory hindfoot alignment in patients with end-stage osteoarthritis who undergo total knee arthroplasty (TKA)? (2) Where in the hindfoot does the compensation occur? METHODS: Between January 1, 2005, and December 31, 2009, one surgeon (JJC) obtained full-length radiographs on all patients undergoing primary TKA (N=518) as part of routine practice; patients were analyzed for the current study and after meeting inclusion criteria, a total of 401 knees in 324 patients were reviewed for this analysis. Preoperative standing long-leg AP radiographs and Saltzman hindfoot views were analyzed for the following measurements: mechanical axis angle, Saltzman hindfoot alignment and angle, anatomic lateral distal tibial angle, and the ankle line convergence angle. Statistical analysis included two-tailed Pearson correlations and linear regression models. Intraobserver and interobserver intraclass coefficients for the measurements considered were evaluated and all were excellent (in excess of 0.8). RESULTS: As the mechanical axis angle becomes either more varus or valgus, the hindfoot will subsequently orient in more valgus or varus position, respectively. For every degree increase in the valgus mechanical axis angle, the hindfoot shifts into varus by -0.43° (95% confidence interval [CI], -0.76° to -0.1°; r=-0.302, p=0.0012). For every degree increase in the varus mechanical axis angle, the hindfoot shifts into valgus by -0.49° (95% CI, -0.67° to -0.31°; r=-0.347, p<0.0001). In addition, the subtalar joint had a strong positive correlation (r=0.848, r2=0.72, p<0.0001) with the Saltzman hindfoot angle, whereas the anatomic lateral distal tibial angle (r=0.450, r2=0.20, p<0.0001) and the ankle line convergence angle (r=0.319, r2=0.10, p<0.0001) had a moderate positive correlation. The coefficient of determination (r2) shows that 72% of the variance in the overall hindfoot angle can be explained by changes in the subtalar joint orientation. CONCLUSIONS: These findings have implications for treating patients with both knee and foot/ankle problems. For example, a patient with varus arthritis of the knee should be examined for fixed hindfoot valgus deformity. The concern is that patients undergoing TKA, who also present with a stiff subtalar joint, may have exacerbated, post-TKA foot/ankle pain or disability or malalignment of the lower extremity mechanical axis as a result of the inability of the subtalar joint to reorient itself after knee realignment. A prospective study is underway to confirm this speculation. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Benchmarking Protocols for Evaluating Grasp Strength, Grasp Cycle Time, Finger Strength, and Finger Repeatability of Robot End-effectors.

This paper describes a set of metrics and supporting benchmarking protocols for determining the performance characteristics of robot end-effectors. In the short-term, these tools are proving useful as a common ground for assessing and comparing end-effectors. The long-term goal is a standard framework for providing technical specifications for robotic end-effectors to help pair technologies to application spaces. This paper presents a subset of the metrics - grasp strength, grasp cycle time, finger strength, and finger repeatability - with accompanying measurement techniques and supporting test artifacts. The application of these metrics and protocols is demonstrated using example implementations to characterize a variety of robot end-effectors, with example data sets and test designs provided for downloading.

Sagittal Distal Tibial Articular Angle and the Relationship to Talar Subluxation in Total Ankle Arthroplasty.

BACKGROUND: Longevity of total ankle replacement (TAR) depends heavily on anatomic alignment. The lateral talar station (LTS) classifies the sagittal position of the talus relative to the tibia. We hypothesized that correcting the sagittal distal tibial articular angle (sDTAA) during TAR would anatomically realign the tibiotalar joint and potentially reduce the risk of prosthesis subluxation. METHODS: The LTS (millimeters) and sDTAA (degrees) were measured twice by 2 blinded observers using weight-bearing lateral ankle radiographs obtained before (n = 96) and after (n = 94) TAR, with excellent interobserver and intraobserver reliability (correlation coefficient >0.9). RESULTS: Preoperative LTS was as follows: anterior (60.4%), posterior (27.1%), and neutral (12.5%). A strong preoperative correlation was found between LTS and sDTAA (r = 0.81; P < .0001). In ankles that were initially anterior and became less anterior postoperatively (n = 41), LTS decreased from an average 8.1 mm to 6.5 mm and the LTS changed 1.1 mm per degree of sDTAA change. In ankles that were initially posterior (n = 25), LTS increased from an average of -5.1 mm to -2.8 mm and the LTS changed 0.6 mm per degree of sDTAA change. The correlation between LTS and sDTAA was reduced postoperatively (r = 0.62; P < .0001). CONCLUSIONS: Our results suggest that rather than following generic recommendations, the surgeon should customize the sagittal distal tibial cut to the individual patient based on the preoperative LTS in order to achieve neutral TAR alignment. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Lateral talar station: a clinically reproducible measure of sagittal talar position.

BACKGROUND: The sagittal relationship of the talus to the tibial shaft can prove invaluable to the orthopedist in understanding and effectively treating ankle pathologies such as ligamentous laxity and ankle arthritis. Any useful radiographic analysis tool to assess the lateral position of the talus must be employable reliably in the clinical setting. Previously published measurements to assess the lateral translational relationship of the talus relative to the tibial axis may not be available in the clinical setting or may be subject to significant inaccuracies. We have defined a sagittal talar position measurement (lateral talar station; LTS), which we postulated could be used reproducibly on clinical radiographs by the orthopedist to define the position of the talus as it relates to the anatomic tibial axis. In addition, we defined the normal range of the LTS measurement. METHODS: A retrospective cohort of patients (121 ankles, 104 patients) who presented to our clinic with foot pain between 2005 and 2011 was evaluated for inclusion in the study. Exclusion criteria included patients with ankle trauma, instability, prior ankle surgery, or radiographic evidence of ankle osteoarthrosis. The final cohort consisted of 82 ankles. The LTS was measured digitally for each subject on weight-bearing lateral ankle radiographs by 3 observers. The mean LTS and standard deviation was determined for the entire cohort. In addition, as a means of validating our methodology, we performed an assessment of interobserver and intraobserver reliability in terms of the LTS measurements. RESULTS: The LTS measurements for the entire cohort fit a Gaussian distribution with a mean of 1.17 mm (SD = 0.9893 mm). Interobserver intraclass coefficients for 2 observers (medical student and radiologist) and intraobserver intraclass coefficients for 1 reader (orthopaedic surgeon) indicated excellent reliability, being above 0.9. CONCLUSION: The LTS was a reliable measure that could be used on weight-bearing lateral ankle radiographs to define sagittal position of the talus in a clinical setting. The normal distribution for the LTS was described in our study population. LEVEL OF EVIDENCE: Level IV, case series.