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Janie Cournoyer, David Koncan, Michael D. Gilchrist, and T. Blaine Hoshizaki

Understanding the relationship between head mass and neck stiffness during direct head impacts is especially concerning in youth sports where athletes have higher proportional head mass to neck strength. This study compared 2 neck stiffness conditions for peak linear and rotational acceleration and brain tissue deformations across 3 impact velocities, 3 impact locations, and 2 striking masses. A pendulum fitted with a nylon cap was used to impact a fifth percentile hybrid III headform equipped with 9 accelerometers and fitted with a youth American football helmet. The 2 neck stiffness conditions consisted of a neckform with and without resistance in 3 planes, representing the upper trapezius, the splenius capitis, and the sternocleidomastoid muscles. Increased neck stiffness resulted in significant changes in head kinematics and maximum principal strain specific to impact velocity, impact location, and striking mass.

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Melissa Doozan, David M. Bazett-Jones, and Neal R. Glaviano

Two-dimensional assessments of the lower extremity and trunk are becoming more common in the sports medicine community. However, there is little evidence evaluating expert versus novice reliability or agreement of these measurements in healthy or pathological populations. The purpose of this study is to evaluate expert versus novice reliability and agreement of two-dimensional squatting kinematics in females with and without patellofemoral pain. There was good–excellent reliability and acceptable agreement in squatting kinematics when comparing healthy and patellofemoral pain participants between the two assessors. Minimal training is required for novice assessors to measure two-dimensional squatting kinematics in healthy or pathological patients.

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Michael A. Hunt, Christopher K. Cochrane, Andrew M. Schmidt, Honglin Zhang, David J. Stockton, Alec H. Black, and David R. Wilson

Knee osteoarthritis is thought to result, in part, from excessive and unbalanced joint loading. Toe-in and toe-out gait modifications produce alterations in external knee joint moments, and some improvements in pain over the short- and long-term. The aim of this study was to probe mechanisms of altered joint loading through the assessment of tibiofemoral contact in standing with toe-in and toe-out positions using an open magnetic resonance scanner. In this study, 15 young, healthy participants underwent standing magnetic resonance imaging of one of their knees in 3 foot positions. Images were analyzed to determine contact in the tibiofemoral joint, with primary outcomes including centroid of contact and contact area for each compartment and overall. The centroid of contact shifted laterally in the lateral compartment with both toe-in and toe-out postures, compared with the neutral position (P < .01), while contact area in the medial and lateral compartments showed no statistical differences. Findings from this study indicate that changes in the loading anatomy are present in the tibiofemoral joint with toe-in and toe-out and that a small amount of lateralization of contact, especially in the lateral compartment, does occur with these altered lower limb orientations.

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Daniel J. Davis and John H. Challis

Time-differentiating kinematic signals from optical motion capture amplifies the inherent noise content of those signals. Commonly, biomechanists address this problem by applying a Butterworth filter with the same cutoff frequency to all noisy displacement signals prior to differentiation. Nonstationary signals, those with time-varying frequency content, are widespread in biomechanics (eg, those containing an impact) and may necessitate a different filtering approach. A recently introduced signal filtering approach wherein signals are divided into sections based on their energy content and then Butterworth filtered with section-specific cutoff frequencies improved second derivative estimates in a nonstationary kinematic signal. Utilizing this signal-section filtering approach for estimating running vertical ground reaction forces saw more of the signal’s high-frequency content surrounding heel strike maintained without allowing inappropriate amounts of noise contamination in the remainder of the signal. Thus, this signal-section filtering approach resulted in superior estimates of vertical ground reaction forces compared with approaches that either used the same filter cutoff frequency across the entirety of each signal or across the entirety of all signals. Filtering kinematic signals using this signal-section filtering approach is useful in processing data from tasks containing an impact when accurate signal second derivative estimation is of interest.

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Michael J. Cools, Weston T. Northam, Michael Boyd, Andrew Alexander, Jason P. Mihalik, Kevin M. Guskiewicz, and Kevin A. Carneiro

Primary care providers (PCPs) are evaluating increasing numbers of concussions, but it is unknown how often they are documenting concussion-specific history and physical examination findings vital for this process. This study reviews clinical documentation to determine how PCPs are evaluating concussed patients. PCPs often did not document important aspects of concussion history, including dizziness (48%), nausea (48%), vision changes (54%), cognitive complaints (54%), emotional changes (83%), sleep difficulties (84%), and neck pain (87%). Additionally, they often did not document important aspects of a concussion physical examination, including detailed neurologic examination (73%), clinical cognitive assessment (87%), balance testing (59%), and neck evaluation (54%). Omitting these parts of the history and physical examination could result in a premature return to play.

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Jennifer A. Hogg, Terry Ackerman, Anh-Dung Nguyen, Scott E. Ross, Randy J. Schmitz, Jos Vanrenterghem, and Sandra J. Shultz

Context: A bias toward femoral internal rotation is a potential precursor to functional valgus collapse. The gluteal muscles may play a critical role in mitigating these effects. Objective: Determine the extent to which gluteal strength and activation mediate associations between femoral alignment measures and functional valgus collapse. Design: Cross-sectional. Setting: Research laboratory. Patients or Other Participants: Forty-five females (age = 20.1 [1.7] y; height = 165.2 [7.6] cm; weight = 68.6 [13.1] kg) and 45 males (age = 20.8 [2.0] y; height = 177.5 [8.7] cm; weight = 82.7 [16.5] kg), healthy for 6 months prior. Intervention(s): Femoral alignment was measured prone. Hip-extension and abduction strength were obtained using a handheld dynamometer. Three-dimensional biomechanics and surface electromyography were obtained during single-leg forward landings. Main Outcome Measures: Forward stepwise multiple linear regressions determined the influence of femoral alignment on functional valgus collapse and the mediating effects of gluteus maximus and medius strength and activation. Results: In females, less hip abduction strength predicted greater peak hip adduction angle (R 2 change = .10; P = .02), and greater hip-extensor activation predicted greater peak knee internal rotation angle (R 2 change = .14; P = .01). In males, lesser hip abduction strength predicted smaller peak knee abduction moment (R 2 change = .11; P = .03), and the combination of lesser hip abduction peak torque and lesser gluteus medius activation predicted greater hip internal rotation angle (R 2 change = .15; P = .04). No meaningful mediation effects were observed (υadj < .01). Conclusions: In females, after accounting for femoral alignment, less gluteal strength and higher muscle activation were marginally associated with valgus movement. In males, less gluteal strength was associated with a more varus posture. Gluteal strength did not mediate femoral alignment. Future research should determine the capability of females to use their strength efficiently.

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Olivia Bartlett and James L. Farnsworth II

Clinical Scenario: Kinesiophobia is a common psychological phenomenon that occurs following injury involving fear of movement. These psychological factors contribute to the variability among patients’ perceived disability scores following injury. In addition, the psychophysiological, behavioral, and cognitive factors of kinesiophobia have been shown to be predictive of a patient’s self-reported disability and pain. Previous kinesiophobia research has mostly focused on lower-extremity injuries. There are fewer studies that investigate upper-extremity injuries despite the influence that upper-extremity injuries can have on an individual’s activities of daily living and, therefore, disability scores. The lack of research calls for a critical evaluation and appraisal of available evidence regarding kinesiophobia and its contribution to perceived disability for the upper-extremity. Focused Clinical Question: How does kinesiophobia in patients with upper-extremity injuries influence perceptions of disability and quality of life measurements? Summary of Key Findings: Two cross-sectional studies and one cohort study were included. The first study found a positive relationship between kinesiophobia and a high degree of perceived disability. Another study found that kinesiophobia and catastrophic thinking scores were the most important predictors of perceived upper-extremity disability. The third study found that kinesiophobia contributes to self-reported disability in the shoulder. Clinical Bottom Line: There is moderate evidence that supports the relationship between kinesiophobia and perceived disability, and the relationship between elevated perceptions of disability and increased kinesiophobia scores in patients with an upper-extremity injury. Clinicians should evaluate and monitor kinesiophobia in patients following injury, a condition that can enhance perceptions of disability. An elevated perception of disability can create a cycle of fear that leads to hypervigilance and fear-avoidance behavior. Strength of Recommendation: Consistent findings from reviewed studies suggest there is grade B evidence to support that kinesiophobia is related to an increased perceived disability following upper-extremity injuries.

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Inmaculada Reina-Martin, Santiago Navarro-Ledesma, Ana Belen Ortega-Avila, Kevin Deschamps, Alfonso Martinez-Franco, Alejandro Luque-Suarez, and Gabriel Gijon-Nogueron

Background: Imaging diagnosis plays a fundamental role in the evaluation and management of injuries suffered in sports activities. Objective: To analyze the differences in the thickness of the Achilles tendon, patellar tendon, plantar fascia, and posterior tibial tendon in the following levels of physical activity: persons who run regularly, persons otherwise physically active, and persons with a sedentary lifestyle. Design: Cross-sectional and observational. Participants: The 91 volunteers recruited from students at the university and the Triathlon Club from December 2016 to June 2019. The data were obtained (age, body mass index, and visual analog scale for quality of life together with the ultrasound measurements). Results: Tendon and ligament thickness was greater in the runners group than in the sedentary and active groups with the exception of the posterior tibial tendon. The thickness of the Achilles tendon was greater in the runners than in the other groups for both limbs (P = .007 and P = .005). This was also the case for the cross-sectional area (P < .01) and the plantar fascia at the heel insertion in both limbs (P = .034 and P = .026) and for patellar tendon thickness for the longitudinal measurement (P < .01). At the transversal level, however, the differences were only significant in the right limb (P = .040). Conclusion: The thickness of the Achilles tendon, plantar fascia, and patellar tendon is greater in runners than in persons who are otherwise active or who are sedentary.

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Jeffrey B. Driban and Patrick O. McKeon

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Nicholas C. Clark and Elaine M. Mullally

Context: Single- versus double-leg landing events occur the majority of the time in a netball match. Landings are involved in large proportions of netball noncontact knee injury events. Of all landing-induced anterior cruciate ligament injuries, most occur during single-leg landings. Knowledge of whether different single-leg functional performance tests capture the same or different aspects of lower-limb motor performance will therefore inform clinicians’ reasoning processes and assist in netball noncontact knee injury prevention screening. Objective: To determine the correlation between the triple hop for distance (THD), single hop for distance (SHD), and vertical hop (VH) for the right and left lower limbs in adult female netball players. Design: Cross-sectional. Setting: Local community netball club. Participants: A total of 23 players (age 28.7 [6.2] y; height 171.6 [7.0] cm; mass 68.2 [9.8] kg). Interventions: There were 3 measured trials (right and left) for THD, SHD, and VH, respectively. Main Outcome Measures: Mean hop distance (percentage of leg length [%LL]), Pearson intertest correlation (r), and coefficient of determination (r 2). Results: Values (right and left; mean [SD]) were as follows: THD, 508.5 (71.8) %LL and 510.9 (56.7) %LL; SHD, 183.4 (24.6) %LL and 183.0 (21.5) %LL; and VH, 21.3 (5.2) %LL and 20.6 (5.0) %LL. All correlations were significant (P ≤ .05), r/r 2 values (right and left) were THD–SHD, .91/.83 and .87/.76; THD–VH, .59/.35 and .51/.26; and SHD–VH, .50/.25 and .37/.17. A very large proportion of variance (76%–83%) was shared between the THD and SHD. A small proportion of variance was shared between the THD and VH (25%–35%) and SHD and VH (17%–25%). Conclusion: The THD and SHD capture highly similar aspects of lower-limb motor performance. In contrast, the VH captures aspects of lower-limb motor performance different to the THD or SHD. Either the THD or the SHD can be chosen for use within netball knee injury prevention screening protocols according to which is reasoned as most appropriate at a specific point in time. The VH, however, should be employed consistently alongside rather than in place of the THD or SHD.