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Cameron Haun, Cathleen N. Brown, Kimberly Hannigan, and Samuel T. Johnson

Clinical Scenario: Deformation of the arch, as measured by navicular drop (ND), is linked to lower-extremity musculoskeletal injuries. The short foot exercise (SFE) has been used to strengthen the intrinsic foot muscles that support the arch. Clinical Question: Does the SFE decrease ND in healthy adults? Summary of Key Findings: Three studies that examined the use of the SFE on ND were included. A randomized control trial that compared the SFE to a towel-curl exercise and a control group found no significant differences between the 3 groups. A randomized control trial compared the SFE to the use of arch support insoles in individuals with a flexible flatfoot and found a significant improvement in the SFE group. A prospective cohort study, without a control group, reported a significant decrease in ND following a 4-week SFE intervention without a regression at an 8-week follow-up. Overall, two of the three studies reported a significant reduction in ND following an SFE. Clinical Bottom Line: There is preliminary data supporting the use of the SFE to decrease ND—particularly in individuals with a flexible flatfoot. However, issues with the study designs make it difficult to interpret the data. Strength of Recommendation: Due to limited evidence, there is grade B evidence to support the use of the SFE to decrease ND.

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Yumeng Li, Jupil Ko, Marika A. Walker, Cathleen N. Brown, and Kathy J. Simpson

The purpose of the present study was to examine the effect of chronic ankle instability (CAI) on lower-extremity joint coordination and stiffness during landing. A total of 21 female participants with CAI and 21 pair-matched healthy controls participated in the study. Lower-extremity joint kinematics were collected using a 7-camera motion capture system, and ground reaction forces were collected using 2 force plates during drop landings. Coupling angles were computed based on the vector coding method to assess joint coordination. Coupling angles were compared between the CAI and control groups using circular Watson–Williams tests. Joint stiffness was compared between the groups using independent t tests. Participants with CAI exhibited strategies involving altered joint coordination including a knee flexion dominant pattern during 30% and 70% of their landing phase and a more in-phase motion pattern between the knee and hip joints during 30% and 40% and 90% and 100% of the landing phase. In addition, increased ankle inversion and knee flexion stiffness were observed in the CAI group. These altered joint coordination and stiffness could be considered as a protective strategy utilized to effectively absorb energy, stabilize the body and ankle, and prevent excessive ankle inversion. However, this strategy could result in greater mechanical demands on the knee joint.

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Jae P. Yom, Kathy J. Simpson, Scott W. Arnett, and Cathleen N. Brown

One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity.

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Eric D. Merritt, Cathleen N. Brown, Robin M. Queen, Kathy J. Simpson, and Julianne D. Schmidt

Context:

Dynamic balance deficits exist following a concussion, sometimes years after injury. However, clinicians lack practical tools for assessing dynamic balance.

Objectives:

To determine if there are significant differences in static and dynamic balance performance between individuals with and without a history of concussion.

Design:

Cross sectional.

Setting:

Clinical research laboratory.

Patients or Other Participants:

45 collegiate student-athletes with a history of concussion (23 males, 22 females; age = 20.0 ± 1.4 y; height = 175.8 ± 11.6 cm; mass = 76.4 ± 19.2 kg) and 45 matched controls with no history of concussion (23 males, 22 females; age = 20.0 ± 1.3 y; height = 178.8 ± 13.2 cm; mass = 75.7 ± 18.2 kg).

Interventions:

Participants completed a static (Balance Error Scoring System) and dynamic (Y Balance Test-Lower Quarter) balance assessment.

Main Outcome Measures:

A composite score was calculated from the mean normalized Y Balance Test-Lower Quarter reach distances. Firm, foam, and overall errors were counted during the Balance Error Scoring System by a single reliable rater. One-way ANOVAs were used to compare balance performance between groups. Pearson’s correlations were performed to determine the relationship between the time since the most recent concussion and balance performance. A Bonferonni adjusted a priori α < 0.025 was used for all analyses.

Results:

Static and dynamic balance performance did not significantly differ between groups. No significant correlation was found between the time since the most recent concussion and balance performance.

Conclusions:

Collegiate athletes with a history of concussion do not present with static or dynamic balance deficits when measured using clinical assessments. More research is needed to determine whether the Y Balance Test-Lower Quarter is sensitive to acute balance deficits following concussion.

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Jupil Ko, Erik Wikstrom, Yumeng Li, Michelle Weber, and Cathleen N. Brown

Context: The modified Star Excursion Balance Test (mSEBT) and Y-Balance Test (YBT) are common dynamic postural stability assessments for individuals with chronic ankle instability (CAI). However, the reach distance measurement technique and movement strategy used during the mSEBT and YBT differ. To date, no studies have compared task performance differences on these tests in CAI patients. Objective: To determine whether individuals with CAI perform the mSEBT and YBT differently. Design: Cross-sectional. Setting: Biomechanics laboratory. Participants: Of 97 consented participants, 86 (43 females, 43 males; age 21.5 [3.3] y, height 169.8 [10.3] cm, mass 69.5 [13.4] kg), who reported ≤25 on the Cumberland Ankle Instability Tool, ≥11 on the Identification of Functional Ankle Instability, and had a history of a moderate to severe ankle sprain(s) participated. Interventions: Participants were instructed to perform the mSEBT and YBT in a predetermined counterbalanced order. Three anterior, posteromedial, and posterolateral trials of each test were completed on the involved limb after 4 practice trials. Test direction order was randomized for each participant. Main Outcome Measures: Normalized (expressed in percentage) reach distance in each direction. Paired sample t tests were performed to compare each of the 3 directions between the mSEBT and YBT. Results: Significantly shorter reach distances in the anterior (58.9% [5.8%] vs 61.4% [5.4%], P = .001) and the posteromedial (98.8% [8.6%] vs 100.8% [8.1%], P = .003) directions were noted on the mSEBT relative to the YBT. No differences in the posterolateral directions were observed. Conclusions: Within those with CAI, mSEBT and YBT normalized reach distances differ in the anterior and posteriomedial directions. As a result, clinicians and researchers should not directly compare the results of these tests.

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Yumeng Li, Rumit S. Kakar, Marika A. Walker, Yang-Chieh Fu, Timothy S. Oswald, Cathleen N. Brown, and Kathy J. Simpson

The purpose of the study was to determine if the intratrunk coordination of axial rotation exhibited by individuals with spinal fusion for adolescent idiopathic scoliosis (SF-AIS) during running varies from healthy individuals and how the coordination differs among adjacent trunk-segment pairs. Axial rotations of trunk segments (upper, middle, lower trunk) and pelvis were collected for 11 SF-AIS participants and 11 matched controls during running. Cross-correlation determined the phase lag between the adjacent segment motions. The coupling angle was generated using the vector coding method and classified into 1 of the 4 major, modified coordination patterns: in-phase, anti-phase, superior, and inferior phase. Two-way, mixed-model ANCOVA was employed to test phase lag, cross-correlation r, and time spent in each major coordination pattern. A significantly lower phase lag for SF-AIS was observed compared with controls. Qualitatively, there was a tendency that SF-AIS participants spent less time in anti-phase for middle-lower trunk and lower trunk-pelvis coordinations compared to controls. Phase lag and anti-phase time was significantly increased from cephalic to caudal segment pairs, regardless of group. In conclusion, SF-AIS participants and controls displayed similar patterns of intra-trunk coordination; however, the spinal fusion hindered decoupling of intra-trunk motions particularly between the lower trunk-pelvic motion.

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Kathy J. Simpson, Jae P. Yom, Yang-Chieh Fu, Scott W. Arnett, Sean O’Rourke, and Cathleen N. Brown

The objective of the study was to determine if prophylactic ankle bracing worn by females during landings produces abnormal lower extremity mechanics. Angular kinematic and ground reaction force (GRF) data were obtained for 16 athletically experienced females who performed brace and no-brace drop landings. The brace condition displayed reduced in/external rotation and flexion displacements about the ankle and knee joints and increased vertical and mediolateral GRF peak magnitudes and rate of vertical GRF application (paired t test, P < .05). The ankle and knee joints landed in a less plantar flexed and more flexed position, respectively. No significant ab/adduction outcomes may have occurred due to interparticipant variability and/or a lack of brace restriction. Conclusion: During typical landings, this lace-up brace increases vertical GRF, decreases ankle and knee joint displacements of flexion and int/external rotation, but minimally affects ab/adduction displacements.

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Adam B. Rosen, Jupil Ko, Kathy J. Simpson, and Cathleen N. Brown

Patellar tendinopathy is often managed with a patellar tendon strap, however, their effectiveness is unsubstantiated. The purpose of this study was to determine if straps altered pain or lower extremity kinetics of individuals with patellar tendinopathy during landing. Thirty participants with patellar tendinopathy and 30 controls completed drop jumps with and without patellar tendon straps. Wearing the strap, tendinopathy participants demonstrated significantly decreased pain and reduced knee adductor moment; all participants displayed significantly decreased anterior ground reaction force while wearing a strap. Patellar tendon strapping may reduce pain due to alterations in direction and magnitude of loading.