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Mason D. Smith and David R. Bell

Context:

Anterior cruciate ligament (ACL) reconstruction is the standard of care for individuals with ACL rupture. Balance deficits have been observed in patients with ACL reconstruction (ACLR) using advanced posturography, which is the current gold standard. It is unclear if postural-control deficits exist when assessed by the Balance Error Scoring System (BESS), which is a clinical assessment of balance.

Objective:

The purpose of this study is to determine if postural-control deficits are present in individuals with ACLR as measured by the BESS.

Participants:

Thirty participants were included in this study. Fifteen had a history of unilateral ACLR and were compared with 15 matched controls.

Interventions:

The BESS consists of 3 stances (double-limb, single-limb, and tandem) on 2 surfaces (firm and foam). Participants begin in each stance with hands on their hips and eyes closed while trying to stand as still as possible for 20 s.

Main Outcome Measures:

Each participant performed 3 trials of each stance (18 total), and errors were assessed during each trial and summed to create a total score.

Results:

We observed a significant group × stance interaction (P = .004) and a significant main effect for stance (P < .001). Post hoc analysis revealed that the ACLR group had worse balance on the single-leg foam stance than did controls. Finally, the reconstructed group had more errors when total BESS score was examined (P = .02).

Conclusions:

Balance deficits exist in individuals with ACLR as measured by the BESS. Total BESS score was different between groups. The only condition that differed between groups was the single-leg stance on the unstable foam surface.

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Timothy C. Mauntel, Eric G. Post, Darin A. Padua, and David R. Bell

A disparity exists between the rates of male and female lower extremity injuries. One factor that may contribute to this disparity is high-risk biomechanical patterns that are commonly displayed by females. It is unknown what biomechanical differences exist between males and females during an overhead squat. This study compared lower extremity biomechanics during an overhead squat and ranges of motion between males and females. An electromagnetic motion tracking system interfaced with a force platform was used to quantify peak lower extremity kinematics and kinetics during the descent phase of each squat. Range of motion measurements were assessed with a standard goniometer. Differences between male and female kinematics, kinetics, and ranges of motion were identified with t tests. Males displayed greater peak knee valgus angle, peak hip flexion angle, peak vertical ground reaction forces, and peak hip extension moments. Males also displayed less active ankle dorsiflexion with the knee extended and hip internal and external rotation than females. No other differences were observed. The biomechanical differences between males and females during the overhead squat may result from differences in lower extremity ranges of motion. Therefore, sex-specific injury prevention programs should be developed to improve biomechanics and ranges of motion.

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Eric G. Post, Matthew Olson, Stephanie Trigsted, Scott Hetzel, and David R. Bell

Context: The overhead squat test (OHS) is a functional screening exam that is used to identify high-risk movement profiles such as medial knee displacement (MKD). The reliability and discriminative ability of observational screening during the OHS to identify MKD have yet to be established. Objectives: To investigate the reliability and discriminative ability of observational screening for MKD during the OHS. Study Design: Clinical measurement, cross-sectional. Participants: 100 college students were video-recorded performing the OHS. Three certified athletic trainers classified the knee posture of each subject during the OHS on 2 different occasions using screening guidelines. Main Outcome Measures: Ratings were evaluated by calculating kappa coefficients for intra- and interrater levels of agreements. MKD was measured using motion analysis. Results: Intrarater reliability ranged from .60-.76 with an average value of .70. Interrater reliability was substantial (kappa > .60) for both observation sessions (Fleiss kappa session 1 = .69, session 2 = .70). Sensitivity ranged was .58-.83, while specificity ranged was .70-.88. The MKD group displayed significantly more displacement than the no-MKD group (P < .001). There was a moderate positive correlation (r = .48, P < .001) between knee-posture group and MKD assessed using motion analysis. Conclusion: The OHS has substantial reliability and is able to assess the presence of MKD. The OHS should be used as part of a comprehensive examination that evaluates multiple movement patterns and risk levels.

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Mayrena I. Hernandez, Kevin M. Biese, Dan A. Schaefer, Eric G. Post, David R. Bell, and M. Alison Brooks

Context: Sport specialization among youth athletes has been associated with increased risk of overuse injuries. Previous research demonstrates that children perceive specialization to be beneficial in making their high school team and receiving athletic college scholarships. Previous research demonstrates that parents play a significant role in their child’s sport experience. However, it is unknown if parents and children answer questions related to specialization factors in a similar manner. Objective: To evaluate the beliefs of youth athletes and parents on factors related to sport specialization and evaluate the level of agreement between dyads on sports specialization. Design: Cross-sectional. Setting: Online and paper surveys. Patients or Other Participants: Aim 1: 1998 participants (993 children and 1005 parents). Aim 2: 77 paired parent–child dyads. Interventions: Self-administered survey. Main Outcome Measures: The responses were summarized via frequency and proportions (%). Chi-squares were calculated between parent and child responses. Kappa coefficients were calculated for dyads to determine level of agreement. Sport specialization was classified using a common 3-point scale. Results: The parents were more concerned about risk of injury in sports compared with children (P < .001, χ2 = 231.4; parent: extremely: 7.1%; child: extremely: 3.7%). However, children were more likely to believe that specialization was associated with their chances of obtaining an athletic college scholarship compared with parents (P < .001, χ2 = 201.6; parent: very/extremely likely: 13.7%; child: very/extremely likely: 15.8%). Dyad subanalysis indicated a moderate level of agreement for “quitting other sports to focus on one sport” (κ = .50) and a low level of agreement for “identifying a primary sport” (κ = .30) and “training >8 months per year in primary sport” (κ = .32). Conclusions: Parents and youth athletes had differing beliefs on the factors related to sport specialization. Dyad analysis shows that parents and children answer sport specialization classification questions differently. Health care providers should be aware of these differences, and messaging should be individualized to the audience.

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David R. Bell, Megan P. Myrick, J. Troy Blackburn, Sandra J. Shultz, Kevin M. Guskiewicz, and Darin A. Padua

Context:

Preventing noncontact ACL injuries has been a major focus of athletic trainers and researchers. One factor that may influence female noncontact ACL injury is the fluctuating concentrations of hormones in the body.

Objective:

To determine whether muscle properties change across the menstrual cycle.

Design:

Repeated measures. Testing was performed within 3 d after the onset of menses and ovulation. Repeated-measures ANOVAs were used to determine changes in variables across the menstrual cycle, and Pearson correlations were used to determine relationships between variables.

Participants:

8 women with normal menstrual cycles.

Main Outcome Measures:

Active hamstring stiffness and hamstring extensibility.

Results:

Hamstring extensibility (P = .003) increased at the ovulation testing session but hamstring muscle stiffness (P = .66) did not.

Conclusions:

The results indicate that hamstring muscle stiffness did not change across the menstrual cycle and hamstring extensibility increased at ovulation, when estrogen concentration increases.