Does prior concussion lead to biomechanical alterations associated with lateral ankle sprain and anterior cruciate ligament injury? A systematic review and meta-analysis.

OBJECTIVE: To determine whether individuals with a prior concussion exhibit biomechanical alterations in balance, gait and jump-landing tasks with and without cognitive demands that are associated with risk of lateral ankle sprain (LAS) and anterior cruciate ligament (ACL) injury. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Five electronic databases (Web of Science, Scopus, PubMed, SPORTDiscus and CiNAHL) were searched in April 2023. ELIGIBILITY CRITERIA: Included studies involved (1) concussed participants, (2) outcome measures of spatiotemporal, kinematic or kinetic data and (3) a comparison or the data necessary to compare biomechanical variables between individuals with and without concussion history or before and after a concussion. RESULTS: Twenty-seven studies were included involving 1544 participants (concussion group (n=757); non-concussion group (n=787)). Individuals with a recent concussion history (within 2 months) had decreased postural stability (g=0.34, 95% CI 0.20 to 0.49, p<0.001) and slower locomotion-related performance (g=0.26, 95% CI 0.11 to 0.41, p<0.001), both of which are associated with LAS injury risk. Furthermore, alterations in frontal plane kinetics (g=0.41, 95% CI 0.03 to 0.79, p=0.033) and sagittal plane kinematics (g=0.30, 95% CI 0.11 to 0.50, p=0.002) were observed in individuals approximately 2 years following concussion, both of which are associated with ACL injury risk. The moderator analyses indicated cognitive demands (ie, working memory, inhibitory control tasks) affected frontal plane kinematics (p=0.009), but not sagittal plane kinematics and locomotion-related performance, between the concussion and non-concussion groups. CONCLUSION: Following a recent concussion, individuals display decreased postural stability and slower locomotion-related performance, both of which are associated with LAS injury risk. Moreover, individuals within 2 years following a concussion also adopt a more erect landing posture with greater knee internal adduction moment, both of which are associated with ACL injury risk. While adding cognitive demands to jump-landing tasks affected frontal plane kinematics during landing, the altered movement patterns in locomotion and sagittal plane kinematics postconcussion persisted regardless of additional cognitive demands. PROSPERO REGISTRATION NUMBER: CRD42021248916.

Epidemiology of Bone Stress Injuries and Healthcare Utilization in PAC-12 Cross-Country Athletes.

CONTEXT: Bone stress injury (BSI) is common in collegiate athletics. Injury rate and healthcare utilization is not well documented in running athletes. OBJECTIVE: The purpose of this study was to describe the rate, classification, and healthcare utilization in collegiate cross-country runners with BSI. DESIGN: Descriptive Epidemiology Study. SETTING: Sports medicine facilities participating in the PAC-12 Health Analytics Program. PATIENTS OR OTHER PARTICIPANTS: Collegiate cross-country athletes. MAIN OUTCOME MEASURES: Counts of injury and healthcare resources utilized for each injury. Injury rates were calculated based on athlete seasons. RESULTS: A total of 168 BSIs were reported over four seasons from 80 team season (M: 34, F: 46) and 1,220 athlete seasons, resulting in 1,764 AT services and 117 physician encounters. BSIs represented 20% of all injuries reported by cross-country athletes. The average bone stress injury rate was 0.14 per athlete season. Injury rates were higher in female athletes (0.16) compared to males (0.10) and rates were higher in the 2019-2020 season (0.20) compared to the 2020-21(0.14), 2018-2019 (0.12) and 2021-2022 (0.10) seasons. A majority of BSI's occurred in the lower leg (23.8%) and the foot (23.8%). Most injuries were classified as overuse and time-loss (73%) and accounted for the majority of AT services (75%) and physician encounters (73%). On average, there were 10.89 AT services per overuse-TL injury and 12.20 AT service per overuse-NTL injury. Mean occurrence was lower for physician encounters (0.70), prescription medications (0.04), tests (0.75), procedures (0.01), and surgery (0.02) compared to AT services. CONCLUSIONS: BSIs are common in collegiate cross- country runners and require considerable athletic training resources. Athletic trainers should be appropriately staffed for this population and suspected BSIs should b e confirmed with medical diagnosis. Future investigations should track treatment codes associated with BSI to determine best-practice patterns.

Acute and Overuse, Time-Loss and Non-Time-Loss Lateral Ankle Sprains and Health Care Utilization in Collegiate Student-Athletes.

CONTEXT: Health care utilization and the occurrence of non-time-loss (NTL) lateral ankle sprains is not well documented in collegiate athletes but could provide better estimates of injury burden and inform clinician workload. DESIGN: Descriptive epidemiologic study. METHODS: Lateral ankle sprain injury occurrence for Division I collegiate student-athletes in a conference with 32 sports representing 732 team seasons was collected during the 2018-2019 through 2020-2021 academic years. Injuries were designated as acute or overuse, and time-loss (TL) or NTL. Associated health care utilization, including athletic training services (AT services), and physician encounters were reported along with anatomical structures involved and season of occurrence. RESULTS: A total of 1242 lateral ankle sprains were reported over the 3 years from 732 team seasons and 17,431 player seasons, resulting in 12,728 AT services and 370 physician encounters. Most lateral ankle sprains were acute-TL (59.7%), which were associated with the majority of AT services (74.1%) and physician encounters (70.0%). Acute-NTL sprains represented 37.8% of lateral ankle sprains and were associated with 22.3% of AT services and 27.0% of physician encounters. On average, there were 12.7 (5.8) AT services per acute-TL sprain and 6.0 (3.6) per acute-NTL sprain. Most sprains involved "ankle lateral ligaments" (45.6%), and very few were attributed to overuse mechanisms (2.4%). CONCLUSIONS: Lateral ligament sprains are a common injury across many sports and result in substantial health care utilization from ATs and physicians, including NTL lateral ankle sprains. Although TL injuries were the majority of sprains, a substantial proportion of sprains were NTL and accounted for a considerable proportion of health care utilization.

Hysteresis and stiffness of the lateral ankle complex in those with chronic ankle instability.

The role of mechanical laxity and viscoelastic tissue properties in chronic ankle instability (CAI) is unclear, but may influence repeated injury. The purpose was to determine if lateral ankle complex stiffness and hysteresis was altered in CAI individuals with and without mechanical laxity, compared to copers and uninjured controls. Thirty-five recreational athletes (19 females, 22.1 ± 2.7 years, 69.7 ± 15.7 kg, 168.4 ± 10.7 cm) were assessed for ankle injury history and self-reported instability. An instrumented arthrometer was applied and laxity, stiffness and hysteresis values were captured. Results from ANOVA tests indicated the CAI with laxity group had lower beginning- (3.2 ± 0.6 N/mm) and end-range stiffness (4.5 ± 0.4 N/mm) than the CAI without laxity group (4.7 ± 0.6; 6.0 ± 0.6 N/mm) and uninjured controls (4.6 ± 1.1; 5.8 ± 0.8 N/mm, p < 0.003). Hysteresis was greater in the CAI with laxity group than without laxity (91.0 ± 17.3 vs 62.8 ± 12.0 dN•mm; p = 0.03). Altered tissue properties in a CAI with laxity group likely indicate diminished ability of the lateral ankle complex to respond to loading. Accurately assessing, then avoiding or restoring tissue impairments after injury, may encourage better patient outcomes.

The Effects of Contralateral Trunk Tilt on Elbow Varus Torque in Baseball Pitchers: A Critically Appraised Topic.

Clinical Scenario: Ulnar collateral ligament injuries are common in baseball pitchers, with excessive elbow varus torque linked to medial elbow injuries. Trunk tilt, or motion in the frontal plane, could be an identifiable and modifiable factor in medial elbow loading. Clinical Question: In high school through professional baseball pitchers, how does increased contralateral trunk tilt compared with no/limited contralateral trunk tilt influence elbow varus torque? Summary of Key Findings: Four studies were included: all were labeled as "controlled" or "descriptive laboratory studies," representing cross-sectional observational analytic design. One study compared biomechanics of professional pitchers with and without ulnar collateral ligament reconstruction. Two studies measured biomechanics in college pitchers, one of which also included simulations of joint angles. The fourth study measured biomechanics of high school pitchers. All studies measured trunk tilt and its relationship to elbow varus torque, with 3 of the studies linking increased contralateral trunk tilt with increased elbow varus torque. Clinical Bottom Line: Moderate evidence indicated as contralateral trunk tilt increased, so did elbow varus torque, indicating trunk tilt may be a modifiable factor to decrease medial elbow loading during pitching. Strength of Recommendation: Majority consistent findings from the level 3 cross-sectional observational analytic designs suggest grade B evidence in support of trunk tilt as a factor in increasing elbow varus torque.

Joint Coordination and Stiffness During Landing in Individuals With Chronic Ankle Instability.

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.

The Effects of the Short Foot Exercise on Navicular Drop: A Critically Appraised Topic.

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.

Lower limb kinematics of unicompartmental knee arthroplasty individuals during stair ascent.

OBJECTIVE: Purpose of the study was to compare lower-limb kinematics and interlimb asymmetry during stair ascent in individuals post-medial or lateral unicompartmental knee arthroplasty (UKA). METHODS: 60 patients (20 medial; 10 lateral) post-UKA and 30 matched healthy controls performed stair ascent. Spatio-temporal, lower-limb kinematics and interlimb asymmetries during stair ascent were compared. RESULTS: Medial-UKA group displayed 5° less knee extension of the UKA limb than controls (p = 0.005) and 2° less than the contralateral limb during stance phase. No interlimb asymmetries were found for lateral-UKA. CONCLUSION: Patients post-UKA demonstrate satisfactory lower-limb kinematics and minimal interlimb asymmetry during stair ascent compared to healthy individuals.

Performance Differences Between the Modified Star Excursion Balance Test and the Y-Balance Test in Individuals With Chronic Ankle Instability.

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.

Cross-cultural adaptation and validation of an ankle instability questionnaire for use in Chinese-speaking population.

BACKGROUND: The Identification of Functional Ankle Instability (IdFAI) is a valid and reliable tool to identify chronic ankle instability; however, it was developed in English, thus limiting its usage only to those who can read and write in English. The objectives of our study were to (1) cross-culturally adapt a Chinese (Mandarin) version of the IdFAI and (2) determine the psychometric properties of the Chinese version IdFAI. METHODS: The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages: (1) initial translation, (2) synthesis of the translations, (3) back translation, (4) developing the pre-final version for field testing, (5) testing the pre-final version, and (6) finalizing the Chinese version of IdFAI (IdFAI-C). Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups: bilingual (n = 20) and Chinese (n = 625). RESULTS: A high degree of agreement was found between the English version of IdFAI and IdFAI-C (intra-class correlation2,1 = 0.995). An excellent internal consistency (Cronbach's α = 0.89), test-retest reliability (intra-class correlation2,1 = 0.970), and construct validity (r(625) = 0.67) was also found for the IdFAI-C. In addition, the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI. CONCLUSION: The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability. Therefore, we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.

Biomechanics of ankle giving way: A case report of accidental ankle giving way during the drop landing test.

BACKGROUND: Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation. However, without sufficient ankle kinetics and muscle activity information in the literature, the detailed mechanism of ankle sprain is still unrevealed. The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability (CAI) and compare to their normal trials with data of kinematics, kinetics, and electromyography (EMG). CASE DESCRIPTION: Two young female participants accidentally experienced the ankle giving way when landing on a 25° lateral-tilted force plate. 3D kinematics, kinetics, and muscle activity were recorded for the lower extremity. Qualitative comparisons were made between the giving way trials and normal trials for joint angles, angular velocities, moments, centers of pressure and EMG linear envelopes. RESULTS: One participant's giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials. Another participant's giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials. CONCLUSION: A vulnerable ankle position (i.e., more inverted and internally rotated), and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains. A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.

Spine and Lower Extremity Kinematics Exhibited During Running by Adolescent Idiopathic Scoliosis Patients With Spinal Fusion.

STUDY DESIGN: Case-controlled design; biomechanics laboratory setting. OBJECTIVE: To compare the spine and lower extremity kinematics displayed during high-effort running between individuals with spinal fusion surgery for adolescent idiopathic scoliosis (SF-AIS) and healthy controls (CON). SUMMARY OF BACKGROUND DATA: Individuals with SF-AIS often return to exercise and sports that include running. However, how these individuals produce the spinal rotations needed during high-effort running and thus compensate for the loss of spinal flexibility is not known. METHODS: Ten SF-AIS (posterior-approach spinal fusion; postoperative time: 2.0 ± 0.6 years; physically active) and 10 CON individuals, pair-matched for gender, age, mass, height, and level of physical activity participated. SF-AIS individuals ran on a treadmill at a self-selected submaximal speed perceived as "hard" (15/20 on Borg perceived-effort scale), and CON ran at the SF-AIS pair-matched speed. 3D motion capture system was used to generate trunk and pelvis segmental angles (trunk segments = upper trunk [C7-T8], middle trunk [T9-T12], lower trunk [L1-L5]), relative angles (relative angles between the two consecutive trunk segments), and lower extremity joint angles. The group differences between the SF-AIS and CON were assessed using one-way analysis of covariance (with running speed as the covariate) for trunk, lower extremity, and step kinematics. RESULTS: SF-AIS participants exhibited a significantly greater (6.1° greater) lower trunk and (6.3° greater) pelvis segmental axial rotation compared with CON during running. In addition, SF-AIS participants displayed a 9.2° less ankle plantarflexion during the support phase. There were no significant differences detected for step kinematics. CONCLUSION: Possibly because of relearned compensatory mechanism, individuals with SF-AIS displayed similar patterns of spine, lower extremity, and step kinematics as healthy controls during high-effort running with some exceptions. LEVEL OF EVIDENCE: Level III.

Postural control of individuals with spinal fusion for adolescent idiopathic scoliosis.

BACKGROUND: The purpose of the study was to assess the postural stability and complexity of postural control for moderately physically active individuals with spinal fusion for adolescent idiopathic scoliosis at two years post-operation. METHODS: Limit of stability test and sensory organization test were conducted for 10 moderately physically-active participants with spinal fusion and 10 controls pair-matched for mass, height and physical activity level. During the limit of stability test, participants were instructed to lean the center of gravity as far as possible toward 8 predetermined directions and the maximum excursion and direction control were analyzed. During the sensory organization test, participants were instructed to maintain as still as possible in six test conditions and equilibrium scores and sway area of center of pressure were analyzed. Multi-scale entropy of center of pressure was calculated to quantify sway complexity. FINDINGS: Most postural stability outcomes of spinal fusion participants were comparable to controls except for significantly reduced equilibrium scores (p = 0.039, partial η2 = 0.217). Moreover, spinal fusion participants exhibited tendencies of reduced direction control (p = 0.053) during the limit of stability test and greater sway area (p = 0.052) during the sensory organization test. INTERPRETATION: Although the center of gravity control might be affected, spinal fusion individuals who were moderately physically active likely progressively learned to adapt postoperatively to their fused spine to meet the postural demands required when performing physical movements. We suggest that spinal fusion is a satisfactory treatment in regard to the recovery of postural stability.

The relationship between acute pain and dynamic postural stability indices in individuals with patellar tendinopathy.

BACKGROUND: Patellar tendinopathy is a common condition resulting in persistent pain, frequently reported during physical activity. The relationship between dynamic postural stability and pain in these individuals is unclear and how it may affect postural stability. RESEARCH QUESTION: Is there a relationship between acute pain and dynamic postural stability indices in individuals with patellar tendinopathy? METHODS: Twenty-two recreationally active individuals with patellar tendinopathy participated. Participants performed a two-legged jump and landed on a single test-limb on a force platform. They completed 100 mm visual analogue scales (VAS) before and after landing trials. Anterior-posterior (APSI), medial-lateral (MLSI), vertical (VSI), and composite (DPSI) stability indices were calculated from ground reaction force data. The relationship between stability indices and VAS for pain as well as pain change scores were assessed via non-parametric Spearman's rho (ρ) rank correlations (p≤.05). RESULTS: Baseline pain was not significantly correlated with any stability indices. Post-landing pain was significantly correlated with MLSI (ρ = 0.540, p = 0.004) while, VSI (ρ = 0.353, p = 0.053) and DPSI (ρ = 0.347, p = 0.057) had moderate, yet insignificant correlations. Pain change scores demonstrated a large correlation with MLSI (ρ = 0.598, p = 0.002). SIGNIFICANCE: As pain increased in individuals with patellar tendinopathy, dynamic postural stability indices values increased, indicating more difficulty transitioning from a dynamic to static state. Although balance deficits are not typically associated with patellar tendinopathy, it appears pain and dynamic postural stability may be related in these individuals.

Functional performance tests identify lateral ankle sprain risk: A prospective pilot study in adolescent soccer players.

Determining the clinical utility of functional performance tests (FPTs) and establishing cutoff scores could be useful in identifying those athletes who could benefit from effective injury prevention interventions. Our purpose was to determine the accuracy of FPTs in identifying adolescent athletes who go on to experience lateral ankle sprain(s) and establish specific cutoff scores capable of identifying those who sustain a lateral ankle sprain in the near future. Sixty-four participants (age = 15.5 ± 1.3 years; height = 161.7 ± 7.7 cm; mass = 57.1 ± 8.4 kg) were recruited from a junior soccer club and tracked for 10 months. Participants performed the anterior (AN), posterior-medial (PM), and posterior-lateral (PL) reach directions of the Star Excursion Balance Test (SEBT) and the Single-Leg Hop Test (SLHT) in pre-season, and then were followed for the 10-month competitive season (12 injured, 52 uninjured). Significant Area Under the Curve (AUC) values and cutoff scores were found for the PM (AUC = 0.78; 95% CI 0.61-0.95; P = 0.003; Sn = 0.83; Sp = 0.77; cutoff = 76%) and the PL (AUC = 0.82; 95% CI 0.71-0.94; P = 0.001; Sn = 0.92; Sp = 0.65; cutoff = 70%) reach directions of the SEBT and the SLHT (AUC = 0.77; 95% CI 0.60-0.95; P = 0.003; Sn = 0.67; Sp = 0.94; cutoff = 15.4 seconds). The PM and PL reach directions of the SEBT and the SLHT may be useful as pre-season screening measures to help clinicians identify adolescents who will go on to experience a lateral ankle sprain.

Functional performance deficits in adolescent athletes with a history of lateral ankle sprain(s).

OBJECTIVE: To determine if adolescent athletes with a history of lateral ankle sprain(s) (LAS) displayed deficits on functional performance tests (FPTs) and if deficits on FPT were related to the number of previous LAS. DESIGN: Cross-sectional study. SETTING: Biomechanics Laboratory. PARTICIPANTS: The injured group (n = 24) had a history of ≥1 moderate-severe LAS. The uninjured group (n = 34) had no history of LAS. MAIN OUTCOME MEASURE(S): The average reach distance of three trials in each direction of the star excursion balance test (SEBT) was normalized to leg length (%). The average of two trials of single-leg-hop test (SLHT) was calculated in seconds. RESULTS: The injured group performed significantly worse in 3 directions of SEBT than the uninjured group (P < 0.05). SLHT was significantly slower in the injured group compared to the uninjured group (P < 0.05). Statistically significant, strong to moderate inverse relationships were found between the numbers of LAS and each of the three directions of the SEBT (P ≤ 0.01). No relationship was revealed between the number of LAS and the SLHT (P > 0.05). CONCLUSION(S): Adolescent athletes with a history of LAS exhibit functional performance deficits on the SEBT and SLHT. Therefore, the SEBT and SLHT may provide clinicians cost- and time-effective objective tools.

Does variability within natural turfgrass sports fields influence ground-derived injuries?

Natural turfgrass sports fields exhibit within-field variations due to climatic conditions, field construction, field management, and foot traffic patterns from field usage. Variations within a field could influence the playing surface predictability and require athletes to make abrupt or frequent adjustments that lead to increased ground-derived injury occurrence. This study introduces a new methodology aimed at evaluating the potential relationship between within-field variations of turfgrass sports field properties and ground-derived athlete injuries. Collegiate Club Sport athletes self-reported ground-derived injuries over two years. Soil moisture, turfgrass quality, surface hardness, and turfgrass shear strength were quantified from their two home fields. Hot spot analysis identified significantly high (hot spots) and low (cold spots) values within the fields. Injury locations were compared to hot spot maps each month. Binomial proportion tests determined if there were differences between observed injury proportions and expected proportions. Twenty-three ground-derived injuries were reported overall. The observed injury proportions occurring in turfgrass quality cold spots [0.52 (95% CI 0.29-0.76)] and soil moisture hot spots [0.43 (95% CI 0.22-0.66)] was significantly higher than expected [0.20 (p < .001) and 0.21 (p < .05), respectively]. Most injuries in significant areas of turfgrass quality, soil moisture, and surface hardness were along edges of hot and cold spots. These results suggest a potential relationship between within-field variations and ground-derived injuries, particularly in transition areas between non-significant and significant high and low values. Future larger-scale studies can incorporate the reported methodology to validate this relationship and implement strategies that reduce ground-derived injuries.

Cross-cultural adaptation, reliability, and validation of the Korean version of the identification functional ankle instability (IdFAI).

PURPOSE: To cross-culturally adapt the Identification Functional Ankle Instability for use with Korean-speaking participants. METHODS: The English version of the IdFAI was cross-culturally adapted into Korean based on the guidelines. The psychometric properties in the Korean version of the IdFAI were measured for test-retest reliability, internal consistency, criterion-related validity, discriminative validity, and measurement error 181 native Korean-speakers. RESULTS: Intra-class correlation coefficients (ICC2,1) between the English and Korean versions of the IdFAI for test-retest reliability was 0.98 (standard error of measurement = 1.41). The Cronbach's alpha coefficient was 0.89 for the Korean versions of IdFAI. The Korean versions of the IdFAI had a strong correlation with the SF-36 (rs = -0.69, p < .001) and the Korean version of the Cumberland Ankle Instability Tool (rs = -0.65, p < .001). The cutoff score of >10 was the optimal cutoff score to distinguish between the group memberships. The minimally detectable change of the Korean versions of the IdFAI score was 3.91. CONCLUSION: The Korean versions of the IdFAI have shown to be an excellent, reliable, and valid instrument. The Korean versions of the IdFAI can be utilized to assess the presence of Chronic Ankle Instability by researchers and clinicians working among Korean-speaking populations. Implications for rehabilitation The high recurrence rate of sprains may result into Chronic Ankle Instability (CAI). The Identification of Functional Ankle Instability Tool (IdFAI) has been validated and recommended to identify patients with Chronic Ankle Instability (CAI). The Korean version of the Identification of Functional Ankle Instability Tool (IdFAI) may be also recommend to researchers and clinicians for assessing the presence of Chronic Ankle Instability (CAI) in Korean-speaking population.

Does chronic ankle instability influence lower extremity muscle activation of females during landing?

Much remains unclear about how chronic ankle instability (CAI) could affect knee muscle activations and interact with knee biomechanics. Therefore, the purpose of this study was to assess the influence of CAI on the lower extremity muscle activation at the ankle and knee joints during landings on a tilted surface. A surface electromyography system and two force plates were used to collect lower extremity muscle activation of 21 young female individuals with CAI and 21 pair-matched controls during a double-leg landing with test limb landing on the tilted surface. In the pre-landing phase, compared to controls, CAI participants displayed a reduced ankle evertor activation that could place CAI at a high risk of giving way or sprain injury. In the landing phase, an increased tibialis anterior activation of CAI led to increased co-contraction of ankle muscles in the sagittal and frontal plane. A greater ankle muscle co-contraction could increase the ankle stability during landings but may adversely influence the knee muscle activations (e.g., a greater co-contraction ratio of quadriceps to hamstrings). Relevant training programs (e.g., increasing pre-landing peroneal activation, and optimizing activation ratio of quadriceps to hamstrings) may help individuals with CAI improving ankle stability and reduce atypical knee loading during landings.

The Influence of Heavier Football Helmet Faceguards on Head Impact Location and Severity.

OBJECTIVE: To determine whether players with heavier faceguards have increased odds of sustaining top of the head impacts and head impacts of higher severity. DESIGN: Cohort study. SETTING: On-field. PARTICIPANTS: Thirty-five division I collegiate football players. INTERVENTIONS: Faceguard mass was measured. Head impact location and severity (linear acceleration [gravity], rotational acceleration [radian per square second], and Head Impact Technology severity profile [unitless]) were captured for 19 379 total head impacts at practices using the Head Impact Telemetry System. MAIN OUTCOME MEASURES: Players' faceguards were categorized as either heavier (>480 g) or lighter (≤480 g) using a median split. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for sustaining top of the head impacts between faceguard groups using a random intercepts generalized logit model. We compared head impact severity between groups using random intercepts general linear models (α = 0.05). Player position was included in all models. RESULTS: Overall, the 4 head impact locations were equally distributed across faceguard groups (F(3,26) = 2.16, P = 0.117). Football players with heavier faceguards sustained a higher proportion impacts to the top of the head (24.7% vs 17.5%) and had slightly increased odds of sustaining top (OR, 1.72; 95% CI, 1.01-2.94) head impacts rather than front of the head impacts. CONCLUSIONS: Football players wearing heavier faceguards might be slightly more prone to sustaining a higher proportion of top of the head impacts, suggesting that greater faceguard mass may make players more likely to lower their head before collision. Individuals involved with equipment selection should consider the potential influence of faceguard design on head impact biomechanics when recommending the use of a heavier faceguard.