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Context: Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military. Design: Prospective cohort study. Methods: Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period. Results: A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94–1.14; P =.49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87–1.06; P =.47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02–1.10; P =.01), and the odds ratio was 1.02 (95% CI, 0.98–1.07; P =.29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus. Conclusions: Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation. [ABSTRACT FROM AUTHOR]

Individuals with anterior cruciate ligament reconstruction (ACLR) often fail to return to their previous level of sport performance. Although multifaceted, this inability to regain preinjury performance may be influenced by impaired plyometric ability attributable to chronic quadriceps dysfunction. Whole-body vibration (WBV) acutely improves quadriceps function and biomechanics after ACLR, but its effects on jumping performance outcomes such as jump height, the reactive strength index (RSI), and knee work and power are unknown. To evaluate the acute effects of WBV on measures of jumping performance in those with ACLR. Crossover study design. Research laboratory. Thirty-six individuals with primary, unilateral ACLR. Participants stood on a WBV platform in a mini-squat position while vibration or no vibration (control) was applied during six 60-second bouts with 2 minutes of rest between bouts. Double-leg jumping tasks were completed preintervention and postintervention (WBV or control) and consisted of jumping off a 30-cm box to 2 force plates half the participant's height away. The jumping task required participants to maximally jump vertically upon striking the force plates. Whole-body vibration did not produce significant improvements in any of the study outcomes (ie, jump height, RSI, and knee work and power) in either limb (P =.053–.839). These results suggest that a single bout of WBV is insufficient for improving jumping performance in individuals with ACLR. As such, using WBV to acutely improve jumping performance post-ACLR is likely not warranted. Future research should evaluate the effects of repeated exposure to WBV in combination with other plyometric interventions on jumping performance. [ABSTRACT FROM AUTHOR]

Context: Anterior cruciate ligament (ACL) injuries are a common and devastating injury in women's soccer. Several risk factors for ACL injury have been identified, but have not yet been examined as potentially dynamic risk factors, which may change throughout a collegiate soccer season. Design: Prospective cohort study. Methods: Nine common clinical screening assessments for ACL injury risk, consisting of range of motion, movement quality, and power, were assessed in 29 Division I collegiate women's soccer players. Preseason and midseason values were compared for significant differences. Change scores for each risk factor were also correlated with cumulative training loads during the first 10 weeks of a competitive soccer season. Results: Hip external rotation range of motion and power had statistically significant and meaningful differences at midseason compared with preseason, indicating they are dynamic risk factors. There were no significant associations between the observed risk factor changes and cumulative training load. Conclusions: Hip external rotation range of motion and power are dynamic risk factors for ACL injury in women's collegiate soccer athletes. Serial screening of these risk factors may elucidate stronger associations with injury risk and improve prognostic accuracy of screening tools. [ABSTRACT FROM AUTHOR]

Objective: The association between knee injury and knee osteoarthritis (OA) is understudied relative to its importance, particularly in younger populations. This study was undertaken to examine the association of knee injury with radiographic features of knee OA in military officers, who have a physically demanding profession and high rates of knee injury. Methods: Participants were recruited in 2015–2017 from an existing program that enrolled 6,452 military officers during 2004–2009. Officers with a history of knee ligament or meniscal injuries (n = 117 via medical record review) were compared to officers with no history of knee injury (n = 143). Bilateral posteroanterior knee radiographs were obtained using a standardized fixed‐flexion positioning frame. All images were read for Kellgren/Lawrence (K/L) grade, osteophyte (OST), and joint space narrowing (JSN) scores. Data were analyzed using linear‐risk regression models with generalized estimating equations. Results: Injured and noninjured participants were similar (mean age 28 years, mean body mass index 25 kg/m2, ~40% female). The mean time from first knee injury to imaging among injured participants was 9.2 years. Compared with noninjured knees, greater prevalence of radiographic OA (K/L grade ≥ 2), OST (grade ≥ 1), and JSN (grade ≥ 1) was observed among injured knees, with prevalence differences of +16% (95% confidence interval [95% CI] 10%, 22%), +29% (95% CI 20%, 38%), and + 17% (95% CI 10%, 24%), respectively. Approximately 1 in 6 officers with prior knee injury progressed to radiographic OA by age 30 years. Conclusion: At the midpoint of a projected 20‐year military career, officers with a history of traumatic knee injury have a markedly increased prevalence of knee radiographic OA compared to officers without injury. [ABSTRACT FROM AUTHOR]

The Osteoarthritis Action Alliance formed a secondary prevention task group to develop a consensus on secondary prevention recommendations to reduce the risk of osteoarthritis after a knee injury. Our goal was to provide clinicians with secondary prevention recommendations that are intended to reduce the risk of osteoarthritis after a person has sustained an anterior cruciate ligament injury. Specifically, this manuscript describes our methods, literature reviews, and dissenting opinions to elaborate on the rationale for our recommendations and to identify critical gaps. Consensus process. Virtual video conference calls and online voting. The Secondary Prevention Task Group consisted of 29 members from various clinical backgrounds. The group initially convened online in August 2020 to discuss the target population, goals, and key topics. After a second call, the task group divided into 9 subgroups to draft the recommendations and supportive text for crucial content areas. Twenty-one members completed 2 rounds of voting and revising the recommendations and supportive text between February and April 2021. A virtual meeting was held to review the wording of the recommendations and obtain final votes. We defined consensus as >80% of voting members supporting a proposed recommendation. The group achieved consensus on 15 of 16 recommendations. The recommendations address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models. This consensus statement reflects information synthesized from an interdisciplinary group of experts based on the best available evidence from the literature or personal experience. We hope this document raises awareness among clinicians and researchers to take steps to mitigate the risk of osteoarthritis after an anterior cruciate ligament injury. [ABSTRACT FROM AUTHOR]

Those with chronic ankle instability (CAI) demonstrate deleterious changes in talar cartilage composition, resulting in alterations of talar cartilage loading behavior. Common impairments associated with CAI may play a role in cartilage behavior in response to mechanical loading. To identify mechanical and sensorimotor outcomes that are linked with the magnitude of talar cartilage deformation after a static loading protocol in patients with and those without CAI. Cross-sectional study. Laboratory setting. Thirty individuals with CAI and 30 healthy individuals. After a 60-minute off-loading period, ultrasonographic images of the talar cartilage were acquired immediately before and after a 2-minute static loading protocol (single-legged stance). Talar cartilage images were obtained and manually segmented to enable calculation of medial, lateral, and overall average talar thickness. The percentage change, relative to the average baseline thickness, was used for further analysis. Mechanical (ankle joint laxity) and sensorimotor (static balance and Star Excursion Balance Test) outcomes were captured. Partial correlations were computed to determine associations between cartilage deformation magnitude and the mechanical and sensorimotor outcomes after accounting for body weight. In the CAI group, greater inversion laxity was associated with greater overall (r = −0.42, P =.03) and medial (r = −0.48, P =.01) talar cartilage deformation after a 2-minute static loading protocol. Similarly, poorer medial-lateral static balance was linked with greater overall (r = 0.47, P =.01) and lateral (r = 0.50, P =.01) talar cartilage deformation. In the control group, shorter posterolateral Star Excursion Balance Test reach distance was associated with greater lateral cartilage deformation (r = 0.42, P =.03). No other significant associations were observed. In those with CAI, inversion laxity and poor static postural control were moderately associated with greater talar cartilage deformation after a 2-minute static loading protocol. These results suggest that targeting mechanical instability and poor balance in those with CAI via intervention strategies may improve how the talar cartilage responds to static loading conditions. [ABSTRACT FROM AUTHOR]

Researchers have not established if overloading or underloading movement profiles are present in symptomatic and asymptomatic athletes with patellar tendon structural abnormality (PTA) compared with healthy athletes. To compare involved-limb landing biomechanics between male athletes with and those without patellar tendinopathy. Cross-sectional study. Laboratory. A total of 43 male athletes were grouped based on patellar tendon pain and ultrasound imaging of the proximal patellar tendon: symptomatic with PTA (SYM; n = 13; age = 19.62 ± 1.61 years, height = 1.82 ± 0.05 m, mass = 83.46 ± 5.12 kg), asymptomatic with PTA (ASYM; n = 15; age = 21.13 ± 1.88 years, height = 1.84 ± 0.07 m, mass = 81.45 ± 13.26 kg), and healthy control (CON; n = 15; age = 19.60 ± 1.55 years, height = 1.84 ± 0.09 m, mass = 79.09 ± 12.37 kg). Three-dimensional biomechanics were collected during a double-limb jump-landing task. Kinematic (knee-flexion angle [KF]) and kinetic (vertical ground reaction force, internal knee-extension moment [KEM], patellar tendon force [FPT]) variables were analyzed as continuous waveforms during the stance phase for the involved limb. Mean values were calculated for each 1% of stance, normalized over 202 data points (0%–100%), and plotted with 95% CIs. Statistical significance was defined as a lack of 95% CI overlap for a minimum of a consecutive 3% of the stance phase. The SYM group had less KF than the CON group throughout the stance phase (8%–76%: Cohen d = 1.14 ± 0.12, mean difference [MD] = 15.83° ± 2.71°). The ASYM group had less KF than the CON group in the early (8%–13%: Cohen d = 0.99 ± 0.04, MD = 7.99° ± 0.39°; 21%–24%: Cohen d = 1.01 ± 0.01, MD = 11.11° ± 0.32°) and late (74%–94%: Cohen d = 0.96 ± 0.07, MD = 9.55° ± 1.13°) stance phases. The SYM group had a smaller KEM (6.5%–9%: Cohen d = 1.21 ± 0.08, MD = 0.04 ± 0.004 N·m/[Nbw·mht]) and less FPT (6%–9%: Cohen d = 1.15 ± 0.15, MD = 0.85 ± 0.15 body weight) than the CON group in the early stance phase. The SYM group also displayed a smaller KEM (38%–56%: Cohen d = 1.17 ± 0.06, MD = 0.03 ± 0.001 N·m/[Nbw·mht]) and less FPT (36%–60%: Cohen d = 1.22 ± 0.08, MD = 0.66 ± 0.05 body weight) than the ASYM group in the midstance phase. The SYM group demonstrated a patellar tendon load-avoidance profile compared with the ASYM and CON groups. The ASYM group showed no evidence of overloading compared with the CON group. Our findings support the need for individualized treatments for athletes with tendinopathy to maximize load capacity. [ABSTRACT FROM AUTHOR]

Lower extremity bone stress injuries (BSIs) place a significant burden on the health and readiness of the US Armed Forces. To determine if preinjury baseline performance on an expanded and automated 22-item version of the Landing Error Scoring System (LESS-22) was associated with the incidence of BSIs in a military training population. Prospective cohort study. US Military Academy at West Point, NY. A total of 2235 incoming cadets (510 females [22.8%]). Multivariable Poisson regression models were used to produce adjusted incidence rate ratios (IRRs) to quantify the association between preinjury LESS scores and BSI incidence rate during follow-up and were adjusted for pertinent risk factors. Risk factors were included as covariates in the final model if the 95% CI for the crude IRR did not contain 1.00. A total of 54 BSIs occurred during the study period, resulting in an overall incidence rate of 0.07 BSI per 1000 person-days (95% CI = 0.05, 0.09). The mean number of exposure days was 345.4 ± 61.12 (range = 3–368 days). The final model was adjusted for sex and body mass index and yielded an adjusted IRR for a LESS-22 score of 1.06 (95% CI = 1.002, 1.13; P =.04), indicating that each additional LESS error documented at baseline was associated with a 6.0% increase in the incidence rate of BSI during the follow-up period. In addition, 6 individual LESS-22 items, including 2 newly added items, were significantly associated with the BSI incidence. We provided evidence that performance on the expanded and automated version of the LESS was associated with the BSI incidence in a military training population. The automated LESS-22 may be a scalable solution for screening military training populations for BSI risk. [ABSTRACT FROM AUTHOR]

Background: Sport specialization in youth athletes is associated with increased risk for musculoskeletal injury; however, little is known about whether sport specialization is associated with lower extremity movement quality. The purpose of this study was to examine differences in lower extremity movement quality by level of sport specialization in US Service Academy cadets. Hypothesis: Cadets who report an increased level of sport specialization would have a lower level of movement quality than those who are less specialized. Study Design: Cross-sectional analysis from an ongoing prospective cohort study. Level of Evidence: Level 3. Methods: Cadets completed the Landing Error Scoring System (LESS) and a baseline questionnaire evaluating level of sport specialization during high school. Data were analyzed using separate 1-way analysis of variance models. Results: Among all participants (n = 1950), 1045 (53.6%) reported low sport specialization, 600 (30.8%) reported moderate sport specialization, and 305 (15.6%) reported high sport specialization at the time of data collection during the first week. Ages ranged from 17 to 23 years. Men (1491) and women (459) reported comparable specialization levels (P = 0.45). There were no statistically significant differences in lower extremity movement quality by level of specialization for all subjects combined (P = 0.15) or when only men were included in the analyses (P = 0.69). However, there were statistically significant differences in movement quality by level of specialization in women (P = 0.02). Moderately specialized women had the best movement quality (mean, 4.63; SD, 2.21) followed by those with high specialization (mean, 4.90; SD, 2.08) and those with low levels of specialization (mean, 5.23; SD, 2.07). Conclusion: Women reporting moderate sport specialization had improved movement quality and significantly better LESS scores compared to those with high/low specialization. Clinical Relevance: Athletes, especially women, should be encouraged to avoid early sport specialization to optimize movement quality, which may affect injury risk. [ABSTRACT FROM AUTHOR]

Introduction Sport and tactical populations are often impacted by musculoskeletal injury. Many publications have highlighted that risk is correlated with multiple variables. There do not appear to be existing studies that have evaluated a predetermined combination of risk factors that provide a pragmatic model for application in tactical and/or sports settings. Purpose To develop and test the predictive capability of multivariable risk models of lower extremity musculoskeletal injury during cadet basic training at the U.S.Military Academy. Materials and Methods Cadets from the class of 2022 served as the study population. Sex and injury history were collected by questionnaire. Body Mass Index (BMI) and aerobic fitness were calculated during testing in the first week of training. Movement screening was performed using the Landing Error Scoring System during week 1 and cadence was collected using an accelerometer worn throughout initial training. Kaplan–Meier survival curves estimated group differences in time to the first musculoskeletal injury during training. Cox regression was used to estimate hazard ratios (HRs) and Akaike Information Criterion (AIC) was used to compare model fit. Results Cox modeling using HRs indicated that the following variables were associated with injury risk : Sex, history of injury, Landing Error Scoring System Score Category, and Physical Fitness Test (PT) Run Score. When controlling for sex and history of injury, amodel including aerobic fitness and BMI outperformed the model including movement screening risk and cadence (AIC: 1068.56 vs. 1074.11) and a model containing all variables that were significant in the univariable analysis was the most precise (AIC: 1063.68). Conclusions In addition to variables typically collected in this tactical setting (Injury History, BMI, and aerobic fitness), the inclusion of kinematic testing appears to enhance the precision of the risk identification model and will likely continue to be included in screening cadets at greater risk. [ABSTRACT FROM AUTHOR]

Context: The Y-Balance Test Lower Quarter (YBT-LQ) is a widely utilized tool for evaluating dynamic postural control, requiring a combination of mobility and strength. This study aimed to investigate the combined relationship between isometric thigh muscle strength and joint kinematics on YBT-LQ performance., Design: Cross-sectional laboratory study., Methods: Isometric quadriceps and hamstrings strength were measured before the YBT-LQ in 39 healthy participants (27 females and 12 males). The test was performed under 3-dimensional markerless motion capture, where joint kinematics were extracted from the maximum reach position from each direction. Three multivariable linear regression models were then used to determine the strongest combination of predictors for YBT-LQ performance., Results: Greater hamstrings strength and increased knee flexion, ankle dorsiflexion, and trunk ipsilateral-flexion joint angles explained 56.8% (P < .001) of the variance in anterior reach. Hip flexion, knee flexion, and ankle dorsiflexion angles were the strongest predictors for posteromedial reach distance, explaining 73.0% of the variance (P < .001). Last, 43.3% (P < .001) of the variance in posterolateral reach distance was predicted by hamstring strength and knee-flexion angle., Conclusions: These results emphasize the importance of hamstring strength in YBT-LQ performance across different reach directions. Additionally, the kinematics illustrate a potential movement strategy for maximizing reach distance on the YBT-LQ in healthy individuals. Clinicians can utilize this information to guide interventions aimed at improving dynamic postural control, particularly by focusing on increasing hamstring strength and testing for impairments in specific movement patterns.

Background: Muscular strength deficits are common after ACL injury. While the Limb Symmetry Index (LSI), using the uninvolved limb as a reference, is widely used, negative strength adaptations may affect both limbs post-injury. It is uncertain how the strength of the uninvolved limb in those with an ACL injury compares to uninjured individuals, making it unclear whether it is appropriate as a benchmark for determining sufficient strength., Purpose: To compare the strength of key lower extremity muscles of the uninvolved limb in those with history of ACL injury (ACL-I) to the dominant limb in individuals with no history of ACL injury (control)., Study Design: Cross-sectional study. Methods: A total of 5,727 military cadets were examined, with 82 females and 126 males in the ACL-I group and 2,146 females and 3,373 males in the control group. Maximum isometric strength was assessed for six muscle groups measured with a hand-held dynamometer. Separate two-way ANOVAs with limb and sex were performed for each muscle group., Results: Significant main effects for limb were observed with the uninvolved limb in the ACL-I group displaying greater strength compared to the dominant limb in the control group for the quadriceps, hamstrings, and gluteus medius, but effect sizes were small (Cohen's d <0.25). Significant main effects for sex were observed with greater male muscular strength in all six muscle groups with small to large effect sizes (Cohen's d 0.49-1.46). No limb-by-sex interactions were observed., Conclusions: There was no evidence of reduced strength in the uninvolved limb in those with a history of ACL injury compared to the dominant limb in those with no prior ACL injury. This finding suggests that, after clearance to return to activities, the uninvolved limb can be used as a standard for comparison of sufficient strength, including when using the LSI. Level of Evidence: Level 3., Competing Interests: The authors report no conflicts of interest., (© The Author(s).)

Context: Lower extremity joint (LE) kinematics during landing tasks are important predictors of injury risk and performance outcomes in athletes., Objective: To establish sex-related differences and normative ranges for LE kinematics during the jump-landing task in a large cohort of healthy military service academy cadets., Design: Cross-Sectional Study., Setting: US Air Force, Naval, and Military Academies., Participants: 5308 cadets (2062 females [38.8%])., Main Outcome Measure(s): Sex-related differences in LE kinematics were analyzed using independent samples t-tests. Mean differences (MD) and effect sizes (d) were reported for interpretability. Normative ranges for hip and knee joint angles were established separately for males and females at initial contact (IC) and 50% of the stance phase., Results: Compared to males, moderate effect sizes (d ≥ .5) were observed for knee external rotation (negative value) where females displayed greater motion at IC and at 50% stance (MD: - 3.9˚ and -5.0˚, respectively, p < .001). The following findings were of small effect size (.2 ≥ d > .5). Females exhibited less knee and hip flexion at IC (MD: -1.8˚ and -0.5˚, respectively, p < .001) and at 50% stance (MD: -4.1˚ and -4.6˚, respectfully, p < .001). This was accompanied by females having greater knee valgus (negative value) and hip adduction at IC (MD: -2.2˚ and 1.06˚, respectively, p < .001) and at 50% stance (MD: -3.2˚ and 1.8˚, respectfully, p < .001)., Conclusion: This study establishes normative ranges for LE kinematics during the jump-landing task in a large cohort of healthy military service academy cadets entering their first year. Sex- related differences in LE kinematics were observed, highlighting the importance of considering sex as a factor in the evaluation of lower extremity movement quality and management of injury risk.