Yearly changes in active joint stiffness may help explain when neuromuscular sex differences emerge in adolescent athletes that may relate to increased anterior cruciate ligament injury risk in females.
Pubertal males would demonstrate increases in knee stiffness while pubertal females would not. Second, postpubertal female athletes would have significantly lower knee joint stiffness than postpubertal male athletes.
Cohort Study; Level of Evidence 2 and Cross-Sectional Study; Level of Evidence 3.
Two hundred sixty-five females and 50 males participated in 2 testing sessions approximately 1 year apart. The subjects were classified as either pubertal (n = 182, age 12.4 +/- 0.9 years) or postpubertal (n = 133, age 14.5 +/- 1.4 years) based on the modified Pubertal Maturational Observational Scale at each visit. Active joint stiffness of the ankle, knee, and hip was estimated during a drop vertical jump. Stiffness was calculated as the slope of the moment-angle curve from a least squares linear regression during the stance phase.
All athletes showed increased active knee stiffness during the span of a year (P < 0.05). However, this increase was not different when stiffness was normalized to body mass. Only males demonstrated greater magnitudes of ankle and hip active stiffness (P < .05). Peak ankle and hip moments, but not knee moments, in postpubertal males were significantly greater than postpubertal females (P < .05). Females had a higher knee to hip moment ratio than males (P < .05).
Both males and females showed increased active knee stiffness during the span of a year; males demonstrated increased ankle and hip active stiffness as well. Differences in hip joint posture at initial contact (greater flexion in males) and external hip flexion moment (greater flexion magnitude in males) may indicate that males use a different hip recruitment strategy during drop vertical jumps than females.
"Deficits in a variety of these same sensorimotor mechanisms have been correlated with increased ACL injury risk
[48-50]. Notably, three studies reported that neuromuscular control of knee motion and landing forces is significantly worse in females than in males during the transition from pre-pubertal to pubertal stages, with females showing regressions in control abilities
[Show abstract][Hide abstract] ABSTRACT: The increased participation of children and adolescents in organized sports worldwide is a welcome trend given evidence of lower physical fitness and increased prevalence of overweight in this population. However, the increased sports activity of children from an early age and continued through the years of growth, against a background of their unique vulnerability to injury, gives rise to concern about the risk and severity of injury. Three types of injury-anterior cruciate ligament (ACL) injury, concussion, and physeal injury - are considered potentially serious given their frequency, potential for adverse long-term health outcomes, and escalating healthcare costs. Concussion is probably the hottest topic in sports injury currently with voracious media coverage and exploding research interest. Given the negative cognitive effects of concussion, it has the potential to have a great impact on children and adolescents during their formative years and potentially impair school achievement and, if concussion management is not managed appropriately, there can be long term negative impact on cognitive development and ability to resume sports participation. Sudden and gradual onset physeal injury is a unique injury to the pediatric population which can adversely affect growth if not managed correctly. Although data are lacking, the frequency of stress-related physeal injury appears to be increasing. If mismanaged, physeal injuries can also lead to long-term complications which could negatively affect ability to participate in sports. Management of ACL injuries is an area of controversy and if not managed appropriately, can affect long-term growth and recovery as well as the ability to participate in sports. This article considers the young athlete's vulnerability to injury, with special reference to ACL injury, concussion, and physeal injury, and reviews current research on epidemiology, diagnosis, treatment, and prevention of these injury types. This article is intended as an overview of these injury types for medical students, healthcare professionals and researchers.
"), as previously described (Ford et al., 2010). The single-leg landing task consisted of a vertical jump to grab a basketball suspended at a height of 80% of the participant's maximum vertical jump height, a single-leg landing, and an immediate lateral cut in the opposite direction of the landing foot (e.g., landing on the right following by a cut to the left) (Fig. 2(b)). "
[Show abstract][Hide abstract] ABSTRACT: Excessive knee abduction loading is a contributing factor to anterior cruciate ligament (ACL) injury risk. The purpose of this study was to determine whether a double-leg landing training program with real-time visual feedback improves frontal-plane mechanics during double- and single-leg landings. Knee abduction angles and moments and vertical ground reaction forces (GRF) of 21 recreationally active women were quantified for double- and single-leg landings before and after the training program. This program consisted of two sessions of double-leg jump landings with real-time visual feedback on knee abduction moments for the experimental group and without real-time feedback for the control group. No significant differences were found between training groups. In comparison with pre-training data, peak knee abduction moments decreased 12% post-training for both double- and single-leg landings; whereas peak vertical GRF decreased 8% post-training for double-leg landings only, irrespective of training group. Real-time feedback on knee abduction moments, therefore, did not significantly improve frontal-plane knee mechanics during landings. The effect of the training program on knee abduction moments, however, transferred from the double-leg landings (simple task) to single-leg landings (more complex task). Consequently, ACL injury prevention efforts may not need to focus on complex tasks during which injury occurs.
Scandinavian Journal of Medicine and Science in Sports 01/2013; 24(4). DOI:10.1111/sms.12051 · 2.90 Impact Factor
"For instance, 88% (7 out of 8 studies) reported no sex differences in hip flexion angle at initial ground contact--a point in time when lower-leg posture is critical as most noncontact ACL ruptures occur milliseconds post-contact . Some studies, however, reported either lower or greater hip flexion angles in females compared to males [10,26,29] (Table 3). As for hip flexion moment, no significant differences between sexes were found for the five studies that investigated this dependent variable [10,22,32,36,40] (Table 3). "
[Show abstract][Hide abstract] ABSTRACT: Anterior cruciate ligament (ACL) injuries continue to present in epidemic-like proportions, carrying significant short- and longer-term debilitative effects. With females suffering these injuries at a higher rate than males, an abundance of research focuses on delineating the sex-specific nature of the underlying injury mechanism. Examinations of sex-dimorphic lower-limb landing mechanics are common since such factors are readily screenable and modifiable. The purpose of this paper was to critically review the published literature that currently exists in this area to gain greater insight into the aetiology of ACL injuries in females and males. Using strict search criteria, 31 articles investigating sex-based differences in explicit knee and/or hip landing biomechanical variables exhibited during vertical landings were selected and subsequently examined. Study outcomes did not support the generally accepted view that significant sex-based differences exist in lower-limb landing mechanics. In fact, a lack of agreement was evident in the literature for the majority of variables examined, with no sex differences evident when consensus was reached. The one exception was that women were typically found to land with greater peak knee abduction angles than males. Considering knee abduction increases ACL loading and prospectively predicts female ACL injury risk, its contribution to sex-specific injury mechanisms and resultant injury rates seems plausible. As for the lack of consensus observed for most variables, it may arise from study-based variations in test populations and landing tasks, in conjunction with the limited ability to accurately measure lower-limb mechanics via standard motion capture methods. Regardless, laboratory-based comparisons of male and female landing mechanics do not appear sufficient to elucidate causes of injury and their potential sex-specificity. Sex-specific in vivo joint mechanical data, if collected accurately, may be more beneficial when used to drive models (e.g., cadaveric and computational) that can additionally quantify the resultant ACL load response. Without these steps, sex-dimorphic landing mechanics data will play a limited role in identifying the aetiology of ACL injuries in women and men.
Sports Medicine Arthroscopy Rehabilitation Therapy & Technology 03/2012; 4(1):10. DOI:10.1186/1758-2555-4-10
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