Effect of Age at Menarche on Anterior Cruciate Ligament Injury Incidence and Anterior Knee Laxity in Collegiate Athletes

Female athletes suffer painful, costly, and career-limiting non-contact anterior cruciate ligament (ACL) injuries more often than males. Previous research suggests that pubertal neuromusculoskeletal development contributes to this sex-bias, but the manner in which variation in pubertal development affects injury risk within females is poorly understood. Age at menarche is a variable, significant pubertal developmental event, signaling the onset of estrogen cycling and affecting musculoskeletal development. Earlier menarche may increase injury risk, possibly by increasing anterior knee laxity through prolonged estrogen exposure. The purpose of this case-control study was to test the primary hypothesis that collegiate athletes with previous ACL injuries have earlier age at menarche than their uninjured peers, and to test the secondary hypothesis that earlier menarche is related to greater anterior knee laxity in injured and uninjured athletes. The study sample consisted of female NCAA Division-I varsity athletes (N=14 injured, N=120 uninjured). Outcome measures included: menstrual history and ACL injury details (injury age, activity at time of injury, contact vs. non-contact), assessed by questionnaire; and anterior knee laxity assessed by KT-1000 arthrometer. Correlation, t-tests, and regression analysis were used to test for associations between age at menarche, injury incidence, and knee laxity. Fourteen athletes reported ≥1 non-contact ACL injury, and had significantly earlier menarche than uninjured athletes (12.6±1.3 y vs. 13.4±1.4 y; P=0.05). Earlier menarche also significantly predicted injury status (Wald c2=7.43; Pb=-1.02±0.37; OR=0.36; 95% CI:0.17-0.75), but was not correlated with anterior knee laxity. Within injured athletes, however, laxity in the unaffected knee was significantly related to time since menarche (r2=0.79, Pr2=0.72,

Genetic Architecture of Knee Radiographic Joint Space in Healthy Young Adults

Evidence of a significant genetic component to the age-related degenerative joint disease osteoarthritis has been established, but the nature of genetic influences on normal joint morphology in healthy individuals remains unclear. Following up on our previous findings on the influence of body habitus on phenotypic variation in knee joint space [Duren et al., Human Biology 78:353–364 (2006)], the objective of the current study was to estimate the heritability of radiographic joint space in the knees of healthy young adults from a community-based sample of families.Asample of 253 subjects (mean age= 18.02 years) from 87 randomly ascertained nuclear and extended families was examined. Joint width (JW) and minimum joint space in the medial (MJS) and lateral (LJS) knee compartments were measured. A maximum-likelihood variance components method was used to estimate the heritability of MJS, LJS, and JW. Covariate effects of age, sex, age-by-sex interactions, stature, weight, and BMI were simultaneously estimated. Genetic correlation analyses were then conducted to examine relationships between trait pairs. MJS, LJS, and JW were each significantly heritable ( p \u3c 0.001), with heritabilities of 0.52, 0.53, and 0.63, respectively. The genetic correlation between MJS and LJS was not significantly different from 1. Genetic correlations between each joint space measure and JW were not significantly different from 0. This study demonstrates a significant genetic component to radiographic knee joint space during young adulthood in healthy subjects. This suggests that there are specific but as yet unidentified genes that influence the morphology of healthy articular cartilage, the target tissue of osteoarthritis. Genetic correlation analyses indicate complete pleiotropy between MJS and LJS but genetic independence of joint space and JW

Relationships Between Age at Menarche, Walking Gait Base of Support, and Stance Phase Frontal Plane Knee Biomechanics in Adolescent Girls

Background Age at menarche impacts patterns of pubertal growth and skeletal development. These effects may carry over into variation in biomechanical profiles involved in sports-related traumatic and overuse knee injuries. The present study investigated whether age at menarche is a potential indicator of knee injury risk through its influence on knee biomechanics during normal walking. Objective To test the hypothesis that earlier menarche is related to postpubertal biomechanical risk factors for knee injuries, including a wider, more immature gait base of support, and greater valgus knee angles and moments. Design Cross-sectional observational study. Setting University research facility. Participants Healthy, postmenarcheal, adolescent girls. Methods Age at menarche was obtained by recall questionnaire. Pubertal growth and anthropometric data were collected by using standard methods. Biomechanical data were taken from tests of walking gait at self-selected speed. Reflective marker position data were collected with a 3-dimensional quantitative motion analysis system, and 3 force plates recorded kinetic data. Main Outcome Measures Age at menarche; growth and anthropometric measurements; base of support; static knee frontal plane angle; and dynamic knee frontal plane angles and moments during stance. Results Earlier menarche was correlated significantly with abbreviated pubertal growth and postpubertal retention of immature traits, including a wider base of support. Earlier menarche and wider base of support were both correlated with more valgus static knee angles, more valgus knee abduction angles and moments at foot-strike, and a more valgus peak knee abduction angle during stance. Peak knee abduction moment during stance was not correlated with age at menarche or base of support. Conclusions Earlier menarche and its effects on growth are associated with retention of a relatively immature gait base of support and a tendency for static and dynamic valgus knee alignment. This biomechanical profile may put girls with earlier menarche at greater risk for sports-related knee injuries. Level of Evidence Not applicable

Radiographic Joint Space of the Knee in Healthy Young Adults

The primary objective of this study was to characterize normal variation in radiographic joint space of the knee in a large sample of healthy young adults and to identify factors that contribute to this variation.We measured radiographic knee joint space in 279 skeletally mature subjects, age between 16 and 22 years, who participated in the Fels Longitudinal Study. Minimum joint space was measured in the medial and lateral knee compartments. Independent sample tests and correlation analyses were performed to examine sex differences and associations between joint space, joint size, and body size [weight, stature, body mass index (BMI)]. Results show that young men have thicker articular cartilage than young women in both the medial and lateral compartments of the knee. Significant positive correlations were found between joint space and body size measures in the total sample. When the sexes were considered independently, however, correlations between joint space and body size were significant in men only. Regression analyses of the combined-sex sample identified sex, BMI, and joint width as significant explanatory factors of medial joint space, together accounting for 26% of the observed variance. In contrast, sex was the sole significant explanatory factor of lateral joint space, explaining 19% of the observed variance. Results of this study show that during early adulthood, when articular cartilage is healthy and at its peak thickness, men have thicker knee cartilage than women. At this young age body size accounts for a modest proportion of the variation observed in knee cartilage thickness

Age-Related Changes in Spatiotemporal Characteristics of Gait Accompany Ongoing Lower Limb Linear Growth in Late Childhood and Early Adolescence

Walking gait is generally held to reach maturity, including walking at adult-like velocities, by 7-8 years of age. Lower limb length, however, is a major determinant of gait, and continues to increase until 13-15 years of age. This study used a sample from the Fels Longitudinal Study (ages 8-30 years) to test the hypothesis that walking with adult-like velocity on immature lower limbs results in the retention of immature gait characteristics during late childhood and early adolescence. There was no relationship between walking velocity and age in this sample, whereas the lower limb continued to grow, reaching maturity at 13.2 years in females and 15.6 years in males. Piecewise linear mixed models regression analysis revealed significant age-related trends in normalized cadence, initial double support time, single support time, base of support, and normalized step length in both sexes. Each trend reached its own, variable-specific age at maturity, after which the gait variables\u27 relationships with age reached plateaus and did not differ significantly from zero. Offsets in ages at maturity occurred among the gait variables, and between the gait variables and lower limb length. The sexes also differed in their patterns of maturation. Generally, however, immature walkers of both sexes took more frequent and relatively longer steps than did mature walkers. These results support the hypothesis that maturational changes in gait accompany ongoing lower limb growth, with implications for diagnosing, preventing, and treating movement-related disorders and injuries during late childhood and early adolescence. © 2012 Elsevier B.V

Relationships Between Age at Menarche, Walking Gait Base of Support, and Stance Phase Frontal Plane Knee Biomechanics in Adolescent Girls

Background Age at menarche impacts patterns of pubertal growth and skeletal development. These effects may carry over into variation in biomechanical profiles involved in sports-related traumatic and overuse knee injuries. The present study investigated whether age at menarche is a potential indicator of knee injury risk through its influence on knee biomechanics during normal walking. Objective To test the hypothesis that earlier menarche is related to postpubertal biomechanical risk factors for knee injuries, including a wider, more immature gait base of support, and greater valgus knee angles and moments. Design Cross-sectional observational study. Setting University research facility. Participants Healthy, postmenarcheal, adolescent girls. Methods Age at menarche was obtained by recall questionnaire. Pubertal growth and anthropometric data were collected by using standard methods. Biomechanical data were taken from tests of walking gait at self-selected speed. Reflective marker position data were collected with a 3-dimensional quantitative motion analysis system, and 3 force plates recorded kinetic data. Main Outcome Measures Age at menarche; growth and anthropometric measurements; base of support; static knee frontal plane angle; and dynamic knee frontal plane angles and moments during stance. Results Earlier menarche was correlated significantly with abbreviated pubertal growth and postpubertal retention of immature traits, including a wider base of support. Earlier menarche and wider base of support were both correlated with more valgus static knee angles, more valgus knee abduction angles and moments at foot-strike, and a more valgus peak knee abduction angle during stance. Peak knee abduction moment during stance was not correlated with age at menarche or base of support. Conclusions Earlier menarche and its effects on growth are associated with retention of a relatively immature gait base of support and a tendency for static and dynamic valgus knee alignment. This biomechanical profile may put girls with earlier menarche at greater risk for sports-related knee injuries. Level of Evidence Not applicable

Age-Related Changes in Spatiotemporal Characteristics of Gait Accompany Ongoing Lower Limb Linear Growth in Late Childhood and Early Adolescence

Walking gait is generally held to reach maturity, including walking at adult-like velocities, by 7-8 years of age. Lower limb length, however, is a major determinant of gait, and continues to increase until 13-15 years of age. This study used a sample from the Fels Longitudinal Study (ages 8-30 years) to test the hypothesis that walking with adult-like velocity on immature lower limbs results in the retention of immature gait characteristics during late childhood and early adolescence. There was no relationship between walking velocity and age in this sample, whereas the lower limb continued to grow, reaching maturity at 13.2 years in females and 15.6 years in males. Piecewise linear mixed models regression analysis revealed significant age-related trends in normalized cadence, initial double support time, single support time, base of support, and normalized step length in both sexes. Each trend reached its own, variable-specific age at maturity, after which the gait variables\u27 relationships with age reached plateaus and did not differ significantly from zero. Offsets in ages at maturity occurred among the gait variables, and between the gait variables and lower limb length. The sexes also differed in their patterns of maturation. Generally, however, immature walkers of both sexes took more frequent and relatively longer steps than did mature walkers. These results support the hypothesis that maturational changes in gait accompany ongoing lower limb growth, with implications for diagnosing, preventing, and treating movement-related disorders and injuries during late childhood and early adolescence. © 2012 Elsevier B.V

Estimating peak height velocity in individuals: a comparison of statistical methods

Background Estimates pertaining to the timing of the adolescent growth spurt (e.g. peak height velocity; PHV), including age at peak height velocity (aPHV), play a critical role in the diagnosis, treatment, and management of skeletal growth and/or developmental disorders. Yet, distinct statistical methodologies often result in large estimate discrepancies. Aim The aim of the present study was to assess the advantages and disadvantages of three modelling methodologies for height as well as to determine how estimates derived from these methodologies may differ, particularly those that may be useful in paediatric clinical practice. Subjects and methods Height data from 686 individuals of the Fels Longitudinal Study were modelled using 5th order polynomials, natural cubic splines, and SuperImposition by Translation and Rotation (SITAR) to determine aPHV and PHV for all individuals together (i.e. population average) by sex and separately for each individual. Estimates within and between methodologies were calculated and compared. Results In general, mean aPHV was earlier, and PHV was greater for individuals when compared to estimates from population average models. Significant differences between mean aPHV and PHV for individuals were observed in all three methodologies, with SITAR exhibiting the latest aPHV and largest PHV estimates. Conclusion Each statistical methodology has a number of advantages when used for specific purposes. For modelling growth in individuals, as one would in paediatric clinical practice, we recommend the use of the 5th order polynomial methodology due to its parameter flexibility

Skeletal Growth and the Changing Genetic Landscape During Childhood and Adulthood

Growth, development, and decline of the human skeleton are of central importance to physical anthropology. All processes of skeletal growth (longitudinal growth as well as gains and losses of bone mass) are subjected to environmental and genetic influences. These influences, and their relative contributions to the phenotype, can be asserted at any stage of life. We present here the gross phenotypic and genetic landscapes of four skeletal traits, and show how they vary across the life span. Phenotypic sex differences are found in bone diameter and cortical index (a ratio of cortical thickness over bone diameter) at a very early age and continue throughout most of life. Sexual dimorphism in summed cortical thickness and bone length, however, is not evident until shortly after the pubertal growth spurt. Genetic contributions (heritability) to these skeletal phenotypes are generally moderate to high. Bone length and bone diameter (which both scale with body size) tend to have the highest heritability, with heritability of bone length fairly stable across ages (with a notable dip in early childhood) and that of bone diameter peaking in early childhood. The bone traits summed cortical thickness and cortical index that may better reflect bone mass, a more plastic phenomenon, have slightly lower genetic influences, on average. Results from our phenotypic and genetic landscapes serve three key purposes: 1) demonstration of the integrated nature of the genetic and environmental underpinnings of skeletal form, 2) identification of periods of bone\u27s relative sensitivity to genetic and environmental influences, 3) and stimulation of hypotheses predicting the effects of exposure to environmental variables on the skeleton, given variation in the underlying genetic architecture. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc