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Cincinnati, United States

Faigenbaum A.D.,The College of New Jersey | Myer G.D.,Sports Medicine Biodynamics Center | Myer G.D.,University of Cincinnati | Myer G.D.,Ohio State University
Current Sports Medicine Reports

Although the benefits of regular physical activity are widely acknowledged, recent epidemiological findings indicate that a growing number of youth are not as active as they should be. The impact of a sedentary lifestyle during childhood and adolescence on lifelong pathological processes and associated health care costs has created a need for immediate action to manage, if not prevent, unhealthy behaviors during this vulnerable period of life. The concept of identifying children with exercise deficit disorder early in life and prescribing effective exercise interventions to prevent the cascade of adverse health outcomes later in life is needed to raise public awareness, focus on primary prevention, and impact the collective behaviors of health care providers, government officials, school administrators, public health agencies, and insurance companies. Copyright © 2012 by the American College of Sports Medicine. Source

Quatman C.E.,Ohio State University | Kiapour A.M.,University of Toledo | Demetropoulos C.K.,University of Toledo | Kiapour A.,University of Toledo | And 7 more authors.
American Journal of Sports Medicine

Background: Strong biomechanical and epidemiological evidence associates knee valgus collapse with isolated, noncontact anterior cruciate ligament (ACL) injuries. However, a concomitant injury to the medial collateral ligament (MCL) would be expected under valgus collapse, based on the MCLs anatomic orientation and biomechanical role in knee stability. Purpose/Hypothesis: The purpose of this study was to investigate the relative ACL to MCL strain patterns during physiological simulations of a wide range of high-risk dynamic landing scenarios. We hypothesized that both knee abduction and internal tibial rotation moments would generate a disproportionate increase in the ACL strain relative to the MCL strain. However, the physiological range of knee abduction and internal tibial rotation moments that produce ACL injuries are not of sufficient magnitude to compromise the MCLs integrity consistently. Study Design: Controlled laboratory study. Methods: A novel in sim approach was used to test our hypothesis. Seventeen cadaveric lower extremities (mean age, 45 6 7 years; 9 female and 8 male) were tested to simulate a broad range of landings after a jump under anterior tibial shear force, knee abduction, and internal tibial rotation at 25° of knee flexion. The ACL and MCL strains were quantified using differential variable reluctance transducers. An extensively validated, detailed finite element model of the lower extremity was used to help better interpret experimental findings. Results: Anterior cruciate ligament failure occurred in 15 of 17 specimens (88%). Increased anterior tibial shear force and knee abduction and internal tibial rotation moments resulted in significantly higher ACL:MCL strain ratios (P<.05). Under all modes of single-planar and multiplanar loading, the ACL:MCL strain ratio remained greater than 1.7, while the relative ACL strain was significantly higher than the relative MCL strain (P < .01). Relative change in the ACL strain was demonstrated to be significantly greater under combined multiplanar loading compared with anterior tibial shear force (P = .016), knee abduction (P = .018), and internal tibial rotation (P<.0005) moments alone. Conclusion: While both the ACL and the MCL resist knee valgus during landing, physiological magnitudes of the applied loads leading to high ACL strain levels and injuries were not sufficient to compromise the MCLs integrity. Clinical Relevance: A better understanding of injury mechanisms may provide insight that improves current risk screening and injury prevention strategies. Current findings support multiplanar knee valgus collapse as a primary factor contributing to a noncontact ACL injury. © 2013 The Author(s). Source

Levine J.W.,University of Toledo | Kiapour A.M.,University of Toledo | Quatman C.E.,Ohio State University | Wordeman S.C.,Ohio State University | And 4 more authors.
American Journal of Sports Medicine

Background: The functional disability and high costs of treating anterior cruciate ligament (ACL) injuries have generated a great deal of interest in understanding the mechanism of noncontact ACL injuries. Secondary bone bruises have been reported in over 80% of partial and complete ACL ruptures. Purpose: The objectives of this study were (1) to quantify ACL strain under a range of physiologically relevant loading conditions and (2) to evaluate soft tissue and bony injury patterns associated with applied loading conditions thought to be responsible for many noncontact ACL injuries. Study Design: Controlled laboratory study. Methods: Seventeen cadaveric legs (age, 45 ± 7 years; 9 female and 8 male) were tested utilizing a custom-designed drop stand to simulate landing. Specimens were randomly assigned between 2 loading groups that evaluated ACL strain under either knee abduction or internal tibial rotation moments. In each group, combinations of anterior tibial shear force, and knee abduction and internal tibial rotation moments under axial impact loading were applied sequentially until failure. Specimens were tested at 25° of flexion under simulated 1200-N quadriceps and 800-N hamstring loads. A differential variable reluctance transducer was used to calculate ACL strain across the anteromedial bundle. A general linear model was used to compare peak ACL strain at failure. Correlations between simulated knee injury patterns and loading conditions were evaluated by the x2 test for independence. Results: Anterior cruciate ligament failure was generated in 15 of 17 specimens (88%). A clinically relevant distribution of failure patterns was observed including medial collateral ligament tears and damage to the menisci, cartilage, and subchondral bone. Only abduction significantly contributed to calculated peak ACL strain at failure (P = .002). While ACL disruption patterns were independent of the loading mechanism, tibial plateau injury patterns (locations) were significantly (P = .002) dependent on the applied loading conditions. Damage to the articular cartilage along with depression of the midlateral tibial plateau was primarily associated with knee abduction moments, while cartilage damage with depression of the posterolateral tibial plateau was primarily associated with internal tibial rotation moments. Conclusion: The current findings demonstrate the relationship between the location of the tibial plateau injury and ACL injury mechanisms. The resultant injury locations were similar to the clinically observed bone bruises across the tibial plateau during a noncontact ACL injury. These findings indicate that abduction combined with other modes of loading (multiplanar loading) may act to produce ACL injuries. Clinical Relevance: A better understanding of ACL injury mechanisms and associated risk factors may improve current preventive, surgical, and rehabilitation strategies and limit the risk of ACL and secondary injuries, which may in turn minimize the future development of posttraumatic osteoarthritis of the knee. © 2012 The Author(s). Source

Faigenbaum A.D.,The College of New Jersey | Myer G.D.,Cincinnati Childrens Hospital Medical Center | Myer G.D.,Sports Medicine Biodynamics Center | Myer G.D.,Rocky Mountain University of Health Professions
British Journal of Sports Medicine

A literature review was employed to evaluate the current epidemiology of injury related to the safety and efficacy of youth resistance training. Several case study reports and retrospective questionnaires regarding resistance exercise and the competitive sports of weightlifting and powerlifting reveal that injuries have occurred in young lifters, although a majority can be classified as accidental. Lack of qualified instruction that underlies poor exercise technique and inappropriate training loads could explain, at least partly, some of the reported injuries. Current research indicates that resistance training can be a safe, effective and worthwhile activity for children and adolescents provided that qualified professionals supervise all training sessions and provide age-appropriate instruction on proper lifting procedures and safe training guidelines. Regular participation in a multifaceted resistance training programme that begins during the preseason and includes instruction on movement biomechanics may reduce the risk of sports-related injuries in young athletes. Strategies for enhancing the safety of youth resistance training are discussed. Source

Quatman C.E.,Ohio State University | Quatman C.E.,Sports Medicine Biodynamics Center | Quatman C.E.,University of Toledo | Hettrich C.M.,Vanderbilt University | And 2 more authors.
American Journal of Sports Medicine

Background: Current diagnostic strategies for detection of structural articular cartilage abnormalities, the earliest structural signs of osteoarthritis, often do not capture the condition until it is too far advanced for the most potential benefit of noninvasive interventions.Purpose: To systematically review the literature relative to the following questions: (1) Is magnetic resonance imaging (MRI) a valid, sensitive, specific, accurate, and reliable instrument to identify knee articular cartilage abnormalities compared with arthroscopy? (2) Is MRI a sensitive tool that can be utilized to identify early cartilage degeneration?Study Design: Systematic review.Methods: A systematic search was performed in November 2010 using PubMed MEDLINE (from 1966), CINAHL (from 1982), SPORTDiscus (from 1985), SCOPUS (from 1996), and EMBASE (from 1974) databases.Results: Fourteen level I and 13 level II studies were identified that met inclusion criteria and provided information related to diagnostic performance of MRI compared with arthroscopic evaluation. The diagnostic performance of MRI demonstrated a large range of sensitivities, specificities, and accuracies. The sensitivity for identifying articular cartilage abnormalities in the knee joint was reported between 26% and 96%. Specificity and accuracy were reported between 50% and 100% and between 49% and 94%, respectively. The sensitivity, specificity, and accuracy for identifying early osteoarthritis were reported between 0% and 86%, 48% and 95%, and 5% and 94%, respectively. As a result of inconsistencies between imaging techniques and methodological shortcomings of many of the studies, a meta-analysis was not performed, and it was difficult to fully synthesize the information to state firm conclusions about the diagnostic performance of MRI.Conclusion: There is evidence in some MRI protocols that MRI is a relatively valid, sensitive, specific, accurate, and reliable clinical tool for identifying articular cartilage degeneration. Because of heterogeneity of MRI sequences, it is not possible to make definitive conclusions regarding its global clinical utility for guiding diagnosis and treatment strategies.Clinical Relevance: Traumatic sports injuries to the knee may be significant precursor events to early onset of posttraumatic osteoarthritis. Magnetic resonance imaging may aid in early identification of structural injuries to articular cartilage as evidenced by articular cartilage degeneration grading. © 2011 The Author(s). Source

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