Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy.

STUDY DESIGN: Case-control. OBJECTIVE: To examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT. BACKGROUND: PT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT. METHODS: 11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests. RESULTS: Patients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (-21.1° ± 5.9° vs. -14.8° ± 5.5°, P = .023) and step down (-15.6° ± 5.5° vs. -9.0° ± 6.0°, P = .017). CONCLUSIONS: Patients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.

Youth Distance Running: Strategies for Training and Injury Reduction.

Running is a popular sport for children in the United States. However, review of available literature on health effects and safety recommendations for youth running has not been previously conducted. Unique factors for injury include periods of growth during puberty and potential for growth plate injury. Youth runners may benefit from activities that incorporate high-impact loading and multidirectional movement for optimal bone maturation, exercises to strengthen tendons and muscles, and strategies aimed at improving running biomechanics to reduce risk of injury. In addition, addressing lifestyle factors, including nutrition and sleep is essential for a runner's general health. Similar to other sports, sports specialization should not be encouraged in youth runners. Reducing running-related injury in growing children and assessing readiness for running should be based on a combination of physical, emotional, psychological, social, and cognitive factors. Youth runners require individualized training and competition to safely participate in the sport.

High-field magnetic resonance imaging assessment of articular cartilage before and after marathon running: does long-distance running lead to cartilage damage?

BACKGROUND: There is continuing controversy whether long-distance running results in irreversible articular cartilage damage. New quantitative magnetic resonance imaging (MRI) techniques used at 3.0 T have been developed including T1rho (T1ρ) and T2 relaxation time measurements that detect early cartilage proteoglycan and collagen breakdown. HYPOTHESIS: Marathon runners will demonstrate T1ρ and T2 changes in articular cartilage on MRI after a marathon, which are not seen in nonrunners. These changes are reversible. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Ten asymptomatic marathon runners had 3-T knee MRI scans 2 weeks before, within 48 hours after, and 10 to 12 weeks after running a marathon. The T1ρ and T2 MRI sequences in runners were compared with those of 10 age- and gender-matched controls who had MRI performed at baseline and 10 to 12 weeks. RESULTS: Runners did not demonstrate any gross morphologic MRI changes after running a marathon. Postmarathon studies, however, revealed significantly higher T2 and T1ρ values in all articular cartilage areas of the knee (P < .01) except the lateral compartment. The T2 values recovered to baseline except in the medial femoral condyle after 3 months. Average T1ρ values increased after the marathon from 37.0 to 38.9 (P < .001) and remained increased at 3 months. CONCLUSION: Runners showed elevated T1ρ and T2 values after a marathon, suggesting biochemical changes in articular cartilage, T1ρ values remain elevated after 3 months of reduced activity. The patellofemoral joint and medial compartment of the knee show the highest signal changes, suggesting they are at higher risk for degeneration.

Heat injury prevention practices in high school football.

OBJECTIVE: To survey high school American football programs regarding current prevention measures for reducing heat injuries during the football season. DESIGN: Web-based survey of 27 questions based on consensus statement guidelines by the American College of Sports Medicine on reducing heat injury risk in youth football. SETTING: National (United States) and community-based. PARTICIPANTS: High school programs receiving survey distribution from their state athletic association and the National Federation of State High School Associations. MAIN OUTCOME MEASURES: Responses (percentage and incidence) to questions on preseason acclimatization procedures, practice modification protocols, preparticipation risk factors, hydration management strategies, rest period strategies, heat injury education and policies, and preparation for heat-related emergency care. RESULTS: A total of 540 high school football programs from 26 states completed the survey. The reported number of preseason heat injuries per program (1.38+/-2.08) was greater (P<0.001) compared to during the regular season (0.98+/-1.84). Programs modified equipment configurations during preseason (no helmets or pads, 31.3%; just helmets, 57.0%; helmets and shoulder pads only, 33.5%) or altered the practice schedule when there was excessive heat. Hydration management, education, and preparation for dealing with an acute heat injury varied among programs. CONCLUSIONS: Greater implementation of effective prevention measures to reduce the incidence of heat-related injury and death in high school American football is needed. Strategies should focus on modifying practices appropriately on a day-to-day basis to minimize heat strain and optimize hydration, identifying and educating at-risk individuals during the preparticipation period, and developing an emergency action plan for effectively managing heat injuries.