An understanding of knee ligament anatomy and biomechanics is foundational for physicians treating knee injuries, especially the more rare and morbid multiligamentous knee injuries. This chapter examines the roles that the cruciate and collateral anatomy and morphology play in their kinematics. Additionally, the biomechanics of the ACL, PCL, MCL, and LCL are discussed as they have surgical and reconstructive implications.

Study Design. Descriptive epidemiology study. Objective. The purpose of this study was to describe the epidemiology of neck and cervical spine injuries in collegiate athletes over a 5-year period. Summary of Background Data. The incidence and etiology of neck and cervical spine injuries in National Collegiate Athletic Association (NCAA) athletes has not been well defined in recent years. Methods. The incidence and characteristics of neck and cervical spine injuries were identified utilizing the NCAA Injury Surveillance Program database. Rates of injury were calculated as the number of injuries divided by the total number of athlete-exposures (AEs). AEs were defined as any student participation in one NCAA-sanctioned practice or competition. Results. Nationally, there were an estimated 11,510 neck and cervical spine injuries over the 5-year period. These occurred at a rate of 7.05 per 100,000 athlete-exposures (AEs). The rate of neck and cervical spine injuries in men was 2.66 per 100,000 AEs, while women suffered injuries at a rate of 1.95 per 100,000 AEs. In sex-comparable sports, men were 1.36 times more likely to suffer a neck or cervical spine injury compared with women. Men's football (29.09 per 100,000 AEs) and women's field hockey (11.51 per 100,000 AEs) were the sports with the highest rates of injuries. These injuries were 3.94 times more likely to occur during competition compared with practice. In-season injury rates were the highest, at 8.18 per 100,000 AEs. Conclusion. The vast majority of neck and cervical spine injuries in NCAA athletes are minor and uncommon. Across all sports in both sexes, the majority of injuries were new, and occurred during in-season competitions. Most athletes returned to play within 24 hours of injury. These data can inform players, parents, coaches, athletic trainers, and physicians regarding the prevalence and rates of these injuries and potentially inform decision-making regarding injury prevention, treatment, and rehabilitation. Level of Evidence: 4

Background:The National Football League (NFL) combine has been found to play a significant role in NFL draft decisions. Previous studies have demonstrated correlations between a player's combine metrics and draft position and performance, but no study has investigated the purposes of our study, the relationship between these combine tests and NFL career longevity. Methods: A retrospective review of combine test results from all offensive players participating in the NFL combine from 2005-2015 was completed. Tests included height, weight, BMI, 10-, 20-, 40-yard dash, bench press, vertical jump, broad jump, short shuttle, and 3-cone. Career length was determined by online review of NFL rosters from 2005-2017. Statistical analysis using logistic regression was completed to determine the association of each player's original (O) and normalized (N) combine test results with career longevity. Results: Quarterbacks on an NFL roster at year five were 0.75 inches taller than quarterbacks not on a roster (p<0.05). There was an association between 10-yard (RB: p<0.05; WR: p<0.05), 20-yard (RB: p<0.05; WR: p<0.05) and 40-yard (RB: p<0.05; WR: p<0.05) dash times, as well as broad jump (RB: p<0.05; WR: p <0.05), for running backs (RB) and wide receivers (WR) on a roster at 5-years. Tight ends on a roster at 5-years were found to have performed significantly better in the vertical jump (p<0.05) and broad jump (p<0.05), while also having greater body weight (p<0.05) than those not on a roster. Vertical jump (p<0.05), broad jump (p<0.05) and 40-yard dash (p<0.05) were found to be associated with offensive lineman on an NFL roster at 5-years. Conclusion:The combine has been used by NFL teams to gather objective data about player's athleticism, and this study shows the specific drills and corresponding traits that are related to longer careers for each position. This study found associations between traits that are reflected by the tests performed at the NFL combine and career longevity. The findings of this study may serve as an additional resource for teams to assist in the assessment of a player's potential career longevity based on their individual combine results.