Review Question - QID 218588

Previous concussions have been associated with the development of anterior cruciate ligament (ACL) tears.

ACL tears are a common injury in sports, especially in contact sports like soccer, football, and basketball. There are several risk factors associated with ACL tears, including gender, hormonal changes, neuromuscular factors, previous injury, landing mechanics, playing surface, and genetic factors. Female athletes are at a higher risk of ACL injury compared to male athletes, due to differences in muscle strength, hormonal differences, and the way the knee joint is aligned. Poorly developed quadriceps and hamstrings muscles, poor proprioception, and previous ACL injuries can also increase the risk of ACL injury. Previous concussions have been linked to an increased ACL tear rate which is believed to be from neuromuscular alterations.

Taylor et al. performed a cross-sectional study aimed to assess the association between concussion and cognitive test performance in a sample of 5616 high school and junior high school athletes. The study found that ever having a concussion was associated with a decrease in overall cognitive function and in specific cognitive domains such as verbal memory, visual memory, and impulse control. The number of concussions and age at first concussions were also found to be associated with cognitive function, with early childhood concussions resulting in greater negative effects. They concluded that the effects of concussions on cognitive function can be present years after the injury, indicating that the effects of concussions on cognitive function may be more persistent than previously thought.

McPherson et al. studied the risk of ACL injury after a previous concussion through the Rochester Epidemiology Project database. They found the rate of prior concussion was higher in ACL-injured cases (2.4%) compared to matched controls with no ACL injury (1.5%), which corresponds to an odds ratio of 1.6. They concluded that standard clinical assessments should consider concussion symptom resolution as well as assessment of neuromuscular factors associated with the risk of injuries.

McAllister et al. reviewed sport-related concussions in athletes. They stated the main concern is that repetitive concussions may lead to long-term cognitive decline, neurobehavioral changes, and neurodegenerative diseases. They conclude that a full understanding of this topic requires attention to not only the effects of repetitive concussions but also overall exposure to repetitive head impacts.

Incorrect answers:
Answer 1: Varus knee alignment has not been specifically associated with an increased ACL tear rate.
Answer 3: Leg length discrepancies have not been associated with an increased ACL tear rate.
Answer 4: Previous meniscus tears have not been associated with an increased ACL tear rate.
Answer 5: Increased hamstring muscle tone counteracts the deformity of an ACL-deficient knee, thereby protecting the ligament.