Why did you do this study?
Recent work here at UNC as well as other locations around the world has identified increased lower extremity musculoskeletal injury rates following concussion. These findings, in conjunction with published data revealing movement deficiencies after brain injury, suggest proper motor control may be impaired after concussion. Importantly, these motor control impairments have been identified past return to play following concussion. Increased injury rates have been noted for up to a year following brain injury. Because researchers have not investigated beyond a year following concussion, it is unknown what long-term consequences movement deficits and increased rates of lower extremity musculoskeletal injuries may have on late-life degenerative musculoskeletal conditions, such as osteoarthritis (OA). Understanding possible connections between concussions and late-life degenerative conditions is an important step to increase our understanding of potential long-term deficits from sport-related concussion.
What did you do and what did you find in this study?
The purpose of our study was to investigate the self-reported prevalence of OA in retired National Football League (NFL) players by examining the association of concussion and lower extremity injury history. We analyzed data from an ongoing general health survey consisting of over 2,600 former NFL players. Retired players were grouped based on reported concussion and lower extremity history. The groups ranged from players with 0 concussions and 0 lower extremity injuries to players with 3+ concussions and 2+ lower extremity injuries. We found retired players who suffered 0 concussions and 0 lower extremity injuries during their professional football careers reported the lowest prevalence of OA (21.1%), while those that suffered 3+ concussions and 2+ lower extremity injuries during their professional careers had the largest prevalence of OA (50.6%). After controlling for BMI while playing, NFL years played, and age at time of survey, the lifetime prevalence of OA was significantly higher in the majority of the other concussion/lower extremity groups as compared to the group with 0 concussions and 0 lower extremity injuries.
How do these findings impact the public?
Our results suggest concussion may be an important moderating factor in the relationship between lower extremity injury history and OA. This investigation is the first to explore the connection between concussion history and late-life degenerative conditions. It is important to realize our findings are preliminary, and we did not directly investigate the underlying pathophysiology between the apparent OA prevalence increase and concussion. While our findings cause concern for the long-term physical health of those who have suffered multiple concussions, it is important to consider the numerous physical, psychological, and cognitive benefits associated with sports participation. We believe our findings help establish the basis by which future research can examine the underlying cause of higher OA prevalence in those who have suffered multiple concussions. After more causative associations are established, researchers and clinicians can work together to develop intervention and rehabilitation strategies to help combat the increased risk of injury following concussion as well as the increased prevalence of OA in those that have suffered multiple brain injuries.