Individual and combined effects of sport-related concussion and ACL injury on neurocognitive and neuromechanical reaction time

Recent epidemiological data indicates a potential connection between sport-related concussion (SRC) and elevated anterior cruciate ligament (ACL) injury risk. Limited research exists quantifying cognitive and motor outcome measures between SRC and ACL injury history. To examine the individual and combined effects of a history of SRC and ACL injury and reconstruction (ACLR) on neurocognitive and neuromechanical function. Cross-sectional study. Research laboratory. 47 recreationally active college individuals with either an injury history of SRC (n=12), ACLR (n=12), combination of SRC+ACLR (n=11), or uninjured controls (n=12). Participants completed a neurological battery using the C3 Logix application and TRAZER system for neuromechanical reaction time (RT). C3 Logix sub-tests consisted of the Trail Making Test (TMT) A,B, and B -/minus A, simple and choice RT, and processing speed. TRAZER sub-tests consisted of simple, Flanker-task, and Stroop-task RT. Participants were categorized into 3 group comparisons of either: (i) SRC, ACLR, SRC+ACLR, and controls, (ii) Any or No SRC overall, (iii) Any or No ACLR overall. No differences were demonstrated between SRC, ACLR, SRC+ACLR, and controls on TMT (p=.07-.14), neurocognitive (p=.14-.93) or neuromechanical (p=.64-.99) performance. Those with Any SRC had slower TMT B-A times (p=.03), while those with Any ACLR had slower Trail A (p=.02) times when compared to those with no ACLR. No differences were noted for TRAZER simple, Flanker, or Stroop RT for Any or No SRC and ACLR groups. College students with a combined effect of SRC and ACLR did not differ from other groups on neurocognition and neuromechanical reaction time. Individuals with a history of SRC or ACLR had worse TMT, leading to inquiry about potential long-term neurological deficits, despite no differences in those with a combined history.