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

Context: 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.

Objective: To examine the individual and combined effects of a history of SRC and ACL injury and reconstruction (ACLR) on neurocognitive and neuromechanical function.

Design: Cross-sectional study.

Setting: Research laboratory.

Patients or other participants: 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).

Main outcome measures: 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.

Results: 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.

Conclusions: 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.