The Association Between Self-reported Knee Function And Simple Reaction Time After ACL Reconstruction

Individuals with slower reaction time (RT) are at greater risk of sustaining a lower extremity (LE) injury. However, it is unclear whether RT may be associated with other pertinent outcomes, like self-reported knee function, in patients with a LE injury, such as ACL reconstruction (ACLR). PURPOSE: To examine the association between simple RT (SRT) and self-reported knee function via the Knee Injury and Osteoarthritis Outcome Score (KOOS). We hypothesized that slower SRT is associated with lower self-reported knee function. METHODS: 20 participants (15 female; age = 26.4 ± 6.2 years; time since surgery = 21.2 ± 15.2 months) were recruited from local clinics and the community. Participants were included if between the ages of 14 and 35 and at least 4 months post-ACLR. A computerized sensorimotor assessment of SRT (ms) was performed using a tablet. Participants were instructed to keep each index finger on green circles displayed on the tablet screen. Once the circle changed to red, the participant lifted the corresponding finger as quickly as possible to measure SRT. Participants also completed the KOOS to examine self-reported knee function. This contains 5 subscales for pain, symptoms, activities of daily living, sport and recreation function, and quality of life. Pearson product correlations were calculated to determine the relationship between SRT and KOOS scores. R-values were interpreted as weak (0.00-0.39), moderate (0.40-0.69), and strong (>0.70). Significance was set a priori at p ≤ 0.05. RESULTS: Descriptive statistics are presented in Table 1. A significant, moderate, negative association was identified between SRT and all KOOS subscales (r = -0.45 to -0.67, p < 0.05). CONCLUSION: Individuals post-ACLR with worse self-reported knee function exhibit slower SRT. This is concerning as it implies global neuroplastic changes that may increase the risk of repeat or future injury. Future research should be targeted to examine these changes post-ACLR. Table 1. - Correlation Matrix between Simple Reaction Time and KOOS subscales RT (ms) KOOS-QOL KOOS-ADL KOOS-Pain KOOS-Sport KOOS-Symptoms RT 1.0 KOOS-QOL -0.4971*(0.026) 1.0 KOOS-ADL -0.6461*(0.002) 0.4910*(0.01) 1.0 KOOS-Pain -0.6734*(0.001) 0.6171*(0.008) 0.7770*(<0.001) 1.0 KOOS-Sport -0.4493*(0.047) 0.6440*(0.0004) 0.6944*(0.0001) 0.7482*(<0.001) 1.0 KOOS-Symptoms -0.6614*(0.002) 0.5738*(0.002) 0.5098*(0.008) 0.7113*(<0.001) 0.5059*(0.008) 1.0 Mean 340.55 63.75 96.18 88.54 78.75 80.54 SD 38.21 17.98 6.44 11.33 17.46 11.90 Supported by: GB is supported by NIH CCIH under award number 5T32AT003378-18