Multiple Object Tracking And Knee Symptoms In Healthy Controls And Individuals With ACL Reconstruction

PURPOSE: The ability to visually track objects in dynamic environments is an important aspect of safely returning to play after ACL reconstruction (ACLR). Previous work has shown that individuals experience deficits in neurocognitive function and unacceptable knee symptoms after ACLR which may impact with performance. The purpose of this study is to examine the association between knee symptoms and multiple object tracking (MOT) in individuals with ACLR and healthy controls. METHODS: This data is from an ongoing cohort study. ACLR participants were included if they had a history of primary ACLR (time since ACLR=21.1 [9.7] months). Healthy controls were matched to ACLR participants based on age, sex, and reported a Tegner Activity Scale (TAS) score ≥5 (physically active). 14 healthy (age=19.9 [2] yrs, TAS=7.1 ± 2.5) and 27 ACLR (age=21 [7.7] yrs, TAS=8.4 ± 1.2) completed a computerized assessment that tests how well individuals can divide attention between moving objects. MOT is reported as a composite score with higher scores indicating better performance. Participants completed the Knee injury and Osteoarthritis Outcome Score (KOOS), a reliable measure with a symptom subscale (KOOS-Sx). Higher scores on the KOOS-Sx indicate less knee symptoms with a cutoff score of ≤85.7 indicating clinically unacceptable symptoms. An ANCOVA was conducted with MOT score as the dependent variable, group (ACLR or healthy), and KOOS-Sx score as the covariate. α was set a priori to p<0.05. RESULTS: The overall model was insignificant (Table 1, adj r2=0.0921). Post-hoc Mann-Whitney tests revealed group differences in KOOS-Sx (ACLR 79.6 ± 13.8, Healthy 95.7 ± 4.2, p=0.0001) but no differences in MOT (ACLR 1594.8 ± 538.3 MOT, Healthy 1332.5 ± 497.1 MOT p=.15). CONCLUSION: The ACLR group demonstrated unacceptable knee symptoms compared to healthy controls, however, this was not associated with visual tracking performance. Knee symptoms may affect neurocognitive function during other tasks. Table 1. - ANCOVA Model for Multiple Object Tracking and KOOS Symptoms Between Groups Source Partial SS df MS F Partial η (95% CI) P-Value Model 1564861.6 2 782430.82 3.03 0.14 (<.00001 - .031) 0.0602 Group (ACLR v Healthy) 1443516.7 1 14435.16 5.59 0.13 (0.0007 - 0.32) 0.0233 KOOS Symptoms 930776.98 1 930776.98 3.60 0.07 (<0.00001 - 0.27) 0.0653 Residual 9815403.8 38 258300.1