An Examination of the Relationship Between Fear of Reinjury and Neuromuscular, Musculoskeletal, and Biomechanical Characteristics at the Time of Return to Sport following Anterior Cruciate Ligament Reconstruction.

Background: Kinesiophobia is linked to reinjury risk, decreased physical performance and a major cause of sport dropout following ACL reconstruction (ACLR). Identifying deficits based on kinesiophobia may help with the development of strategies to improve outcomes and decrease the risk of reinjury. Purpose: The purpose of this study was to compare individuals with high and low TSK-11 scores across modifiable neuromuscular, musculoskeletal, and biomechanical characteristics at the time of RTS. Study design: Cross-sectional study. Methods: Participants within two months of RTS clearance were recruited from a single academic institution between August 2018 and December 2019. Kinesiophobia was measured using the TSK-11. Lower extremity strength was evaluated using isometric and isokinetic testing. Dynamic postural stability was assessed with a double leg jump to single leg landing onto force plates, from which a dynamic postural stability index was calculated. Jump-landing biomechanics were assessed using a single leg stop jump (SLSJ), and single leg hop performance was measured with a triple hop test. Participants were categorized into low (<17) or high (≥17) kinesiophobia groups based on TSK-11 scores. Means and SD were calculated for all variables. Comparisons were made between groups in lower extremity range of motion, strength, dynamic postural stability, jump landing and single leg hop performance. Independent sample t-tests and Mann-Whitney U tests were used to compare variables between high and low kinesiophobia groups, with Cohen's d used to estimate effect sizes. Results: Twenty-seven participants (14 males, 13 females; age = 20.6 ± 6.5; pre-injury Tegner Activity Level = 7.7 ± 1.3) cleared for RTS post-unilateral ACLR volunteered for this study (10 ± 2 months post-ACLR). A significant difference was found between high and low TSK-11 groups for weight-bearing ankle dorsiflexion lunge test (p = 0.011) and single leg stop jump task maximum knee valgus angle (p = 0.007). There was no significant difference between the two groups for any other variable. Conclusion: Few differences in neuromuscular, musculoskeletal, and biomechanical function were identified between low and high TSK-11 scores at RTS. Results suggest that athletes in this cohort returning to sport have relatively low TSK-11 scores, and that higher scores may be attributed to other factors. Due to the small sample size and relatively low TSK-11 scores, further research is needed to confirm the relationship between kinesiophobia and variables commonly assessed at the time of RTS following ACLR. Level of Evidence: 3b.