Pain-related fear induces aberrant drop jump landing biomechanics in healthy and anterior cruciate ligament reconstructed females

Purpose: Rupture of the anterior cruciate ligament (ACL) is a prevalent and debilitating injury typically arising from aberrant biomechanics during landing or deceleration tasks. Pain-related fear, a component of kinesiophobia, has been associated with poor functional outcomes and altered movement patterns in individuals with ACL reconstruction (ACLr), however, the influence of pain-related fear on landing mechanics remains unclear. The purpose of this investigation was to examine the effects of pain-related fear on landing movement patterns in a population of ACLr and healthy females. Methods: Thirty-two females (15 recreationally active with a history of ACLr and 17 recreationally active with no history of ACLr) took part. Participants performed five trials of a drop jump (DJ) task (Baseline), underwent a pain stimulus (PS) familiarization task utilizing an electrical stimulus to induce pain-related fear, and performed a subsequent round of DJs while under threat of PS (PS-threat). Lower extremity and trunk kinematics, ground reaction force (GRF) data and muscle activation were analyzed. Results: At baseline, ACLr participants scored higher (21 +/- 5.5) on the TSK-11 compared to healthy participants (17 +/- 3.4) (p = 0.007). For both groups, the PS intervention significantly increased pain-related fear (ACLr p < 0.001; Healthy p < 0.001). When comparing baseline to PS-threat trials, ACLr participants experienced a significant increase in peak GRF (p = 0.005), decreases in hip (p = 0.003) and knee (p = 0.005) flexion, decreased contact time (p = 0.006) and decreased muscle preactivation for all muscles tested (p < 0.05). Healthy participants experienced significant increases in peak GRF (p = 0.014) and decreased hip (p = 0.005) and trunk peak (p = 0.004) flexion. Conclusions: Pain-related fear alters landing biomechanics in healthy and ACLr females. This may implicate pain-related fear as a contributor to movement alterations commonly associated with ACL injury risk.