Vasquez, Bryana Nicole2023-06-282023-06-282023-06-27vt_gsexam:37904http://hdl.handle.net/10919/115550Anterior cruciate ligament (ACL) injuries are common orthopaedic injuries among athletes who participate in sports that involve cutting and changing directions. Many of these adolescent athletes intend to return to sports (RTS), and therefore undergo ACL reconstruction (ACLR). These athletes exhibit unfavorable landing biomechanics from muscle atrophy and asymmetrical neuromuscular control post-ACLR, putting them at a higher risk of re-injury. Thus, rehabilitation following ACLR is important to improve kinetic and kinematic outcomes and reduce re-injury risk. Biofeedback during rehabilitation is thought to be one way to potentially restore neuromuscular control deficits of athletes recovering from ACLR. Therefore, understanding the effectiveness of a biofeedback intervention on factors associated with re-injury among post-ACLR patients is essential in successful RTS. The purpose of this study is to analyze the effect of a 6-week biofeedback intervention on eccentric knee joint power (ECCKP), limb stiffness, and limb stiffness symmetry (using normalized symmetry index, NSI), in addition to secondary lower extremity outcomes that are associated with these metrics, during landing among patients following ACLR. This study used data collected from an ACL-Biofeedback Trial (ClinicalTrials.gov: AR069865) where participants were randomized into a biofeedback (BF) or control group (C). The BF group received visual and tactile feedback during a series of controlled squats while the C group participated in several online and in-person educational sessions. Participants completed 10 stop-jump tasks before (pre), after (post), and 6 weeks after (ret) the intervention. Kinetic, kinematic, and ground reaction forces (GRF) were collected from embedded force plates and 3D motion capture. Partaking in a biofeedback intervention did not improve ECCKP, limb stiffness, or limb stiffness NSI compared to controls. A group-by-time interaction was found for hip excursion (p=0.035), and a main effect of time was found for ECCKP, with this variable increasing by 18.5% from pre to ret (p=0.001). In addition, when considering surgical versus non-surgical limbs, this cohort exhibited interlimb asymmetries in stiffness, peak resultant GRF (rGRF), and time to reach peak rGRF (p<0.009). Further, a group-by-limb interaction (p=0.005) and a 7.1% reduction in peak rGRF were found from post to ret (p=0.02). Participants in this study also exhibited limb stiffness asymmetry greater than 10%, which supports existing literature that observed interlimb asymmetries in athletes following ACLR around the typical RTS time (9-12 months post-ACLR). The results from this analysis demonstrated that the current biofeedback intervention was inadequate in improving ECCKP, limb stiffness, and limb stiffness NSI, but additional biofeedback studies with larger sample sizes that investigate task dependencies are needed to better understand the effectiveness of biofeedback interventions.ETDenIn CopyrightACLRBiofeedbackKnee PowerLimb StiffnessAsymmetryThesis