Collections > Electronic Theses and Dissertations > Double and Single Leg Landing Biomechanics in Adolescent Female Athletes with a History of Anterior Cruciate Ligament Reconstruction and the Effects of Verbal Instructions on Acute Alterations in Landing

Young female athletes that return to sport following anterior cruciate ligament (ACL) injury and reconstruction (ACLR) are at great risk of secondary injury. Landing biomechanics in adolescent females following ACLR have not been studied and it is unknown if verbal instructions to acutely alter landing are effective in a previously injured population. The purpose of this study was to investigate trunk and bilateral lower extremity biomechanics in adolescent female athletes with and without a history of ACLR and to determine the effectiveness of verbal instructions in altering landing forces. Twenty-two ACLR (age=16.68 ± 1.55yrs, height=166.80 ± 6.04cm, mass=61.08 ± 8.78kg) and 25 control (CON; age=16.91 ± 1.23yrs, height=170.22 ± 7.40cm, mass=63.32 ± 7.59kg) participants completed this study. Participants performed a double-leg jump landing and single-leg double hop for biomechanical analysis. Verbal instructions conditions (soft landing or equal landing on both limbs) were provided to influence the jump-landing task in comparison to baseline. During the jump-landing, ACLR group participants relied on the contralateral Uninjured limb to absorb landing forces through greater sagittal plane displacement and larger internal joint moments and forces. The ACLR Injured limb utilized greater frontal plane hip motion compared to the Uninjured limb. During the single-leg hop, ACLR participants utilized less sagittal plane with greater frontal and transverse plane motion, and reduced landing forces when compared to the Uninjured and CON participants. The verbal instructions interventions caused similar changes in the ACLR Injured limb and healthy CON limbs. However, the ACLR Uninjured limb demonstrated greater magnitude decreases in vertical ground reaction (VGRF) compared to the Injured and matched CON limb following the soft landing instructions and greater decreased in VGRF and anterior tibial shear forces following the equal landing instructions compared to the Injured limb. These results highlight asymmetrical biomechanics between the ACLR limbs and differences between the ACLR group and CON group, potentially placing the ACLR group participants at greater risk for secondary ACL injury. The results of this investigation provide significant evidence for the importance of evaluating quality of movement to aid in return to play decision-making.