Quadriceps Avoidance Characteristics of Persons with a Reconstructed Anterior Cruciate Ligament during a Forward Lunge
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Anterior cruciate ligament (ACL) tears are injuries that often require surgery and physical therapy. Previous research have shown that patients after ACL reconstruction develop a compensatory mechanism called quadriceps avoidance where the use of the quadriceps is avoided and greater knee flexion is demonstrated during gait. Quadriceps avoidance is considered to be an abnormal movement pattern that can have negative effects after ACL reconstruction especially when it is adopted for a long time. While quadriceps avoidance has been well documented in gait, it has not been researched much in more strenuous functional movements such as the forward lunge that often comprise physical activity. The knowledge about the quadriceps avoidance characteristics that an ACL reconstruction brings about during functional movement is limited; thus not much is known regarding the long-term functional outcomes of ACL reconstruction. Thus, the main purpose of this investigation was to quantitatively examine the quadriceps avoidance characteristics of an ACLR group during four phases of a forward lunge by comparing them to the same characteristics of a healthy control group and the uninvolved group. Nineteen participants (13 healthy control, 6 ACLR) were recruited for this study. Reflective motion capture markers were attached to participants who completed 10 repetitions of the forward lunge onto a force platform with each leg alternating leading legs with their arms across their chest. Using marker and force platform data, the moments about the knee in three dimensions were computed. There were no differences between control and ACLR participants in any of the knee moment outcome measures in any of the four phases along the sagittal, frontal, and transverse anatomical planes that were investigated (p > 0.05). No differences in knee moments indicate that ACLR limbs exhibited a level of quadriceps avoidance that was not different than the level exhibited by healthy control or uninvolved limbs when lunging forward. These findings suggest that current treatment methods are able to restore normal quadriceps avoidance characteristics and the injury risk posed by these characteristics to ACLR individuals are no greater than the risk posed to healthy individuals when participating in full physical activity after surgery.