Ferber, Reed, 1970-2008-02-102008-02-1020010-493-35824-2https://hdl.handle.net/1794/148Adviser: Louis R. Osternig. xix, 196 leavesA print copy of this title is available through the UO Libraries under the call number: SCIENCE RD561 .F47 2001The purpose of this study was to investigate the gait patterns in persons with chronic ACL deficiency (ACLD: n = 10) who subsequently undergo surgical repair, and to determine how these individuals respond to an unexpected forward perturbations (FP) compared to healthy controls (n = 10). An unexpected FP was applied using a moveable force plate imbedded in a walkway. During nonperturbed (NP) gait, ACLD subjects exhibited similar knee moment patterns compared to healthy adults but appeared to accommodate to ACLD through alterations of hip and ankle joint kinematic, kinetic, and muscle power patterns. Three months following surgery, these same subjects demonstrated a significantly different knee moment pattern and were significantly more flexed at the knee and hip during NP gait. These data suggest that time since injury plays an important role in the adaptation of gait mechanics and must be considered when evaluating post-surgical ACL subjects. These data also suggest that ACL surgery significantly alters lower extremity gait patterns and that the re-establishment of pre-injury gait patterns takes longer than 3 months to occur. When healthy adults experienced an unexpected FP, the hip was favored in maintaining control of the upper body and in preventing collapse. In response to the same FP, ACLD subjects demonstrated a hip moment pattern similar to controls but a greater knee extensor moment. The increased knee moment pattern was more prevalent 3 months following surgery. These data suggest that ACLD and ACLR subjects rely more on knee extensor muscles for the prevention of collapse when reacting to an unexpected FP. Bilateral accommodations to ACL injury and surgery during NP and FP gait were also examined. During NP gait, healthy adults demonstrated asymmetrical hip moment and power patterns whereas ACLD and ACLR subjects exhibited symmetrical hip but asymmetrical knee mechanics. In response to the FP, healthy adults exhibited lower extremity joint symmetry but the ACLD and ACLR group exhibited asymmetrical knee moment and power patterns. These findings suggest that ACL injury and surgery result in bilateral joint accommodations and that when investigating ACL injured populations, bilateral control population data should be used in addition to non-injured limb data.6806291 bytes1473 bytes286070 bytes312893 bytesapplication/pdftext/plaintext/plaintext/plainen-USAnterior cruciate ligament -- Wounds and injuriesAnterior cruciate ligament -- Surgery -- Patients -- RehabilitationGait disordersGait in humans -- Physiological aspectsKnee -- Surgery -- Patients -- RehabilitationThesis