title: Dynamic stability in the anterior cruciate ligament deficient knee.
abstract: Some individuals can stabilize their knees following anterior cruciate ligament rupture even during activities involving cutting and pivoting (copers), others have instability with daily activities (non-copers). Movement and muscle activation patterns of 11 copers, ten non-copers and ten uninjured subjects were studied during walking and jogging. Results indicate that distinct gait adaptations appeared primarily in the non-copers. Copers used joint ranges of motion, moments and muscle activation patterns similar to uninjured subjects. Non-copers reduced their knee motion, and external knee flexion moments that correlated well with quadriceps strength. Non-copers also achieved peak hamstring activity later in the weight acceptance phase and used a strategy involving more generalized co-contraction. Both copers and non-copers had high levels of quadriceps femoris muscle activity. The reduced knee moment in the involved limbs of the non-copers did not represent "quadriceps avoidance" but rather represented a strategy of general co-contraction with a greater relative contribution from the hamstring muscles.
authors.affiliation: Department of Physical Therapy, University of Delaware, 303 McKinly Laboratory, Newark, DE 19716, USA. krudolph@udel.edu
authors.forename: K S
authors.initials: KS
authors.lastname: Rudolph
authors.forename: M J
authors.initials: MJ
authors.lastname: Axe
authors.forename: T S
authors.initials: TS
authors.lastname: Buchanan
authors.forename: J P
authors.initials: JP
authors.lastname: Scholz
authors.forename: L
authors.initials: L
authors.lastname: Snyder-Mackler
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007718:Knee Injuries / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D016059:Range of Motion, Articular; D012421:Rupture; D013848:Thigh / Q000502:physiology