title: Popliteus function in ACL-deficient patients.
abstract: Anterior cruciate ligament (ACL) injuries commonly result in anterolateral rotary instability and a 'pivot shift' phenomenon. Since popliteus muscle stimulation causes a pivot shift, some postulate the popliteus muscle plays a role in causing pivot shifts. To see if patients with pivot shifts exhibited excessive popliteus muscle activity, we studied fine-wire EMGs of the popliteus in 16 normal subjects and 10 ACL-deficient subjects. Subjects performed six activities (level walking and jogging, ascending walking and jogging, and descending walking and jogging). Except for minor timing differences in ascending treadmill and ascending jogging, the signals were similar for injured and uninjured limbs; similar variance ratios suggested similar pattern variability. Thus, we observed only minor popliteus EMG signal differences in this group of patients. We conclude that the popliteus muscle does not actively contribute to instability in the studied activities.
authors.affiliation: Department of Orthopaedic Surgery, University of Iowa, Iowa City 52242, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Weresh
authors.forename: R H
authors.initials: RH
authors.lastname: Gabel
authors.forename: R A
authors.initials: RA
authors.lastname: Brand
authors.forename: D S
authors.initials: DS
authors.lastname: Tearse
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D004576:Electromyography; D005260:Female; D006801:Humans; D007590:Jogging / Q000502:physiology; D007593:Joint Instability / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016138:Walking / Q000502:physiology