title: Knee motions during maximum flexion in fixed and mobile-bearing arthroplasties.
abstract: Full flexion is a critical performance requirement for patients in Asia and the Middle East, and increasingly for patients in Europe and North America who have total knee arthroplasty. There has been considerable work characterizing maximum flexion in terms of clinical, surgical, and preoperative factors, but less in vivo experimental work after rehabilitation. The purpose of the current investigation was to determine whether anteroposterior tibiofemoral translation influenced maximum weightbearing knee flexion in patients with good or excellent clinical and functional outcomes. One hundred twenty-one knees in 93 subjects, including 16 different articular surface designs, were studied using fluoroscopy and shape matching to determine knee kinematics in a weightbearing deep flexion activity. A relatively posterior position of the femur on the tibia was significantly correlated with greater maximum knee flexion. Posterior-stabilized arthroplasties had significantly more posterior femoral position and maximum flexion than posterior cruciate-retaining fixed-bearing arthroplasties, which had more posterior femoral position and greater maximum flexion than mobile-bearing arthroplasties. Posterior bone-implant impingement was observed in 28% of knees. Tibiofemoral motions influence the mechanics of weightbearing deep flexion in well-functioning knee arthroplasties.
authors.affiliation: The Biomotion Foundation, West Palm Beach, FL 33401, USA. banks@alum.mit.edu
authors.forename: Scott
authors.initials: S
authors.lastname: Banks
authors.forename: Johan
authors.initials: J
authors.lastname: Bellemans
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nozaki
authors.forename: Leo A
authors.initials: LA
authors.lastname: Whiteside
authors.forename: Melinda
authors.initials: M
authors.lastname: Harman
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Hodge
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D011474:Prosthesis Design