title: Total knee replacement with natural rollback.
abstract: A novel class of total knee replacement (AEQUOS G1) is introduced which features a unique design of the articular surfaces. Based on the anatomy of the human knee and differing from all other prostheses, the lateral tibial "plateau" is convexly curved and the lateral femoral condyle is posteriorly shifted in relation to the medial femoral condyle. Under compressive forces the configuration of the articular surfaces of human knees constrains the relative motion of femur and tibia in flexion/extension. This constrained motion is equivalent to that of a four-bar linkage, the virtual 4 pivots of which are given by the centres of curvature of the articulating surfaces. The dimensions of the four-bar linkage were optimized to the effect that constrained motion of the total knee replacement (TKR) follows the flexional motion of the human knee in close approximation, particularly during gait. In pilot studies lateral X-ray pictures have demonstrated that AEQUOS G1 can feature the natural rollback in vivo. Rollback relieves the load of the patello-femoral joint and minimizes retropatellar pressure. This mechanism should reduce the prevalence of anterior knee pain. The articulating surfaces roll predominantly in the stance phase. Consequently sliding friction is replaced by the lesser rolling friction under load. Producing rollback should minimize material wear due to friction and maximize the lifetime of the prosthesis. To definitely confirm these theses one has to wait for the long term results.
authors.affiliation: Department of Trauma Surgery, Plastic and Reconstructive Surgery, Georg August University of Göttingen, Germany.
authors.forename: Martin Michael
authors.initials: MM
authors.lastname: Wachowski
authors.forename: Tim Alexander
authors.initials: TA
authors.lastname: Walde
authors.forename: Peter
authors.initials: P
authors.lastname: Balcarek
authors.forename: Jan Philipp
authors.initials: JP
authors.lastname: Schüttrumpf
authors.forename: Stephan
authors.initials: S
authors.lastname: Frosch
authors.forename: Caspar
authors.initials: C
authors.lastname: Stauffenberg
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Frosch
authors.forename: Christoph
authors.initials: C
authors.lastname: Fiedler
authors.forename: Jochen
authors.initials: J
authors.lastname: Fanghänel
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kubein-Meesenburg
authors.forename: Hans
authors.initials: H
authors.lastname: Nägerl
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000502:physiology; D005269:Femur / Q000033:anatomy & histology / Q000502:physiology; D017276:Friction; D005684:Gait / Q000502:physiology; D006801:Humans; D007717:Knee / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D007720:Knee Prosthesis; D010329:Patella / Q000502:physiology; D017847:Patellar Ligament / Q000502:physiology; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D013977:Tibia / Q000033:anatomy & histology / Q000502:physiology