title: Optimal graft stiffness and pre-strain restore normal joint motion and cartilage responses in ACL reconstructed knee.
abstract: Anterior cruciate ligament (ACL) rupture leads to abnormal loading of the knee joint and increases the risk of osteoarthritis. It is unclear how different ACL reconstruction techniques affect knee joint motion and mechanics. As the in vivo measurement of knee joint loading is not possible, we used finite element analysis to assess the outcome of ACL reconstruction techniques. Effects of different ACL reconstruction techniques on knee joint mechanics were studied using six models during gait; with 1) healthy ACL, 2) ACL rupture, 3) single bundle ACL reconstruction, 4) double bundle ACL reconstruction, 5) weakened (softer) single bundle reconstruction and 6) single bundle reconstruction with less pre-strain. Early in the gait, the ACL rupture caused substantially increased tibial translation in the anterior direction as well as a smaller but increased lateral translation and internal tibial rotation. ACL rupture substantially reduced average stresses and strains, while local peak stresses and strains could be either increased or decreased. Single bundle and double bundle reconstructions restored joint motion close to normal levels. However, cartilage strains and stresses were elevated during the entire gait cycle. Models with modulated graft stiffness and pre-strain restored the joint motion and cartilage stresses and strains close to the normal, healthy levels. Results suggest that rather than the choice of reconstruction technique, stiffness and pre-strain of the ACL reconstruction affect the motion and mechanics of the operated knee. We suggest that an optimal choice of graft properties might help restore normal knee joint function and cartilage responses, thus, minimizing the risk of osteoarthritis.
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland. Electronic address: kimmo.halonen@uef.fi.
authors.forename: K S
authors.initials: KS
authors.lastname: Halonen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.
authors.forename: M E
authors.initials: ME
authors.lastname: Mononen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital (KUH), POB 100, FI-70029 Kuopio, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Töyräs
authors.affiliation: Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital (KUH), POB 100, FI-70029 Kuopio, Finland; Kuopio Musculoskeletal Research Unit (KMRU), University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Kröger
authors.affiliation: Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital (KUH), POB 100, FI-70029 Kuopio, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Joukainen
authors.affiliation: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital (KUH), POB 100, FI-70029 Kuopio, Finland.
authors.forename: R K
authors.initials: RK
authors.lastname: Korhonen
mesh_terms: D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003198:Computer Simulation; D020342:Finite Element Analysis; D005684:Gait; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008954:Models, Biological; D008962:Models, Theoretical; D016059:Range of Motion, Articular; D013977:Tibia / Q000503:physiopathology
keywords: Anterior cruciate ligament; Articular cartilage; Finite element analysis; Gait; Graft; Knee joint; Reconstruction