title: Experimental evaluation of a new morphological approximation of the articular surfaces of the ankle joint.
abstract: The mechanical characteristics of the ankle such as its kinematics and load transfer properties are influenced by the geometry of the articulating surfaces. A recent, image-based study found that these surfaces can be approximated by a saddle-shaped, skewed, truncated cone with its apex oriented laterally. The goal of this study was to establish a reliable experimental technique to study the relationship between the geometry of the articular surfaces of the ankle and its mobility and stability characteristics and to use this technique to determine if morphological approximations of the ankle surfaces based on recent discoveries, produce close to normal behavior. The study was performed on ten cadavers. For each specimen, a process based on medical imaging, modeling and 3D printing was used to produce two subject specific artificial implantable sets of the ankle surfaces. One set was a replica of the natural surfaces. The second approximated the ankle surfaces as an original saddle-shaped truncated cone with apex oriented laterally. Testing under cyclic loading conditions was then performed on each specimen following a previously established technique to determine its mobility and stability characteristics under three different conditions: natural surfaces; artificial surfaces replicating the natural surface morphology; and artificial approximation based on the saddle-shaped truncated cone concept. A repeated measure analysis of variance was then used to compare between the three conditions. The results show that (1): the artificial surfaces replicating natural morphology produce close to natural mobility and stability behavior thus establishing the reliability of the technique; and (2): the approximated surfaces based on saddle-shaped truncated cone concept produce mobility and stability behavior close to the ankle with natural surfaces.
authors.affiliation: Movement Analysis Laboratory, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Belvedere
authors.affiliation: Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA, USA. Electronic address: ssiegler@coe.drexel.edu.
authors.forename: Sorin
authors.initials: S
authors.lastname: Siegler
authors.affiliation: 1st Orthopaedic-Traumatologic Clinic, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ensini
authors.affiliation: Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Toy
authors.affiliation: Movement Analysis Laboratory, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Caravaggi
authors.affiliation: Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA, USA.
authors.forename: Ramya
authors.initials: R
authors.lastname: Namani
authors.affiliation: Movement Analysis Laboratory, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Giannini
authors.affiliation: Nursing, Technical and Rehabilitation Assistance Service, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Durante
authors.affiliation: Movement Analysis Laboratory, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Leardini
mesh_terms: D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D008875:Middle Aged; D057054:Molecular Imaging; D015203:Reproducibility of Results; D013499:Surface Properties; D055815:Young Adult
keywords: Ankle; Approximation; In vitro; Kinematics; Morphology