title: Biomechanical methods for the assessment of fracture repair.
abstract: The progress of fracture healing is directly related to an increasing stiffness and strength of the healing fracture. Similarly the weight bearing capacity of a bone directly relates to the mechanical stability of the fracture. Therefore, assessing the progress of fracture repair can be based on the measurement of the mechanical stability of the healing fracture. However, fracture stability is difficult to assess directly due to various obstacles of which shielding of the mechanical properties by the fracture fixation construct is the most relevant one. Several assessment methods have been proposed to overcome these obstacles and to obtain some sort of mechanical surrogate describing the stability of the fracture. The most direct method is the measurement of the flexibility of a fracture under a given external load, which comprises the challenge of accurately measuring the deformation of the bone. Alternative approaches include the measurement of load share between implant and bone by internal or by external sensors. A direct 3 dimensional measurement of bone displacement is provided by radiostereometric analysis which can assess fracture migration and can detect fracture movement under load. More indirect mechanical methods induce cyclic perturbations within the bone and measure the response as a function of healing time. At lower frequencies the perturbations are induced in the form of vibration and at higher frequencies in the form of ultrasonic waves. Both methods provide surrogates for the mechanical properties at the fracture site. Although biomechanical properties of a healing fracture provide a direct and clinically relevant measure for fracture healing, their application will in the near future be limited to clinical studies or research settings.
authors.affiliation: Institute of Biomechanics, Trauma Center Murnau, Prof. Kuentscher-Str. 8, 82418 Murnau, Germany; Institute of Biomechanics, Paracelsus Medical University Salzburg, Strubergasse 21, Salzburg, Austria. Electronic address: biomechanik@bgu-murnau.de.
authors.forename: P
authors.initials: P
authors.lastname: Augat
authors.affiliation: Berufsgenossnschaftliches Unfallkrankenhaus Hamburg, Bergedorfer Straße 10, 21033 Hamburg, Germany. Electronic address: m.faschingbauer@buk-hamburg.de.
authors.forename: M
authors.initials: M
authors.lastname: Faschingbauer
authors.affiliation: Berufsgenossnschaftliches Unfallkrankenhaus Hamburg, Bergedorfer Straße 10, 21033 Hamburg, Germany. Electronic address: k.seide@buk-hamburg.de.
authors.forename: K
authors.initials: K
authors.lastname: Seide
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: tobitak.ort@gmail.com.
authors.forename: K
authors.initials: K
authors.lastname: Tobita
authors.affiliation: Department of Orthopaedics and Trauma, Royal Adelaide Hospital and Centre for Orthopaedic and Trauma Research, The University of Adelaide, Adelaide, SA 5000, Australia. Electronic address: Stuart.Callary@health.sa.gov.au.
authors.forename: S A
authors.initials: SA
authors.lastname: Callary
authors.affiliation: Department of Orthopaedics and Trauma, Royal Adelaide Hospital and Centre for Orthopaedic and Trauma Research, The University of Adelaide, Adelaide, SA 5000, Australia. Electronic address: bogdansolomon@mac.com.
authors.forename: L B
authors.initials: LB
authors.lastname: Solomon
authors.affiliation: Department of Trauma, Hand & Reconstructive Surgery, University of Saarland, Kirrberger Strasse, 66421 Homburg/Saar, Germany. Electronic address: joerg.holstein@uks.eu.
authors.forename: J H
authors.initials: JH
authors.lastname: Holstein
mesh_terms: D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000502:physiology*; D017102:Fracture Healing / Q000502:physiology*; D006801:Humans; D059869:Radiostereometric Analysis; D013314:Stress, Mechanical; D013686:Telemetry; D014463:Ultrasonography; D014732:Vibration / Q000627:therapeutic use; D016474:Weight-Bearing / Q000502:physiology*
keywords: Assessment of fracture repair; Biomechanics; Fracture stability