title: The biomechanical effect of bone quality and fracture topography on locking plate fixation in periprosthetic femoral fractures.
abstract: Optimal management of periprosthetic femoral fractures (PFF) around a well fixed prosthesis (Vancouver B1) remains controversial as adequate fixation needs to be achieved without compromising the stability of the prosthesis. The aim of this study was to highlight the effect of bone quality i.e. canal thickness ratio (CTR), and fracture topography i.e. fracture angle and its position in relation to the stem, on the biomechanics of a locking plate for a Vancouver B1 fracture. A previously corroborated simplified finite element model of a femur with a cemented total hip replacement stem was used in this study. Canal thickness ratio (CTR) and fracture topography were altered in several models and the effect of these variations on the von Mises stress on the locking plate as well as the fracture displacement was studied. Increasing the CTR led to reduction of the von Mises stress on the locking plate as well as the fracture movement. In respect to the fracture angle with the medial cortex, it was shown that acute angles resulted in lower von Mises stress on the plate as opposed to obtuse angles. Furthermore, acute fracture angles resulted in lower fracture displacement compared to the other fractures considered here. Fractures around the tip of the stem had the same biomechanical effect on the locking plate. However, fractures more distal to the stem led to subsequent increase of stress, strain, and fracture displacement. Results highlight that in good bone quality and acute fracture angles, single locking plate fixation is perhaps an appropriate management method. On the contrary, for poor bone quality and obtuse fracture angles alternative management methods might be required as the fixation might be under higher risk of failure. Clinical studies for the management of PFF are required to further support our findings.
authors.affiliation: Academic Department of Orthopaedics and Trauma, Division of Surgery, Aristotle University Medical School, University Campus, 54 124 Thessaloniki, Greece. Electronic address: leonidou@doctors.org.uk.
authors.forename: Andreas
authors.initials: A
authors.lastname: Leonidou
authors.affiliation: Medical and Biological Engineering, School of Engineering, University of Hull, Hull HU6 7RX, UK.
authors.forename: Mehran
authors.initials: M
authors.lastname: Moazen
authors.affiliation: Academic Department of Orthopaedics and Trauma, Division of Surgery, Aristotle University Medical School, University Campus, 54 124 Thessaloniki, Greece; 4th Department of Trauma & Orthopaedics, KAT Hospital, Nikis 2, Kifissia, 14561 Athens, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Lepetsos
authors.affiliation: Academic Department of Orthopaedics and Trauma, Division of Surgery, Aristotle University Medical School, University Campus, 54 124 Thessaloniki, Greece.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Graham
authors.affiliation: 4th Department of Trauma & Orthopaedics, KAT Hospital, Nikis 2, Kifissia, 14561 Athens, Greece.
authors.forename: George A
authors.initials: GA
authors.lastname: Macheras
authors.affiliation: Academic Department of Orthopaedics and Trauma, Division of Surgery, Aristotle University Medical School, University Campus, 54 124 Thessaloniki, Greece; Department of Surgery and Cancer, Division of Surgery, Imperial College London, B-block Hammersmith Hospital, Du-Cane Road, London W12 0HS, UK.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Tsiridis
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D015519:Bone Density; D001860:Bone Plates; D005264:Femoral Fractures / Q000503:physiopathology* / Q000601:surgery; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D057068:Periprosthetic Fractures / Q000503:physiopathology* / Q000601:surgery
keywords: Bone quality; Finite element analysis; Fracture angle; Fracture level; Fracture topography; Periprosthetic femoral fracture