title: Plate fixation of periprosthetic femur fractures: What happens to the cement mantle?
abstract: Osteosynthesis of periprosthetic femur fractures by screw fixation around the implanted prosthetic stem is currently regarded as the biomechanically superior option compared with cerclage. The aim of this biomechanical study was damage analysis of the cement mantle after revision screw insertion. A prosthetic stem (Bicontact) was implanted in 20 cadaveric femora in cemented technique. A locking compression plate (Synthes) was then applied to the lateral femur at the level of the prosthetic stem. The method of plate fixation to the femur was assigned randomly to three groups: bicortical non-locking screws, monocortical locking screws, and bicortical locking screws. This was followed by applying a fluctuating axial load (2100 N, 0.5 Hz) for 20,000 cycles. After testing, macroscopic and microscopic evaluations of the cement mantle were conducted. Cracks formed in the cement mantle in 14% of the 80 screw holes. The type of screw (bicortical or monocortical; locking or non-locking) had no significant effect on the number of cracks (p = 0.52). The relationship between manifestation of crack damage and cement mantle thickness was not significant (p = 0.36), whereas the relationship between crack formation and screw position was significant (p = 0.019). Those screws whose circumference was only partially within the cement mantle yielded a significantly lower number of cracks compared with screws positioned completely within the cement mantle or even touching the prosthetic stem. In order to reduce the incidence of crack formation in the cement mantle during plate osteosynthesis of periprosthetic femur fractures, the screws should not be either placed within the cement mantle or make direct contact with the stem.
authors.affiliation: 1 Clinic for Orthopaedics and Traumatology, Albert Ludwigs University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Konstantinidis
authors.affiliation: 2 Clinic for Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, Leipzig, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: 1 Clinic for Orthopaedics and Traumatology, Albert Ludwigs University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Bernstein
authors.affiliation: 1 Clinic for Orthopaedics and Traumatology, Albert Ludwigs University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Hirschmüller
authors.affiliation: 3 Department of Traumatology and Reconstructive Surgery, BG Trauma Center Tübingen, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Schröter
authors.affiliation: 1 Clinic for Orthopaedics and Traumatology, Albert Ludwigs University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Norbert Paul
authors.initials: NP
authors.lastname: Südkamp
authors.affiliation: 4 Clinic for orthopedics and traumatology, Clinic Heidenheim, Heidenheim, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Helwig
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D001843:Bone Cements; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal; D006622:Hip Prosthesis; D006801:Humans; D057068:Periprosthetic Fractures / Q000601:surgery*; D011475:Prosthesis Failure
chemical_list: D001843:Bone Cements
keywords: Biomedical cements; Total Hip Athroplasty; angle stable screws; periprosthetic fracture; plate osteosynthesis