J C Katthagen1, M Schwarze2, L Bauer3, J Meyer-Kobbe3, C Voigt3, C Hurschler2, H Lill3. 1. Department of Reconstructive and Trauma Surgery, Diakoniekrankenhaus Friederikenstift gGmbH, Humboldtstr. 5, 30169 Hannover, Germany. Electronic address: christoph.katthagen@ddh-gruppe.de. 2. Laboratory of Biomechanics and Biomaterials, Medizinische Hochschule Hannover (MHH), Anna-von-Borries-Str. 1-7, 30625 Hannover, Germany. 3. Department of Reconstructive and Trauma Surgery, Diakoniekrankenhaus Friederikenstift gGmbH, Humboldtstr. 5, 30169 Hannover, Germany.
Abstract
BACKGROUND: The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck. HYPOTHESIS: The additional calcar screw improves stiffness and failure load. METHODS:Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05). RESULTS: No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases. DISCUSSION: The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.
RCT Entities:
BACKGROUND: The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck. HYPOTHESIS: The additional calcar screw improves stiffness and failure load. METHODS: Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05). RESULTS: No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases. DISCUSSION: The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.
Authors: Simon A Euler; Maximilian Petri; Melanie B Venderley; Grant J Dornan; Werner Schmoelz; Travis Lee Turnbull; Michael Plecko; Franz S Kralinger; Peter J Millett Journal: Int Orthop Date: 2017-05-11 Impact factor: 3.075
Authors: Jan Theopold; Stefan Schleifenbaum; Mirijam Müller; Michael Werner; Niels Hammer; Christoph Josten; Pierre Hepp Journal: PLoS One Date: 2018-10-29 Impact factor: 3.240