Jan Christoph Katthagen1, Michael Schwarze2, Josefin Meyer-Kobbe3, Christine Voigt3, Christof Hurschler2, Helmut Lill3. 1. Department of Trauma and Reconstructive 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 Trauma and Reconstructive Surgery, Diakoniekrankenhaus Friederikenstift gGmbH, Humboldtstr. 5, 30169 Hannover, Germany.
Abstract
BACKGROUND: The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest. METHODS: Thirty-two fresh frozen humeri were randomized in four equal groups. An unstable 2-part fracture was fixed by locked plating in all specimens. The basic screw setup was supplemented by additional calcar screws in one group. Humeral head screws were replaced by dynamic locking screws in a second group. The third group featured an additional corticocancellous femoral head allograft. Assessment of stiffness was followed by cyclic loading and load to failure tests. Resulting stiffness, fracture gap deflection and ultimate load were compared utilizing Bonferroni corrected t-test for independent samples. FINDINGS: The mechanical effect of additional calcar screws was non-significant as compared to the basic screw configuration whereas bone block insertion significantly increased construct stiffness and failure load. The use of dynamic locking screws did not significantly reduce construct stiffness when compared to conventional locking screws. INTERPRETATION: Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement.
BACKGROUND: The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest. METHODS: Thirty-two fresh frozen humeri were randomized in four equal groups. An unstable 2-part fracture was fixed by locked plating in all specimens. The basic screw setup was supplemented by additional calcar screws in one group. Humeral head screws were replaced by dynamic locking screws in a second group. The third group featured an additional corticocancellous femoral head allograft. Assessment of stiffness was followed by cyclic loading and load to failure tests. Resulting stiffness, fracture gap deflection and ultimate load were compared utilizing Bonferroni corrected t-test for independent samples. FINDINGS: The mechanical effect of additional calcar screws was non-significant as compared to the basic screw configuration whereas bone block insertion significantly increased construct stiffness and failure load. The use of dynamic locking screws did not significantly reduce construct stiffness when compared to conventional locking screws. INTERPRETATION: Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement.
Authors: Sjur Oppebøen; Annette K B Wikerøy; Hendrik F S Fuglesang; Filip C Dolatowski; Per-Henrik Randsborg Journal: J Orthop Surg Res Date: 2018-08-09 Impact factor: 2.359
Authors: Christoph J Laux; Florian Grubhofer; Clément M L Werner; Hans-Peter Simmen; Georg Osterhoff Journal: J Orthop Surg Res Date: 2017-09-25 Impact factor: 2.359
Authors: Guan-Ming Kuang; Tak Man Wong; Jun Wu; Jun Ouyang; Haihua Guo; Yapeng Zhou; Christian Fang; Frankie K L Leung; William Lu Journal: Geriatr Orthop Surg Rehabil Date: 2018-10-08
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