Christina Salas1, Justin A Brantley2, James Clark3, Mahmoud Reda Taha4, Orrin B Myers5, Deana Mercer3. 1. Department of Orthopaedics and Rehabilitation, University of New Mexico, Albuquerque, NM; Department of Mechanical Engineering, University of New Mexico, Albuquerque, NM; Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM. Electronic address: chrsalas@salud.unm.edu. 2. Department of Orthopaedics and Rehabilitation, University of New Mexico, Albuquerque, NM; Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM. 3. Department of Orthopaedics and Rehabilitation, University of New Mexico, Albuquerque, NM. 4. Department of Civil Engineering, University of New Mexico, Albuquerque, NM. 5. Department of Internal Medicine, University of New Mexico, Albuquerque, NM.
Abstract
PURPOSE: "Damage" is an engineering term defining a period between a state of material perfection and the onset of crack initiation. Clinically, it is a loss of fixation due to microstructural breakdown, indirectly measured as a reduction of stiffness of the bone-implant construct, normalized by the cross-sectional area and length of the bone. The purpose of this study was to characterize damage in a cadaver model of extra-articular distal radius fracture with dorsal comminution treated using 2-column volar distal radius plates. METHODS: Ten matched distal radii were randomly divided into 2 groups: group I specimens were treated with a volar distal radius plate with an independent, 2-tiered scaffold design; group II specimens (contralateral limbs) were treated with a volar plate with a single-head design for enhanced ulnar buttressing. Specimens were cyclically loaded to simulate a 6-month postoperative load-bearing period. We report damage after a defined protocol of cyclical loading and load to failure simulating a fall on an outstretched hand. RESULTS: Group II specimens experienced more damage under cyclic loading conditions than group I specimens. Group I specimens were stiffer than group II specimens under load-to-failure conditions. Ultimate force at failure in group I and group II specimens was not different. Specimens failed by plate bending (group I, n = 6/10; group II, n = 2/10) and fracture of the lunate facet (group I, n = 4/10; group II, n = 8/10). CONCLUSIONS: Group I specimens had less screw cutout at the lunate facet than group II specimens under cyclic loading as indicated by lower damage measures and fewer facet fractures during load-to-failure testing. The overall strength of the construct is not affected by plate design. CLINICAL RELEVANCE: Microstructural damage or a loss of fixation due to an overly rigid volar plate design may cause malunion or nonunion of fracture fragments and lead to bone-implant instability.
PURPOSE: "Damage" is an engineering term defining a period between a state of material perfection and the onset of crack initiation. Clinically, it is a loss of fixation due to microstructural breakdown, indirectly measured as a reduction of stiffness of the bone-implant construct, normalized by the cross-sectional area and length of the bone. The purpose of this study was to characterize damage in a cadaver model of extra-articular distal radius fracture with dorsal comminution treated using 2-column volar distal radius plates. METHODS: Ten matched distal radii were randomly divided into 2 groups: group I specimens were treated with a volar distal radius plate with an independent, 2-tiered scaffold design; group II specimens (contralateral limbs) were treated with a volar plate with a single-head design for enhanced ulnar buttressing. Specimens were cyclically loaded to simulate a 6-month postoperative load-bearing period. We report damage after a defined protocol of cyclical loading and load to failure simulating a fall on an outstretched hand. RESULTS: Group II specimens experienced more damage under cyclic loading conditions than group I specimens. Group I specimens were stiffer than group II specimens under load-to-failure conditions. Ultimate force at failure in group I and group II specimens was not different. Specimens failed by plate bending (group I, n = 6/10; group II, n = 2/10) and fracture of the lunate facet (group I, n = 4/10; group II, n = 8/10). CONCLUSIONS: Group I specimens had less screw cutout at the lunate facet than group II specimens under cyclic loading as indicated by lower damage measures and fewer facet fractures during load-to-failure testing. The overall strength of the construct is not affected by plate design. CLINICAL RELEVANCE: Microstructural damage or a loss of fixation due to an overly rigid volar plate design may cause malunion or nonunion of fracture fragments and lead to bone-implant instability.
Authors: Daniel A Rikli; Philipp Honigmann; Reto Babst; Alessandra Cristalli; Michael M Morlock; Thomas Mittlmeier Journal: J Hand Surg Am Date: 2007-01 Impact factor: 2.230
Authors: Isabella Mehling; Daniela Klitscher; Andreas P Mehling; Tobias E Nowak; Werner Sternstein; Pol M Rommens; Lars P Müller Journal: J Orthop Trauma Date: 2012-07 Impact factor: 2.512
Authors: David M Lichtman; Randipsingh R Bindra; Martin I Boyer; Matthew D Putnam; David Ring; David J Slutsky; John S Taras; William C Watters; Michael J Goldberg; Michael Keith; Charles M Turkelson; Janet L Wies; Robert H Haralson; Kevin M Boyer; Kristin Hitchcock; Laura Raymond Journal: J Am Acad Orthop Surg Date: 2010-03 Impact factor: 3.020