Plate selection for fixation of extra-articular distal humerus fractures: A biomechanical comparison of three different implants |
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Institution: | 1. University of California, Irvine, Department of Orthopaedic Surgery, 101 The City Drive South, Pavilion III, Building 29A, 2nd Floor, Orange, CA 92868, United States;2. University of Washington, Department of Orthopaedics and Sports Medicine, 4245 Roosevelt Way N.E., Seattle, WA 98105, United States;3. DePuy Synthes Mechanical Testing Laboratory, 1301 Goshen Parkway, West Chester, PA 19380, United States;4. University of Pennsylvania, Department of Orthopaedic Surgery, 3400 Spruce Street, 2 Silverstein Pavilion, Philadelphia, PA 19104, United States;1. Department for Orthopaedic Surgery, Medical School Hannover, Diakovere Annastift, Hannover, Germany;2. Department for Orthopaedic Surgery and Traumatology, Diakovere Friederikenstift, Hannover, Germany;3. Department for Orthopaedic and Trauma Surgery, University Medical Center of Cologne, Cologne, Germany;4. Department for Traumatology and Orthopaedic Surgery, BG Unfallklinik Frankfurt am Main, Frankfurt am Main, Germany;1. Department of Hand Surgery, Massachusetts General Hospital, Boston, MA;1. The American Board of Orthopaedic Surgery, 400 Silver Cedar Court, Chapel Hill, NC 27514, USA;2. Department of Orthopaedic Surgery, University of South Florida, 13220 USF Laurel Drive, Tampa, FL 33612, USA;3. Florida Orthopaedic Institute, 13020 Telecom Parkway North, Tampa, FL 33637, USA;4. Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, 4301 Jones Bridge Road, Bethesda, MD 20814, USA;5. Foundation for Orthopaedic Research and Education, 13020 Telecom Parkway North, Tampa, FL 33637, USA;1. Department of Orthopaedics, Chinese PLA General Hospital, No. 28 Fuxin Road, Beijing 100853, PR China;2. Medical College, Nankai University, No. 94 Weijin Road, Tianjin 300071, PR China |
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Abstract: | Operative fixation of extra-articular distal humerus using a single posterolateral column plate has been described but the biomechanical properties or limits of this technique is undefined. The purpose of this study was to evaluate the mechanical properties of distal humerus fracture fixation using three standard fixation constructs.Two equal groups were created from forty sawbones humeri. Osteotomies were created at 80 mm or 50 mm from the tip of the trochlea. In the proximal osteotomy group, sawbones were fixed with an 8-hole 3.5 mm LCP or with a 6-hole posterolateral plate. In the distal group, sawbones were fixed with 9-hole medial and lateral 3.5 mm distal humerus plates and ten sawbones were fixed with a 6-hole posterolateral plate. Biomechanical testing was performed using a servohydraulic testing machine. Testing in extension as well as internal and external rotation was performed. Destructive testing was also performed with failure being defined as hardware pullout, sawbone failure or cortical contact at the osteotomy.In the proximal osteotomy group, the average bending stiffness and torsional stiffness was significantly greater with the posterolateral plate than with the 3.5 mm LCP. In the distal osteotomy group, the average bending stiffness and torsional stiffness was significantly greater with the posterolateral plate than the 3.5 mm LCP. In extension testing, the yield strength was significantly greater with the posterolateral plate in the proximal osteotomy specimens, and the dual plating construct in the distal osteotomy specimens. The yield strength of specimens in axial torsion was significantly greater with the posterolateral plate in the proximal osteotomy specimens, and the dual plating construct in the distal osteotomy specimens.Limited biomechanical data to support the use of a pre-contoured posterolateral distal humerus LCP for fixation of extra-articular distal humerus exists. We have found that this implant provided significantly greater bending stiffness, torsional stiffness, and yield strength than a single 3.5 mm LCP plate for osteotomies created 80 mm from the trochlea. At the more distal osteotomy, dual plating was biomechanically superior. Our results suggest that single posterolateral column fixation of extra-articular humerus fractures is appropriate for more proximal fractures but that dual plate fixation is superior for more distal fractures. |
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Keywords: | Distal humerus Extra-articular Biomechanical Posterolateral plate |
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