OJO  Vol.4 No.4 , April 2014
A Finite Element Model of Locked Plating in Femoral Shaft Fractures
Abstract: Introduction: The Locking Compression Plate (LCP) system is a versatile technology that can be used either through conventional compression plating techniques or as an internal fixator with locking head screws. There have been only a few biomechanical studies examining the role of locked screw configuration on construct stability with most recommendations based upon empirical evidence or data from compression plating. This study will attempt to determine how different locked screw configurations, fracture gaps (distance between bone fragments), and interface gaps (distance between plate and bone) will affect the peak stress(von Mises stress) experienced by the plate-screw construct and, thereby, look at ways to minimize the risk of hardware failure. Materials Methods: A finite element model (FEM) was developed of a transverse mid shaft femoral fracture bridged by an eight-hole titanium LCP. Seven different screw configurations were investigated. Three different fracture gaps and three different interface gaps were studied as well. Results: The 1368 configuration was found to experience the least peak stress of 2.10 GPa while the 2367, 2457, and all filled configurations were found to have the highest peak stress (25.29 GPa, 22.78 GPa, and 23.54 GPa, respectively). Peak stress increased when the interface gap increased. Peak stress also increased as the fracture gap increased, with the largest jump between the 1 mm and 2 mm gaps. Conclusions: Every fracture is unique, and has a vast amount of parameters that must be considered when the surgeon is developing a treatment plan. For transverse femoral shaft fractures, the results of this study suggest that a working length of 2 screw holes on either side of the fracture may also lead to lower peak stress. In addition, our results demonstrate that minimizing the fracture gap and interface gap will lead to decreased stress in the plate-screw construct.
Cite this paper: Schwartz, B. , Amirouche, F. , Choi, K. , Mejia, A. , Gonzalez, M. and Seiler, J. (2014) A Finite Element Model of Locked Plating in Femoral Shaft Fractures. Open Journal of Orthopedics, 4, 104-112. doi: 10.4236/ojo.2014.44018.

[1]   Egol, K.A., et al. (2004) Biomechanics of Locked Plates and Screws. Journal of Orthopaedic Trauma, 18, 488-493.

[2]   Miller, D.L., Goswami, T. and Prayson, M.J. (2008) Overview of the Locking Compression Plate and Its Clinical Applications in Fracture Healing. Journal of Surgical Orthopaedic Advances, 17, 271-281.

[3]   Miller, D.L. and Goswami, T. (2007) A Review of Locking Compression Plate Biomechanics and Their Advantages as Internal Fixators in Fracture Healing. Clinical Biomechanics, 22, 1049-1062.

[4]   Mehin, R., et al. (2009) A Biomechanical Study of Conventional Acetabular Internal Fracture Fixation versus Locking Plate Fixation. Canadian journal of surgery (Journal Canadien de Chirurgie), 52, 221-228.

[5]   Wagner, M. (2003) General Principles for the Clinical Use of the LCP. Injury, 34, B31-B42.

[6]   Perren, S.M. (2002) Evolution of the Internal Fixation of Long Bone fractures. The Scientific Basis of Biological Internal Fixation: Choosing a New Balance between Stability and Biology. The Journal of Bone and Joint Surgery (British Volume), 84, 1093-1110.

[7]   Tornkvist, H., Hearn, T.C. and Schatzker, J. (1996) The Strength of Plate Fixation in Relation to the Number and Spacing of Bone Screws. Journal of Orthopaedic Trauma, 10, 204-208.

[8]   Fulkerson, E., et al. (2006) Fixation of Diaphyseal Fractures with a Segmental Defect: A Biomechanical Comparison of Locked and Conventional Plating Techniques. The Journal of Trauma, 60, 830-835.

[9]   Sommer, C., et al. (2004) Locking Compression Plate Loosening and Plate Breakage: A Report of Four Cases. Journal of Orthopaedic Trauma, 18, 571-577.

[10]   Sommer, C., et al. (2003) First Clinical Results of the Locking Compression Plate (LCP). Injury, 34, B43-B54.

[11]   Stoffel, K., Dieter, U., Stachowiak, G., Gächter, A. and Kuste, M.S. (2003) Biomechanical Testing of the LCP—How Can Stability in Locked Internal Fixators Be Controlled? Injury, 34, 11-19.

[12]   Gautier, E. and Sommer, C. (2003) Guidelines for the Clinical Application of the LCP. Injury, 34, 63-76.

[13]   Ahmad, M., Nanda, R., Bajwa, A.S., Candal-Couto, J., Green, S. and Hui, A.C. (2007) Biomechanical Testing of the Locking Compression Plate: When Does the Distance between Bone and Implant Significantly Reduce Construct Stability? Injury, 38, 358-364.

[14]   Senalp, A.Z., Kurtaran, O. and Kurtaran, H. (2006) Dynamic and Fatigue Behavior of Newly Designed Stem Shapes for Hip Prosthesis Using Finite Element Analysis. Materials & Design, 28, 1577-1583.

[15]   Ratner, B., Hoffman, A.S., Schoen, F. and Lemons, J. (1996) Biomaterial Science—An Introduction to Materials in Medicine. Academic Press, San Diego.

[16]   Riemer, B.L., Butterfield, S.L., Burke, C.J. and Mathews, D. (1992) Immediate Plate Fixation of Highly Comminuted Femoral Diaphyseal Fractures in Blunt Polytrauma Patients. Orthopedics, 15, 907-916.

[17]   Ellis, T., Bourgeault, C.A. and Kyle, R.F. (2001) Screw Position Affects Dynamic Compression Plate Strain in an in Vitro Fracture Model. Journal of Orthopaedic Trauma, 15, 333-337.

[18]   Field, J.R., Törnkvist, H., Hearn, T.C., Sumner-Smith, G. and Woodside, T.D. (1999) The Influence of Screw Omission on Construction Stiffness and Bone Surface Strain in the Application of Bone Plates to Cadaveric Bone. Injury, 30, 591-598.

[19]   Hertel, R., Eijer, H., Meisser, A., Hauke, C. and Perren, S.M. (2001) Biomechanical and Biological Considerations Relating to the Clinical Use of the Point Contact-Fixator—Evaluation of the Device Handling Test in the Treatment of Diaphyseal Fractures of the Radius and/or Ulna. Injury, 32, 10-14.

[20]   Johnston, S.A., Lancaster, R.L., Hubbard, R.P. and Probst, C.W. (1991) A Biomechanical Comparison of 7-Hole 3.5 mm Broad and 5-Hole 4.5 mm Narrow Dynamic Compression Plates. Veterinary Surgery, 20, 235-239.