The purpose of this study was to compare the stiffness of a Type II external skeletal fixator (ESF) to a 3.5 mm locking compression plate (LCP) in axial compression, mediolateral, and craniocaudal bending in a fracture gap model. The hypothesis was that the Type II ESF would demonstrate comparable stiffness to the LCP. A bone simulant consisting of short fiber reinforced epoxy cylinders and a 40 mm fracture gap was used. The LCP construct consisted of a 12 hole 3.5 mm plate with three 3.5 mm bicortical locking screws per fragment. The Type II ESF construct consisted of 3 proximal full fixation pins (Centerface®) per fragment in the mediolateral plane, and 2 carbon fiber connecting rods. Five constructs of each were tested in non-destructive mediolateral and craniocaudal bending, and axial compression. Stiffness was determined from the slope of the elastic portion of force-displacement curves. A one-way ANOVA and a Tukey-Kramer multiple comparisons test were performed, with significance defined as p < 0.05. In mediolateral bending, the stiffness of the Type II ESF (mean ± standard deviation; 1584.2 N/mm ± 202.8 N/mm) was significantly greater than that of the LCP (110.0 N/mm ± 13.4 N/mm). In axial compression, the stiffness of the Type II ESF (679.1 N/mm ± 20.1 N/mm) was significantly greater than that of the LCP (221.2 N/mm ± 19.1 N/mm). There was no significant difference between the constructs in craniocaudal bending. This information can aid in decision-making for fracture fixation, although ideal stiffness for healing remains unknown. / Master of Science / Optimum fracture stabilization requires a balance between providing a stable mechanical environment and preserving the blood supply to healing tissues. When the complexity of a fracture precludes reconstruction of the bony column, the fixation method chosen for repair must counteract the forces of weight bearing, including compression and bending. Knowledge of the relative construct stiffness is important for a clinician to determine the ability of a fixation technique to withstand all forces acting on a fracture, while supporting bone healing. The purpose of this study was to compare the stiffness of a Type II external skeletal fixator (ESF) and a locking compression plate (LCP) when non-destructive physiologic loads are applied in axial compression, mediolateral bending, and craniocaudal bending. Five constructs of each were tested in non-destructive mediolateral and craniocaudal bending, and axial compression. Stiffness was determined from the slope of the elastic portion of force-displacement curves. There was a significant difference between the stiffnesses of the Type II ESF and the LCP in all modes of loading except craniocaudal bending. The Type II ESF was significantly stiffer in mediolateral bending than the LCP, and the Type II ESF was significantly stiffer in axial compression compared to the LCP. There was no statistically significant difference in stiffness in craniocaudal bending. This information will aid a clinician in selecting an appropriate fixation method for a non-reconstructable fracture, but further studies are required to assess the importance of increased stiffness in a clinical setting.