Biomechanical evaluation of locking plates vs. iliosacral screws in vertically unstable sacral fractures [presentation]
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SUMMARY: A locking plate is a biomechanically superior construct for posterior fixation of vertically unstable sacral fracture when compared to the current gold standard of iliosacral screws alone. METHODS: Comminuted Orthopaedic Trauma Association type 61-C1.3a2c5 sacral fractures were created in 20 4th generation composite hemipelvi models making two groups of 10 specimens each. The control group was fixed posteriorly with two 6.5 mm steel alloy cannulated screws into the body of both S1 and S2 while in the experimental group, a two-hole polyaxial locking plate was applied to the ilium and two 5.0 mm solid titanium alloy screws were directed into the body of S1 and S2. Weightbearing was simulated with axial load applied through the body of S1 and ipsilateral acetabulum using a hydraulically actuated load frame.
Stiffness and load failure data were collected electronically and energy absorption was calculated. RESULTS: Construct stiffness (p=0.00086), failure load (p<0.0001), and energy absorption (p=0.00027) all favored the locking plate group. Post testing inspection demonstrated lateral ilium wall fractures in the control group; however, no such fractures occurred in experimental group treated with a plate. CONCLUSION: In this vertically unstable sacral fracture model, a locking plate increased construct stiffness, failure load, and energy absorption significantly when compared to the current gold standard of cannulated iliosacral screw alone.
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