Biomechanical Analysis of Retrograde Superior Ramus Screw Fi
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A study was performed to investigate the biomechanical performance of different size and length retrograde superior ramus screws that suggests more efficacy with longer bicortical screw fixation.

In osteoporotic composite hemipelvis bone models, a vertical superior ramus fracture was formed. Following reduction, four fixation groups were formed by inserting either a solid 4.5 mm or a cannulated 7.0 mm screw with a length of 80 mm (short) or 140 mm (long). There was also a category with an intact osteotomy and another with an unstabilized osteotomy. 5000 cycles of cyclic loading were performed on the samples, with data collected at regular intervals. Load to failure was achieved at the end of the cyclic loading.

Results:
--The displacement after 5000 cycles for 4.5 mm short screws was significantly greater than 4.5 mm long and 7.0 mm short screws.

--At 5000 cycles, the 4.5-mm short screws had a significantly lower stiffness and lower load to failure than all other screws and were not different from the osteotomy model.

In comparison to all other screws, short 4.5-mm screws showed greater displacement, lower stiffness, and lower load to failure. The biomechanical efficiency of the 4.5-mm short screws was comparable to that of the unstabilized controls. Where possible, a longer bicortical screw fixation is recommended.

Source: https://journals.lww.com/jorthotrauma/Abstract/2021/04000/Biomechanical_Analysis_of_Retrograde_Superior.5.aspx
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