The effects of screw number and length on two methods of tension band plating.

Bovine ribs were used to evaluate the effects that screw length and number have on two types of tension bands. Five trials each were done with one, two, three, or four screws per segment, using screws 4, 8, 12, or 16 mm in length and 2-mm adaptation plates or 2-mm mini-dynamic compression plates. The fractured ribs were subjected to increasing weights until failure. With the 2-mm adaptation plate, screw length played no role in the amount of weight resisted. Increasing the number of screws per segment increased the weight resisted to up to three screws per segment, after which no additional benefit was realized (P < .001). For the 2-mm mini-dynamic compression plate, increasing screw length increased the weight resisted up to three screws per segment, after which length had no effect (P < .001). Increasing the number of screws per segment increased the weight resisted up to three screws per segment, after which no additional benefit was realized (P < .001).