Evaluation of fixation devices for prevention of rotation in transverse fractures of the canine femoral shaft: an in vitro study.

The effectiveness of various fixation techniques in preventing rotation of fracture segments in transverse fractures of the canine femoral diaphysis was evaluated under laboratory conditions. Single intramedullary Steinmann pins, single Küntscher nails, multiple intramedullary Steinmann pins, and an intramedullary Steinmann pin with a 1/2 Kirschner splint fixation sustained mean torque moments of 0.31, 0.61, 1.26, and 1.63 Newton meters, respectively, before rotation of the fracture segments occurred. Four-pin (full Kirschner) splints were more effective, sustaining a mean torque moment of 5.35 Newton meters before rotation occurred. The canine femoral medullary canal had an average isthmus length of 2.0 to 2.5 cm. The restricted area of implant-cortex contact limited the effectiveness of the intramedullary fixation devices in preventing fracture segment rotation.