A simple two-ring circular fixator construct is often used to distract fractures out to length and facilitate reduction when performing minimally invasive plate osteosynthesis. This is particularly useful when addressing antebrachial or crural fractures.
A Kirschner wire is placed in both the proximal and distal metaphyseal region of the radius or tibia in the true medial-to-lateral plane, then attached to the abaxial surface of the respective rings of the fixator and tensioned appropriately (if larger diameter rings are used). The rings are articulated with two or three segments of all-thread rod with paired nylon nuts securing each ring's individual rods. The position of the nuts on the rods are adjusted to increase the distance between the rings – thus distracting the secured bone segments.
The fractured bone is distracted out to normal length which should help bring the fracture into alignment. If necessary the bone segments can be translated along the fixation wires to improve frontal plane reduction (in some instances, it is helpful to slightly over distract the fracture to accomplish translation). The flexion-extension plane of the joint proximal and distal to the fracture are assessed and if necessary, the position of the wire can be adjusted about the circumference of the ring to correct rotational malalignment.
Once reduction is deemed acceptable, two short plate insertion incisions, one proximal and one distal, are made remote to the fracture site and an epiperiosteal tunnel is developed with a pair of Metzenbaum scissors. An appropriately contoured bone plate is inserted through the epiperiosteal tunnel and secured to the bone with screws placed through the plate insertion incisions. Additional screws can be placed, if warranted, through separate small stab incisions made over selected screw holes in the plate. When finished, the Kirschner wires and fixator are removed.
Tip submitted by Dan Lewis, DVM, DACVS – University of Florida, Gainesville, FL