Biomechanics of the symphysis
The mandibular symphysis undergoes torsional forces (twisting) during
function. Therefore, fixation strategies must take this into account. When
using anything less stable than a reconstruction plate, two points of fixation
should be applied.
In general, the further apart the points of fixation, the more stable the
construct. For symphysis fractures, when two lag screws are applied, they
should be separated as much as possible without injuring vital structures.
Illustration shows Champy’s ideal lines of osteosynthesis for symphysis