[Osteosynthesis of the odontoid process by a clover-shaped plate]. / L'ostéosynthèse par la plaque en trèfle des fractures de l'apophyse odontoïde.

UNLABELLED: The goal was to design an osteosynthesis material able to stabilize after reduction a fracture of the odontoid process without C1-C2 arthrodesis. MATERIAL AND METHODS: The implant comprises a clover shaped plate which has to be applied on one hand on the anterior face of the dens (one leaf), and on the other hand on the anterior face of C3 (2 leaves are applied with a screw one screw for each leaf). A barrel fastened to the 3 leaves (implanted on the anterior face of the leaves, at their junction) gives way to a vertically oriented screw which will carry out dens fixation. The screw makes the compression possible. Placement through a pre-sterno-mastoid-approach, needs a special plate support and 18/10 Kirchner pins preparing the passage of the screw. RESULTS: This screw-plate designed for dens fractures (especially those with anterior displacement incompatible with a simple screwing) led to bone union in all cases. A C2-C3 subluxation operated on with the same technique was reduced and stabilized: a C2-C3 ankylosis was the consequence of a C2-C3 arthrodesis combined with the osteosynthesis. No complication was observed. DISCUSSION AND CONCLUSION: This technique is the only one able to perform dens osteosynthesis without implying postoperative immobilization. It is a significant advantage in elderly or multitrauma patients. A part from dens fractures, it can also help to manage dislocations, subluxations and serious C2-C3 sprains and even combinations as fractures of the odontoid process with axis pedicles fractures.