Dynamic intervertebral connection device with controlled multidirectional deflection

An osteosynthesis device for a vertebral column, the device comprising at least one elastically deformable connection system connected at opposite ends to at least first and second fixing portions suitable for being fixed to vertebrae by means of bone anchoring elements,

• wherein the elastically deformable connection system comprises:
• a deformable connection member presenting:
• in a “sagittal” plane, determined stiffness for exerting a return force on flexion-extension movements between the fixing portions;
• in a “frontal” plane perpendicular to the sagittal plane, determined stiffness for exerting a return force on lateral inflexion movements between first and second fixing portions, the stiffness of the deformable connection member in the frontal plane being less than its stiffness in the sagittal plane;
• and
• along an axis defined by the intersection between the sagittal and frontal planes, determined stiffness for exerting a return force on traction-compression movements between the fixing portions;
• and means for limiting flexion-extension, traction-compression, and lateral inflexion movements between the fixing portions, said means comprising a box having an inside surface;
• wherein the deformable connection member is mounted inside the box such that a space is defined between the inside surface of the box and the deformable connection member to allow movement of the deformable connection member relative to the box;
• and
• wherein the deformable connection member is implemented by means of a flat element extending in the frontal plane and presenting thickness in the sagittal plane, the flat element possessing at least a first end connected to the first fixing portion and a second end connected to the second fixing portion.