The invention relates to an intervertebral implant including a wedge which is inserted between two spinous processes and has two opposite grooves in which said spinous processes engage, which grooves have substantially parallel axes, and each of which grooves is defined by two flanges. The wedge has at least one central opening between said two grooves and said central opening passes completely through said wedge along an axis Ac substantially parallel to the axes Ag1 and Ag2 of said grooves, which renders said wedge elastically deformable.