An intervertebral device (1) to be placed between two spinous processes of two adjacent vertebrae, comprising a spacer (10) having two opposite grooves (14A, 14B). Each groove is configured to engage a spinous process. At least one porous layer (51A, 52A, 53A, 51B, 52B, 53B) is fixed onto an inner face of each groove. This porous layer is adapted to interface with the spinous process by allowing bone growth in the porous layer. One or several elongated members (30A, 30B) are adapted to surround the spinous processes for maintaining the spinous processes engaged into the grooves (14A, 14B).
