An implantable device , especially, for maintaining an intervertebral space between overlying and underlying vertebrae , comprising: - an intervertebral wedge comprising an upper bearing zone , in particular over at least a portion of the lamina of the overlying vertebra, and a lower bearing zone , in particular over at least a portion of the lamina of the underlying vertebra, separated by a minimum distance Da to maintain an intervertebral space, and - a first lateral spring , and a second lateral spring, each having a position A relative to the intervertebral wedge in a position for inserting the implantable device , and a position B relative to the intervertebral wedge , in a position for implanting the implantable device, the positions A and B being different, and in that the first lateral spring , and the second lateral spring, are configured: - to freely move from position A to position B, and - to form retention components arranged relative to the intervertebral wedge to block the migration of the intervertebral wedge toward the spinal canal at least in position B, characterized in that : - the first lateral spring comprises a first armature comprising one or more at least partially metallic elongated element(s) , in that the first armature comprises a first upper arm and a first lower arm which diverge from each other, and in that the first armature comprises a first intermediate arm , continuous or discontinuous, in connection with the first upper arm and with the first lower arm . - an intervertebral wedge comprising an upper bearing zone , in particular over at least a portion of the lamina of the overlying vertebra, and a lower bearing zone , in particular over at least a portion of the lamina of the underlying vertebra, separated by a minimum distance Da to maintain an intervertebral space, and - a first lateral spring , and a second lateral spring, each having a position A relative to the intervertebral wedge in a position for inserting the implantable device , and a position B relative to the intervertebral wedge , in a position for implanting the implantable device, the positions A and B being different, and in that the first lateral spring , and the second lateral spring, are configured: - to freely move from position A to position B, and - to form retention components arranged relative to the intervertebral wedge to block the migration of the intervertebral wedge toward the spinal canal at least in position B, characterized in that : - the first lateral spring comprises a first armature comprising one or more at least partially metallic elongated element(s) , in that the first armature comprises a first upper arm and a first lower arm which diverge from each other, and in that the first armature comprises a first intermediate arm , continuous or discontinuous, in connection with the first upper arm and with the first lower arm . - to freely move from position A to position B, and - to form retention components arranged relative to the intervertebral wedge to block the migration of the intervertebral wedge toward the spinal canal at least in position B, characterized in that : - the first lateral spring comprises a first armature comprising one or more at least partially metallic elongated element(s) , in that the first armature comprises a first upper arm and a first lower arm which diverge from each other, and in that the first armature comprises a first intermediate arm , continuous or discontinuous, in connection with the first upper arm and with the first lower arm . - the first lateral spring comprises a first armature comprising one or more at least partially metallic elongated element(s) , in that the first armature comprises a first upper arm and a first lower arm which diverge from each other, and in that the first armature comprises a first intermediate arm , continuous or discontinuous, in connection with the first upper arm and with the first lower arm . <EOS>