An implant for maintaining a given minimum inter-spinous-process spacing includes an implant body with a number of segments hingedly interconnected so as to assume a straightened state for delivery along a conduit and a curved deployed state. An elongated tightening element is anchored at the distal segment of the implant body and passes along a channel extending along the implant body. Tension applied to the tightening element biases the implant body from the straightened state to the curved deployed state. Preferably, when the tightening element is deflected to reach the curved deployed state, a locking arrangement locks the tightening element relative to the implant body, thereby retaining the implant in the curved deployed state. A distal portion of the implant body is preferably formed with a set of lateral projections to inhibit withdrawal of the distal portion between adjacent spinous processes after deployment.