A medical device (10) includes an implant body (20) with a number of segments (30) hingedly interconnected so as to assume a straightened state for delivery and a flexed or roughly curved deployed state. Implant body may have engagement elements on at least two different segments, for example on a majority of segments. An elongated locking element anchored at the distal segment of the implant body may have projections for at least each engagement element. Tension applied to the locking element biases the implant body from the straightened state to the flexed deployed state. When the locking element is deflected to reach the curved deployed state, flexing segments of the implant body lock by matching engagement elements of the implant body with projections of the locking element. A very secure lock may be formed to prevent opening after deployment.