A fastener is provided for inserting into a body tissue. The fastener has a head and an anchoring portion comprising a plurality of distally extending legs. Each leg terminates in an anchoring element configured to penetrate tissue and to cause a net lateral resistance force on the leg during penetration. The legs are configured and structured so that when the net lateral resistance force on the anchoring element exceeds a predetermined level, at least a portion of the leg is deflected laterally away from a pre-insertion configuration and so that when the net lateral force is subsequently reduced below the predetermined level, the at least a portion of the leg is biased back toward the pre-insertion configuration.
