A system, comprising: a tissue anchor , the tissue anchor comprising: an anchoring portion configured to be rotatable about a longitudinal axis (ax1) of the anchor ; and an anchor head fixedly coupled to the anchoring portion , such that rotating the anchoring portion into tissue moves the anchor head distally along the longitudinal axis (ax1) toward the tissue, a socket shaped to receive the anchor head within the socket , wherein the tissue anchor is configured to have: a first state in which the anchor head is seated snugly within the socket , such that torque applied by a driver to the tissue anchor rotates the socket , the anchor head , and the anchoring portion , thereby facilitating screwing of the anchoring portion into the tissue, and a second state in which the anchor head is disposed distally from the socket , such that torque applied by the driver to the tissue anchor rotates the socket relative to the anchor head and the anchoring portion ; wherein the tissue anchor is configured to transition from the first state to the second state, responsively to the anchoring portion having been screwed into the tissue sufficiently deep such that further screwing of the anchoring portion into the tissue pulls the anchor head distally out of the socket while the tissue resists further distal movement of the socket . a tissue anchor , the tissue anchor comprising: an anchoring portion configured to be rotatable about a longitudinal axis (ax1) of the anchor ; and an anchor head fixedly coupled to the anchoring portion , such that rotating the anchoring portion into tissue moves the anchor head distally along the longitudinal axis (ax1) toward the tissue, a socket shaped to receive the anchor head within the socket , an anchoring portion configured to be rotatable about a longitudinal axis (ax1) of the anchor ; and an anchor head fixedly coupled to the anchoring portion , such that rotating the anchoring portion into tissue moves the anchor head distally along the longitudinal axis (ax1) toward the tissue, a socket shaped to receive the anchor head within the socket , wherein the tissue anchor is configured to have: a first state in which the anchor head is seated snugly within the socket , such that torque applied by a driver to the tissue anchor rotates the socket , the anchor head , and the anchoring portion , thereby facilitating screwing of the anchoring portion into the tissue, and a second state in which the anchor head is disposed distally from the socket , such that torque applied by the driver to the tissue anchor rotates the socket relative to the anchor head and the anchoring portion ; wherein the tissue anchor is configured to transition from the first state to the second state, responsively to the anchoring portion having been screwed into the tissue sufficiently deep such that further screwing of the anchoring portion into the tissue pulls the anchor head distally out of the socket while the tissue resists further distal movement of the socket . a first state in which the anchor head is seated snugly within the socket , such that torque applied by a driver to the tissue anchor rotates the socket , the anchor head , and the anchoring portion , thereby facilitating screwing of the anchoring portion into the tissue, and a second state in which the anchor head is disposed distally from the socket , such that torque applied by the driver to the tissue anchor rotates the socket relative to the anchor head and the anchoring portion ; wherein the tissue anchor is configured to transition from the first state to the second state, responsively to the anchoring portion having been screwed into the tissue sufficiently deep such that further screwing of the anchoring portion into the tissue pulls the anchor head distally out of the socket while the tissue resists further distal movement of the socket . <EOS>