Soft tissue anchors and implantation techniques

A method comprising:

• providing a tissue anchor, which includes a proximal head at a proximal end of the tissue anchor, and a helical tissue-coupling element disposed about a longitudinal axis thereof, extending to the proximal head, and having a distal tissue-penetrating tip, wherein the helical tissue-coupling element includes a first helical portion and a second helical portion, wherein the second helical portion is more distal than the first helical portion, wherein (a) the first and the second helical portions of the helical tissue-coupling element have a first axial stiffness and a second axial stiffness, and (b) the second axial stiffness is greater than the first axial stiffness, such that if excessive tension is applied to the helical tissue-coupling element, the helical tissue-coupling element generally elongates along the first helical portion before along the second helical portion, such that the first helical portion serves as a mechanical fuse that reduces force applied to the second helical portion;
• and
• advancing the helical tissue-coupling element into soft tissue.