An anchor device for attaching materials within bone including a body having a distal end region, a proximal end region, and a plurality of struts extending between the distal end region to the proximal end region and at least partially surrounding an interior volume of the body. The anchor device includes an attachment feature positioned within the interior volume of the body and coupled near the distal end region. The attachment feature is configured to secure material to the body. Upon removal of a constraint and after delivery of the anchor device into bone, the body passively transitions from a constrained, delivery configuration that is radially contracted and axially elongated to a relaxed, deployment configuration that is radially expanded and axially shortened.
