A fastener for attachment to tissue or bone comprising: a first arm having a proximal end and a distal end, a second arm having a proximal end and a distal end, and a bridge connecting the first arm and second arm, wherein each of the first and second arms include a trunk portion (106A, 106B) extending over at least a portion of the length thereof, each trunk portion (106A, 106B) having a lateral extent larger than a lateral extent of the bridge or of a non-trunk arm portion adjacent thereto such that the fastener includes a first change in lateral stiffness disposed proximate the bridge or non-trunk arm portion in abutment with the first trunk portion and a second change in lateral stiffness disposed proximate the bridge or non-trunk arm portion in abutment with the second trunk portion; and each trunk portion (106A, 106B) including a first proximal projection and a second distal projection, disposed distal to said proximal projection, the first Proximal projection including a first proximal surface extending away from the trunk portion in a first direction, the first direction being such that the first proximal surface will engage the tissue or bone when the trunk portion is inserted therein so that a first moment is applied to the trunk portion in response to a pullout force on the bridge, the second distal projection including a second proximal surface extending away from the trunk portion in a second direction, the second direction being such that the second proximal surface will engage the tissue or bone when the trunk portion is inserted therein so that a second moment is applied to the trunk portion in response to a pullout force on the bridge, said fastener being characterized in that each of the trunk portions (106A, 106B) includes a localized area of weakness (120A, 120B) proximate the second distal projection thereon such that the second moment causes a first rotation of the trunk portion about the area of weakness (120A, 120B). a first arm having a proximal end and a distal end, a second arm having a proximal end and a distal end, and a bridge connecting the first arm and second arm, wherein each of the first and second arms include a trunk portion (106A, 106B) extending over at least a portion of the length thereof, each trunk portion (106A, 106B) having a lateral extent larger than a lateral extent of the bridge or of a non-trunk arm portion adjacent thereto such that the fastener includes a first change in lateral stiffness disposed proximate the bridge or non-trunk arm portion in abutment with the first trunk portion and a second change in lateral stiffness disposed proximate the bridge or non-trunk arm portion in abutment with the second trunk portion; and each trunk portion (106A, 106B) including a first proximal projection and a second distal projection, disposed distal to said proximal projection, the first Proximal projection including a first proximal surface extending away from the trunk portion in a first direction, the first direction being such that the first proximal surface will engage the tissue or bone when the trunk portion is inserted therein so that a first moment is applied to the trunk portion in response to a pullout force on the bridge, the second distal projection including a second proximal surface extending away from the trunk portion in a second direction, the second direction being such that the second proximal surface will engage the tissue or bone when the trunk portion is inserted therein so that a second moment is applied to the trunk portion in response to a pullout force on the bridge, said fastener being characterized in that each of the trunk portions (106A, 106B) includes a localized area of weakness (120A, 120B) proximate the second distal projection thereon such that the second moment causes a first rotation of the trunk portion about the area of weakness (120A, 120B).