An anchor assembly for anchoring a tendon to bone, comprising: a sheath having a substantially solid distal end , at least two sidewalls extending proximally from the distal end , the sidewalls being separated by at least two slots and the sidewalls defining an inner lumen therebetween, at least one of anti-plunge tab (1 10a, 1 10b, 110c, 110d) extending from a proximal-most end of the sheath adjacent to at least one of the slots , the at least one anti-plunge tab (1 10a, 1 10b, 1 10c, 1 10d) preventing over-insertion of the sheath into a bone hole, and at least one retaining tab extending from the sheath at a location distal to the at least one anti-plunge tab , the at least one retaining tab being positioned a distance apart from the at least one anti-plunge tab , the distance being configured such that when the at least one anti-plunge tab is positioned on a proximal surface of a cortical bone, the at least one retaining tab will extend beneath a distal surface of the cortical bone; and an expander configured to be received between the at least two sidewalls on the sheath to cause the sheath to expand and engage bone; characterized in that : the at least one anti-plunge tab is co-planar with the at least one retaining tab . a sheath having a substantially solid distal end , at least two sidewalls extending proximally from the distal end , the sidewalls being separated by at least two slots and the sidewalls defining an inner lumen therebetween, at least one of anti-plunge tab (1 10a, 1 10b, 110c, 110d) extending from a proximal-most end of the sheath adjacent to at least one of the slots , the at least one anti-plunge tab (1 10a, 1 10b, 1 10c, 1 10d) preventing over-insertion of the sheath into a bone hole, and at least one retaining tab extending from the sheath at a location distal to the at least one anti-plunge tab , the at least one retaining tab being positioned a distance apart from the at least one anti-plunge tab , the distance being configured such that when the at least one anti-plunge tab is positioned on a proximal surface of a cortical bone, the at least one retaining tab will extend beneath a distal surface of the cortical bone; and a substantially solid distal end , at least two sidewalls extending proximally from the distal end , the sidewalls being separated by at least two slots and the sidewalls defining an inner lumen therebetween, at least one of anti-plunge tab (1 10a, 1 10b, 110c, 110d) extending from a proximal-most end of the sheath adjacent to at least one of the slots , the at least one anti-plunge tab (1 10a, 1 10b, 1 10c, 1 10d) preventing over-insertion of the sheath into a bone hole, and at least one retaining tab extending from the sheath at a location distal to the at least one anti-plunge tab , the at least one retaining tab being positioned a distance apart from the at least one anti-plunge tab , the distance being configured such that when the at least one anti-plunge tab is positioned on a proximal surface of a cortical bone, the at least one retaining tab will extend beneath a distal surface of the cortical bone; and an expander configured to be received between the at least two sidewalls on the sheath to cause the sheath to expand and engage bone; characterized in that : the at least one anti-plunge tab is co-planar with the at least one retaining tab . <EOS>