increase cavity volume and surface area while minimizing overall size consequently the present exemplary interbody spacer 100 employs geometry that provides for a small spacer with relatively large surface area and internal cavity 118 other cavities and geometries may be included in the spacer structure such as cutouts or holes 116 according to one exemplary embodiment the interbody spacer 100 has an upper face 124 and an opposing lower face 126 a series of ridges 128 traverse the upper and lower faces 124 126 the ridges 128 are configured to facilitate the insertion of the interbody spacer 100 by preventing retrograde motion and slippage during the insertion process after the surgery is complete the ridges 128 also may provide increase surface area encourage bone growth and or prevent dislocation of the interbody spacer 100 additionally as illustrated in fig1 a and 1b the present interbody spacer 100 includes frictionally engaging features on at least one end of the spacer 100 according to one exemplary embodiment any number of protruding features materials or rough surface finishes disposed on at least one end of an interbody spacer 100 may be used to pivotably direct an interbody spacer 100 during surgical insertion particularly according to one exemplary embodiment the interbody spacer 100 has a plurality of teeth 120 disposed about the perimeter of the rounded proximal end 112 the teeth 120 allow for an insertion instrument to firmly grip the interbody spacer 100 and aid in the manipulation of the interbody spacer 100 during insertion in one exemplary embodiment the teeth 120 when coupled with an appropriate insertion instrument may simplify a tlif procedure by allowing the pivoting and tamping of the interbody spacer 100 without having to release it from the grasp of the insertion instrument as shown more particularly in.