US Patent 7141068 Spinal spacer assembly

A spinal spacer assembly comprises spacer tubes of different cross sections including kidney shaped, oblong, oval and round. The spacer tubes have internal ribs for receiving top and bottom end caps. Such end caps are pressed into the top and bottom openings of the spacer tube so as to be supported on and frictionally engage the internal ribs. The end caps are flush with the tops and bottoms of the spacer tubes except for serrations on the end caps which may project outwardly therefrom.