Bone screw and systems for bone fusion

A bone fusion system, comprising:

• a bone fusion device having an anterior wall, posterior wall, a first lateral wall, a second lateral wall, and a central cavity open to a superior and an inferior surface, wherein
• the anterior wall has a central access port extending therethrough, and at least one pair of a first bone screw passage and second bone screw passage in an oblique angle around the access port through the anterior wall,
• the posterior wall having a blind-hole at the midpoint of its proximal surface, the blind-hole being configured to detachably receive a distal end of a rod arrangement in a fastening unit specifically configured for fixing the bone fusion device into a human or animal body;
• and
• a bone screw in at least one of the bone screw passages, wherein the bone screw comprises:
• an elongated shaft having a straight proximal region and a tapered distal region with one or more threads disposed along the length of the tapered distal region, and one or more helical indentations disposed along the elongated shaft in a direction opposite to the direction of said one or more threads;
• a head disposed at the proximal end of the elongated shaft;
• and
• a tip disposed at the distal end of the elongated shaft.