A threaded implant can be provided with an elongated main body having external threads configured to thread into bone, and an internal support structure located within the external threads. The internal support structure has a helical arrangement that extends in an opposite direction to the external threads. Other threaded implants and methods are also disclosed.

A hard-tissue implant is provided. The implant includes a shaft, a surface of the shaft, pillars for contacting a hard tissue, slots to be occupied by the hard tissue, and a thread disposed helically along the shaft, extending radially from the shaft, and having a plurality of grooves oriented transversely with respect to the thread that define a series of thread segments and thread gaps along the thread. The implant has a Young's modulus of elasticity of at least 3 GPa and a ratio of (i) the sum of the volumes of the slots and the thread gaps to (ii) the sum of the volumes of the pillars and the thread segments and the volumes of the slots and the thread gaps of 0.40:1 to 0.90:1. Also provided is a method of use of the implant for fusion of two or more bones in an individual in need thereof.

A threaded implant can be provided with an elongated main body having external threads configured to thread into bone, and an internal support structure located within the external threads. The internal support structure has a helical arrangement that extends in an opposite direction to the external threads. Other threaded implants and methods are also disclosed.

A threaded implant can be provided with an elongated main body having external threads configured to thread into bone, and an internal support structure located within the external threads. The internal support structure has a helical arrangement that extends in an opposite direction to the external threads. Other threaded implants and methods are also disclosed.