Effect Of Stress On Cementless Femm

The cementless femoral stems are initially proximally porous-coated or fully-coated with Titanium.4 The initial (or primary) fixation of the cementless stems is obtained by press-fitting a slightly oversized stem, then the secondary (or long-term) fixation is obtained through bone ingrowth49, where bone grows insides a porous or onto a roughened surface.50 The primary fixation is critical to achieving the long-term fixation, because the micromotions between bone and the implant due to poor initial fixation can induce fibrous bone tissue grows into the surface of the implants instead of hard bone, which results in inadequate bone growth for long-term fixation.51, 52 In addition, bone remodeling will happen around the stem as a consequence of bone (femur) adaption to the stress change when the femoral stem is implanted into the femur.53 The implanted stem shares the external (hip joint and muscle) loads, which are only carried by the femur itself before the implantation, with the bone resulting in the reduction of stress carried by bone.