Based on our experience with an anatomically shaped-femoral stem - helitorsion stem - and on the concept of rotatory locking, we presents our results in osteointegration and bone remodeling.

The study is documented in a prospective study of 84 consecutive helitorsion implants with 6 years 8 month follow-up with no exclusion critera relative to age, gendre, morphology of the femur, bone density, etiology. The stem: forged titanium alloy; roughness 6.5 achieved with corundum treatment; conical proximally, cylindrical distally; double curvature in the sagittal plane; in the horizontal plane, replicates the natural helix of the femurits main feature-; HA coating(200μm) over its proximal 2/3. Stem insertion: helicoidal motion along the long axis of the femur and rotation in the horizontal plane. Rotation is mandatory. The stem is pushed down until the oval shape of the stem matches the oval shape of the femur – at each metaphyseal level – over a more or less extended height depending on the femoral morpho-type; this horizontal locking prevents further downard motion.

This uncemenred helitorsion stem yelds remarkably good radiological results: there is a radiological silence. We think that is attribuable to helitorsion with ensures an even distribution of loads, and applies oblique and not perpendicular loads to the bone-implant interface