Implant with porous surface

DETAILED DESCRIPTION OF THE INVENTION FIG.
1A shows a portion of an implant surface 1 having surface pores 2 arranged in a square pattern.
FIG.
1B shows a portion of an implant surface 1 having surface pores 2 arranged in a hexagonal or rhombic pattern.
FIG.
1C shows a portion of an implant surface 1 having surface pores 2 arranged in a spiral pattern.
FIG.
2 shows a number of surface pores 2 having elevations 3 extending more or less continuously around the edge of the pore.
The elevations 3 have the form of crater formations, which may arise at the formation of the surface pores through working by means of laser if such parameters as supplied power, time etc.
are properly set.
FIG.
3 illustrates how a pore 2 and the region adjacent to the pore may look in a typical case according to the invention.
In the drawing, the diameter of the pore 2 is designated D and its depth is designated d.
The maximal height of the elevation or elevations 3 over the material surface 4 surrounding the edge of the pore is designated h.
The ratio between the diameter and the depth of the surface pores, D/d, and the height h of the elevation 3 are important for achieving improved retention.
Thus D/d should be at least 0.
5, for example 0.
1-10, more usually in the range 0.
5-2.
The mean diameter of the surface pores 2 lies between 100-200 .
mu.
m, optimally between 125-180 .
mu.
m.
A suitable mean diameter is about 150 .
mu.
m.
The surface pore depth is related to the diameter such that D/d is at least 0.
5, typically not more than 10, for example 0.
1-10, more usually in the range 0.
5-2.
The pore depth may be between 10-400 .
mu.
m, for example 50-200 .
mu.
m.
The height h under these conditions should be at least 1 .
mu.
m, preferably at least 5 .
mu.
m.
The maximal height h is generally in the region of 20 .
mu.
m.
The distance between adjacent surface pores should be between 50-200 .
mu.
m.
Typically, this distance is in the region of 75-150 .
mu.
m.
FIG.
4 shows surface pores 2' having incline d pore walls 5, which in combination with the elevations 3 further enhances the retention