ARTIFICIAL JOINT STEM
Stable fixation to a bone. An artificial joint stem includes a base having a surface, and a first coating film located in a first region on the surface of the base. The first region includes a second region having a portion where the first coating film is not located. The second region includes a third region in which the first coating film is located and around which the first coating film is not located.
1 . An artificial joint stem comprising:
a base having a surface; and
a first coating film located in a first region on the surface of the base, wherein
the first region comprises a second region having a portion where the first coating film is not located; and
the second region comprises a third region in which the first coating film is located and around which the first coating film is not located.
2 . The artificial joint stem according to claim 1 , wherein
in a region of the first region adjacent to the second region, a thickness of the first coating film decreases toward the second region.
3 . The artificial joint stem according to claim 1 , wherein
when a side embedded in a bone when the artificial joint stem is used is defined as a distal side and an opposite side is defined as a proximal side, the second region is a region at an end portion on the proximal side or an end portion on the distal side in the first region.
4 . The artificial joint stem according to claim 3 , wherein
the second region is a region at the end portion on the distal side in the first region.
5 . The artificial joint stem according to claim claim 1 , wherein
the second region comprises a fourth region in which the first coating film is not located and around which the first coating film is located.
6 . The artificial joint stem according to claim 1 , wherein
the base has a groove; and
the first region in which the first coating film is disposed comprises at least a part of the groove.
7 . The artificial joint stem according to claim 6 , wherein
for an inside portion of the groove and an outside portion of the groove adjacent to each other in the first region, a thickness of the first coating film in the inside portion of the groove is greater than a thickness of the first coating film in the outside portion of the groove.
8 . The artificial joint stem according to claim 6 , wherein
a thickness of the first coating film in the inside portion of the groove increases toward a depth direction of the groove.
9 . The artificial joint stem according to claim 6 , wherein
for an inside portion of the groove and an outside portion of the groove adjacent to each other in the first region, a surface roughness of the first coating film in the inside portion of the groove is higher than a surface roughness of the first coating film in the outside portion of the groove.
10 . The artificial joint stem according to claim 6 , wherein
when a side embedded in a bone when the artificial joint stem is used is defined as a distal side and an opposite side is defined as a proximal side, a thickness of the first coating film in an inside portion of the groove decreases from the proximal side toward the distal side.
11 . The artificial joint stem according to claim 6 , wherein
in the second region, a ratio of a surface area of a region where the first coating film is not located to a surface area of an inside portion of the groove is less than a ratio of the surface area of the region where the first coating film is not located to a surface area of an outside portion of the groove.
12 . The artificial joint stem according to claim 1 , wherein
the base has a groove; and
for an inside portion of the groove and an outside portion of the groove adjacent to each other, a surface roughness of the inside portion of the groove is different from a surface roughness of the outside portion of the groove.
13 . The artificial joint stem according to claim 12 , wherein
the surface roughness of the inside portion of the groove is higher than the surface roughness of the outside portion of the groove.
14 . The artificial joint stem according to claim 12 , wherein
the surface roughness of the inside portion of the groove is lower than the surface roughness of the outside portion of the groove.
15 . The artificial joint stem according to claim 12 , wherein
the surface roughness of the inside portion of the groove increases toward a depth direction of the groove.
16 . The artificial joint stem according to claim 1 , further comprising:
a second coating film located on the first region where the first coating film is located, wherein
the second coating film contains a calcium phosphate-based material.