Abstract
It is difficult to place cementless acetabular components, as performed in Europe and America, because the majority of cases of osteoarthritis (OA) of the hip in Japan are caused by acetabular dysplasia.
The characteristics of Japanese OA of the hip are discussed as follows;
1: There is often a superoanterior acetabular bony defect due to acetabular dysplasia.
2: It is difficult to insert the cementless acetabular components into the small and shallow acetabulum.
3: It is difficult to find the true anatomical position of the acetabulum because of curtain osteophytes producing a ‘double floor’ of the acetabulum
4: The press-fit technique for fixation of the acetabular components is not effective in some cases. Therefore, screw fixation is necessary for certain primary fixation.
5: Excessive anteversion of the femoral neck exists in some cases.
6: Some cases have large marginal osteophytes around the acetabulum.
The problems these characteristics can induce are discussed as follows;
1: Bony containment is insufficient if the cementless acetabular component is placed at the anatomical position of the acetabulum.
2: The placement of the cementless acetabular components tends to be in the lateral position.
3: If large artificial femoral heads are becoming larger, then the thickness of the polyethylene liners are becoming thinner.
4: With screw fixation there is a risk of injuring blood vessels.
5: Bony or soft tissue impingement might cause some limitation to the range of motion or it may increase the risk of dislocation.
In this paper we will be explaining tips, tricks, and pitfalls to help ensure a successful placement of the cementless acetabular components based on the above.
