Advantages of
larger ball heads
The wear rate of BIOLOX® ceramics is almost independent of ball head diameter
There is general agreement that the risk of impingement, subluxation and dislocation in artificial hip joints is greatly reduced if the range of motion is increased. Larger ball heads reduce these risks. As the ball head diameter increases, so does the range of motion and joint stability, but so also does the wear rate. For conventional wear couples, such as those making use of metal - polyethylene, the wear rate increase is significant and this significant increase has limited the size of ball head which can be used in practise. On the other hand, for BIOLOX® wear couples the wear rate increase is so small that it is hardly detectable. Thus, for ceramic wear couples the wear rate is almost independent of the ball head diameter. For this reason, in contrast to other wear couples, there is no disadvantage with respect to abrasion and wear in using a larger ball head diameter. The main reason for this behaviour is the extremely low wear rate of BIOLOX® ceramics and the subsequent avoidance of osteolysis and other undesirable human-body reactions, such as allergies. BIOLOX® ceramics cause no allergic reactions.
You can download an animation (increased range of motion with larger ball head diameters) in the following media formats:
MPEG-1, 3.31 MB
QuickTime, 3.09 MB
RealMedia, 459 KB
For any given cup wall-thickness a larger ball head size can be used
A further significant advantage of BIOLOX®forte wear couples is that for any given size of acetabular cup, a larger ball head diameter can be used. This is because, in contrast to polyethylene inserts, the minimum permitted insert wall-thickness is smaller with BIOLOX®forte.
For further information, please have a look at the brochure „It's in Your Hands: The Low Wear Choice Against Osteolysis.“