Pyramid uncemented hip shell
Both the Pyramid uncemented hip shell as well as the hip revision shell have a good seating behavior and excellent primary stability. Due to the pyramid-shaped teeth (unidirectional macro structure) on the outer surface of the shell a secure anchoring in the acetabulum is given.
Both shell types made of titanium alloy are treated with a two-layer coating:
- First it is covered with a 200 µm thick pure titanium vacuum plasma layer (Ti-VPS).
- Then it is coated with a 20µm thick layer of dicalcium phosphate (CaP) (for more information see the Coating section).
With this double-layer special coating rapid bone growth and thus early mobility for the patient is ensured.
Furthermore, the Pyramid uncemented hip shell is designed according to the press-fit concept. This means that the shell is pressed into the acetabulum using a constant oversize of the shell outer diameter compared to the drilling diameter. In this way, and with a flattened pole, a stable connection between acetabulum and hip shell is made.
In order to prevent any material growing or flowing into the thin space between shell and inlay, the threaded hole in the pole is hermetically sealed with a screw after implantation.
The articulation concept is designed so that the largest possible ball heads can be used with small cup diameters. E.g. a 36mm ball head fits into an acetabular cup with an outer diameter of 50mm plus inlay. Consequently, the hip cups offer a high degree of security against dislocation.