Der Unfallchirurg
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There are two specific problems in using metallic or ceramic heads for hip prostheses: (1) the amount of polyethylene abrasions in the cup caused by the heads (especially a metal head). (2) the polyethylene abrasions caused by Al2O3 ceramic heads is far less than metal heads, but its ability to adapt geometrically is limited due to its being less strong. The abrasions appear because of geometric differences in the prosthetic joint, local problems in the surface architecture and physical/chemical interactions between the different materials. ⋯ Testing 2,000,000 cycles in a bodylike liquid under permanent loads of 90 kPa, periodically increasing up to 250 kPa, simulating normal stress situations (i.e., walking), the "Titan-Niob Ceramic Multilayer Sandwich Head" showed major advantages over the metal heads and also over the ceramic heads even though the ceramic head has been accepted so far to have the best friction coefficient. Furthermore, there has been no problem in surface fracture with the "Titan-Niob Ceramic Multilayer Sandwich Head".
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Case Reports
Avulsion of the anterior superior iliac spine in two adolescent sisters: operative versus conservative treatment.
We compared the results of treatment of identical injuries to the anterior superior iliac spine in two adolescent sisters, one treated conservatively and the other operatively. The functional results of both treatments were good, but the rehabilitation period was shorter with operative treatment, allowing an earlier return to athletic activity. Treatment by open reduction and internal fixation should be considered in patients requiring a short convalescence. Familial coincidence of avulsion fracture of the anterior superior iliac spine has not previously been described in the literature.