[The LSP test for determining oscillation resistance of spinal implants].
OBJECTIVE
New spinal implants need to be tested for primary stability in vitro under standardized laboratory conditions. To ensure the reliability of the test procedures, quality assurance standards in accordance with ISO 9000 were introduced to standardize testing including experimental set ups, loading and test frequency. These standards, however, require a relatively long time to implement.


METHODS
The LSP test was used to compare various surface treatments by different shot peening processes applied to spinal rods for dorsal spine implant systems. 6 rods made of two different cp-Titanium materials (Ti-2 and Ti-4) were tested. Dynamic tests were performed with the MTS 810 mono-axial servo-hydraulic test equipment. Beginning with a load of 200 N the rods were subjected to tensile and compressive loads, which were increased in steps of 100 N after every 50.000 cycles until rod failure.


RESULTS
Results were available after one to two weeks. The best results (LSP 167 million) were achieved with Ti-4 rods shot peened with steel balls and glass beads. In comparison, the lowest LSP value of 81 million was found with Ti-2 rods shot peened with glass beads only.


CONCLUSIONS
This high speed testing method has reduced the development time from two years to 6 months.
Schuh
A
A
Orthopädische Klinik Rummelsberg, D-90592 Schwarzenbruck.
Lorenz
S
S
Holzwarth
U
U
D001696:Biomechanical Phenomena / Q000592:standards*; D006801:Humans; D008422:Materials Testing / Q000592:standards*; D008432:Mathematical Computing; D011474:Prosthesis Design; D011786:Quality Control; D013123:Spinal Fusion / Q000295:instrumentation*; D013718:Tensile Strength; D014025:Titanium; D016474:Weight-Bearing
D014025:Titanium