[Secondary stability of cemented and non-cemented acetabular implants ex-vivo under dynamic load]

OBJECTIVE: To measure the bone-prosthetic implant interface micromovement during the application of physiological load by using a material testing system (MTS). METHODS: The cadaveric hip specimens were used to simulate a single leg stance and the joint in the neutral position. Micromovement was recorded via a 3-dimensional transducer in the acetabula of postmortem specimens, which had been preserved in formalin. The study data of the cemented and uncemented prosthsis refereed to the lone-term clinical process and the radiological status and experimental results. RESULTS: Cemented cups showed higher transverse relative motion up to 90 microm, whereas the maximum transverse movement of the non-cemented cup was 60 microm. Orthogonal motion perpendicular to the implant surface showed compression for all cups at all sites. CONCLUSION: The results indicate that there are large differences in survival time between 2 groups. That could not be compared statistically in secondary stability. Nevertheless, according to the results, the amount of micromotion of press-fit cup is relatively less than that of cemented polyethylene cup, which is instrumental in bone ingrowth and secondary stability.