Introduction and Objectives: The goal of cementless endoprosthetic hip surgery is to improve bone attachment. The gold standard method for evaluating periprosthetic bone characteristics is densitometry. This study was designed to compare periprosthetic bone mass in 2 groups of patients: less than 3 years and more than 3 years after implantation.

Materials and Methods: A total of 195 type ABG-II total hip prostheses were implanted from November 1997 to March 2003. This implant is a hemispheric cup coated with hydroxyapatite, which can additionally be anchored with screws and a short anatomic stem with metaphyseal fixation. DeLee and Gruen zones were analysed.

Results: During the study period, patients with implants less than 3 years old showed no significant changes in bone mineral density around the stem or the cup. In area 7, a statistically significant reduction was noted after 3 years (0.5218g/cm3, p< 0.001). In Gruen’s zones 3 and 4 a non-significant gain was observed after 3 years (1.1618g/cm3).

Discussion and Conclusions: In cup studies, a statistically insignificant increase in density was observed in zone I after 3 years. Noteworthy findings included a loss of function in DeLee zone III and Gruen zones 1 and 7, which has not yet had clinical consequences (at a maximum 6 year follow-up time).