O1235 PERIPROSTHETIC BONE REMODELLING AND ITS RELATION WITH MIGRATION OF THE STEM 5 YEARS AFTER CEMENTED TOTAL HIP ARTHROPLASTY. WITH COMPARISON OF 5 STEM DESIGNS

Abstract

Aims: Comparing periprosthetic bone remodeling in 5 stem designs and the effects of the bone remodeling on stem migration. Methods: Bone remodeling at the proximal femur in 89 cemented THA of 5 stem designs (Exeter,Sp2_aluminum,Sp2_CoCr,SHP,Spectron) were followed up at 1 week, 2 years, and 5 years postoperatively by measuring bone mineral density (BMD) in 7 Gruen zones using dual energy x-ray absorptiometer (DEXA). The migrations of the femoral stem measured by Radiostereometric Analysis (RSA) during the same time period were compared with the changes in BMD. Results: An 8% to 25% decrease in BMD at the proximal femur, especially at the medial cortex, was found 5 years after cemented THA. Exeter showed the most favourable bone remodeling, whereas the SHP and Sp2_CoCr stems showed the worst bone remodeling (with bone loss of 15–27%), and the bone loss in Sp2_aluminum and Spectron stems were between (8–13%). The majority of the bone loss occurred within 2 years without major progress thereafter. The rate of the bone loss was significantly related to the design of the stem as well as gender and body mass index (BMI). A significant relation between the rate of bone loss and the migration of the femoral stem could not be established by the current study. Conclusions: The stiffness of the stem as well as the concept of stem design significantly affected the bone remodeling at the proximal femur. However, the rate of bone loss seemingly did not affect the migration of the femoral stem in the current study.