CHANGES IN BONE-MINERAL DENSITY ADJACENT TO 2 BIOMECHANICALLY DIFFERENT TYPES OF CEMENTLESS FEMORAL STEMS IN TOTAL HIP-ARTHROPLASTY

We have compared the differences in bone mineral density (BMD) adjacen t to two biomechanically different cementless femoral sterns used for total hip arthroplasty. Measurements were performed 12 to 38 months af ter surgery in a cross sectional study of 29 patients. Of these, 15 ha d arthroplasties using an ''off the shelf'' type cementless femoral st ern (Spotorno), while 14 had a custom made cementless stem (Evolution- K). Dual X-my absorptiometry (DXA) measurements revealed that the pati ents who had a Spotorno stern had a significantly lower BMD in the ope rated leg compared to the non-operated sine in both Gruen zones 1 and 7, whereas no significant differences were found in these areas in the Evolution-K group. For both types of prosthesis there was a significa nt and similar decrease in BMD of the proximal tibia on the operated s ine.