Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup.
51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years.
Mean cup rotation around the x-axis was 0.13° for the cemented group and -0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p