Uncemented femoral stem design influences the occurrence rate of postoperative fractures after primary hip arthroplasty: a comparison of the Image and Profile stems.

Two consecutive series of hip arthroplasties with closely similar anatomic uncemented femoral implants [207 Profile (DePuy) and 171 Image (Smith&Nephew) stems] were compared with regard to postoperative femoral fractures. All arthroplasties were performed by senior staff surgeons, mainly on patients below 65 years of age. In the Image group the occurrence rate of postoperative periprosthetic femoral fractures was higher (9.36%) compared to the Profile group (2.99%) and fractures occurred earlier (1.69 y vs. 8.84 y). The bulkier proximal part, the thinner cylindrical distal two thirds and the larger offset probably resulted in less rotational stability and increased proximal torsional load transfer during activities of daily living. This resulted in femoral fractures after minor trauma, without osteolysis. This study emphasizes the need for close follow-up when introducing new implants, even if they rely on known principles and feature only minor changes from proven concepts.