Five-year Migration Pattern and Bone Mineral Density for the Tri-Lock and Summit Femoral Stems.

The incidence of primary hip joint prosthesis is 180 per. 100,000 inhabitants. In male patients younger than 50 years the 10-years survival of the prosthesis is 89 % and 82 % over 15 years. In women younger than 50 years the 10-years survival of the prosthesis is 87 % and 78 % over 15 years. As revision surgery is associated with higher complication risk for the patient and poorer out-come and implant survival it is necessary to examine possible methods that may increase long-term survival of the primary hip prosthesis or facilitate better outcomes after revision of hip joint prostheses for younger patients. In younger patients the prosthesis often is inserted without the use of cement. When not using cement, it is crucial for the final result, that there is a direct bone ingrowth of the prosthesis. The chance of getting bone ingrowth depends firstly on a good immediate mechanical fixation at surgery and secondly on osteoconductive abilities of the prosthetic surface. This study investigates a new bone sparing implant with a new surface compared to a conventional implant.