The primary purpose of this study of metal-on-metal (MoM) hip resurfacing was to compare the effect of using a cementless or cemented femoral component on the subsequent bone mineral density (BMD) of the femoral neck.

This was a single-centre, prospective, double-blinded control trial which randomised 120 patients (105 men and 15 women) with a mean age of 49.4 years (21 to 68) to receive either a cemented or cementless femoral component. Follow-up was to two years. Outcome measures included total and six-point region-of-interest BMD of the femoral neck, radiological measurements of acetabular inclination, neck-shaft and stem-shaft angles, and functional outcome scores including the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index and the University of California at Los Angeles activity scale.

In total, 17 patients were lost to follow-up leaving 103 patients at two years. There were no revisions in the cementless group and three revisions (5%) in the cemented group (two because of hip pain and one for pseudotumour).

The total BMD was significantly higher in the cementless group at six months (p < 0.001) and one year (p = 0.01) than in the cemented group, although there was a loss of statistical significance in the difference at two years (p = 0.155).

All patient outcomes improved significantly: there were no significant differences between the two groups.

The results show better preservation of femoral neck BMD with a cementless femoral component after two years of follow-up. Further investigation is needed to establish whether this translates into improved survivorship.

Cite this article: Bone Joint J 2015;97-B:1608–14.

Introduction: This prospective study focuses on the issue of a reliable prosthesis/bone fixation and compares the clinical and radiological outcome of the cemented and uncemented version of the prosthesis.

Methods: The prosthesis ensures congruent area contact with physiological kinematics resulting from imitation of the healthy morphology of the femoral condyle and unrestricted movement of the polyethylene bearing. From 1991 to 12/2007 we performed 624 medial implantations with cement (age 51–95, mean 71 years) and 185 cementless (age 40–84, mean 65 years). Other criteria as were similar. The follow up is (1.6–17) mean 9 years and seized 93% of the cases. They are assessed according to the KSRS and analyzed radiologically (F. C. Ewald).

Results: Knee Score (pre/post) cemented 41/93, cement-less 39/95. Function Score (pre/post) cemented 56/90, cementless 59/94. ROM increased for the cemented group Flex/Ex 107°/5° to 121°/2°, for the cementless Flex/Ex 107°/4° to 124°/1°.

Loosening needing revision: 15 times (2.5%) in the cemented group and 3 times (1.7%) in the cementless group. The survival rate (endpoint revision) is at 10 years: cemented 93.7%, cementless 94.5%.

The radiological investigation showed less radiolucent lines in the cementless cases in comparison to the cemented.

Conclusion: The prosthesis gives excellent results in the cemented and cementless application. The knee and function scores show similar improvements. The loosening rate of the cementless cases is even lower despite the higher physical demands of this 6 year younger group. The cementless fixation is attractive for younger patients and is pre-eminent for the mini-invasive implantation technique.