The primary focus of this study is to investigate whether increased bone density of the graft in revision arthroplasty of the hip can cause a decreased micromotion of the implant relative to the femur.

Morsellized compacted bone allograft can be used for revision arthroplasty of the hip. Treating the graft locally with an antiresorptive substance such as a bisphosphonate has decreased the graft resorption in animal studies and led to a remained bone density in a human series of 16 patients. In the present study we investigate if this increased bone density of the graft also causes a decreased micromotion of the implant relative the femur. 36 patients are planned to participate in a 1:1 randomized and prospective study comparing the bisphosphonate Clodronate to saline. Primary outcome will be micromotion over the first year but also secondary parameters such as late micromotion (between 12 and 24 months), re-loosening subjective outcome and safety.

We hypothesize that rinsing the graft in a bisphosphonate solution prevents its resorption and therefore may reduce the risk of mechanical failure. Patients are followed with radiograms, RSA (radiostereography) preop, postop, at 6 weeks, at 12 and 24 months and subjective months and subjective parameters including Womac and SF 12. The treatment is simple, cheap and appears virtually risk-free.

Inclusion Criteria:

• Patients with aseptic loosening and osteolysis scheduled for hip revision using allograft and impaction technique
• Obtained informed consent
• Pregnancy excluded in women of childbearing age

Exclusion Criteria:

• Patients with known renal disease or S-creatinine >175 mcmol/L
• Patients with S-calcium 2.75 mmol/L
• Patients with diagnosed Rheumatoid arthritis
• Patients with active primary hyperparathyroidism