Risedronate does not enhance fixation or BMD in revision cups: randomised study with three years follow-up

Bisphosphonates may improve implant fixation by inhibition of bone resorption and stimulation of osteoblasts by up regulation of BMP-2. However, there are few clinical studies in this area.

Does treatment with oral bisphosphonates improve implant fixation and bone remodelling around the acetabular component after revision arthroplasty with or without use of morselised allograft?

Fifty-three patients received university pharmacy blinded medication for three months: 5 mg risedronate or placebo one dosage and 1 g calcium carbonate and 800IE cholecalciferol per day. Forty-one patients were operated upon with revision of the cup. The revisions were performed with an uncemented (Trilogy, Zimmer, Warsaw, USA) or a cemented (Ogee, Depuy Int, England) cup. Radiostereometric analysis was obtained within one week after the operation, at three and six months, and after one, two and three years to study cup migration. Bone mineral density was measured postoperatively, at six months, one and two years, using DEXA. The presence and extension of radiolucent lines and graft remodelling were studied on conventional radiography.

The risendronate group revealed less anterior-posterior rotation at 6 months. We found no significant differences in migration at three years, change in bone mineral density, or graft remodelling and radiolucent lines formation between groups.

We could not demonstrate any beneficial effects of oral administration of risedronate on the fixation, bone mineral density or bone remodelling of revision cups using various amount of bone graft.