Local treatment with the bisphosphonate alendronate combined with bone compaction may improve implant fixation, according to a 12-week canine study presented Monday at the 52nd annual meeting of the Orthopedic Research Society in Chicago, Illinois.¹

The new paired-design study of 10 canines compared the biochemical and histomorphometric effects of implant fixation using bone compaction with 10 mg of local alendronate or bone compaction with a saline application. Implants in the study were composed of plasma sprayed titanium. Either alendronate or the saline application were injected into the bone cavity with a syringe.

"We found a 100% increase in biomechanical fixation, a 30% increase in bone in contact with the implant, and a 140% increase in the bone around the implant in the alendronate group," says lead author Thomas Jakobsen, BmedSc, of the Orthopaedic Research Laboratory in the department of orthopaedics at Aarhus University Hospital in Aarhus, Denmark. Due to its effects on the autograft, alendronate leads to increased osteoconduction and results in increased osteointegration and increased biofixation, explains Jakobsen. The most important observation, he points out, is that "local alendronate plus bone compaction equals implant fixation."

Benefits of local administration

There are some significant advantages to local administration of alendronate, says Jakobsen. For example, local application allowed for high local bisphosphonate concentrations with no systemic effects. "This may be important for young patients because it is a great feat to improve implant fixation in these patients compared to older patients," he says.
 
"This is quite a novel application [of alendronate], and it has some definite potential," says Paul H. Wooley, PhD, director of biomedical research and professor of orthopaedic surgery, immunology, and biomedical engineering at Wayne State University School of Medicine in Detroit, Michigan. "I have never been comfortable with the side effects of systemic alendronate. The new use of local administration of alendronate in implant fixation "may move ahead pretty quickly," Dr. Wooley predicts.

Joan Bechtold, PhD, director of the Orthopaedic Biomechanics Lab at the Minneapolis Medical Research Foundation in Minnesota and a study co-author, adds that "we need a long-term study to see if slowing bone remodeling has an effect on the ability of bone to repair itself over time."

Reference

1. Jakobsen T, Kold S, Bechtold JE, et al. Local alendronate treatment increases fixation of implants inserted with bone compaction: 12 week canine study. Presented at: 52nd Annual Meeting of the Orthopaedic Research Society. March 18–22, 2006; Chicago, Ill. Abstract 89.