Bisphosphonate used to reduce postoperative THA implant movement shows promise at early follow-up
VIENNA — At a minimum of 2 years follow-up after total hip arthroplasty (THA), patients who received a single preoperative infusion of a bone-building bisphosphonate showed minimal acetabular cup migration and decreased femoral stem subsidence vs. those who received a placebo injection, according to a study by Austrian investigators.
For their research, Gerald Friedl, MD, of the University of Graz, Austria, and his colleagues received the Bronze Free Paper Award during the 10th EFORT Congress, here.
All 50 patients in the randomized, double-blind, placebo-controlled study had end-stage osteonecrosis of the femoral head.
Prior to undergoing THA surgery, 25 patients in the treatment group received a 4-mg injection of Zometa (zoledronic acid, Novartis) and 25 patients in the placebo group received a saline solution injection. Patients and investigators were blinded to how patients were randomized.
“A single infusion of zoledronic acid was found to improve the initial fixation in cementless THA and shows this can have promise in the long term,” Friedl said at the meeting.
For their analysis, Friedl and colleagues assessed implant fixation, bone turnover and clinical results using digital radiographs, biochemical markers and the clinical Harris Hip Score (HSS). The HSS showed excellent values in both groups; however, one hip needed revising so it was excluded from the final analysis, he said.
By 2 years postoperative, the placebo group’s stems had migrated up to -1.2 mm +/- 0.6 SD and kept migrating. Investigators observed transverse cup migration in that group of about 0.6 mm and vertical migration of about 0.6 mm.
By comparison, cup migration in the treatment group was limited to about 0.15 mm transversely and 0.06 mm vertically, respectively, according to the study abstract.
Stem migration was similar in both groups, with a trend toward less migration seen in the treatment group, Friedl added.
More than half the patients in the treatment group presented with transient flu-like symptoms but had no serious adverse events, he explained.
“We found that age is affecting the subsidence,” Friedl said.
Consequently, after investigators adjusted their analysis for confounding factors such as age, “The older patients had more subsidence than the younger patients in both groups, the placebo and the zoledronic [acid] groups,” he added.
A Danish doctor in the audience asked Friedl whether he ordered DEXA scans for the patients studied, since it would be interesting to see if those results correlated with implant status.
“No, we did not because it has not been shown that there is a relationship between the bone quality and excellence and the implant movement,” he replied.
- Friedl G, Aigner R, Radl R, et al. Viability of a single infusion of zoledronic acid (ZOL) to reduce implant failure rate in THA — Results from a randomized, double-blind, controlled trial. Paper F595. Presented at the 10th EFORT Congress. June 3-6, 2009. Vienna.
- Friedl G, Radl R, Stihsen C, et al. The effect of a single infusion of zoledronic acid in early implant migration in total hip arthroplasty. A randomized, double-blind, controlled trial. J Bone Joint Surg Am. 2009;91(2):274-81.