Osteoporosis Drugs May Prolong Life of Joint Implants

http://www.medpagetoday.com/Surgery/Orthopedics/30070?utm_content=&utm_medium=email&utm_campaign=DailyHeadlines&utm_source=WC&eun=g273261d0r&userid=273261&email=netfrenzy2000@yahoo.com&mu_id=

By John Gever, Senior Editor, MedPage Today Published: December 07, 2011 Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

Action Points   Explain that patients taking bisphosphonates after hip or knee replacement surgery were only half as likely to need revision procedures within five years compared with patients not receiving the drugs. Point out that the study also found that bisphosphonates' apparent protective effect was somewhat stronger for knee replacements compared with hip implants, and that the effect was even more pronounced for patients with osteoarthritis. Patients taking bisphosphonates after hip or knee replacement surgery were only half as likely to need revision procedures within five years as were patients not receiving the drugs, a review of British registry data found. Among some 42,000 patients undergoing primary hip or knee arthroplasty from 1986 to 2006, 0.93% of those taking bisphosphonates had revision surgery within five years versus 1.96% of other patients in the U.K. General Practice Research Database (hazard ratio 0.54, 95% CI 0.29 to 0.99, P=0.047), reported Nigel K. Arden, MD, MSc, of the University of Oxford in Oxford, England, and colleagues. The researchers calculated that treating 107 arthroplasty patients with bisphosphonates would prevent one patient from needing revision, according to their online report in BMJ. Arden and colleagues also found that bisphosphonates' apparent protective effect was somewhat stronger for knee replacements versus hip implants. The effect was even more pronounced for patients with osteoarthritis, they indicated. But they stopped short of recommending that bisphosphonate treatment be included in routine patient management. "If these findings are replicated in other observational cohorts, a randomized clinical trial is needed to test the efficacy and cost effectiveness of bisphosphonate use at or before the time of surgery to improve implant survival and reduce fracture risk," the researchers wrote. They also suggested that future studies attempt to pin down patient subgroups likely to benefit most from the treatment. Because bisphosphonates inhibit bone resorption, it has been suggested that they may delay or prevent remodeling of the bone that holds joint implants in place. Arden and colleagues noted that clinical trials have been performed with differing results. None of those, however, used subsequent revision as the primary outcome measure. In the current study, Arden and colleagues searched the British registry data for patients undergoing total arthroplasty of the hip or knee, initially identifying 48,453. About 6,500 of these were excluded because they had diagnoses of rheumatoid arthritis, were younger than 40, or had suffered a hip fracture before the replacement procedure. Just over half of the remaining 41,995 had hip or knee replacements. Median follow-up in the study was 3.5 years (interquartile range 1.6 to 6.3). Overall, 1,912 of the arthroplasty patients had taken bisphosphonates with a median duration of treatment of 3.07 years (interquartile range 1.65 to 5.20). The median time from first bisphosphonate prescription to primary surgery was 11.8 months (14.5 months before surgery to 39.5 months after). Among those with hip arthroplasties, bisphosphonate treatment was associated with moderately lower rates of revision at some point during follow-up -- 0.8% in users versus 1.3% in nonusers. In the knee replacement group, 0.3% of users had revision surgery at some point compared with 1.2% of nonusers. Arden and colleagues also constructed a model that adjusted for the likelihood that a patient would be prescribed bisphosphonates, on the basis of age, sex, and other factors known to be associated with bisphosphonate usage. It yielded the following hazard ratios for revision overall and in three major patient subgroups: Overall: HR 0.54 (95% CI 0.29 to 0.99) Knee replacements: HR 0.40 (95% CI 0.15 to 1.07) Hip replacements: HR 0.64 (95% CI 0.32 to 1.28) Diagnosed with osteoarthritis: HR 0.40 (95% CI 0.17 to 0.93) The researchers noted that, with only 11 revision procedures performed on bisphosphonate users in the study (eight hips, three knees), it was underpowered for these subgroup analyses. Other limitations included unmeasured potential confounders and the use of incomplete and possibly inaccurate registry data. In particular, the data did not specify the laterality of surgery, so it was possible that some "revisions" were actually primary procedures on the contralateral joint. But Arden and colleagues argued that their analysis probably had few such errors, because the overall revision rates they calculated were similar to those seen in more comprehensive data sets. The study was funded primarily by the U.K. National Institute for Health Research. Several authors including Arden reported consulting fees, research grants, and/or other payments from Novartis, Alliance for Better Health, Lilly, Merck, Roche, Novartis, Smith and Nephew, Q-MED, NicOx, Servier, GlaxoSmithKline, Schering-Plough, Pfizer, Rottapharm, and Amgen.

Primary source: BMJ Source reference: Prieto-Alhambra D, et al "Association between bisphosphonate use and implant survival after primary total arthroplasty of the knee or hip: population based retrospective cohort study" BMJ 2011; DOI: 10.1136/bmj.d7222.