Do Bisphosphonates Affect Fusion Rates in Osteoporotic Patients?

The answer to that question, if you check the literature, is mixed, according to a team from the Keck School of Medicine at the University of Southern California in Los Angeles. A new study helps to bring clarity to this question.

Their study, “The impact of bisphosphonates on postoperative complication rates in osteoporotic patients undergoing posterior lumbar fusion,” was published in the January 4, 2021 edition of the European Spine Journal.

Jeffrey Wang, M.D., chief of the Orthopaedic Spine Service at the Keck School of Medicine, University of Southern California in Los Angeles explained the genesis and purpose of this important study to OTW, “We are always concerned when patients with osteoporosis require spinal surgery, especially when they need a fusion that requires the placement of instrumentation and bone healing. We knew that these patients were at higher risk, and many surgeons will discuss a potentially higher complication rate in terms of fixation failure and/or ultimate fusion outcomes.”

“In an effort to improve bone quality, we will often postpone surgery and use medications that could improve the bone quality, prior to performing that surgery. We wanted to quantify in a large database, the potentially increased risks of spine surgery in these patients who were taking bisphosphonates to further characterize the potential for increased complications, when performing posterior lumbar surgery.”

Using the Pearl Diver Patient Record Database (over 76 million patient records) the team searched for adults who had undergone posterior lumbar fusion. Using diagnostic codes, these patients were divided into groups based on a preoperative diagnosis of osteoporosis. This resulted in three groups: patients with osteoporosis taking bisphosphonates, patients with osteoporosis not taking bisphosphonates, and patients with no prior diagnosis of osteoporosis not taking bisphosphonates.

A surprised Dr. Wang told OTW, “I expected to find an increased complication rate, however, we did not find a statistically significantly higher rate of complications overall in patients either taking bisphosphonates, or those with osteoporosis, having a lumbar fusion surgery. The power of the study was the use of large numbers of potential patients in a large database. The weakness is the lack of patient-specific information, so the results need to be taken in the appropriate context.”

“I think this tells us in a large database of patients, that in general, these patients do not have an overall increased complication rate with posterior lumbar spinal surgery. However, this could be the result of careful planning, choosing the appropriate surgery, and perhaps limiting the surgery. These smaller details are the ones that we will not sort out as well with the use of larger databases. However, the power of a large database is the large pool of potential patients, which can give us trends when comparing patients characteristics.”

When OTW asked might future research might proceed, Dr. Wang noted, “We definitely need further research in this area, in the form of smaller but with more detailed data, to fully understand the increased risks involved with surgery in this patient population. We also need to delve into the individual characteristics of the patients, to really understand the increased risks, and how to mitigate these risks in this patient population.”