Correct diagnosis of sacroiliac joint (SIJ) pain is notedly difficult. Aside from cases of spondyloarthropathy-related sacroiliitis or SIJ trauma, it is rarely possible to confirm SIJ pain using changes seen on imaging. With so many cases of unconfirmed SIJ pain, it has been challenging to fairly evaluate therapeutic use of SIJ injections (local anesthetic plus corticosteroid).
New research suggests that earlier studies have undervalued the efficacy of SIJ injections for true SIJ pain. “In the past, skeptics may have argued that SIJ injections just aren’t a good treatment,” said Byron Schneider, M.D., an assistant professor in physical medicine and rehabilitation at Vanderbilt University Medical Center. “But the results of SIJ injections change significantly if you establish a higher level of scrutiny to identify patients who really do have SIJ pain.”
Connecting Anesthetic Response and Subsequent Pain Relief
In a study at Stanford University co-led by Schneider and David J. Kennedy, M.D., also now at Vanderbilt, 26 patients with suspected pain originating from the SIJ (pain rated 4 or higher on the 0-10 numerical rating scale, or NRS) received fluoroscopically confirmed injections of anesthetic and corticosteroid in the SIJ joint. After one patient was withdrawn (due to imaging challenges), 11 of 25 patients had immediate 100 percent relief post-injection. When considering 80 percent relief or greater or 50 percent relief or greater, the numbers increased to 13/25 and 18/25 patients, respectively.
The study found that pain relief at two and four weeks demonstrated the high predictive value of initial positive response to later effects of the corticosteroid. While only 4 of 25 patients reported 100 percent pain relief at two and four weeks, the proportion increased to over half (6 of 11 patients) in those with an initial 100 percent relief response to injection.
Patients were also assessed for functional improvement using the Oswestry Disability Index (ODI). As with NRS, patients responding to injection with initial improvement of 15 points or more in the ODI were also more likely to show functional improvement at two and four weeks.
“After pinpointing those with strong evidence of true SIJ pain, we found the evidence for injections looks much better.”
“This was the first study to quantify positive predictive value and negative predictive value, sensitivity, and specificity of the anesthetic response to an SIJ injection and subsequent relief,” Schneider said. “After pinpointing those with strong evidence of true SIJ pain, we found the evidence for injections looks much better.”
Better Diagnosing Joint Pain
Schneider and colleagues are continuing their research into how SIJ pain can be diagnosed more accurately – and which steroid therapies may be most effective. “One of our current studies examines how patients with 80 percent or more pain relief after the anesthetic phase of their injection will respond to different types of steroids,” Schneider said.
“We’re also interested in modeling how to better treat patients with a negative response to the anesthetic,” Schneider said. “It may be possible to develop an algorithm for identifying other related structures to the SIJ that are the source of those patients’ pain. While these patients don’t need an intraarticular injection, they do need an effective procedure.”
Given limited screening value to physical exams, Schneider believes response to anesthetic will remain one of the most effective and affordable options to diagnose SIJ pain. Ideally, this could mean administering more anesthetic-only injections as a diagnostic step. “I would argue we probably should be doing that more in the U.S.,” Schneider said. “However, the high value placed on patient satisfaction and insurance policies that limit injections per year are driving against that approach.”
“In coming years, we need to continue efforts to better treat patients, but we also need improved coverage policies and guidelines where there is solid evidence. Both elements are part of ensuring the right patients receive the right treatments,” Schneider said.