Medical Student Oregon Health and Science University Portland, Oregon, United States
Introduction: Interspinous process devices (IPDs) were first developed as a minimally invasive alternative to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates in earlier studies, there has been minimal adoption by the spine surgery community. In contrast, an increasing number of proceduralists, such as pain specialists, have started incorporating IPD into their clinical practice. No studies to date have attempted to clarify nationwide trends in utilization and postoperative outcomes following IPD implantation. Here, we leveraged a national claims database to examine the patient characteristics associated with IPD insertion and assess reoperation rates.
Methods: Using the PearlDiver database of 151 million longitudinally followed patients, we identified all patients who underwent one or two-level IPD implantation between 2010 and 2018 without previous spinal decompression. Patients were stratified by type of device inserted (one vs. two-level) and whether they required subsequent reoperation. Demographic and clinical variables between patient strata were compared using T-tests and Chi-squared tests. Logistic Regression was performed to identify predictors of IPD type (one vs. two-level) and reoperation. A right-censored Kaplan Meier (KM) curve was plotted for durations of reoperation free survival. All statistics were performed using R with a significance threshold of α = 0.05.
Results: We identified 2,343 patients that were implanted with either one (n=996) or two-level (n=1,347) IPDs. Patients who were older (OR, 1.03, 95% CI, 1.02-1.04, p< 0.001), male (OR, 1.25, 95% CI, 1.05-1.49, p=0.014), and obese at time of surgery (OR, 1.21, 95% CI, 1.01-1.44, p = 0.035) were significantly more likely to receive a two-level IPD versus a single-level IPD. Older age was the only variable associated with reoperation, exerting a significant protective effect against reoperation following IPD implantation (OR, 0.97, 95% CI, 0.95-0.99, p< 0.001). Interestingly, the median reoperation free survival time could not be determined as less than 5% of all patients (n=127) required reoperation by the 3-year postoperative mark.
Conclusion : Our results indicate that the rate of reoperation following IPD implantation may be lower than previously reported. Improvements in technology and patient selection may have led to a decrease in reoperations compared to prior studies.
