Effectiveness of Interspinous Process Devices in Managing Adjacent Segment Degeneration Following Lumbar Spinal Fusion: A Systematic Review and Meta-Analysis.

Adjacent segment degeneration (ASD) is a significant complication following lumbar spinal fusion, often necessitating further surgical interventions and impairing patient outcomes. Interspinous process devices were introduced as an alternative treatment for spinal stenosis and degenerative spondylolisthesis and can potentially reduce the incidence of ASDd. This systematic review and meta-analysis aims to evaluate the effectiveness of interspinous process devices or IPDs in managing ASD following a previous spinal fusion compared to traditional fusion techniques. Electronic databases, including PubMed, Embase, and the Cochrane Library, were queried for studies assessing IPDs against traditional lumbar fusion methods for managing ASD after previous lumbar fusion, which had been published between January 2014 and the present. Statistical analysis was conducted using Review Manager 5.4. Seven retrospective cohort studies involving 546 patients met the inclusion criteria. The analysis revealed that IPDs were associated with a statistically significant reduction in the incidence of ASD (OR = 0.28, 95% CI: 0.16 to 0.51, < 0.0001, and I = 0% after excluding outliers). The ODI demonstrated a non-significant trend towards improved outcomes with IPDs at the 2-year follow-up (SMD = -3.94; 95% CI: -11.72 to 3.85). Range of motion (ROM) was better preserved with IPDs compared to fusion (SMD = 0.00, 95% CI: -0.41 to 0.41, = 1.00, I = 60%). The visual analogue scale or VAS lower back pain scores were significantly reduced at the 2-year follow-up (SMD = -0.69, 95% CI: -1.18 to -0.19, = 0.006, and I = 74%). VAS leg pain showed consistent improvements (SMD = -0.29; 95% CI: -0.63 to 0.04). Intraoperative blood loss was significantly lower with IPDs (SMD = -2.07; 95% CI: -3.27 to -0.87, = 0.0007, and I = 95%), and operation times were shorter (SMD = -2.22, 95% CI: -3.31 to -1.12, < 0.0001, and I = 94%). The judicious use of IPDs might benefit a subset of patients, particularly those who are not suitable candidates for major corrective surgery.