Standalone interspinous process devices for lumbar spinal stenosis: a critical literature review

Interspinous process devices (IPDs) have been widely promoted as a minimally invasive alternative to traditional decompressive surgery for lumbar spinal stenosis (LSS). However, their clinical durability, safety, and comparative effectiveness have remained controversial. This review aims to review and synthesize the biomechanical rationale, clinical outcomes, safety profile, and limitations of IPDs for the treatment of LSS. A literature review was conducted using PubMed for clinical studies published between 2000 and 2025 on IPDs. These studies were further categorized by device design, indication, and surgical approach: non-fusion/motion-preserving, fusion/stand-alone, and hybrid/dynamic stabilization. Biomechanical studies demonstrate that IPDs can consistently increase canal and foraminal dimensions, selectively restrict lumbar extension, and reduce extension-related intradiscal and facet joint pain while preserving motion in other planes. Clinically, short-term improvement was shown particularly in patients with posture-dependent moderate LSS. However, the durability of benefit varies across devices, and several comparative trials and registry-based analyses display higher reoperation and revision rates compared to conventional decompressive surgery. The most commonly reported complications include device migration/malposition and spinous process fractures, leading to revision procedures. Another prevalent issue is the amount of industry funding among IPD studies, which can also influence reported outcomes. IPDs may provide short-term symptomatic relief for selective patients with LSS, but tend to be associated with variable durability and risks of reintervention. However, long-term benefits in pain, function, or quality of life are currently unclear. Structural correction or indirect decompression alone does not reliably lead to symptomatic relief, especially in patients with chronic radiculopathy or central sensitization. Future studies should consist of large randomized controlled trials that are independently funded to determine comparative effectiveness and optimal patient selection.