Axial loading during MRI reveals insufficient effect of percutaneous interspinous implants (Aperius™ PerCLID™) on spinal canal area

Purpose To evaluate the effect on the spinal canal at the treated and adjacent level(s), in patients treated for lumbar spinal stenosis (LSS) with percutaneous interspinous process device (IPD) Aperius™ or open decompressive surgery (ODS), using axial loading of the spine during MRI (alMRI). Materials Nineteen LSS patients (mean age 67 years, range 49–78) treated with IPDs in 29 spine levels and 13 LSS patients (mean age 63 years, range 46–76) operated with ODS in 22 spine levels were examined with alMRI pre- and 3 months postoperatively. Radiological effects were evaluated by measuring the dural sac cross-sectional area (DSCSA) and by morphological grading of nerve root affection. Results For the IPD group, no DSCSA increase was observed at the operated level (p = 0.42); however, a decrease was observed in adjacent levels (p = 0.05). No effect was seen regarding morphological grading (operated level: p = 0.71/adjacent level: p = 0.94). For the ODS group, beneficial effects were seen for the operated level, both regarding DSCSA (p < 0.001) and for morphological grading (p < 0.0001). No changes were seen for adjacent levels (DSCSA; p = 0.47/morphological grading: p = 0.95). Postoperatively, a significant difference between the groups existed at the operated level regarding both evaluated parameters (p < 0.003). Conclusions With the spine imaged in an axial loaded position, no significant radiological effects of an IPD could be detected postoperatively at the treated level, while increased DSCSA was displayed for the ODS group. In addition, reduced DSCSA in adjacent levels was detected for the IPD group. Thus, the beneficial effects of IPD implants on the spinal canal must be questioned. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Controversies about Interspinous Process Devices in the Treatment of Degenerative Lumbar Spine Diseases: Past, Present, and Future

A large number of interspinous process devices (IPD) have been recently introduced to the lumbar spine market as an alternative to conventional decompressive surgery in managing symptomatic lumbar spinal pathology, especially in the older population. Despite the fact that they are composed of a wide range of different materials including titanium, polyetheretherketone, and elastomeric compounds, the aim of these devices is to unload spine, restoring foraminal height, and stabilize the spine by distracting the spinous processes. Although the initial reports represented the IPD as a safe, effective, and minimally invasive surgical alternative for relief of neurological symptoms in patients with low back degenerative diseases, recent studies have demonstrated less impressive clinical results and higher rate of failure than initially reported. The purpose of this paper is to provide a comprehensive overview on interspinous implants, their mechanisms of action, safety, cost, and effectiveness in the treatment of lumbar stenosis and degenerative disc diseases.

SURGICAL TREATMENT OF LUMBAR SEGMENT DISEASE WITH INTERSPINOUS IMPLANT: REVIEW

Interspinous implants (ISP) represent a contemporary non-fusion surgical option in the treatment of lumbar segment disease. Several devices have been developed within the last two decades and have been variously supported by investigations into their clinical and biomechanical efficacy. Spinal stenosis and facet arthropathy are reported as the primary clinical indications for their use, with degenerative disc disease and segmental instability recently extending their application. The principle common to all interspinous systems is an induced distraction of the interspinous space, resulting in reduced approximation of pain-sensitive and space-occupying tissue. Collectively, these devices are considered to prevent adjacent segment overload by restoring physiologic load transmission. This review article summarizes existing published literature, describes four different interspinous implants — the DIAM, Wallis, X-Stop and Coflex systems, and outlines clinical trials in progress. The design and surgical technique characteristics, mechanism of action, and clinical indications for interspinous implants are reviewed. Recommendations for future research of interspinous implants in the treatment of lumbar segment disease are made.