Development of percutaneously insertable/removable interspinous process spacer for treatment of posture-dependent lumbar spinal-canal stenosis: preclinical feasibility study using porcine model

Abstract

Purpose A procedure using an interspinous process spacer (IPS) was recently developed for the treatment of posture-dependent lumbar spinal-canal stenosis (LSS) patients. We developed a novel IPS which can be inserted with simpler procedures and removed percutaneously. The objectives of this study were: (1) to evaluate the feasibility and safety of this novel technique, and (2) to assess the effectiveness of this spacer in terms of preventing an increase of epidural pressure in lumbar extension using a porcine model. Methods Eight young pigs were used. Under general anesthesia and image guidance, the spacers were inserted. Three months after operation, MR images were taken and all spacers were removed. Blood samples were obtained before and 1, 3, 7 days after surgery. After killing the animals, the lumbar spines were observed macroscopically. Another six animals were used. Under general anesthesia and image guidance, a flexible pressure transducer was inserted into the epidural space and epidural pressure was measured in neutral and at maximum extension with and without spacer insertion. Results Percutaneous insertion and removal of the spacer was successful for all animals through small skin incisions. MR images showed minimal damage to the muscle.No significant up-regulation of Interleukin-6 (IL-6) and CRP was detected. Macroscopic observation of the lumbar spine 3 months after the operation revealed that the area of the interspinous process contacting with the inserted spacer showed some bone erosion/remodeling. Insertion of the spacer did not affect the epidural pressure in neutral but significantly prevented an increase of epidural pressure in lumber extension. Conclusions This study demonstrated that the percutaneous insertion and removal of a novel IPS was feasible and safe using a simple technique. Furthermore, this procedure can be recognized as minimally invasive surgery from the viewpoint of skin incision, short insertion track, inflammatory mediators, and muscle damage. Improvements should be attempted in future studies using softer or more elastic materials for the spacer to lessen bone erosion/ remodeling at contacting area of the inserted spacer.

Successful use of percutaneous interspinous spacers and adjunctive spinoplasty in a 9 year cohort of patients

“…LSS is also a disease of the elderly who inherently carry a greater anesthetic risk. Minimally invasive and percutaneously inserted interspinous spacers have been shown to be both non-inferior in terms of patient outcomes and to have decisive benefits in terms of operating times and blood loss 2–26. This cohort of patients, the largest in a single study, confirms the existing cited literature which shows improvement in patient symptomatology and function after interspinous spacer insertion.…”

“…Interspinous spacers or percutaneous interspinous devices (PID) have been developed as an alternative, less invasive therapy. These devices are designed to be inserted between two adjacent spinous processes using either minimally invasive surgical techniques or percutaneous image guidance 5. They then act, in conjunction with the intact interspinous ligament and paravertebral muscles, to prevent excessive lordosis in the spine, mimicking the way patients relieve their symptoms with forced flexion 6.…”

Posterior Arch Augmentation (Spinoplasty) before and after Single and Double Interspinous Spacer Introduction at the Same Level: Preventing and Treating the Failure?

“…Chronic radicular nerve ischaemia secondary to radicular vein compression related to spinal canal and/or foraminal stenosis is generally advocated as the cause of the symptoms, and posterior arch distraction frequently offers a solution to the disease, according to several biomechanical studies [2][3] .…”

“…Lumbar spinal canal stenosis (LSCS) is one of the most common degenerative diseases in elderly patients, generally responsible for neurogenic claudication, numbness and weakness to the lower limbs, finally leading to paraparesis 1 . Chronic radicular nerve ischaemia secondary to radicular vein compression related to spinal canal and/or foraminal stenosis is generally advocated as the cause of the symptoms, and posterior arch distraction frequently offers a solution to the disease, according to several biomechanical studies [2][3] .…”