Interspinous devices offer a treatment option for individuals experiencing persistent back and leg pain due to certain spinal conditions. These small, implantable devices alleviate discomfort by addressing issues within the lower back. Their purpose involves creating more space in the spinal column, which can reduce pressure on nerves and improve comfort and mobility.
Understanding the Interspinous Device
An interspinous device is a small implant placed between the spinous processes, the bony projections of the vertebrae in the lower back. These devices are made from various materials, including titanium, silicone, or polyetheretherketone (PEEK). Designs vary, including U-shapes with wings or static spacers. They primarily treat lumbar spinal stenosis, a narrowing of the spinal canal in the lower back. This narrowing compresses spinal nerves, causing pain and numbness.
How Interspinous Devices Function
Interspinous devices distract or gently separate the spinous processes of adjacent vertebrae. This separation limits spinal extension (backward bending) at the treated level. This increases space within the spinal canal and neural exit foramen, where nerves exit the spine. Pressure on compressed nerves is relieved, alleviating symptoms like leg pain, numbness, and weakness that worsen with spinal extension. Some devices are static spacers, providing consistent distraction, while dynamic or flexible devices act as shock absorbers during spinal movement.
The Implantation Procedure
Implanting an interspinous device is a minimally invasive surgical procedure. It is often performed under local anesthesia with sedation, or general anesthesia. A small incision, about 1 inch long, is made in the middle of the lower back.
Through this incision, the surgeon uses fluoroscopic guidance (real-time X-ray imaging) to accurately position the device between the spinous processes. A sizing distractor may create space before device insertion. The procedure takes 15 to 90 minutes, depending on the number of devices implanted. Patients typically have a short hospital stay, often discharged the same day or within 24 hours.
Patient Considerations and Expected Outcomes
Patient selection for interspinous devices involves individuals with moderate lumbar spinal stenosis who experience neurogenic claudication (leg pain that improves with bending forward). Candidates have not found sufficient relief from conservative treatments like physical therapy or medication for at least six months. The devices are not suitable for severe stenosis, significant spinal instability, or severe osteoporosis.
Patients can expect improvement in symptoms like leg pain and numbness, with some experiencing immediate relief. While often effective, potential complications include infection, device migration or dislocation, or spinous process fracture. These are relatively uncommon. In some instances, patients might not experience adequate pain relief or symptoms could recur, potentially requiring further surgery.