New technology in the spine market is expanding faster than the size of the universe. There are three main areas of focus.
1. Interspinous process devices. These devices treat lumbar spinal stenosis; they are placed between the spinous processes to separate the bones and indirectly decompress the stenotic lumbar spinal canal. Lumbar spinal stenosis produces the symptoms of intermittant neurogenic claudication, which usually appears in elderly patients and is clinically characterized by difficulty with prolonged standing and walking, relief upon sitting down, and improvement in symptoms with lumbar spinal flexion (the so-called shopping cart position).
These new devices are a hot topic at the national spine meetings and are attracting much enthusiasm and financial support. Clinically, the only device that’s currently FDA-approved is the X-Stop produced by Kyphon, which was recently acquired by Medtronic Danek for $3.9 billion (yes, with a B). This company’s only other product is the Kyphoplasty Balloon, which is used to expand osteoporotic compression fractures in the elderly.
These interspinous process devices are being marketed as “minimally invasive” in that they typically require only a 1-in. incision and are completed in less than 30 minutes. The brochure describes performing the surgery under local anesthesia, although I don’t know of anyone who does this. The technique involves separating the paraspinal muscles down to the level of the lamina, inserting the device between the bones and securing it with a fixation wing.
Other companies are trying to develop percutaneous devices, but none have sought FDA approval. Within 36 months, I expect there to be three to six devices that will be the second generation of this technology.
2. Artificial cervical disc. Cervical degenerative arthritis is a very common clinical problem, and artificial cervical disc technology stands to offer significant treatment options for people who suffer from cervical radiculopathy. The current standard of care for a cervical herniation involves and anterior cervical discectomy and fusion, usually using a plate and allograft. In 2007, a cervical disc was approved by the FDA for use. A recent prospective randomized trial comparing a cervical fusion to the cervical artificial disc demonstrated similar clinical improvements by the two treatments. The hope is that long-term studies will prove that preservation of motion will lessen the wear and tear on the discs next to the surgical area; this may take a decade to prove.
The cervical disc may have difficulty gaining approval from private payers, since the technology is theoretically related to its cousin, the artificial lumbar disc. The lumbar disc had high expectations when it was launched in 2005, but estimates about its sales volume were off by 90 percent. Insurance companies simply are not allowing patients to have access to this lumbar technology, and I’m not sure they will allow access to cervical discs, citing concerns about long-term durability and use.
• Dynamic spine stabilization devices. Finally, the issue of dynamic stabilization of the spine must be mentioned in this discussion. I admit have great difficulty discussing this topic with enthusiasm, because I do not believe in the technology or in the language used to support its use. Basically, the technique consists of surgeons’ placing elastic devices after decompressions to stabilize the motion segment but not fuse it — they use the term “soft fusion.” While this topic has garnered a lot of press and titled many meetings, I don’t think it will come to fruition as widespread clinical practice. In fact, a recent article in the journal Spine discredited its use after follow-up studies evaluated the high frequency of post-op device complications.
Dr. Abraham (abrahamatrnsc@aol.com) is a spine surgeon at the Reading Neck and Spine Center in Wyomissing, Pa.