For those experiencing lower back pain, the array of treatment options may seem daunting.
There's physical therapy, medication and surgery, which is a worst-case scenario for many. And what kind of surgery? Fusing bone together to stabilize the vertebrae? Inserting an artificial disk through the abdomen in a procedure that involves carefully bypassing some of the body's most critical organs?
Phoenix mail carrier Rebecca Neal faced that very conundrum. The 39-year-old mother of twins felt a stabbing pain in her lower back while routinely pushing her mail cart in late 2005.
The diagnosis was a herniated disk, and Neal's quality of life quickly tumbled into a drug-filled haze of pain. She couldn't shave her legs, get out of the car or even lie in bed without feeling like her back was being plundered by an ice pick -- never mind tending to her active toddlers.
Instead of opting for standard surgical treatments, she enrolled in a clinical trial sponsored by Eden Prairie-based Disc Dynamics Inc., testing a device that removes the damaged disk and replaces it with a supple polymer implant in a minimally invasive procedure.
The Dascor system, which is available commercially in Europe, is not yet approved for use in the United States. The privately held company recently enrolled 20 patients, including Neal, in a nationwide clinical trial.
They are being followed for two years after surgery.
If that trial is successful, Disc Dynamics will begin a pivotal study of 350 patients next year before seeking approval from the Food and Drug Administration (FDA) to sell the device in the United States. If all goes well, the company hopes to gain FDA approval in 2010. So far, the company says early results from the pilot study are promising. Two months after surgery with the Dascor device, Neal is back at work, walking 5 miles a day, as well as "stooping, lifting, squatting and reaching."
Local roots
The basic idea behind the Dascor system dates to the days of SpineTech, an Edina company that pioneered various devices such as rods, screws and cages used in back surgery.
The Dascor technology languished within SpineTech for several years. "We just didn't have the time or the money to work on it," recalled Dave Stassen, who headed SpineTech at the time. "So it sort of floated away."
SpineTech was sold to a Swiss company in 1998 for $600 million, and Stassen went on to help found the venture capital firm Split Rock Partners. But he never forgot the promise of the Dascor technology, and the potential market for surgical alternatives to treat degenerative disk disease.
Disc Dynamics was founded in 2000 to develop the Dascor technology and has received $65 million from private and venture capital investors. Stassen's Split Rock Partners invested about $10 million in the company, which hired Steven Healy, a veteran of St. Jude Medical Inc., as president and CEO.
The National Institutes of Health estimates that 70 to 85 percent of Americans will experience back pain at some point in their lives. Back pain is the most common reason for time taken off work, and the second most common reason -- after colds -- for a visit to the doctor's office.
The potential market for devices and related biologics treating back maladies is estimated to be $4.1 billion in the United States this year, and is expected to grow 20 percent annually, according to Disc Dynamics' projections.
Deteriorating disks
Disks in the spine are flexible spacers between the bony vertebrae that can deteriorate from injury or aging. Each disk has a fibrous outer rim called the annulus, which helps with stability, twisting and bending. The disk's nucleus provides a needed cushion for the back.
When the nucleus deteriorates, the disks can rub against one another or nerves and cause intense back and leg pain. The Dascor system uses a series of catheters to drill through the outer rim of the disk and remove the diseased nucleus, which has the consistency of a lump of crabmeat.
Another catheter is inserted into the pencil-sized hole with a balloon, which is inflated and filled with a liquid polymer substance that cures into a supple implant, acting as a cushion between the two disks.
"Basically, it's like reinflating a flat tire," Stassen said.
The key to the Dascor surgery is that it is minimally invasive -- a surgeon reaches the spine from the front or side through a small incision. The procedure typically lasts 85 minutes and involves a hospital stay of a day and a half. Other types of back surgery can last several hours and involve a hospital stay of two to five days.
For surgeons such as Dr. Christopher Yeung, of the Arizona Institute of Minimally Invasive Spine Care, the Dascor system offers patients an alternative to more serious surgeries, which are irreversible. If Dascor doesn't work, then fusion or disk replacement surgery can be used. Yeung sees Dascor as a particularly attractive option for younger patients -- in their 30s and 40s -- who want to stay active.
Yeung treated five of the 20 patients in the Dascor study, which did not involve any subjects from Minnesota. So far, he's pleased with the results. He said he envisions a day when some surgeries are out-patient procedures.
About 10 firms are working on technologies to replace the disk's nucleus, Stassen said. Some inject substances that may migrate to other areas of the body, others are preformed implants presenting the challenge of creating an opening large enough to insert the device, challenging the ideal of minimally invasive surgery.
Many surgeons -- and patients -- clearly are ready for an alternative, said Dr. Mahmoud Nagib, a neurosurgeon at Neurosurgical Associates at Abbott Northwestern Hospital, who is not involved with Disc Dynamics' study. Existing surgical alternatives work well, but "if we have something new that can be as minimally invasive as possible, that is something attractive to think about."