Patients who receive a device called the X-STOP® for the treatment of lumbar spinal stenosis usually have mild to moderate symptoms of back and/or buttock and leg pain. The X-STOP® is a metal implant made of titanium. It is designed to fit between the spinous processes of the vertebrae in the lower back. It stays in place permanently without attaching to the bone or ligaments in your back.
There are several advantages of the X-STOP®. It can be inserted using local anesthesia on an outpatient basis. A small incision is made so the procedure is minimally invasive and no bone or soft tissue is removed.
The implant is not close to nerves or the spinal cord. With the implant in place, you won’t have to bend forward to relieve your symptoms (like you did before surgery). The X-STOP® keeps the space between your spinous processes open. With the implant in place, you stand upright without pinching the nerves in your back.
If you experienced pain relief at first and are now having increased pain, it’s probably a good idea to see your orthopedic surgeon right away. Although there may be nothing wrong, some complications such as the implant shifting, sinking down into the bone, or breaking are possible.
There are also reports from some patients of increased pain associated with fracture of the spinous process after X-STOP® implantation. The spinous process is the piece of bone that sticks out behind the vertebra. It is the bump you feel down the back of your spine. A recent study from Tufts University School of Medicine reported a 52 per cent rate of spinous process fractures in patients with lumbar stenosis AND another condition called spondylolisthesis.
Spondylolisthesis describes a condition in which one lumbar vertebra has slipped forward over the vertebra below. This slippage causes a narrowing of the spinal canal and traction (pulling) on the nerve tissue. Although their study was small (only 39 patients), the high rate (52 per cent) of spinous process fractures after X-STOP® implantation was significant.
The surgeons aren’t exactly sure why spondylolisthesis would increase the risk of fracture. They suspect that the change in alignment with the vertebra shifted forward may have something to do with it. The contact points (where the implant rests against the spinous process) may be further back in patients with spondylolisthesis. This placement is against a weaker part of the spinous process contributing to fracture.
If the surgeon suspects a fracture, you will need a CT scan as this type of fracture does not show up on X-rays. But don’t jump to any immediate conclusions that your pain is caused by any of these suggestions. They are merely ideas of things that can cause increased pain after this procedure. A full evaluation is necessary to make an accurate diagnosis.