Osteoporosis is a disease that affects more than 24 million Americans. It results in progressive mineral loss from the bone and changes within the bony architecture, leaving the bones weakened structurally and therefore more subject to fractures.

The vertebral bodies, as a major load bearing structure, are particularly prone to fracture. There are an estimated 700,000 osteoporotic vertebral compression fractures in the United States each year. As many as 1/3 of these will become chronically painful. Eighty-five percent of these fractures are due to primary osteoporosis. These fractures can lead to progressive spinal deformity, causing changes in spine biomechanics contributing to increased risk of further fracture at adjacent levels or progressive malalignment, deformity, and pain. Mortality may be increased as much as 30% in patients with osteoporotic vertebral compression fractures.

Vertebral compression fractures secondary to osteoporosis usually occur after minor trauma or spontaneously. There is usually an acute onset of severe back pain. This back pain, depending on the severity of the fracture, can be mild to severely debilitating. Traditional treatment has been bed rest, pain medication and bracing. Reconstructive surgery has been traditionally reserved for patients with incapacitating pain or patients with loss of neurologic function. Surgery is considered an option of last resort, not only because vertebral compression fractures generally affect patients of advanced age, but also because of the high failure rates of reconstructive surgeries in patients with severe osteoporosis.

In addition to severe pain, vertebral compression fractures frequently cause malalignment of the spine. This has numerous consequences. Any change in alignment leads to abnormal biomechanical forces influencing the rest of the spine. This can lead to further malalignment of the entire spine. Malalignment puts unusual stresses on muscles, tendons, ligaments, and bones throughout the spine. Malalignment and pain can also lead to significant problems with balance or with walking ability and therefore reduce overall levels of activity. Decreased activity can lead to numerous additional medical problems.

Vertebroplasty, first described in 1987, involves the forced injection of a low viscosity polymethylmethacrylate cement into the closed space of a vertebral body. Once polymethylmethacrylate solidifies, it adds significant structural strength to the vertebral body. This added strength is very successful at reducing pain secondary to vertebral compression fractures.

Several problems exist with the vertebroplasty technique. First, the technique makes no attempt nor accomplishes any restoration of normal alignment of the spine. The polymethylmethacrylate hardens and stabilizes the bone in the abnormal configuration that exists after the fracture. Also, the injection of polymethylmethacrylate needs to be performed under high pressure to allow infiltration of the entire vertebral body with the cement. This high-pressure injection can lead to extravasation or “leaking” of the polymethylmethacrylate out of the vertebral body, into spaces around the vertebral body including the spinal canal. Equally as concerning is the possibility that the polymethylmethacrylate could exit the vertebral body via the venous drainage of vertebral bodies and enter into the large veins returning blood to the heart and lungs. This has been described, and when it occurs, the polymethylmethacrylate can become lodged in the lungs and lead to pulmonary compromise and potentially death.

Kyphoplasty is a new technique recently described that involves an introduction of a cannula into the vertebral body followed by the insertion of an inflatable balloon. The balloon is inflated within the vertebral body. When the balloon is inflated, it creates a space within the center of the vertebral body for the injection of polymethylmethacrylate. (See images below.) In addition, the inflation of the balloon itself can also lead to some increase in the vertebral body height and therefore correction of the abnormal configuration of the vertebral body that existed as a result of the fracture. After the balloon is removed, there is an empty space within the vertebral body that allows for the low-pressure injection of the polymethylmethacrylate into the cavity created by the balloon. Injection under low pressure has the advantage of decreasing the rate of leakage of polymethylmethacrylate either into the spinal canal or into the draining veins of the vertebral bodies. Recent reports reveal a high success rate using this technique.

Kyphoplasty procedure.

In summary, vertebral compression fractures are a significant problem not only because of pain, but also because of significant medical complications that arise as a result. There is a significant increase in mortality after vertebral compression fracture. Kyphoplasty, although in its infancy as a procedure, appears to hold promise as a powerful minimally invasive tool in the treatment of the vexing disease of vertebral compression fractures.

The Department of Neurological Surgery at the University of Pittsburgh Medical Center is now performing the kyphoplasty procedure on patients with osteoporotic vertebral compression fractures. Results in these patients will be continuously reviewed to help improve indications and results. Please call our clinical office at (412) 802-8199 for more information.