Vertebral Compression Fracture: Vertebroplasty vs. Vertebral Augmentation
As we get older, our bones become weak and brittle. Osteoporosis, also known as “the silent thief,” is the most common type of bone disease that makes the bones more prone to fracture. An estimated 10 million Americans have osteoporosis, and an additional 34 million have low bone mass. Research findings suggest that osteoporosis is especially common in postmenopausal women, placing them at increased risk for a whole host of problems, such as joint disorders and vertebral abnormalities. In this post, I’m examining vertebral compression fractures specifically; in fact, approximately 25% of all postmenopausal women in the United States have experienced a vertebral compression fracture.
A vertebral compression fracture (VCF) occurs when too much pressure is placed on a weakened vertebra, causing the vertebra to collapse. VCFs are most commonly seen in the thoracic spine—the twelve vertebrae between the neck and the middle of the back—particularly among the lower vertebrae of this section of the spine. This type of fracture is usually defined as a vertebra in the spine that has decreased at least 15 to 20% in height resulting from fracture. VCFs are often the result of a fall or tumors, although for those with more severe osteoporosis, they can be caused by even mild stresses, such as bending over, coughing, or sneezing. Many patients who suffer a VCF recover with the aid of nonsurgical treatments, such as bracing, bed rest, or pain medications, within three months, eliminating the need for surgical treatment. For some patient, however, these treatment prove ineffective; in these cases, two minimally invasive procedures, called vertebroplasty and vertebral augmentation, may be considered as treatment options to treat the patient’s pain and prevent progressive spinal deformity.
Vertebroplasty for the treatment of VCFs was first successfully performed in France in 1984 and was introduced in the United States in the early 1990s. In vertebroplasty procedures, surgeons use X-ray guidance to inject bone cement into the collapsed bone of the vertebral body; the cement mixture hardens within minutes, stabilizing the fracture. The entire procedure is performed through small holes in the patient’s skin, and generally takes from one to two hours, depending on the number of vertebrae being treated. The mechanical support of the bone cement is intended to alleviate pain and prevent further loss of vertebral body height.
Due to the inability of vertebroplasty to restore the height of the compressed vertebral body, however, a related procedure, vertebral augmentation, is more commonly considered. Vertebral augmentation utilizes an inflatable balloon tamp, which creates a cavity for the bone cement, restoring the vertebral body height and minimizing kyphotic deformity. Kyphon (acquired by Medtronic in 2007) was the first company to offer a system for vertebral augmentation, namely its balloon kyphoplasty system. Balloon kyphoplasty continues to be a widely used method for performing vertebral augmentations; in fact, the majority of vertebral augmentations are performed using a bipedicular approach due to the fact that balloon kyphoplasty involves the use of two bone tamps that are inserted through the two pedicles of the vertebra.
Both vertebroplasty and vertebral augmentation are usually done on an outpatient basis, although some patients stay in the hospital overnight. The American Association of Neurological Surgeons states that complication rates for both vertebroplasty and vertebral augmentation procedures have been estimated at less than 2 % for osteoporotic VCFs and up to 10% for malignant tumor-related VCFs; although studies have shown that certain complications, including the compression of neural elements and venous embolism, are more common with vertebroplasty.
Biomechanical studies also demonstrate that vertebral augmentation is superior for straightening out the spinal curve and has less potential for cement leakage compared to vertebroplasty due to lower pressure cement injection and a higher viscous state of bone cement. Because the creation of the cavity with the balloon tamp during a vertebral augmentation procedure facilitates the safe introduction of the bone cement into this defined space, vertebral augmentation is often preferred by both physicians and patients, although it is more costly and complicated than vertebroplasty. This trend is also supported by some negative clinical results, such as studies published in the New England Journal of Medicine that reported unfavorable outcomes for vertebroplasty; these findings contributed to the American Academy of Orthopedic Surgeons’ decision to recommend against vertebroplasty for patients suffering from VCFs. The results strongly influenced many physicians, undermining confidence and reducing patient faith in vertebroplasty.
Despite doubts raised by the negative outcomes reported in the New England Journal of Medicine, vertebroplasty will continue to be performed due to surgeons’ first-hand knowledge of the benefits of vertebroplasty, which is sustaining surgeon confidence in the procedures’ effectiveness as a treatment option for VCFs. As the indications for vertebroplasty and vertebral augmentation continue to expand, well-designed clinical studies supporting the efficacy of the two procedures will be needed to clear the lingering doubts about the efficacy of vertebroplasty to successfully relieve the pain associated with VCFs and to convince greater number of patients to pursue these treatment options.