What's the Difference?
One of the biggest problems with osteoporosis (soft bones) is the development of bone fractures of the spine, hip, and wrist. Of these, spinal compression fractures are the most common, affecting 700,000 Americans each year. These fractures occur when the bone strength is diminished to the point that even minor trauma causes the vertebra to crush. Compression fractures can cause spinal deformity, severe back pain and loss of height. Traditional treatment of compression fractures has included bedrest, pain medications, bracing, and in rare cases surgery. Surgical treatment has been an option of last resort because of the long recovery, poor outcome, and risks. It was only considered in cases of spinal cord compression and for the most significant deformity. Patients with compression fractures secondary to osteoporosis or cancer usually have other medical illnesses. They require a treatment that would allow immediate pain relief, minimal stress on their health, and allow them to return to a full level of activity. Recently two minimally invasive surgical techniques have emerged, Kyphoplasty and Vertebroplasty, as potential answers to the problems posed by osteoporotic compression fractures of the spine.
Vertebroplasty was developed in the mid 1980's by a radiologist in France. It was embraced for use in the USA in the mid 1990's. Kyphoplasty was first described in 1998 by a Berkley California orthopedic surgeon. Let's compare the two procedures, their similarities and differences, and their respective risks and long term prospects for benefit in patients with osteoporosis related compression fractures.
Vertebroplasty begins with the introduction of a needle into the collapsed vertebra under xray guidance. The vertebral body, or front portion of the spine bone, is then injected with bone cement. In order for the cement to be able to enter into the bone, the cement must be in a liquid state and high pressure must be used to push it through the needle. The liquid state cement hardens over a period of 12-15 minutes secondary to a chemical reaction. Once the cement is hard, the bone is stable and immediate weight bearing can be resumed. The French and some American studies found 70 – 90% of patients experienced pain relief.
The problems with Vertebroplasty are two fold. The first is the liquid cement will follow the path of least resistance. Best case scenario is that the collapsed vertebra has a hard outer surface (cortex) of the bone being intact to contain the cement as it is being injected. If there is any defect in the vertebra wall, there is a risk of cement leaking into the spinal canal or into the abdomen or chest. Cement entering into areas that were unintended in an uncontrolled fashion has led to problems in some of these patients, including liquid cement migrating to the lungs or into the spinal canal to compress the spinal cord. The second problem with Vertebroplasty is both a short and long term one. The cement fills the broken vertebra, freezing the spine in its collapsed position. We are all familiar with people who have progressively become â€œhunched overâ€ with time, often secondary to multiple compression fractures. Vertebroplasty does not address the deformity issue nor prevent patients from becoming hunched over.
Kyphoplasty was developed by an orthopedic surgeon to straighten the broken or collapsed vertebra and address the issue of becoming hunched over. One of the basic principles of orthopedics is to straighten or correct broken bones. In other words, "If it''s bent, straighten it ou". Kyphoplasty begins similar to Vertebroplasty, with a needle introduced into the fractured vertebral body. However, that is where any similarity ends. Kyphoplasty calls for insertion of a small tube over the needle. Through this tube, a balloon tipped catheter is inserted into the broken vertebra. The balloon is slowly inflated. With new fractures, inflation of the balloon raises up the collapsed vertebrae to its normal height. More importantly, the balloon creates a space in the bone as it inflates. This space allows for cement to be placed at low pressure and thicker, putty like consistency. This substantially reduces the risk of cement leaking out of the bone. Kyphoplasty patients also describe immediate relief from fracture pain. In our series at the Sonoran Spine published in The Spine Journal last year, we saw pain improvement in 90% of our patients.
Both Vertebroplasty and Kyphoplasty allow surgeons to treat compression fractures through a minimally invasive procedure. Both relieve the pain caused by the vertebral fracture. Only Kyphoplasty allows for correction of the collapsed vertebra and decreases the risk of the patient becoming hunched over. Adding a safer placement of the cement into the fractured vertebra makes Kyphoplasty our clear and safer choice for patients who are suffering from osteoporotic compression fractures.