Vertebroplasty and Kyphoplasty: percutaneous injection procedures for vertebral fractures

Many people are surprised to learn that vertebral fractures are quite common: up to 250,000 vertebral fractures are diagnosed each year. Most of the fractures occur in older people who have fragile bones, with the underlying condition called osteoporosis. Many of these patients have not yet been diagnosed with this condition. The fractures commonly occur with normal activities or minor incidents, such as a misstep or minor fall. In these cases, the weakened bone does not have the strength to handle the forces placed on it.

About half of all vertebral fractures occur silently, without any significant pain. Others can be very painful and disabling. The majority of these fractures, even if they’re painful to start with, heal on their own with little or no residual pain or disability.

Standard treatments for a vertebral fracture include pain medication, progressive activity, and the use of a brace for support. Even when the fracture has healed, there remains a high risk of a new fracture. Evaluation and treatment of the underlying osteoporosis is very important in order to minimize this risk.

To provide relief of the pain of a vertebral fracture, two types of minimally invasive procedures are available. These procedures, vertebroplasty and kyphoplasty, are most commonly used in cases of severe pain caused by a vertebral fracture that does not improve over a number of weeks with pain medication and treatment with a brace.

Both vertebroplasty and kyphoplasty procedures involve the placement of cement into the fractured vertebra through small, minimally invasive incisions in the skin under x-ray guidance.

Vertebroplasty
The procedure known as vertebroplasty is generally done with the patient sedated but awake, in an x-ray suite or an operating room. In vertebroplasty:

  • A bone cement is injected under pressure directly into the fractured vertebra.
     
  • Once in position, the cement hardens in about 10 minutes, congealing the fragments of the fractured vertebra and providing immediate stability.

Kyphoplasty
The procedure known as kyphoplasty is commonly done under general anesthesia in an operating room, although kyphoplasty can also be done under a local anesthesia. In kyphoplasty:

  • A balloon catheter, similar to the one used in angioplasty of the heart, is guided into the vertebra and inflated with a liquid under pressure.
  • As the balloon inflates, it can help to actively restore the collapse in the vertebra due to the fracture and can also correct abnormal wedging of the broken vertebra.
  • Once the balloon is maximally inflated, it is deflated and removed, and the large cavity created is filled with bone cement lower pressure than in a vertebroplasty.
  • The cement then hardens in place, maintaining any correction of collapse and wedging.

Kyphoplasty can also be very helpful when there is severe collapse of the broken vertebra or wedging, with more collapse in the front of the spine than the back resulting in the spine tending to tilt forward. By correcting the wedging, kyphoplasty may help restore the spine to a more normal alignment and prevent severe kyphotic (“hunchback”) deformity to the spine. In someone who has had multiple fractures with previous wedging, kyphoplasty can prevent further worsening of the deformity.

Both techniques are successful about 90% of the time in relieving the pain of fractured vertebrae. Kyphoplasty is more helpful in correcting vertebral collapse and wedging if it is done within six weeks of the fracture.

Potential risks and complications
These cement injection procedures are not without significant risks, so the decision to use these procedures is made on a case-by-case basis and should not be taken lightly.

  • The most common complication is leakage of cement out of the vertebra with injection and before final hardening.
  • If the cement leaks back into the spinal canal it can compress the spinal cord and nerves, causing new pain and neurologic problems.
  • There have also been rare case reports of pulmonary embolism of the lungs and even death associated with these procedures.

Currently, there is no FDA-approved substance to inject into a vertebral body. Bone cement (polymethymethacrylate) has been the only substance substantially studied, but to date it has not received clearance for injection into a vertebral body. Part of the problem with bone cement is that when it is in the very viscous state, it can leak out into the veins around the spine, especially if it is inserted under high pressure. Once it gets into the veins it can embolize to the lungs and there have been case reports of severe morbidity (i.e. respiratory distress or death) associated with embolization.

Overall, however, these percutaneous vertebral body cement injection procedures represent a new advance and a helpful part of the treatment of vertebral fractures in select cases. With all of this in mind, the patient and doctor must sit down and discuss whether such a procedure is right for the patient.

Other considerations
Before kyphoplasty and vertebroplasty were available the gold standard for a compression fracture was rest, time and medications. Compression fractures have a high rate of success in terms of healing although it may take a while (about three months). Generally, most clinicians will wait to see if the fracture will heal on its own.

However, if the patient is in so much pain that he or she cannot function, kyphoplasty or vertebroplasty surgery may be considered sooner. For acute, mild to moderate, activity-related pain, patients are usually advised to probably wait at least three months before making a decision on surgical intervention.

 

Kyphoplasty—a new treatment for osteoporotic fractures

Background and history
The traditional treatment for fractures of the spine caused by osteoporosis has included pain reduction (medication), bed rest and bracing. In 1984, a surgical technique designed to reduce the pain and loss of function called "Percutaneous Vertebroplasty" was developed in France. In 1998, the Food and Drug Administration approved a special balloon, the KyphX Inflatable Bone Tamp, for use in reducing (setting) fragility fractures to help them heal and creating a cavity in the soft inner bone in the vertebral body.

It is estimated that over 36,000 vertebral compression fractures have been treated using the kyphoplasty procedure, and approximately 2,700 physicians have been trained to do the procedure in the US.

What is an osteoporotic fracture?
Osteoporosis—the loss of calcium from bones resulting in weakened bone structure—increases the risk of fracture of vertebral body (the thick block of bone at the front of the vertebrae)

In this type of fracture, the top of the vertebral body collapses down with more collapse in front thus producing the "wedged" vertebrae, the "dowagers" hump and shortened height

The resulting change in height and spinal alignment can lead to serious health problems, including:

  • Chronic or severe pain
  • Limited function and reduced mobility
  • Loss of independence in daily activities
  • Decreased lung capacity
  • Difficulty sleeping

Also, studies show that a first osteoporotic fracture makes it five times more likely further fractures will occur. That is why it is important that patients seek medical treatment for osteoporosis before it reaches the fracture stage.

Kyphoplasty compared with vertebroplasty
Vertebroplasty and kyphoplasty are both minimally invasive surgical procedures for treating osteoporotic fractures where a cement-like material is injected directly into the fractured bone. This stabilizes the fracture and provides immediate pain relief in many cases.

Kyphoplasty includes an additional step. Prior to injecting the cement-like material, a special balloon is inserted and gently inflated inside the fractured vertebrae. The goal of this step is to restore height to the bone thus reducing deformity of the spine. Most patients return to their normal daily activities after either procedure.

Description of kyphoplasty surgery

The goals of this surgical procedure are designed to stop the pain caused by the bone fracture, to stabilize the bone, and to restore some or all of the lost vertebral body height due to the compression fracture.

  1. A small incision is made in the back through which the doctor places a narrow tube. Using fluoroscopy to guide it to the correct position, the tube creates a path through the back into the fractured area through the pedicle of the involved vertebrae.
  2. Using X-ray images, the doctor inserts a special balloon through the tube and into the vertebrae, then gently and carefully inflates it. As the balloon inflates, it elevates the fracture, returning the pieces to a more normal position. It also compacts the soft inner bone to create a cavity inside the vertebrae.
  3. The balloon is removed and the doctor uses specially designed instruments under low pressure to fill the cavity with a cement-like material called polymethylmethacrylate (PMMA). After being injected, the pasty material hardens quickly, stabilizing the bone.

Kyphoplasty is performed at a hospital under local or general anesthesia. Other logistics for a typical procedure are:

  • The procedure takes about one hour for each vertebrae involved
  • Patients will be observed closely in the recovery room immediately following the procedure
  • Patients may spend one day in the hospital
  • Patients should not drive until they are given approval by their doctor. If they are released the day of the surgery, they will need to arrange for transportation home from the hospital

Recovery
Pain relief will be immediate for some patients. In others, elimination or reduction of pain is reported within two days. At home, patients can return to their normal daily activities, although strenuous exertion, such as heavy lifting, should be avoided for at least six weeks.

Patients should see their physician to begin or review their treatment plan for osteoporosis, including medications to prevent further bone loss.

Candidates for kyphoplasty
Kyphoplasty cannot correct an established deformity of the spine, and certain patients with osteoporosis are not candidates for this treatment. Patients experiencing painful symptoms or spinal deformities from recent osteoporotic compression fractures are likely candidates for kyphoplasty. The procedure should be completed within 8 weeks of when the fracture occurs for the highest probability of restoring height.

Risks and complications
Some general surgical risks apply to kyphoplasty, including a reaction to anesthesia and infection. Other risks that are specific to this procedure and vertebroplasty include:

  • Nerve damage or a spinal cord injury from malpositioned instruments placed in the back
  • Nerve injury or spinal cord compression from leaking of the PMMA into veins or epidural space
  • Allergic reaction to the solution used to see the balloon on the x-ray image as it inflates

It is not known whether kyphoplasty or vertebroplasty will increase the number of fractures at adjacent levels of the spine. Bench studies on treated bone have shown that inserting PMMA does not change the stiffness of the bone, but human studies have not been done. Osteoporosis is a chronic, progressive disease. As stated earlier, patients who have sustained these fractures are at an increased risk for additional fractures due to the loss of bone strength caused by the disease.

 

 

 

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