What might go wrong?
As with all major surgical procedures, complications can occur. Some of the most common complications following posterior lumbar fusion include:
- problems with anesthesia
- nerve damage
- problems with the graft or hardware
- muscle disruption
- ongoing pain
This is not intended to be a complete list of the possible complications.
Problems with Anesthesia
Problems can arise when the anesthesia given during surgery causes a reaction with other drugs the patient is taking. In rare cases, a patient may have problems with the anesthesia itself. In addition, anesthesia can affect lung function because the lungs don't expand as well while a person is under anesthesia. Be sure to discuss the risks and your concerns with your anesthesiologist.
Thrombophlebitis (Blood Clots)
Thrombophlebitis, sometimes called deep venous thrombosis (DVT), can occur after any operation. It occurs when the blood in the large veins of the leg forms blood clots. This may cause the leg to swell and become warm to the touch and painful. If the blood clots in the veins break apart, they can travel to the lung, where they lodge in the capillaries and cut off the blood supply to a portion of the lung. This is called a pulmonary embolism. (Pulmonary means lung, and embolism refers to a fragment of something traveling through the vascular system.) Most surgeons take preventing DVT very seriously. There are many ways to reduce the risk of DVT, but probably the most effective is getting you moving as soon as possible. Two other commonly used preventative measures include:
- pressure stockings to keep the blood in the legs moving
- medications that thin the blood and prevent blood clots from forming
Infection following spine surgery is rare but can be a very serious complication. Some infections may show up early, even before you leave the hospital. Infections on the skin's surface usually go away with antibiotics. Deeper infections that spread into the bones and soft tissues of the spine are harder to treat. They may require additional surgery to treat the infected portion of the spine.
Any surgery that is done near the spinal canal can potentially cause injury to the spinal cord or spinal nerves. Injury can occur from bumping or cutting the nerve tissue with a surgical instrument, from swelling around the nerve, or from the formation of scar tissue. An injury to these structures can cause muscle weakness and a loss of sensation to the areas supplied by the nerve.
Problems with the Graft or Hardware
Posterior fusion surgery requires bone to be grafted onto the spinal column. The graft is commonly taken from the top rim of the pelvis. There is a risk of pain, infection, or weakness in the area where the graft is taken.
Sometimes the strips of bone graft don't take and end up dissolving. A second surgery may be needed to remove the strips and apply more graft material. The doctor may need to apply additional metal hardware to hold the new grafts firmly in place.
When instrumentation is used, the screws, rods, or plates can also cause problems. They can loosen and irritate the nearby soft tissues. In rare cases, they may actually break. If your hardware loosens or breaks, the surgeon may suggest another surgery either to take out the hardware or to add more hardware to solve the problem.
During the operation, the surgeon lifts off the small muscles that run along the back of the spinal column. Some of the nerves going to the muscles are cut. Lifting the muscles away from the bone impairs the blood supply to the muscles. Disruption of the nerve and blood supply can cause the muscles to fatigue easily, especially during a long work day and with heavy or repeated lifting. Exercises designed by a physiotherapist boost strength and endurance in the nearby muscles, reducing symptoms from this problem.
Sometimes the bones do not fuse as planned. This is called a nonunion, or pseudarthrosis . (The term pseudarthrosis means false joint.) When more than one level of the spine is fused at one time, there is a greater chance that nonunion will occur. Fusion of more than one level means that two or more consecutive discs are removed and replaced with bone graft. If the joint motion from a nonunion causes pain, you may need a second operation.
In the second procedure, the surgeon usually adds more bone graft. Metal plates and screws may also be added to rigidly secure the bones so they will fuse together.
Posterior lumbar fusion is a complex surgery. Not all patients get complete pain relief with this procedure. Successful fusion occurs in more than 80 percent of surgeries. But a solid fusion does not guarantee freedom from pain or the ability to return to normal activity. If you have pain that continues or becomes unbearable, talk to your surgeon about treatments that can help control your pain.