Scoliosis

Description

Surgery

The goals of scoliosis surgery are threefold:

• Straighten the spine as much as possible in a safe manner.
• Balance the torso and pelvic areas.
• Maintain correction.

These goals are accomplished in a two-component process:

• By fusing (joining together) the vertebrae along the curve.
• By supporting these fused bones with instrumentation (steel rods, hooks, and other devices) attached to the spine.

Many surgical variations exist using different instruments, procedures, and surgical approaches. All of the operations require meticulous skill. In most cases, success depends less on the type of operation than on the skill and experience of the surgeon. The cause of scoliosis often determines the type of procedure. Parents of patients or adult patients should not be shy in asking the surgeon and hospital about their experience with the specific procedures being considered.

Surgical Candidates

Surgery is usually recommended for the following children and adolescents with idiopathic scoliosis:

• All young people whose curve exceeds 50 degrees.
• Growing children whose curve has gone beyond 40 degrees. (There is still some debate, however, about whether all children with curves of 40 degrees should have surgery.)
• Older children who have surgery tend to experience improved well being from the changes in their appearance, even if they have no actual improved physical functioning. Surgery may be required for the following children at as early an age as possible.
• Those whose scoliosis is due to inborn abnormalities. (The younger they are when surgery is performed the better their chances for success.)
• Children with multiple physical handicaps.

It should be noted that procedures will differ depending on whether a child has idiopathic scoliosis or scoliosis due to muscle and nerve disorders (such as muscular dystrophy or cerebral palsy). In the latter cases, children also need a team approach to reduce their risks for serious complications.

Preoperative Care

Before the operation, a complete physical examination is conducted to determine leg lengths, muscle strength, lung function, and any postural abnormalities. The patient is trained in deep breathing and effective coughing to avoid lung congestion after the operation. The patient should also be trained in turning over in bed in a single movement (called log-rolling) before the operation. Psychologic intervention using cognitive-behavioral methods that help young patients cope may be very helpful in reducing anxiety and pain after surgery.

Patients are encouraged to donate their own blood before the operation for use in possible transfusions. The patient should have no sunburn, rashes, or sores on the back before the operation, which will increase the risk for infection.

Fusion

All scoliosis operations involve fusing the vertebrae. The instruments and devices used to support the fusion vary, however.

The Fusion Procedure. The fusion procedure generally is as follows:

• The surgeon first slices flaps to expose the backs of the vertebrae that lie along the curve.
• The surgeon then removes the processes, the bony outgrowths along the vertebrae that allow the spine to twist and bend.
• The surgeon lays matchstick-sized bone grafts vertically across the exposed surface of each vertebra, being careful that they touch adjoining vertebrae.
• The flaps are then folded back to their original position, covering the bone grafts.
• These grafts will regenerate, grow into the bone, and fuse the vertebrae together.

Depending upon the severity and responsiveness to other treatment surgery may be recommended for the scoliosis. Surgical correction involves correcting the curve (although not all the way) and fusing the bones in the curve together. Bone grafts are laid across the exposed surface of each vertebra. These grafts will regenerate, grow into the bone, and fuse the vertebrae together. The bones are held in place with one or two metal rods held down with hooks and screws, which also helps to support the fusion of the vertebrae.

Graft Materials. Bone grafts are taken from the patients hip, ribs, spine, or other bones (called autografts). This is the best quality bone. However, because autografts are taken directly from the scoliosis patient, the operation is longer and the patient experiences more pain afterward. Researchers are also investigating allografts, which are bone grafts taken from another person or a cadaver. This would reduce the pain and duration of the operation. Allografts, however, pose an increased risk for infection from the donor. Longer-term studies are needed to determine the seriousness of this risk.

Investigators have been testing grafts made from ceramic material called tricalcium phosphate (Biosorb). In one comparative French study, these synthetic grafts were completely fused with the original bone in two years, while the natural bone graft was still evident on x-rays. In the study, the use of synthetic graft was associated with better spinal correction and a lower risk for viral infections.

Healing. The healed fusions harden in a straightened position to prevent further curvature, leaving the rest of the spine flexible. It takes about three months for the vertebrae to fuse substantially, although one to two years are required before fusion is complete. Fusion stops growth in the spine, but most growth occurs in the long bones of the body (such as in the legs), anyway. Patients, then, will most likely gain height from both growth in the legs and from the straighter spine. Patients make walk at slightly slower pace after fusion, but balance may improve, and sports activities are not restricted after the procedure.

Instrumentation

Harrington Procedure. Until ten years ago, the standard instruments used in fusion procedures were those of the Harrington procedure, first developed in the 1960s:

• To support the fusion of the vertebrae, the surgeon uses a steel rod, extending from the bottom to the top of the curve. (More than one rod may be used depending on the type of curve and whether kyphosis is present.)
• The rod is attached by hooks that are suspended from pegs inserted into the bone.
• Similar to changing a tire, the steel rod is jacked up and then locked into place to support the spine securely. The surgeon is then ready to fuse the vertebrae together.
• After this operation, patients are required to wear a full body cast and lie in bed for three to six months until fusion is complete enough to stabilize the spine.
• After one to two years, the steel rod is not really necessary, but it is almost always left in place unless infection or other complications occur.

The Harrington procedure is very difficult to undergo, particularly for young people, and although the operation can achieve a correction of the curve of over 50%, studies have reported a loss in this correction of between 10% to 25% over time. The procedure does not correct the rotation of the spine and, therefore, does not improve an existing rib hump that was caused by the rotation. The operation does not interfere with normal pregnancies and deliveries later in life.

Certain complications may occur from this procedure:

• About 40% of Harrington patients have a condition called the flat back syndrome, because the procedure eliminates normal lordosis (the inward curving of the lower back). Flat back syndrome from the Harrington procedure does not cause any immediate pain. In later years, however, the disks may collapse below the fusion, making it difficult to stand erect, and the condition can cause significant pain and emotional distress.
• Studies have reported that five to seven years after their surgery, between a fifth and a third of patients who had the Harrington procedure experienced low back pain. (In one study, only 3% had experienced back pain before surgery.) In such cases, however, the pain was not severe enough to interfere with normal activities and did not require additional surgery.
• In children younger than 11 whose skeleton is immature and who have the Harrington procedure, there is a fairly high risk for a specific curve progression called the crankshaft phenomenon. This condition occurs after the procedure when the front of the fused spine continues to grow. The spine cannot grow longer, so it twists and develops a curvature. In one study that followed patients for between five and 16 years, crankshaft curve progression was moderate, however, with the Cobb angle averaging 9 degrees and rotation averaging 7 degrees.

Cotrel-Dubousset Procedure. The Cotrel-Dubousset procedure not only corrects the curve but may also help to correct rotation, and it does not cause flat back syndrome.

With this procedure, parallel rods are cross-linked for better stability in holding the fused vertebrae. Improvement in correction averaged 66% in one study, with a later correction loss reported to be 5%. (Other studies have reported loss of curvature correction at less than 2%.) Over 95% of patients reported the results to be good or very good (only 86% of patients who had the Harrington procedure experienced the same levels of satisfaction). Patients often go home in five days and may be back in school in three weeks.

Complication rates are similar to the Harrington procedure, but there are some differences:

• Operation time and blood loss are greater than with the Harrington procedure.
• Cotrel-Dubousset and other procedures that are designed to reverse the rotation of the spine have less risk for flat back syndrome but they have a higher risk for spinal imbalance than the Harrington procedure.
• Failure rates after 10 years are about 25%, which is very high. Experts hope that the advances in current scoliosis procedures will help reduce the long-term adverse effects.

The Texas Scottish-Rite Hospital (TSRH) Instrumentation. The Texas Scottish-Rite Hospital (TSRH) instrumentation is similar to the Cotrel-Dubousset procedure in that it uses parallel rods and other devices that reverse rotation as well as improve curvature. TSRH, however, uses smooth rods and hooks that are designed to make removal or adjustment easier later on if complications arise. Complications are similar to the Cotrel-Dubousset procedure.

Additional Forms of Instrumentation. Other instrumentation procedures have refined the hardware used in the Harrington and Cotrel-Dubousset operations.

• Wisconsin segmental spine instrumentation (WSSI) may also be effective. It is as safe as the Harrington rod and nearly as strong as the Luque instrumentation.
• Luque instrumentation was developed to help maintain normal lordosis and experts hoped that bracing would not be needed afterward with this device. A number of studies showed, however, that without braces, correction was lost after this operation, and there also may be a higher risk for spinal cord injury than with standard procedures. Luque instrumentation is used primarily in people whose scoliosis is due to problems of nerves and muscles, such as in children with cerebral palsy.
• The Dorsal Dynamic Spondylodesis (DDS) system, under testing in Germany, is a semirigid system that allows for greater flexibility of the spine.

Instrumentation for Anterior Approach. Specific hardware is needed for the anterior approach, in which the surgeon performs the operation by opening the chest wall. Halm-Zielke instrumentation, for example, uses TSRH instrumentation with bone grafts constructed from ribs to prop open the spaces between the discs. It allows true three-dimensional curve correction. However, it does not solve specific problems with this approach, which are higher risks for kyphosis (an outward curve) and pseudoarthrosis (a false joint at the fusion site). Variants using two rod systems, fusion cages, or other instruments appear to improve this procedure.

The Surgical Approach

Posterior Approach (Through the Back). Generally, surgeons have used a posterior approach for scoliosis, which reaches the surgical area by opening the back of the patient. It has been the gold standard for decades and is generally used with Harrington instrumentation. The approach has advantages and disadvantages.

• Advantages of the Posterior Approach. Surgeons are familiar with it and so fusion rates are excellent, curve correction is good, and it has few complications.
• Disadvantages of the Posterior Approach. There is a risk for the crankshaft phenomenon (a worsening of the curve) later on in preadolescent children. (Newer posterior instrumentation, such as the Isola instrumentation, may prevent this occurrence.) The posterior approach also does not always correct hypokyphosis (the loss of normal outward curvature) in the thoracic (upper) spine. The procedure is not always effective for curves in the thoracolumbar region (the region where the upper and lower spine meet) and may even cause spinal abnormalities there.

Anterior Approach (Through the Chest Wall). Increasingly surgeons are using the anterior approach, in which the surgeon performs the operation by opening the chest wall (called a thoracotomy). With the anterior approach, the surgeon makes an incision in the chest, deflates the lung, and removes a rib in order to reach the spine. This rib can be used during the operation as a strut to support the spine. It also may be repositioned within the patient until it is used for bone grafting during fusion.

This approach also has its advantages and disadvantages:

• Advantages of the Anterior Approach. Because the frontal approach allows the procedure to be performed higher up in the spine than with standard procedures, the patient may have a lower risk for lower-back injury later on. In addition, transfusion rates are much lower with the anterior approach. With increasing experience, the anterior approach is as effective as the posterior approaches.
• Disadvantages of the Anterior Approach. It is a more recent procedure than the posterior approach, and in inexperienced surgeons there is a higher risk for complications than in the more standard posterior approach. One study noted poorer lung function two years after surgery than with the posterior approach, possible because the wide chest incision produces impairs the chest muscles, which can affect lung function afterward. Anterior instrumentation poses a risk for hyperkyphosis (exaggerated outward curvature) and a higher risk for pseudoarthrosis, a painful condition in which a false joint develops at the fusion site. Hardware failure rates may also be higher with the anterior than posterior approach. Increasing experience and newer hardware designs are reducing many of these problems.

The Combined Anterior-Posterior Approach. The combination approach uses an anterior approach first, which allows better correction of the problems. The fusion part of the operation is done with the posterior approach. This is a very long and complex procedure. It appears to be safe, however, and is proving to be useful, even in very young patients, for preventing the crankshaft phenomenon. It may also be used to correct large rigid curves and for specific severe curves in the thoracic spine.

Minimal Access Spinal Approach. Minimal access spinal technologies use a few small incisions and so are far less invasive than the standard so-called open approaches that require wide cuts. The technique uses endoscopy, in which the surgeon makes small incisions and inserts tubes that contain tiny instruments and cameras through the incisions in order to view and execute the procedure. In most cases, the procedure is done in two stages:

• First, an anterior approach is employed to remove disk material and loosen the spine.
• Secondly, a posterior approach is made for fusion and instrumentation.
• Recovery after surgery is rapid. Most patients are out of bed two days after surgery.
• Corrections are reaching 68% in some patients. There is a much more cosmetically appealing result (fewer and smaller scars) with endoscopy, and an easier recovery than with the more invasive approaches.

The endoscopic procedure for scoliosis is complicated and few surgeons can perform it yet. Currently, it is generally used only for single curves in the upper back or for patients with a curve in the upper back and a curve in the lower back that compensates for it. Some surgeons are now able to operate on areas below the diaphragm, including the lumbar spine. The patients must still wear a brace for three months afterward. Long-term studies are required to determine how outcomes compare to standard procedures.

Complications of All Procedures

Complication rates are high (nearly 10%) with any of these procedures, including the standard Harrington method and the newer Cotrel-Dubousset procedure. Complications for all procedures include allergic reactions to anesthesia and also include:

Bleeding. Standard procedures increase the risk for major blood loss during the procedure. Patients are encouraged to donate blood before the operation for use in possible transfusions. Children sometimes require more than one transfusion following surgery. Researchers are investigating various methods for reducing the need for transfusions:

In one study, erythropoietin (rhEPO) was given to patients before the procedure. RhEPO is a hormone that acts in the bone marrow to increase the production of red blood cells. Patients who were given this hormone, particularly those with idiopathic scoliosis, needed fewer transfusions and spent less time in the hospital than those who did not receive rhEPO.

According to a small Canadian study, tranexamic acid, an agent used to reduce transfusions in heart and knee surgeries, may also decrease transfusions in scoliosis surgery. More studies are needed.

Newer endoscopic techniques are reducing the need for transfusions.

Postoperative Pain. There is always some pain after these operations, requiring intravenous administration of potent painkillers right after the operation (endoscopic procedures may require only mild pain relievers). Of some concern is a study suggesting that the use of NSAIDs, or nonsteroidal anti-inflammatory drugs (e.g., aspirin, Motrin, Advil), for pain relief right after fusion may increase the risk for fusion failure. Until more research is conducted, these common painkillers should not be routinely used right after surgery.

Infection. Infection is always a risk with any operation. One study reported changes in the immune system for about three weeks after surgery, which indicates a greater risk for infection. Researchers recommended being very vigilant for signs of infection, including in the pancreas and urinary tract. Antibiotics, given by injection for two to five days after surgery and by mouth for one to two weeks longer, are also recommended.

Nerve Damage. Patients often worry about neurologic injuries, but the risk is actually very low. In general, nerve injury occurs in 1% of patients, with the risk highest in adults. If neurologic damage occurs, it most often causes muscle weakness. Paralysis is very rare and can be prevented by using monitoring techniques during the operation. Nearly all monitoring procedures use a so-called wake-up test, in which the patient is brought out of anesthesia during or at the end of the procedure and assessed for sensations to be sure no injury has occurred. One simple method is to wake patients up in the middle of their operations and ask them to wiggle their toes. More sophisticated methods measure the electrical activity of the spinal cord; if the monitor indicates a fall in electrical response and possible injury, the surgeon adjusts his techniques to avoid further damage to the spinal cord.

Pseudoarthrosis. If the fusion fails to heal, pseudoarthrosis may develop, a painful condition in which a false joint develops at the site. In one study, patients at higher risk for this complication were teenagers who smoked and heavier adolescents (over 154 pounds) who had hyperkyphosis (hunchback). There may be a higher risk for this with the anterior approach. One study reported that pseudoarthrosis may be undiagnosed and rates may average 20% after surgery, therefore acting as a major contributor to post-surgery pain. More work is needed.

Disk Degeneration and Low Back Pain. Fusion in the lumbar area produces great stress on the lower back and eventually can cause disk degeneration. Loss of trunk mobility, balance, and muscle strength from surgical treatments can also cause lower back pain and chronic problems in future years on. Patients who are surgically treated with fusion techniques lose flexibility and the back muscles may be weakened if they were injured during surgery. In most cases, however, the consequences are mild to moderate.

Other Complications. Other problems that can occur include, but are not limited to, the following:

• Dislodgment of hooks or fracture of a fused vertebra.
• Gallstones.
• Pancreatitis (inflammation of the pancreas). Among adolescents, this complication tends to occur more often among those who are older or who have a lower body mass index.
• Intestinal obstruction.
• Serious postoperative complications that involve the lungs and circulation. These complications are highest in children whose scoliosis is due to neuromuscular problems, such as spina bifida, cerebral palsy, or muscular dystrophy. Such children may need to be managed in an adult intensive care unit.

Click the icon to see an image of gallstones.

Postoperative Therapy

Breathing and coughing exercises to rid the lungs of congestion must be performed shortly after the procedure and continued through the recovery process. The patient is usually able to sit up the day after the operation, and most patients can move on their own within a week. A brace may be necessary, depending on the procedure. With the anterior approach in the upper back, patients may have some trouble with activities involving the arms and hands--such as tying shoes and cutting food. In one study, however, occupational therapy using stretching and strengthening exercises allowed for full resumption of daily activities, including dressing, bathing, and grooming, within three months. Patients are often concerned that surgery will stiffen their backs, but most cases of scoliosis affect the upper back, which has only limited movement, so that patients do not notice much difference. It may take a year or more for muscle strength to return. In some cases, the operation cannot completely correct the curve, and one leg may be shorter than the other. Heel lifts may be used in this case.

Revision (Salvage) Surgery

Patients may need corrective surgery called revision or salvage surgery, usually for one of four different reasons:

• Failure of the previous procedure.
• Curvature progression around the fusion site.
• Disk degeneration.
• Poor posture alignment.

Experimental Surgeries in Young People

Vertebral Body Stapling. Vertebral body stapling may eventually prevent curve progression in some young patients with curves less than 50 degrees. It involves stapling the convex (outer) curve of the anterior spine (the side of the spine facing the chest), which should stabilize and help reduce progression of the inner (concave) curve. The procedure uses a special metal device that is clamp-shaped at body temperature but can be straightened when subjected to cold temperatures and inserted into the spine. When it is warmed up, the staple returns to its clamp shape and supports the spine. Currently this is only being performed at one center.