Current treatment approaches in the nonoperative and operative management of adolescent idiopathic scoliosis.

MC Cassella, BS, PT, is Associate Director, Department of Physical Therapy and Occupational Therapy Services, Children's Hospital, 300 Longwood Ave, Boston MA 2115 (USA), Physical Therapy Consultant to the Spinal Program, Children's Hospital, and Lecturer on Orthopaedic Surgery, Harvard Medical School, 25 Shattuck St, Boston, MA 02115. Address correspondence to Ms Cassella at the first address.

JE Hall, MD, is Orthopaedic Surgeon-in-chief, Department of Orthopaedics, Children's Hospital, and Professor of Orthopaedic Surgery, Harvard Medical School.

The word "scoliosis" is derived from the ancient Greek word, Skoli6sis, meaning a curve. In medicine, it means lateral curvature of the spine.1 The spinal column, when examined in the sagittal plane, has normal anterior and posterior curvatures (lordosis and kyphosis, respectively). in the anteroposterior plane, a lateral curvature of over 10 degrees is usually abnormal. The purpose of this article is to review both operative and nonoperative treatment of adolescent idiopathic scoliosis.

Structural Versus Nonstructural Scoliosis

Scoliosis is either structural or nonstructural.

A structural curve usually has a rotary component.(2,3) Clinically, a structural curve will not correct when the trunk is flexed forward and will not fully correct in a supine, bending radiograph. Conversely, a nonstructural curve has no rotary component and will usually straighten when the trunk is flexed forward. When viewed on radiographs, a nonstructural curve will often correct or overcorrect.(2) Some causes of nonstructural scoliosis are leg-length discrepancies, postural problems, muscle spasm (involuntary muscle contraction), and spinal tumors. Nonstructural curves associated with muscle spasm and spinal tumors may even be exaggerated when the patient bends forward. This, however, causes pain, which is not a characteristic of other curves.

Classification

Structural scoliosis is classified by magnitude, location, direction, and etiology.(3) The Cobb method is the most widely accepted method of measuring curve magnitude (Fig. 1).(4) The location of a structural curve is determined by its apical vertebra, which is the spinal segment with the greatest degree of rotation (Fig. 2).(5) In structural scoliosis, the vertebral bodies rotate toward the convex side of the curve. The direction of a structural scoliosis is determined by the convex side of the curve. A structural curve is described by both the location of the apical vertebra and the direction (Tab. 1).(2) For example, if the apex is at T-8, with the convexity of the curve to the right, the curve is described as right thoracic.

Structural curves are further described as major and minor curves. An individual's major curve, by definition, is the largest curve and usually has the greatest degree of vertebral rotation of all the curves present. The minor curves are smaller and have lesser degrees of vertebral rotation. Minor curves are more flexible and usually develop to compensate for the major curve.(2,5)

Although there are many known causes of structural scoliosis, the most common type is idiopathic scoliosis, which occurs during the growing years.(6) Idiopathic scoliosis is categorized by age group: infantile (birth-3-years), 3 juvenile (3-10 years), and adolescent >10 years). This classification indicates the age when the curve was diagnosed; however, age at diagnosis does not always coincide with the time the curve(s) first appeared.

This article will focus on adolescent idiopathic scoliosis, which occurs in about 65% of adolescent patients with structural curves.(6) The term "idiopathic" means of unknown etiology. It is now known that idiopathic scoliosis is genetic in origin; however, the mechanism of development remains unknown. Current theories implicate neural mechanisms involving balance and coordination deficits as etiological factors.(8,9)

Early Detection and School Screening

Lateral curves are often first noticed by parents. Many times parents observe postural abnormalities when their children are wearing bathing suits, or a mother may detect an abnormality when hemming a pair of pants or a skirt. A comment often heard is: "I noticed a problem because I always have to alter her clothes so they will hang evenly."

Lateral curves are also detected by pediatricians during routine physical examinations. The majority of lateral curves, however, are detected in school screening programs. Screening programs began in the 1940s and have become widespread in the United States, Canada, and other countries.(7) School screening is currently mandatory in approximately one third of the schools in the United States. Screening programs are conducted on students aged 10 to 16 years (grades 5-9), because this is the age group of highest risk for adolescent idiopathic Scoliosis.(7,10)

Much has been learned about the natural history of scoliosis from school screening programs. Most of the data generated from screening programs are predictive of prevalence rate. Prevalence rate refers to the proportion of a population with a disease or disorder and is expressed as the number of cases per 1,000 individuals in the population.(11) Most studies reflect a prevalence of 2% to 4% of the population for curves of at least 10 degrees. More important is the prevalence of curves greater than 20 degrees, because children with remaining skeletal growth and this degree of curvature may require treatment.(7) Based on most studies, it is considered that 1 to 3 children per 1,000 screened will have structural curves greater than 20 degrees. Nachemson,(12) using data from many studies, calculated a table showing the decreasing prevalence with increasing curve magnitude (Tab. 2). The female:male ratios appear to be dependent on curve magnitude (Tab. 3).(13)

Criteria for Treatment

Which children with positive findings for scoliosis will require treatment? No data exist as to which curves will tend to progress.(14,15) It is clear, however, that mild curves are very common and rarely progressive. Once a curve has increased beyond 30 degrees in a child with considerable skeletal growth remaining, progression is almost inevitable. Skeletal growth is assessed by the Risser sign (Fig. 3) or by skeletal age.(16,17)

Although school screening programs have helped considerably to identify children with a potentially serious scoliosis, these programs have also caused many children with mild, nonprogressive curves to undergo unnecessary tests and evaluative procedures. One should be very careful in labeling a mild, nonprogressive curve as scoliosis because of the implication for the individual's future, with respect to health and life insurance.

In the past, the only definitive method of assessing curve progression was by roentgenogram. A child whose structural curve is diagnosed at 10 years of age could possibly have one or two roentgenograms every 6 months until the end of skeletal growth, as indicated by radiographic analysis.(17) Alternatives to roentgenography that do not require exposure to radiation are moire shadow photography (Fig. 4) and the Integrated Shape Investigation System (ISIS) topographical scanning system (Fig. 5). Both alternatives have made it possible to monitor children with mild structural curves without exposing them to unnecessary radiation.(18-20) A roentgenogram is necessary only if there is a significant change in the moire pattern or ISIS contour.

Nonoperative Treatment

In our view, there is little doubt among experts that a 25-to 30-degree curve in a growing child with documented progression by roentgenogram will require treatment.(7,12) Controversy remains, however, about the effectiveness of nonoperative regimens.(21)

Lateral Electrical Surface Stimulation

Lateral electrical surface stimulation consists of stimulating the paraspinal musculature on the convex side of the major curve. The technique requires nightly application of intermittent electrical stimulation by use of surface electrodes.(22) The indications for lateral electrical surface stimulation are essentially the same as those for orthotic treatment: skeletal immaturity, a structural curve(s) of 25 to 40 degrees, and documenting progression of the curve(s).(23) This treatment is appealing to children because they have the stimulation at night, while sleeping, and are therefore free from having to wear a brace during the day.

Although early studies using lateral electrical surface stimulation appeared promising, the results of this treatment in recent years, have been disappointing.(21,23) Sullivan et al(23) reported on 142 patients who were treated by the Scolitron method of lateral electrical surface stimulation. One hundred fourteen of the patients (80.1%) were compliant with the treatment, which was continued until skeletal maturity, as determined by radiography. A curve progression of 10% was considered a failure. With this criterion, 56% were classified as failures, 27% as successes, and 17% as undetermined because treatment was not completed. Noncompliant patients were included with the failures. The authors concluded that this method completed the treatment program. Based on these findings, use of this type of brace appears promising, although further investigation with longer follow-up will be necessary.(32)

We believe that successful orthotic management of children with idiopathic scoliosis depends on the following factors: proper curve selection, patient/family commitment and education, and a dedicated team of professionals committed to a successful bracing program. Patients undergoing treatment must be examined at regular intervals (eg, 3 months, 6 months, or more frequently if there are problems) to monitor the effects of treatment.

Team Approach

A treatment team consisting of an orthopedic surgeon, an orthotist, a nurse, and a physical therapist, who monitor this patient population in a clinical setting, makes the long-term management of these patients not only successful but also very rewarding. Patients and their families gain knowledge and support from the professional team as well as from other children and families undergoing similar treatment. The clinician, however, should not attempt to minimize the social impact on the adolescent of wearing a brace and appearing "different" from peers during this crucial period.

Each member of the treatment team plays an important role in the success of the bracing program. In our experience, the orthopedic surgeon performs a clinical assessment, interprets the radiographic findings, and discusses a treatment plan with the patient and family. The orthotist measures the patient and fabricates and fits the brace. The nurse coordinates the clinic, instructs the patient in brace application and skin care, and provides the patient with a schedule for adjusting to the brace. The physical therapist performs a comprehensive assessment, interprets the results, and designs an individual exercise program based on the findings. Each team member provides a great deal of emotional support to both the patient and family throughout the course of treatment. A highly motivated, enthusiastic team can have a very positive influence on both patients and families.

Physical Therapy Management

The role of exercise in the nonoperative management of adolescent idiopathic scoliosis is controversial.(33) There have been attempts to correct structural curves with vigorous exercises alone, stressing active derotation of the spine.(34)

Lovett devoted an entire section of his 1907 text Lateral Curvature of the Spine and Round Shoulders 35 to the appropriate role of exercises. Although Lovett was a strong supporter of the use of exercises in conjunction with the nonoperative approach to the management of adolescent idiopathic scoliosis, he did state,

It is obviously unreasonable to expect free standing gymnastic exercises to straighten marked or severe curves or to change the shape of distorted bones.(35(p120))

Lovett further stated,

The purely gymnastic treatment of severe structural scoliosis is today being largely pursued by two classes of persons.

First, by irresponsible masseurs and medical gymnasts who hold as a tradition that gymnastic exercises are curative or at least helpful in scoliosis and, second, by competent surgeons who do not believe in corsets or Supports.(35(pp120-121))

Today, most experts agree that exercise alone will not affect the progression of a structural scoliosis. There is agreement, however, that a selective exercise program in conjunction with bracing treatment is beneficial.(36,37)

Prior to the initiation of an exercise program, the patient should have a comprehensive assessment, which includes the following measures:

1. Posture-inspection of the patient's natural, relaxed posture in the anterior, posterior, and lateral views.

2. Leg length-measurement of leg lengths, both real (measured from the anterior superior iliac crest to the medial malleolus) and apparent (measured from the umbilicus to the medial malleolus). These measurements are used to determine the presence of leg-length discrepancies that might affect postural alignment and brace fit.

3. Range of motion (ROM)with embphasis in areas that could have a negative effect on brace fit such as the hip flexor, hamstring, tensor fasciae latae, and low back muscles and the trunk and shoulder girdle.

4. Muscle strength-with emphosis on the abdominal musculature.

5. Breathing pattern--essential especially if the patient has a history of asthma or any other respiratory disorder.

6. Functional activity levels-to establish a baseline, in order to assist the patient in returning to prebracing activity levels.

Designing a realistic, individual therapeutic exercise program targeting areas with positive findings can be instrumental in assisting the patient with brace compliance. If the brace fits well and the patient can resume physical activities, he or she is more likely to wear the brace the prescribed number of hours.

The purpose of the exercise program is to help the patient:

1. Develop postural awareness with the ability to maintain corrected alignment not only while wearing the brace but also at the completion of the bracing program.

2. Maintain proper respiration and chest mobility.

3. Maintain muscle strength, especially in the lower and oblique abdominal muscles.

4. Maintain joint ROM and spinal flexibility.

5. Resume prebracing levels of functional activity, Teaching the patient how to move, walk, run, and perform activities while wearing the brace helps the patient to achieve this goal.

In order for the bracing program to be successful, the brace must fit properly. Thus, if a patient has muscle tightness in structures that directly affect brace alignment and fit, appropriate exercises to alleviate this tightness should be implemented. For example, one of the main bracing principles is to reduce lumbar lordosis in an effort to stabilize the pelvis.(38) This is accomplished by building lumbar flexion into the pelvic module, allowing only 15 degrees of lumbar lordosis in most modules.

If a patient has tightness in the iliopsoas muscle, as indicated by a positive Thomas test, this tightness will have an adverse effect on postural alignment in the brace.39 When the patient attempts to stand upright while wearing the brace, he or she must compensate for the hip flexor tightness by either flexing the knee or extending the upper back over the posterior-superior borders of the brace. This compensatory extension results in a flattening of the thoracic spine that could lead to hypokyphosis One of the major goals of the bracing program is to align the trunk over the sacrum. Therefore, teaching the patient correct postural alignment, both with the brace on and with the brace off, is a significant part of the physical therapy program. Often, patients with structural curves are unaware of their asymmetrical posture. In our experience, when patients who are poorly aligned are placed in proper anatomical alignment, the statement is frequently made: "I feel crooked." Establishing normal alignment, both during and after the bracing program, is an ongoing challenge. Use of a mirror to assist the patient in achieving postural awareness and alignment is very helpful (Fig. 7).

Compliance with exercise programs designed to complement brace wearing varies widely.(29) We have observed that patients generally appear to be compliant during the period in which they are initially adjusted to wearing the brace. Once they are fully accustomed to the brace and have resumed normal activities, however, compliance appears to diminish. We believe that patients tend to resume their exercise program when it is time to be weaned from the brace. At this time, they will often comment that their back "feels tired." During this period, they are usually taught vigorous abdominal muscle strengthening exercises.

An important factor to emphasize to both patients and parents is the overall goal of the bracing program, which is prevention of further progression of the curve(s) rather than complete correction of the scoliosis. Long-term results of bracing indicate that curve magnitudes recorded at the completion of the bracing program usually are the same as those recorded at the beginning of bracing (Fig. 8).

Despite the best efforts on the part of the patient, the family, and the treatment team, children with structural curves who meet the criteria for bracing do not respond positively and will require surgical intervention.(29) Fortunately, the majority of patients with moderate, progressive curves, who meet the criteria for bracing and are enrolled in a comprehensive bracing program, will have a successful result and avoid surgery.

Operative Management

Patients with curves that exceed 40 degrees when the patients are still growing and those with curves that are in excess of 50 degrees after the end of growth are candidates for surgical correction.(40) The indications for surgical correction in the adult are somewhat more complex than in the growing child and involve such additional factors as late progression, pain, and decreasing respiratory function.

When nonoperative management fails in a child with idiopathic scoliosis, operative management must be considered, depending on the age of the child. if the child has early-onset idiopathic scoliosis and fails to respond to nonoperative management, then a decision must be made whether to operate on the front of the spine as well as the back. Because of the camshaft phenomenon (as described by Jean Dubousset and colleagues,(41) posterior fusion in a young child (under 10 years of age) will result in tethering the posterior elements. The anterior vertebral bodies will continue to grow, causing increased rotation and curvature by the end of growth.

The eventual success of any correction will depend on the quality of the spinal fusion. It is essential that there be a meticulous dissection of the spine, an adequate resection of the facet joints, a thorough decortication of the posterior elements wherever possible, and some form of supplemental bone graft.

The traditional aims of surgical management of spinal deformities are (1) to straighten the spine as much as possible consistent with safety; (2) to balance the trunk of the pelvis; and (3) to stabilize the spine by arthrodesis, which will maintain the correction.

The actual percentage of correction is less important than the balancing and stability of the spine and the attention to the correction of the spine in three dimensions, including rotation.

For many years, the standard instrumentation has been the Harrington set, consisting of both distraction and compression rods (Fig. 9).(42) The compression rods are used in kyphosis and are contraindicated if the patient has a flat back or thoracic lordosis. Supplemental sublaminal or spinous process wiring has increased the correction and the stability obtained with the use of Harrington instrumentation.(42) This instrumentation is still in wide use in many parts of the world. All of the modifications that have been made to the original Harrington instrumentation have been toward helping to correct the rib hump and obtaining more stability so that less external immobilization will be required.

The Cotrel-dubousset instrumentation, introduced in the United States in 1984, is designed to rotate the spine to obtain correction of the rib hump and to establish a normal sagittal contour with the proper amount of thoracic kyphosis and lumbar lordosis (Fig. 10).(43) The Cotrel-Dubousset set is more stable because of the introduction of cross-linking, using an apparatus to link the two rods to make the system stable in rotation as well as in lateral bending and compression.

Many new types of instrumentation, such as the Texas Scottish-Rite Hospital system, have been developed based on the Cotrel-Dubousset principles and have introduced such advantages as an improved cross-linking apparatus with all open hooks to allow for easier insertion. it must be emphasized, however, that it is more important to adhere to the principles of surgical correction and spine fusion than to dwell on the type of instrumentation used.

Long-term follow-up of patients who have had spinal fusion as adolescents or young adults has shown that it is more important to pay attention to the sagittal contour.(44) Many patients whose lumbar lordosis has been obliterated by the use of a straight Harrington rod have developed a problem known as the flat back syndrome. These patients have great difficulty standing erect because of collapse of the disks below the level of fusion. When they attempt to maintain erect posture, they must either lean forward or flex their knees. The new systems, which allow retention of the normal lumbar lordosis, should minimize this complication in the future.

Other potential complications, such as neurologic problems up to and including paraplegia, are fortunately rare. Their prevention is aided by the use of intraoperative monitoring of spinal cord function and intraoperative wake-up tests.(45)

Physical Therapy Management

The preoperative assessment includes the following measures:

1. Posture-inspection and documentation of postural abnormalities in the anterior, lateral, and posterior views.

2. Range of motion-with emphasis on limitations in the lower extremities that may affect the patient's ability for early postoperative mobilization such as tightness of the hamstring muscles, hip flexors, and heel cords.

3. Leg length-measurement of both real and apparent leg lengths. If the patient has a real leg-length discrepancy wears a prescribed shoe lift, this measure will be needed for postoperative ambulation.

4. Muscle strength-a detailed muscle examination is performed to establish a baseline. Significant areas of weakness are summarized and highlighted so that they will not be attributed to postoperative complications.

5. Respiratory function-with emphasis on lateral costal expansion and diaphragmatic breathing. This measure is particularly important if the patient has a history of asthma or any other respiratory disorders.

Preoperative therapy includes deep-breathing training and instruction in deep, effective coughing. Techniques of postural drainage are reviewed with and explained to the patient in the event of any respiratory postoperative complications. In addition, the patient is shown how to log roll and come to a sitting position.

The primary postoperative goal is early mobilization to prevent postoperative complications. Once again, a team treatment approach is emphasized. The physician, nurse, and physical therapist work together to assist the patient in achieving this goal. Patients are encouraged to breathe deeply and to cough both frequently and effectively. Lower-extremity exercises are indicated only if the patient is having difficulty with early mobilization. Usually, patients are able to sit up in a chair the first postoperative day. External support (ie, a bivalved plastic clamshell brace) may or may not be necessary. Most patients are able to independently ambulate within 4 to 7 postoperative days.

Improved surgical techniques'13 allow for both early mobilization and a shorter hospital stay (about 7-10 days, at the present time, if there are no complications). Operative management of idiopathic scoliosis remains complex, however, and it is clear that further research into etiology is essential in order to prevent the development of idiopathic scoliosis rather than having to resort to extreme measures such as surgery and prolonged bracing to correct it.

Summary

Although the management of adolescent idiopathic scoliosis has improved over the last several years, the treatment remains a very extensive process. Nonoperative and operative regimens are major events for both the patients and their families. The treatment team should never underestimate the effect of treatment on patients and families. Sensitivity, support, honesty, and communication of accurate information are the key ingredients toward successful treatment.

Acknowledgments

We gratefully acknowledge the helpful advice and comments of Alice M Shea, ScD, FIT, Associate for Research and Education, Department of Physical Therapy and Occupational Therapy Services, Children's Hospital, Boston, Mass. Our appreciation is expressed for the photographs taken by James Koepfler, Biomedical Photographer, Department of Orthopaedics, Children's Hospital.

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