- Email: [email protected]
Scoliosis
C h a p t e r
5 8
Scoliosis Paul J. Roubal, PT, PhD
1. What are the major types of scoliosis? • Functional scoliosis—This may be caused by muscle spasm (secondary to lumbar or thoracic injuries) or leg length discrepancy (which causes a lateral shift in the spine). Functional scoliosis resolves with healing of the lumbar or thoracic injuries or correction of the leg length discrepancy. • Structural scoliosis—This type of scoliosis is usually idiopathic. • Congenital scoliosis—This type is caused by vertebral anomalies and is much less common than the other two types of scoliosis.
2. What is the incidence of idiopathic structural scoliosis? Idiopathic scoliosis affects 1 to 4 people per thousand. Curves >20 degrees are 7 times more common in females than males, and curves >30 degrees have a 10:1 female to male ratio. The incidence drops to about 0.3% overall for curves >20 degrees. Idiopathic scoliosis usually occurs in adolescents between 11 and 14 years of age.
3. What are the possible causes of idiopathic scoliosis? The role of genetics has been debated. Family history is not helpful in determining curve magnitude. Some form of multifactorial or autosomal dominant inheritance seems to be involved although most recent research suggests a polygenic inheritance pattern. The proprioceptive system and equilibrium imbalances, possibly related to asymmetry in the brain stem, also may be implicated.
4. Describe the clinical presentation of idiopathic scoliosis. Curves do not straighten when the trunk is flexed forward (Adam’s test). Structural curves exhibit rotatory components during forward flexion, and the patient’s symptoms usually include rib hump or asymmetry in the trunk, referred to as the angle of trunk rotation (ATR). The ATR is easily measured with the scoliosometer.
5. What types of initial screening processes appear most effective in determining whether aggressive active treatment, such as bracing or surgery, is needed? The most common method for determining the presence and severity of scoliosis is Adam’s test combined with the use of the scoliosometer. Moire photography is moderately effective in screening for scoliosis but is much less cost-effective. Two-tier screening programs, which include both an initial screener and a secondary screener, tend to be the most effective in reducing falsepositive diagnoses.
474
Scoliosis
475
6. When is further evaluation of idiopathic scoliosis advisable? In general, patients with curves >15 to 20 degrees and a 5- to 7-degree ATR usually are referred for further follow-up by an orthopaedist. Current data, however, recommend at least a 20-degree curve and 7-degree ATR.
7. Describe the Risser classification. The Risser classification uses ossification of the iliac epiphysis to grade remaining skeletal growth. Ossification starts laterally and runs medially. Ossification of the lateral 25% indicates Risser type 1; of 50%, Risser type 2; of 75%, Risser type 3; complete excursion, Risser type 4; and fusion to the ilium, Risser type 5. Growth in females is usually complete in Risser type 4.
8. Describe the King classification system. The King classification system describes curve types in idiopathic scoliosis, and the system helps to determine surgical treatment. • Type I—primary lumbar and secondary thoracic curves • Type II—primary thoracic and secondary lumbar curves • Type III—thoracic curves only • Type IV—large thoracic curves extending into the lumbar spine • Type V—double thoracic curves Recent studies have demonstrated some reliability problems with the King classification system. A newer system—the Lenke classification of adolescent idiopathic scoliosis—uses three components: curve type, lumbar spine modifiers, and sagittal thoracic modifiers. It is the most common system in use today for determining surgical intervention treatments. The Lenke system has recently been shown to be much more reliable than the King system.
9. Describe the rate of progression of idiopathic scoliosis. Curve progression depends on curve size and Risser sign. For curves <20 degrees that are Risser type 0 or 1, progression occurs in 22% versus only 1.6% for curves above Risser type 2. For curves of 20 to 30 degrees and Risser type 0 or 1, progression occurs in 68% versus only 22% for curves above Risser type 2.
10. What treatment options are available for progressive idiopathic scoliosis? Surgery and bracing have been the gold standard of treatment. There has recently been some research that shows progressive inpatient rehabilitation programs concomitant with development of ongoing home programs derived from this inpatient program have been successful in controlling the progression of scoliotic curves.
11. When should bracing be considered? Curves <20 degrees generally do not require bracing, particularly when patients are more mature (Risser types 3 to 5). Curves <30 degrees that progress 5 degrees or more over 12 months should be braced. For curves >30 degrees, bracing should be initiated immediately. Bracing is not indicated in skeletally mature patients.
12. Describe the bracing used for scoliosis. How long should the brace be worn? The first brace, developed immediately after World War II by Blount et al., was named the Milwaukee brace. It was fairly cumbersome, made with stainless-steel bars, and fitted with side straps to reduce lateral deflection and rotation of the spine at the specific points of apexes of curves. Newer, more comfortable braces include the Boston brace (thoracolumbosacral orthosis [TLSO]), which appears to be the most effective; it is made of molded plastic and fitted to the
476
The Spine
patient. Boston braces enhance adherence to treatment protocols because of ease of use. Generally they must be changed once every 12 to 18 months, depending on the patient’s growth and body changes. Braces are most effective when worn 23 hours per day until skeletal maturity is achieved. The effectiveness of bracing is time-dependent: the more the brace is worn, the better the outcome.
13. What forces in braces reduce progression of scoliotic curves? Computer evaluation of braces determined that the primary correction forces in braces are lateral. Muscle forces and longitudinal traction play minimal roles, if any. Reduction in hyperlordosis also is needed to reduce the curve.
14. What are the outcomes of major brace types in treating idiopathic scoliosis? The Boston brace, Milwaukee brace, and Charleston bending brace are used most commonly to treat idiopathic scoliosis. Recent studies show that the quality of life scores are higher for Milwaukee and Boston braces than for the Charleston brace. For most curves, the Boston brace appears more effective at preventing curves from progressing, as defined by a lower rate of surgery. Surgical rates for the Charleston brace appear to be approximately 50% higher than for either the Milwaukee or the Boston brace. The greatest difference in outcome is found in King type III curves. King type I and II curves have fairly equal results with Charleston and Boston braces. Boston braces are most appropriate for curves with their apex below T8. Milwaukee braces are best used for curves with the apex above T7. Recent strides have been made in developing strap tension systems with strap transducers instrumented to the Boston brace. These tension systems allow optimal prescribed levels of tensioning so the patient may achieve the best curve correction along with a reduction in curve progression.
15. What curves respond best to bracing? Curves without severe lumbar hyperlordosis, thoracic lordosis, or hyperkyphosis respond best to bracing. Risser type 0 curves respond best, whereas Risser type 4 or 5 curves rarely respond well. Double major curves respond less favorably to bracing than other curves.
16. How effective is bracing? Over the years, the efficacy of bracing has been one of the most intensely debated subjects in the treatment of idiopathic scoliosis. Recent reports, however, indicate that the efficacy may be as high as 74% to 81% in halting progression of idiopathic structural scoliosis. In contrast, only 33% of patients do not progress without the use of bracing. Recent studies also show that wearing braces did not affect the quality of life in adolescents compared to observed counterparts. Other recent studies show that brace compliance and a high initial correction are strong indictors for bracing success.
17. What are the indications for surgical intervention? • • • •
Curves >50 degrees in skeletally mature patients Curves progressed beyond 40 degrees in skeletally mature patients Curves >30 degrees with marked rotation Double major curves >30 degrees
18. Define “crankshaft phenomenon.” In a patient with an immature spine, correction of scoliosis with successful posterior fusion may be complicated by continued anterior vertebral body growth, which can increase the curve and vertebral rotation. This problem may be corrected with combined anterior and posterior fusion procedures if a skeletally immature patient must undergo surgery.
Scoliosis
477
19. What type of correction can be expected with surgical intervention? Surgery in idiopathic scoliosis generally reduces the major coronal curve by approximately 50%, vertebral rotation by approximately 10%, and apical translation by an average of approximately 60%.
20. What is the most common form of surgical intervention in idiopathic scoliosis? Segmental instrumentation with multihook systems (e.g., Cotrel-Dubousset system) is the most common approach. Fixation is posterior. For more advanced and rigid curves, both anterior and posterior fusions may be incorporated. Patients should be evaluated on an individual basis.
21. List the complications of surgical intervention for idiopathic scoliosis. • • • • • • • • •
Migration of rods Neurologic damage Pseudarthrosis Renal failure Psychological stress Blood loss Failure of fixation Infection Respiratory distress
22. What types of treatment other than surgery or bracing have been shown to be effective? Numerous studies have demonstrated that lateral electrical stimulation (LES) and exercise, either in or out of the bracing, are ineffective. To date, no research has shown that chiropractic care is effective. Physical therapists have recently been used in progressive inpatient and immediate postinpatient rehabilitation programs for scoliosis.
23. Describe the role of the physical therapist in screening and treating scoliosis. The physical therapist may train screeners, screen patients, and oversee preoperative and postoperative conditioning programs and progression in patient rehabilitation programs. Pain management, either before or after bracing or surgery, also may be needed.
24. Compare the costs of bracing and surgery. Most research shows that the costs of bracing and surgery are somewhat comparable. At the start of the new millennium, total surgical costs, which include preoperative and postsurgical care and bracing as well as other medical care, average approximately $50,000. These costs do not include screening. Overall costs would be decreased if screening was used with bracing. Cost estimates do not include loss of income, welfare, social programs, or other direct or indirect medical costs associated with surgical intervention.
25. What are the long-term curve progressions for surgical-treated versus bracetreated curves? After 22 years, brace-treated curves progressed 7.9 degrees versus 3.5 degrees for surgically treated curves.
26. What are the long-term (20 years or more) quality-of-life outcomes for surgery versus bracing treatment? No correlation exists between curve size after treatment, curve type, total treatment time, or age at completion of treatment. Approximately 49% of those undergoing surgery, 34% of those treated
478
The Spine
with braces, and 15% of controls will have some limitation of social activities, mostly because of physical participation in activities or self-consciousness about appearance. Patients treated for scoliosis have about the same health-related quality of life as the general population.
27. What is the natural history of patients with untreated idiopathic scoliosis? Untreated people with scoliosis are productive and function at a high level at 50-year follow-up. Back pain occurs in 61% as compared to 35% of controls. However, of those with pain 68% describe it as minor or moderate.
Bibliography Blount WP et al: The Milwaukee brace in the operative treatment of scoliosis, J Bone Joint Surg Am 40A:511-525, 1958. Climent JM, Sanchez J: Impact of the type of brace on the quality of life of adolescents with spine deformities, Spine 24:1903-1908, 1999. Danielsson AJ, Nachemson AL: Radiologic findings and curve progression 22 years after treatment for adolescent idiopathic scoliosis: comparison of brace and surgical treatment with matching control group of straight individuals, Spine 26:516-525, 2001. Danielsson AJ et al: Health related quality of life in patients with adolescent idiopathic scoliosis: a matched follow-up at least 20 years after treatment with brace or surgery, Eur Spine J 10:278-288, 2001. Dubousset J, Herring JA, Shufflebarger H: The crankshaft phenomenon, J Pediatr Orthop 9:541-550, 1989. Fernandez-Feliberti R et al: Effectiveness of TLSO bracing in the conservative treatment of idiopathic scoliosis, J Pediatr Orthop 15:176-181, 1995. Howard A, Wright JG, Hedden D: A comparative study of TLSO, Charleston, and Milwaukee braces for idiopathic scoliosis, Spine 23:2404-2411, 1998. Katz DE, Durrani AA: Factors that influence outcome in bracing large curves in patients with adolescent idiopathic scoliosis, Spine 26:2354-2361, 2001. King HA et al: The selection of fusion levels in thoracic idiopathic scoliosis, J Bone Joint Surg 65A:1302-1313, 1983. Landauer F, Wimmer C, Behensky H: Estimating the final outcome of brace treatment for idiopathic thoracic scoliosis at 6-month follow-up journal, 6:201-207, 2003. Lenke LG et al: Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis, J Bone Joint Surg 83A:1169-1181, 2001. Lenke LG et al: The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine, Spine 28:S199-207, 2003. Lou E et al: Intelligent brace system for the treatment of scoliosis, Stud Health Technol Inform 91:397-400, 2002. Lonstein JE, Winter RB: The Milwaukee Brace for the treatment of adolescent idiopathic scoliosis, J Bone Joint Surg 82A:1207-1221, 1994. Mielke CH et al: Surgical treatment of adolescent idiopathic scoliosis: a comparative analysis, J Bone Joint Surg 71A:1170-1177, 1989. Montgomery F, Willner S: The natural history of idiopathic scoliosis: incidence of treatment in 15 cohorts of children born between 1963 and 1977, Spine 22:772-774, 1997. Nachemson AL, Petersen LE: Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis, J Bone Joint Surg 77A:815-822, 1995. Rigo M, Reiter Ch, Weiss HR: Effect of conservative management on the prevalence of surgery in patients with adolescent idiopathic scoliosis, Pediatr Rehabil 6:209-214, 2003. Roubal PJ, Freeman DC, Placzek JD: Costs and effectiveness of scoliosis screening, Physiotherapy 85:259-268, 1999. Ugwonali OF et al: Effect of bracing on the quality of life of adolescents with idiopathic scoliosis, Spine J 4:254-260, 2004. Weinstein SL et al: Health and function of patients with untreated idiopathic scoliosis: a 50 year natural history study, JAMA 5:559-567, 2003. Weiss HR, Weiss G, Schaar HJ: Incidence of surgery in conservatively treated patients with scoliosis, Pediatr Rehabil 6:111-118, 2003. Willers U et al: Long-term results of Harrington instrumentation in idiopathic scoliosis, Spine 18:713-717, 1993.
5 8
Scoliosis Paul J. Roubal, PT, PhD
1. What are the major types of scoliosis? • Functional scoliosis—This may be caused by muscle spasm (secondary to lumbar or thoracic injuries) or leg length discrepancy (which causes a lateral shift in the spine). Functional scoliosis resolves with healing of the lumbar or thoracic injuries or correction of the leg length discrepancy. • Structural scoliosis—This type of scoliosis is usually idiopathic. • Congenital scoliosis—This type is caused by vertebral anomalies and is much less common than the other two types of scoliosis.
2. What is the incidence of idiopathic structural scoliosis? Idiopathic scoliosis affects 1 to 4 people per thousand. Curves >20 degrees are 7 times more common in females than males, and curves >30 degrees have a 10:1 female to male ratio. The incidence drops to about 0.3% overall for curves >20 degrees. Idiopathic scoliosis usually occurs in adolescents between 11 and 14 years of age.
3. What are the possible causes of idiopathic scoliosis? The role of genetics has been debated. Family history is not helpful in determining curve magnitude. Some form of multifactorial or autosomal dominant inheritance seems to be involved although most recent research suggests a polygenic inheritance pattern. The proprioceptive system and equilibrium imbalances, possibly related to asymmetry in the brain stem, also may be implicated.
4. Describe the clinical presentation of idiopathic scoliosis. Curves do not straighten when the trunk is flexed forward (Adam’s test). Structural curves exhibit rotatory components during forward flexion, and the patient’s symptoms usually include rib hump or asymmetry in the trunk, referred to as the angle of trunk rotation (ATR). The ATR is easily measured with the scoliosometer.
5. What types of initial screening processes appear most effective in determining whether aggressive active treatment, such as bracing or surgery, is needed? The most common method for determining the presence and severity of scoliosis is Adam’s test combined with the use of the scoliosometer. Moire photography is moderately effective in screening for scoliosis but is much less cost-effective. Two-tier screening programs, which include both an initial screener and a secondary screener, tend to be the most effective in reducing falsepositive diagnoses.
474
Scoliosis
475
6. When is further evaluation of idiopathic scoliosis advisable? In general, patients with curves >15 to 20 degrees and a 5- to 7-degree ATR usually are referred for further follow-up by an orthopaedist. Current data, however, recommend at least a 20-degree curve and 7-degree ATR.
7. Describe the Risser classification. The Risser classification uses ossification of the iliac epiphysis to grade remaining skeletal growth. Ossification starts laterally and runs medially. Ossification of the lateral 25% indicates Risser type 1; of 50%, Risser type 2; of 75%, Risser type 3; complete excursion, Risser type 4; and fusion to the ilium, Risser type 5. Growth in females is usually complete in Risser type 4.
8. Describe the King classification system. The King classification system describes curve types in idiopathic scoliosis, and the system helps to determine surgical treatment. • Type I—primary lumbar and secondary thoracic curves • Type II—primary thoracic and secondary lumbar curves • Type III—thoracic curves only • Type IV—large thoracic curves extending into the lumbar spine • Type V—double thoracic curves Recent studies have demonstrated some reliability problems with the King classification system. A newer system—the Lenke classification of adolescent idiopathic scoliosis—uses three components: curve type, lumbar spine modifiers, and sagittal thoracic modifiers. It is the most common system in use today for determining surgical intervention treatments. The Lenke system has recently been shown to be much more reliable than the King system.
9. Describe the rate of progression of idiopathic scoliosis. Curve progression depends on curve size and Risser sign. For curves <20 degrees that are Risser type 0 or 1, progression occurs in 22% versus only 1.6% for curves above Risser type 2. For curves of 20 to 30 degrees and Risser type 0 or 1, progression occurs in 68% versus only 22% for curves above Risser type 2.
10. What treatment options are available for progressive idiopathic scoliosis? Surgery and bracing have been the gold standard of treatment. There has recently been some research that shows progressive inpatient rehabilitation programs concomitant with development of ongoing home programs derived from this inpatient program have been successful in controlling the progression of scoliotic curves.
11. When should bracing be considered? Curves <20 degrees generally do not require bracing, particularly when patients are more mature (Risser types 3 to 5). Curves <30 degrees that progress 5 degrees or more over 12 months should be braced. For curves >30 degrees, bracing should be initiated immediately. Bracing is not indicated in skeletally mature patients.
12. Describe the bracing used for scoliosis. How long should the brace be worn? The first brace, developed immediately after World War II by Blount et al., was named the Milwaukee brace. It was fairly cumbersome, made with stainless-steel bars, and fitted with side straps to reduce lateral deflection and rotation of the spine at the specific points of apexes of curves. Newer, more comfortable braces include the Boston brace (thoracolumbosacral orthosis [TLSO]), which appears to be the most effective; it is made of molded plastic and fitted to the
476
The Spine
patient. Boston braces enhance adherence to treatment protocols because of ease of use. Generally they must be changed once every 12 to 18 months, depending on the patient’s growth and body changes. Braces are most effective when worn 23 hours per day until skeletal maturity is achieved. The effectiveness of bracing is time-dependent: the more the brace is worn, the better the outcome.
13. What forces in braces reduce progression of scoliotic curves? Computer evaluation of braces determined that the primary correction forces in braces are lateral. Muscle forces and longitudinal traction play minimal roles, if any. Reduction in hyperlordosis also is needed to reduce the curve.
14. What are the outcomes of major brace types in treating idiopathic scoliosis? The Boston brace, Milwaukee brace, and Charleston bending brace are used most commonly to treat idiopathic scoliosis. Recent studies show that the quality of life scores are higher for Milwaukee and Boston braces than for the Charleston brace. For most curves, the Boston brace appears more effective at preventing curves from progressing, as defined by a lower rate of surgery. Surgical rates for the Charleston brace appear to be approximately 50% higher than for either the Milwaukee or the Boston brace. The greatest difference in outcome is found in King type III curves. King type I and II curves have fairly equal results with Charleston and Boston braces. Boston braces are most appropriate for curves with their apex below T8. Milwaukee braces are best used for curves with the apex above T7. Recent strides have been made in developing strap tension systems with strap transducers instrumented to the Boston brace. These tension systems allow optimal prescribed levels of tensioning so the patient may achieve the best curve correction along with a reduction in curve progression.
15. What curves respond best to bracing? Curves without severe lumbar hyperlordosis, thoracic lordosis, or hyperkyphosis respond best to bracing. Risser type 0 curves respond best, whereas Risser type 4 or 5 curves rarely respond well. Double major curves respond less favorably to bracing than other curves.
16. How effective is bracing? Over the years, the efficacy of bracing has been one of the most intensely debated subjects in the treatment of idiopathic scoliosis. Recent reports, however, indicate that the efficacy may be as high as 74% to 81% in halting progression of idiopathic structural scoliosis. In contrast, only 33% of patients do not progress without the use of bracing. Recent studies also show that wearing braces did not affect the quality of life in adolescents compared to observed counterparts. Other recent studies show that brace compliance and a high initial correction are strong indictors for bracing success.
17. What are the indications for surgical intervention? • • • •
Curves >50 degrees in skeletally mature patients Curves progressed beyond 40 degrees in skeletally mature patients Curves >30 degrees with marked rotation Double major curves >30 degrees
18. Define “crankshaft phenomenon.” In a patient with an immature spine, correction of scoliosis with successful posterior fusion may be complicated by continued anterior vertebral body growth, which can increase the curve and vertebral rotation. This problem may be corrected with combined anterior and posterior fusion procedures if a skeletally immature patient must undergo surgery.
Scoliosis
477
19. What type of correction can be expected with surgical intervention? Surgery in idiopathic scoliosis generally reduces the major coronal curve by approximately 50%, vertebral rotation by approximately 10%, and apical translation by an average of approximately 60%.
20. What is the most common form of surgical intervention in idiopathic scoliosis? Segmental instrumentation with multihook systems (e.g., Cotrel-Dubousset system) is the most common approach. Fixation is posterior. For more advanced and rigid curves, both anterior and posterior fusions may be incorporated. Patients should be evaluated on an individual basis.
21. List the complications of surgical intervention for idiopathic scoliosis. • • • • • • • • •
Migration of rods Neurologic damage Pseudarthrosis Renal failure Psychological stress Blood loss Failure of fixation Infection Respiratory distress
22. What types of treatment other than surgery or bracing have been shown to be effective? Numerous studies have demonstrated that lateral electrical stimulation (LES) and exercise, either in or out of the bracing, are ineffective. To date, no research has shown that chiropractic care is effective. Physical therapists have recently been used in progressive inpatient and immediate postinpatient rehabilitation programs for scoliosis.
23. Describe the role of the physical therapist in screening and treating scoliosis. The physical therapist may train screeners, screen patients, and oversee preoperative and postoperative conditioning programs and progression in patient rehabilitation programs. Pain management, either before or after bracing or surgery, also may be needed.
24. Compare the costs of bracing and surgery. Most research shows that the costs of bracing and surgery are somewhat comparable. At the start of the new millennium, total surgical costs, which include preoperative and postsurgical care and bracing as well as other medical care, average approximately $50,000. These costs do not include screening. Overall costs would be decreased if screening was used with bracing. Cost estimates do not include loss of income, welfare, social programs, or other direct or indirect medical costs associated with surgical intervention.
25. What are the long-term curve progressions for surgical-treated versus bracetreated curves? After 22 years, brace-treated curves progressed 7.9 degrees versus 3.5 degrees for surgically treated curves.
26. What are the long-term (20 years or more) quality-of-life outcomes for surgery versus bracing treatment? No correlation exists between curve size after treatment, curve type, total treatment time, or age at completion of treatment. Approximately 49% of those undergoing surgery, 34% of those treated
478
The Spine
with braces, and 15% of controls will have some limitation of social activities, mostly because of physical participation in activities or self-consciousness about appearance. Patients treated for scoliosis have about the same health-related quality of life as the general population.
27. What is the natural history of patients with untreated idiopathic scoliosis? Untreated people with scoliosis are productive and function at a high level at 50-year follow-up. Back pain occurs in 61% as compared to 35% of controls. However, of those with pain 68% describe it as minor or moderate.
Bibliography Blount WP et al: The Milwaukee brace in the operative treatment of scoliosis, J Bone Joint Surg Am 40A:511-525, 1958. Climent JM, Sanchez J: Impact of the type of brace on the quality of life of adolescents with spine deformities, Spine 24:1903-1908, 1999. Danielsson AJ, Nachemson AL: Radiologic findings and curve progression 22 years after treatment for adolescent idiopathic scoliosis: comparison of brace and surgical treatment with matching control group of straight individuals, Spine 26:516-525, 2001. Danielsson AJ et al: Health related quality of life in patients with adolescent idiopathic scoliosis: a matched follow-up at least 20 years after treatment with brace or surgery, Eur Spine J 10:278-288, 2001. Dubousset J, Herring JA, Shufflebarger H: The crankshaft phenomenon, J Pediatr Orthop 9:541-550, 1989. Fernandez-Feliberti R et al: Effectiveness of TLSO bracing in the conservative treatment of idiopathic scoliosis, J Pediatr Orthop 15:176-181, 1995. Howard A, Wright JG, Hedden D: A comparative study of TLSO, Charleston, and Milwaukee braces for idiopathic scoliosis, Spine 23:2404-2411, 1998. Katz DE, Durrani AA: Factors that influence outcome in bracing large curves in patients with adolescent idiopathic scoliosis, Spine 26:2354-2361, 2001. King HA et al: The selection of fusion levels in thoracic idiopathic scoliosis, J Bone Joint Surg 65A:1302-1313, 1983. Landauer F, Wimmer C, Behensky H: Estimating the final outcome of brace treatment for idiopathic thoracic scoliosis at 6-month follow-up journal, 6:201-207, 2003. Lenke LG et al: Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis, J Bone Joint Surg 83A:1169-1181, 2001. Lenke LG et al: The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine, Spine 28:S199-207, 2003. Lou E et al: Intelligent brace system for the treatment of scoliosis, Stud Health Technol Inform 91:397-400, 2002. Lonstein JE, Winter RB: The Milwaukee Brace for the treatment of adolescent idiopathic scoliosis, J Bone Joint Surg 82A:1207-1221, 1994. Mielke CH et al: Surgical treatment of adolescent idiopathic scoliosis: a comparative analysis, J Bone Joint Surg 71A:1170-1177, 1989. Montgomery F, Willner S: The natural history of idiopathic scoliosis: incidence of treatment in 15 cohorts of children born between 1963 and 1977, Spine 22:772-774, 1997. Nachemson AL, Petersen LE: Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis, J Bone Joint Surg 77A:815-822, 1995. Rigo M, Reiter Ch, Weiss HR: Effect of conservative management on the prevalence of surgery in patients with adolescent idiopathic scoliosis, Pediatr Rehabil 6:209-214, 2003. Roubal PJ, Freeman DC, Placzek JD: Costs and effectiveness of scoliosis screening, Physiotherapy 85:259-268, 1999. Ugwonali OF et al: Effect of bracing on the quality of life of adolescents with idiopathic scoliosis, Spine J 4:254-260, 2004. Weinstein SL et al: Health and function of patients with untreated idiopathic scoliosis: a 50 year natural history study, JAMA 5:559-567, 2003. Weiss HR, Weiss G, Schaar HJ: Incidence of surgery in conservatively treated patients with scoliosis, Pediatr Rehabil 6:111-118, 2003. Willers U et al: Long-term results of Harrington instrumentation in idiopathic scoliosis, Spine 18:713-717, 1993.