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Scoliosis: A straightforward approach to the curved spine
Amy L. Dennis, PA-CMs. Dennis practices family medicine at the Medical Associates Clinic in Platteville, Wis.Some deformities are benign and self-limiting; others may progress. Primary care PAs are uniquely positioned to anticipate, evaluate, and monitor patients.
The term scoliosis describes a lateral curve in the spine and is derived from the Greek word for crookedness. The disorder, defined as a spinal curvature greater than 10 degrees,1 may appear during infancy, early childhood, or adolescence and can be associated with neuromuscular or congenital anomalies. Adolescent idiopathic scoliosis (AIS), which accounts for 65% to 85% of all cases of scoliosis, affects 2% to 3% of children and teenagers 10 to 16 years old, and the disorder is more common in girls than boys.2,3 AIS occurs around the onset of puberty and is not associated with any underlying congenital or neurologic abnormalities. Infantile scoliosis develops before 3 years of age, and juvenile-onset scoliosis is manifested between 3 and 10 years; together they account for fewer than 1% of all cases of scoliosis. Other types include congenital and neuromuscular scoliosis. The congenital form is caused by malformed vertebral bodies and may be associated with renal, cardiac, and intraspinal anomalies. Neuromuscular scoliosis can affect children who have cerebral palsy, spina bifida, or muscular dystrophy. Scoliosis may also develop secondary to connective tissue disorders such as Marfan syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta in children up to age 16 years. During periods of accelerated growth, sustained compression and distraction forces on growth plate chondrocytes create wedge-shaped vertebral bodies that bend the spine laterally.4 Posterior elements (spinous and transverse processes) are directed toward the concavity of the scoliotic curve, causing the spinal column to angulate and rotate. The cosmetic result is asymmetry of the rib cage, resulting in a characteristic rib hump (see Figure 1).
The causes of AISAlthough the etiology of AIS is unknown, hereditary factors are understood to have a role.5-8 An autosomal dominant inheritance pattern is present in some families,9,10 and the daughters of 27% of women whose AIS curvature measures greater than 15 degrees will also be affected.6 The variability in severity of curvature within families suggests that the development of scoliosis is multifactorial.2,11 Current research is focused on growth hormone secretion, connective tissue structure, vestibular dysfunction, melatonin secretion, and platelet microstructure. Although deficits in these areas have been noted in some patient populations, no studies have established any one factor as a cause of AIS.2 Still to be determined is whether the structural changes seen in scoliosis in muscle and other connective tissues are the source of the deformity or secondary to it. History and physical examinationPatients with scoliosis rarely present with a functional deficit. Although severe scoliosis may cause restrictive pulmonary disease and pain, most patients do not exhibit these symptoms until their curves approach 100 degrees.12,13 Curves of this magnitude are uncommon and generally occur only as a consequence of juvenile-onset scoliosis.14 Severe pain or neurologic symptoms are atypical of idiopathic scoliosis. Ask about headache, back or neck pain, sensory or motor changes, and bowel or bladder habit changes. A history of heart or urinary tract problems at birth raises suspicion for congenital scoliosis. A family history of neurofibromatosis or Marfan syndrome suggests a genetic connective tissue disorder,15 and approximately 10% of AIS patients will have a family member affected by idiopathic scoliosis.16 Ask female patients about onset of menses; the growth spurt during which scoliosis is most likely to progress in girls begins 12 to 18 months before menarche. Visual inspection of the back is performed with the patient, dressed in a gown, standing with her back to a seated examiner. Physical exam findings consistent with a diagnosis of scoliosis include shoulder height asymmetry, unilateral scapular prominence, waistline asymmetry, and truncal shift. In the Adams forward-bending test, the patient bends forward at the waist with the knees straight and the palms together, hanging toward the floor (see Figure 2).17 Look for a prominence on one side of the thoracic or lumbar spine. Note that leg-length discrepancies can skew findings; if iliac crest heights are uneven with the patient standing, place a textbook, wooden block, or pad of paper under the foot of the shorter leg to level the pelvis for the examination.
The remainder of the examination includes a careful neurologic evaluation, concentrating on the lower extremities. Deep tendon reflexes at the knee and ankle should be symmetric, and clonus, if present, should not exceed four beats or be sustained. Asymmetric reflexes and excessive clonus suggest a neurologic cause for scoliosis, such as a brain or spinal cord tumor or abnormality. Test lower-extremity strength by having the patient walk on the toes and heels, and note any foot deformity. Large or multiple café-au-lait spots or axillary freckling on skin exam suggests neurofibromatosis. Imaging studiesAlthough spinal deformity can be diagnosed on physical exam, a diagnosis of scoliosis requires standing, upright posteroanterior and lateral radiographs of the full spine. The Cobb method can be used to measure the degree of curvature. Intersecting lines are drawn on the x-ray film from the vertebral bodies above and below the apex of the curve with the greatest tilt (see Figure 3).18 Idiopathic scoliosis is diagnosed only in those cases of a curve greater than 10 degrees and structural changes (such as rotation of the vertebrae). A spinal curve of less than 10 degrees may be diagnosed as postural scoliosis, and a curve that is secondary to a leg-length discrepancy should be diagnosed as functional scoliosis.19
Spinal curves tend to develop in recognizable patterns. The thoracic curve is more obvious on physical exam than is a lumbar curve. Ninety percent of thoracic curves are to the right.20 Suspect a spinal cord abnormality in a left thoracic curve that is accompanied by a history of back pain or headache or if the physical exam reveals muscle weakness, ataxia, or a unilateral cavovarus foot deformity. MRI can detect intraspinal pathology such as a tumor, syringomyelia (cavity in the spinal cord), diastematomyelia (congenital splitting of the spinal cord), Arnold-Chiari malformation, or a tethered cord. These findings may require neurosurgical intervention. MRI should also be obtained in patients who are younger than 8 years when scoliosis is detected or when the curve progresses more than 1 degree each month.15 The natural history of AISWithout intervention, a scoliotic curve may progress between the time of detection and the time of skeletal maturity, with girls showing ten times the risk for curve progression compared to boys.21-23 Skeletal maturity is assessed using the Risser system, which categorizes the degree of ossification of the iliac apophysis, which signals the extent of skeletal maturity (see Table 1).24 Both the Risser grade and degree of the curve guide decisions on treatment and specialist referrals (see Table 2). Tanner staging, wrist-bone age, and menarchal status also give clues to maturity. In the growing patient, curve progression is influenced by growth potential and curve magnitude at time of diagnosis.21,22 Curves that are greater than 30 degrees when first detected are 90% likely to progress.25
In adults, progression depends on the degree of the curve. Minimal progression can be expected in an adult whose curve is less than 30 degrees.5,14 A 40- to 50-degree curve in a skeletally mature person will progress 10 to 15 degrees over a normal lifetime, and curves greater than 50 degrees progress 1 or 2 degrees every year.2,14 Congenital, neuromuscular, and juvenile-onset scoliosis have different natural histories and are approached differently. Congenital scoliosis may be managed surgically during infancy to prevent later severe deformity. A curve associated with juvenile-onset scoliosis progresses slowly until age 10 years and then may progress rapidly. Untreated, early-onset scoliosis may significantly affect adjacent structures and internal organs such as the ribs and the lungs.22 The uneven forces on the spinal column caused by the muscle imbalance of neuromuscular scoliosis increase the curve over time, often despite faithful bracing and proper positioning. These types of scoliosis warrant specialist referral to a pediatric orthopedist. Managing AISOnly 10% of adolescents who have scoliosis will have a curve that progresses sufficiently to require medical intervention.2 Idiopathic curves of less than 20 degrees are considered mild and are treated with observation alone, with careful follow-up exams and radiography repeated every 4 to 6 months. Height should be recorded at each visit to document onset of the adolescent growth spurt. Referral to a pediatric orthopedist or general orthopedist who specializes in spinal deformity should be given for a child or adolescent whose curve exceeds 20 degrees. Surveillance may be stopped once the patient reaches skeletal maturity (generally 2 years after menarche or once the patient has stopped growing). A skeletally mature patient whose curve is less than 20 degrees requires no further treatment and will suffer no functional limitations. Bracing, surgery, and alternative treatmentsBracing This treatment is indicated for a 25- to 40-degree curve in a growing child (Risser grade 0-3). The Boston brace is a low-profile thoracolumbar-sacral orthosis that provides passive correction while the brace is worn, generally 23 hours a day. The Milwaukee brace is used in high thoracic and cervical curves, most often for congenital and juvenile-onset scoliosis. Single thoracolumbar curves can be treated with nighttime bracing with the Charleston side-bending brace. A brace is worn until skeletal maturity is reached (Risser grade 4 or 5) or until no growth has occurred for 6 months. Brace fit and curve progression are evaluated every 4 to 6 months. It is important for patients and families to understand that a brace will not correct the curve but may prevent the curve from progressing. Compliance is an important factor in impeding progression; a Boston brace, for example, should be worn for at least 18 hours a day to control curves greater than 35 degrees, and wearing it full time (23 hours a day) is associated with the highest rates of success, especially in patients with larger curves.25,26 Although recent studies have challenged the effectiveness of braces in patients who have AIS,26,27 many clinicians believe that bracing is effective in carefully selected patient populations (such as girls whose skeletal maturity on the Risser scale is 0 to 2 at initiation of brace treatment).28-30 Surgery Spinal fusion halts spine growth in the fused vertebrae and prevents progression of the scoliotic curve. It is indicated in a 45- to 50-degree curve in a growing child and may be appropriate for a fully grown patient whose curve is greater than 60 degrees. A bone graft is used to create a solid column of bone, and implants are used to stabilize the spine while the fusion consolidates, which usually takes 6 to 12 months. Risks of spinal fusion are serious and include infection, blood loss, and neurologic injury. With adequate pain control, healthy adolescents tolerate surgery well and are able to go home after 4 to 5 days. Most patients will not have to wear a brace and can return to school 2 weeks after surgery. Sports participation is usually restricted for 9 to 12 months.31,32 Alternative treatments Presently, only bracing and orthopedic surgery prevent long-term curve progression in AIS. Chiropractic treatment and surface electrical stimulation have little proven benefit in the management of AIS. Although chiropractic adjustment may reduce the recurrence of back pain in adults who have scoliosis,33 it is ineffective in decreasing the severity of scoliotic curves in adolescents.34 A multicenter study that compared nighttime electrical stimulation with bracing and with observation alone found similar success rates between electrical stimulation and observation alone.30 ConclusionEarly detection is the key to successful management of scoliosis because treatment is more likely to be effective if it can be started while the spine is still growing and before complications have developed. Well-child and athletic participation exams should include careful examination of the spine. Because a physical exam cannot differentiate between idiopathic and congenital scoliosis, baseline radiographs should be ordered for suspicious physical findings in children. Twenty-six states mandate school screening for scoliosis, although some authors doubt the clinical value of school-based screening programs.35-37 The American Academy of Pediatrics recommends scoliosis screening at routine primary-care provider visits at ages 10, 12, 14, and 16 years.38 Early detection allows prompt initiation of conservative therapeutic measures that may prevent progression of curves and avoid the long-term complications of advanced scoliosis. REFERENCES 1. Kane WJ. Scoliosis prevalence: a call for a statement of terms. Clin Orthop. 1977; 126:43-46. 2. Miller NH. Cause and natural history of adolescent idiopathic scoliosis. Orthop Clin North Am. 1999;30:343-352. 3. Yawn BP, Yawn RA, Hodge D, et al. A population-based study of school scoliosis screening. JAMA. 1999;282:1427-1432. 4. Stokes IA, Mente PL, Iatridis JC, et al. Enlargement of growth plate chondrocytes modulated by sustained mechanical loading. J Bone Joint Surg Am. 2002; 84A:1842-1848. 5. Cowell HR, Hall JN, MacEwen GD. Genetic aspects of idiopathic scoliosis: a Nicholas Andry Award essay, 1970. Clin Orthop. 1972;86:121-131. 6. Harrington PR. The etiology of idiopathic scoliosis. Clin Orthop. 1977;126:17-25. 7. Winter RB. Evolution in the treatment of idiopathic scoliosis in Minnesota: a family report. Minn Med. 1982;65:627-629. 8. Wynne-Davies R. Familial (idiopathic) scoliosis: a family survey. J Bone Joint Surg Br. 1968;50:24-30. 9. Carr AJ, Ogilvie DJ, Wordsworth BP, et al. Segregation of structural collagen genes in adolescent idiopathic scoliosis. Clin Orthop. 1992;274:305-310. 10. Wise CA, Barnes R, Gillum J, et al. Localization of susceptibility to familial idiopathic scoliosis. Spine. 2000;25:2372-2380. 11. Ahn UM, Ahn NU, Nallamshetty L, et al. The etiology of adolescent idiopathic scoliosis. Am J Orthop. 2002;31:387-395. 12. Carr AJ. Adolescent idiopathic scoliosis in identical twins. J Bone Joint Surg Br. 1990;72:1077. 13. Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am. 1983;65:447-455. 14. Dickson RA. Conservative treatment for idiopathic scoliosis. J Bone Joint Surg Br. 1985;67:176-181. 15. Renshaw TS. Screening school children for scoliosis. Clin Orthop. 1988;229:26-33. 16. Risenborough EJ, Wynne-Davies R. A genetic survey of idiopathic scoliosis in Boston, Massachusetts. J Bone Joint Surg Am. 1973;55:974-982. 17. Greiner KA. Adolescent idiopathic scoliosis: radiologic decision-making [review]. Am Fam Physician. 2002;65:1817-1822. 18. Cobb JR. Outline for the study of scoliosis. In: Edwards JW, ed. Instructional Course Lectures. Vol 5. Ann Arbor, Mich: American Academy of Orthopaedic Surgeons;1948:261-275. 19. Bunnell WP. The natural history of idiopathic scoliosis. Clin Orthop. 1988;229:20-25. 20. Rinsky LA, Gamble JG. Adolescent idiopathic scoliosis. West J Med. 1988;148:182-191. 21. Bunnell WP. The natural history of idiopathic scoliosis before skeletal maturity. Spine. 1986;11:773-776. 22. Weinstein SL. Idiopathic scoliosis: natural history. Spine. 1986;11:780-783. 23. Lonstein JE, Carlson JM. The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am. 1984;66:1061-1071. 24. Risser JC. The iliac apophysis: an invaluable sign in the management of scoliosis. Clin Orthop. 1958;11:111-119. 25. Nachemson A, Lonstein JE, Weinstein SL. Prevalence and Natural History Committee Report. Paper presented at: Scoliosis Research Society Annual Meeting;1982; Denver, Colo. 26. Goldberg CJ, Moore DP, Fogarty EE, Dowling FE. Adolescent idiopathic scoliosis: the effect of brace treatment on the incidence of surgery. Spine. 2001;26:42-47. 27. Goldberg CJ, Dowling FE, Hall JE, Emans JB. A statistical comparison between natural history of idiopathic scoliosis and brace treatment in skeletally immature adolescent girls. Spine. 1993;18:902-908. 28. Morrissy RT, Weinstein SL, eds. In: Lovell and Winter's Pediatric Orthopaedics. 4th ed. Philadelphia, Pa: Lippincott-Raven; 1996. 29. Wiley JW, Thomson JD, Mitchell TM, et al. Effectiveness of the boston brace in treatment of large curves in adolescent idiopathic scoliosis. Spine. 2000;25:2326-2332. 30. Nachemson AL, Peterson LE. Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis: a prospective, controlled study based on data from the Brace Study of the Scoliosis Research Society. J Bone Joint Surg Am. 1995;77:815-822. 31. Rubery PT, Bradford DS. Athletic activity after spine surgery in children and adolescents: results of a survey. Spine. 2002;27:423-427. 32. Roach JW. Adolescent idiopathic scoliosis. Orthop Clin North Am. 1999;30:353-365. 33. Tarola GA. Manipulation for the control of back pain and curve progression in patients with skeletally mature idiopathic scoliosis: two cases. J Manipulative Physiol Ther. 1994;17:253-257. 34. Lantz CA, Chen J. Effect of chiropractic intervention on small scoliotic curves in younger subjects: a time-series cohort design. J Manipulative Physiol Ther. 2001;24:385-393. 35. Higginson G. Political considerations for changing medical screening programs. JAMA. 1999;282:1472-1474. 36. Leaver JM, Alvik A, Warren MD. Prescriptive screening for adolescent idiopathic scoliosis: a review of the evidence. Int J Epidemiol. 1982;11:101-111. 37. Yawn BP, Yawn RA, Hodge D, et al. A population-based study of school scoliosis screening. JAMA. 1999;282:1427-1432. 38. American Academy of Pediatrics. Committee on Psychological Aspects of Child and Family Health. Guidelines for Health Supervision III. Elk Grove Village, Ill: American Academy of Pediatrics; 1997.
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