Clinical and radiographic evaluations of the spine for better management of your scoliosis patients

Scoliosis is a common finding of patients presenting to chiropractors. The term scoliosis refers to a deformity of the spine affecting the coronal plane to cause a lateral spinal curvature measuring more than 11°; and it derives from the Greek word skoliosis, meaning curvature or crookedness.¹

The most common type of scoliosis is idiopathic in nature and accounts for approximately 70% of all cases. The most usual configuration is the major thoracic curve with a convexity to the right. The three clinical forms of the idiopathic scolioses are infantile (0–4 years), juvenile (4–10 years), and adolescent, affecting patients from 10 years of age to skeletal maturity. Of the idiopathic scolioses, the most common is the adolescent idiopathic variety, which is found more often in females than males.² Idiopathic scoliosis is always a diagnosis of exclusion since congenital, neoplastic, traumatic, infectious, postradiation, antalgic, neuromuscular or neuroectodermal aetiologies^3,4 must be considered before the diagnosis of idiopathic scoliosis can be entertained.

Know the Specifics
A phenomenon known as the Hueter-Volkmann principle states that due to the degree of axial compression at the discovertebral junction, a scoliosis leads to the underdevelopment of a vertebra during skeletal development. The resultant appearance is that of a “wedge-shaped” vertebra. However, any process that leads to the arrest of vertebral growth may confer similar appearances on examination. Radiation treatment, whose port includes a portion of the developing vertebral body, may lead to asymmetric development of the vertebra. Common conditions requiring such radiation treatment include Wilm’s tumors and neuroblastomas.

Congenital scolioses can be caused by a variety of local or generalized spinal conditions, and by definition, are present at birth. Local causes include hemivertebra, butterfly vertebra, and congenital block vertebra. When a congenital defect is detected, consideration must be given to commonly associated abnormalities. These include the genito-urinary system (18%), cardiovascular system (7%), and skeletal system (11%).³ In addition, chiropractors should screen for a combination of abnormalities, known as the VACTER or VATER syndrome—vertebral, anarectal malformations, cardiac, tracheo-oesophageal, and renal/radial ray anomalies. Multiple conditions may lead to the presence of a general congenital scoliosis. These include diastematomyelia (tethered-cord syndrome) and numerous skeletal dysplasias, including the aptly named diastrophic dwarfism (crooked or twisted spine).

Neuromuscular diseases with associated scolioses include cerebral palsy, muscular dystrophy, myelomeningocele, and a previous history of polio. Neuroectodermal disorders commonly associated with scoliosis include Marfan’s syndrome and neurofibromatosis. Neoplastic causes of scoliosis include tumors such as osteoid osteoma, osteoblastoma, and intraspinal tumors.

Additional causes of scoliosis include trauma, infection, and the arthritides. The mechanism by which trauma causes a scoliosis is due in part to antalgia—for example, a transverse process fracture of the lumbar spine resulting in contraction of the quadratus lumborum muscle leading to a transient scoliosis. Infection, either as a discitis or more rarely as a result of tuberculosis, may also be manifested as scoliosis.

The most common disorder in the arthritides category is that of degenerative joint disease of the spine seen to present with a scoliosis and may actually be the result of a hitherto undetected scoliosis. The altered biomechanics of the spine result in abnormal forces being applied to the spine, which leads to early degenerative joint disease evident in the spine and about the sacroiliac joints, affecting the latter in a somewhat asymmetric manner reflecting the uneven distribution of load applied to the joints. As a group, the arthritides may be associated with scoliosis due perhaps to the antalgia, as well as the altered movement resulting from the articular effects. Associations with a variety of disorders have also been documented including spondylolysis and developmental dysplasia of the hip.³

Clinical Procedures
Clinical examination of a scoliosis should include a variety of procedures including visual estimation, leg length assessment, lateral bending, and Adam’s bend test, and the Moire fringe topographic screen. Structural curves do not change with lateral bending and usually are the more extensive curves, resistant to all but the most radical of treatment.

Plain film radiography is a necessary adjunctive tool in the evaluation of a scoliosis. It is used to assess the aetiology, document the location and the degree of curvature, to predict the probability of curve progression, and as a baseline reference to evaluate the degree of change of the angulation in subsequent studies.

While radiographic monitoring of scoliosis is important, repeated exposures to radiation in young women have been found to increase the risk of developing breast cancer. Unfortunately, the majority of idiopathic scolioses are found in this population. To reduce the radiation dose as much as possible, research advocates the use of posterior to anterior (PA) projections (since the bone marrow is less radiosensitive than breast tissue), filters, high-speed film combinations, added filtration, and breast shielding.

Radiographic Evaluation
If radiographic evaluation of a scoliosis is needed, the following features should be identified on each study;

1. The level of the spine involved (eg, lumbar);
2. The side to which the curve is (eg, left convex);
3. The shape of the scoliosis (C- or S-shaped);
4. The most superiorly involved segment;
5. The most inferiorly involved segment;
6. The apical segment (the vertebra that deviates the most laterally and rotates away from the spine the most);
7. Angle of the curve (Cobb method);
8. Compensatory curves; and
9. The potential for progression of the curve (Risser’s sign, vertebral apophyses/PA left wrist).

The most common objective measurement for evaluating the degree of progression of a scoliosis is with a Cobb angle. The most superior and inferior angulated vertebra of the major scoliosis are identified, and then a line is drawn along the superior end plate of the superior segment and along the inferior end-plate of the inferior segment. Tangential lines are then drawn and the angle of intersection calculated. Only a minor discrepancy in the Cobb’s angle is noted using the PA, versus the anterior to posterior projection. Other parameters such as vertebral body rotation, pedicular asymmetry (Nash and Moe method), and degree of kyphosis and lordosis can also be evaluated.

Since skeletal maturity is intimately related to the cessation of the majority of scoliotic progression, determination of skeletal age is of utmost importance for patient management. Skeletal maturity is closely linked with the degree of ossification and fusion of the vertebral apophyses, but is easily evaluated using the iliac apophysis (Risser’s sign). This refers to the degree of ossification of the iliac apophysis, which commences laterally, moves medially, and is divided into quarters. Therefore, if only the lateral portion is ossified, this would be termed a grade 1 Risser’s sign, whereas a grade 5 Risser’s sign refers to the full ossification of the iliac apophysis from lateral to medial and the complete fusion of the apophysis, which occurs from medial to lateral. A lower grade of Risser’s sign has a much higher risk of progression since it indicates that further bone growth is inevitable. A grade 5 Risser’s sign is attained in girls at about 15 years and 3 months, and in boys at about 16 years. A more precise measure of skeletal maturity can be achieved using a PA radiograph of the nondominant hand and comparing it to the Greulich and Pyle Atlas.

Management of Cases
Congenital scolioses progress in 75% of cases: those at highest risk for progression have associated birth deformities, such as unilateral hemivertebra, thoracic, and chest wall abnormalities. Radiographic re-evaluation of the curve should be done every 4–6 months with a skeletally immature patient. Generally, scolioses less than 25° are not treated surgically, unless there is a rapid progression in a pre-adolescent patient. Curves measuring between 25° and 40° are treated with orthotic bracing, electric stimulation on the convexity, and other conservative treatments including chiropractic manipulative therapy.⁴ There is, however, no evidence substantiating the claim that conservative physical therapy will halt or reverse curve progression. One case report⁵ does exist that followed two patients with idiopathic scolioses over a period of 8 years that reported chiropractic care reduced low back pain and claimed to retard the curve progression. However, little reference to the method of measurement of re-evaluation was made.

Surgery is usually reserved for patients whose scolioses are more than 40°, and who are developing associated complications (such as cardiopulmonary failure). Osseous fusion is performed using either implanted bone grafts, pedicle screw fixation, or hardware such as a Harrington rod (though this is less commonly used nowadays). This surgery carries with it inherent surgical risks and long-term complications, such as hardware failure and infection. Of more recent note is the introduction of devices that can correct the deformity in all three planes, for example, the Cotrel-Dubousset system.

Remember also that a left convex scoliosis has a much higher incidence of underlying pathology, such as a tumor or congenital anomalies. Therefore, further imaging is strongly recommended.

Also, in all patients with congenital anomalies of the spine, further evaluation of the genito-urinary system must be performed because of the high incidence of associated abnormalities. Renal hypoplasia/agenesis or a horseshoe kidney (fusion of both kidneys across the midline) may lead to stasis and secondary infections. To investigate this possibility, perform urinalysis to determine if protein or blood is present. Further evaluation with computed tomography, intravenous pyelography, or ultrasound may be warranted due to the long-term complications of undetected infection.

Michelle Wessely, BSc (Chiropractic), DC, DACBR, FCC (Radiology), is the Departmental Head of Radiology at the Institut Franco-European de Chiropratique, Paris, France. She recently completed a radiology research fellowship at the department of osteoradiology, Veterans Affairs Healthcare Center, San Diego, under the direction of Donald Resnick, MD, professor of radiology. Wessely can be reached via email: michelle_wessely@hotmail.com.

References
1. Newman W. Dorlands Illustrated Medical Dictionary. 28th ed. New York: WB Saunders; 1994:1497.
2. Yochum T, Rowe L. Essentials of Skeletal Radiology. 2nd ed. Baltimore: Williams and Wilkins; 1996:305–325.
3. Resnick D. Diagnosis of Bone and Joint Disorders. 5th ed. New York: WB Saunders: 1995:4253–4263.
4. McMaster MJ. James IV lecture: congenital deformities of the spine. J R Coll Surg Edinb. 2002;47(2):475–80.
5. 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(4):253–257.