Scoliosis x ray
|
Scoliosis Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Scoliosis x ray On the Web |
|
American Roentgen Ray Society Images of Scoliosis x ray |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rohan A. Bhimani, M.B.B.S., D.N.B., M.Ch.[2]
Overview
X Ray
- X-rays are vital for initial assessment and to determine progression of the curve.
- Various measurements are done on the x-ray.
Identification of the Apex and Significant Vertebrae
- Identification of the curve apex and significant vertebrae is crucial for denoting the curve type, selecting the surgical approach and instrumentation system, and determining the optimal level for fusion.[1]
Apex Vertebra
- Apex is the vertebra or disk with the greatest rotation or farthest deviation from the center of the vertebral column.
End Vertebrae
- End vertebrae are those with the maximal tilt toward the apex of the curve, and they are used to measure the Cobb angle.
Neutral Vertebrae
- Neutral vertebrae are those that show no evidence of rotation on standing frontal (either posteroanterior [PA] or anteroposterior [AP]) radiographs; their pedicles are in the normal, symmetric positions.
=Stable Vertebrae
- Stable vertebrae are the vertebrae farthest cephalad that are bisected or nearly bisected by the central sacral vertical line (CSVL) at a level below the end vertebra of the distal curve.[2]
- The CSVL is a roughly vertical line that is drawn perpendicular to an imaginary tangential line drawn across the top of the iliac crests on radiographs. It bisects the sacrum.
Measurement of the Cobb Angle
- The Cobb angle of a scoliotic curve is the angle formed by the intersection of two lines, one parallel to the endplate of the superior end vertebra and the other parallel to the endplate of the inferior end vertebra (Image).
- The angle may be plotted manually or digitally.
- It is the main standard for diagnosis, monitoring, therapeutic planning, and epidemiologic analysis of scoliosis.
- A progressive curve that requires management is defined by a Cobb angle increase of 5° or more between consecutive radiographic examinations.
Pitfalls of the Cobb Angle
- It is performed by using a two-dimensional radiographic image of a 3-D deformity and does not take vertebral rotation into account.[3]
- Cobb angle measurement may be inherently difficult.
- A diurnal variation of 5° has been observed in Cobb angle measurements of the same curve over the course of a single day, with an angular increase occurring in the afternoon.[4][5]
- Because of the vertebral rotation associated with scoliosis, it may be difficult to position the patient so as to obtain an accurate frontal view, and the actual Cobb angle might be 20% greater than that plotted on radiographs.
- During surgery, cobb angle decrease due to prone positioning and anesthesia and sometimes followed by a postoperative rebound effect, with a loss of correction when the patient returns to the standing position.
Identification of Primary and Secondary Curves
- Major curves, also called primary curves, are the largest abnormal curves in the scoliotic spine and the first to develop.
- Minor curves, also called secondary curves, are smaller and are considered to develop afterward, to compensate for the perturbation of balance that accompanies the progression of major curves by repositioning the head and trunk over the pelvis to maintain balance.
- The terms major curve and minor curve are sometimes used as synonyms for structural curve and nonstructural curve respectively.
Assessment of Vertebral Alignment and Balance
- The central sacral vertical line(CSVL) drawn on radiographs serves as a reference for identifying stable vertebrae, evaluating coronal balance, and determining the curve type.[2][6][7]
- The plumb line is a vertical line drawn downward from the center of the C7 vertebral body, parallel to the lateral edges of the radiograph.
- Plumb line is used to evaluate coronal balance on standing frontal radiographs and sagittal balance on standing lateral radiographs.
- Coronal balance is assessed by measuring the distance between the CSVL and the plumb line.
- Sagittal balance is evaluated by measuring the distance between the posterosuperior aspect of the S1 vertebral body and the plumb line.
- For both coronal and sagittal measurements, balance is considered abnormal if the distance is greater than 2 cm.
- For measurements of coronal balance, a plumb line located to the right of the CSVL is considered to reflect positive coronal balance.
- On the other hand, a plumb line located to the left of the CSVL is considered to reflect negative coronal balance.
- Similarly, for measurements of sagittal balance, a plumb line that is anterior to the posterosuperior aspect of the S1 body is considered to reflect positive sagittal balance.
- However, a plumb line that is posterior to the posterosuperior aspect of the S1 body is considered to represent negative sagittal balance.
- Many doctors when suspecting scoliosis will exclaim "scolie and AP-Lateral", which are two types of X-ray. The scolie is pictured above, a scolie is an X-ray taken from the rear. An AP-Lateral is taken from the side but the x ray machine is programmed only to show the spine with high definition.
- Full-length standing spine X rays are the standard method for evaluating the severity and progression of the scoliosis, and whether it is congenital or idiopathic in nature. In growing individuals, serial radiographs are obtained at 3-12 month intervals to follow curve progression. In some instances, MRI investigation is warranted.
- The standard method for assessing the curvature quantitatively is measurement of the Cobb angle, which is the angle between two lines, drawn perpendicular to the upper endplate of the uppermost vertebrae involved and the lower endplate of the lowest vertebrae involved. For patients who have two curves, Cobb angles are followed for both curves. In some patients, lateral bending x rays are obtained to assess the flexibility of the curves or the primary and compensatory curves.
References
- ↑ Potter BK, Rosner MK, Lehman RA, Polly DW, Schroeder TM, Kuklo TR (2005). "Reliability of end, neutral, and stable vertebrae identification in adolescent idiopathic scoliosis". Spine (Phila Pa 1976). 30 (14): 1658–63. PMID 16025037.
- ↑ 2.0 2.1 King HA, Moe JH, Bradford DS, Winter RB (1983). "The selection of fusion levels in thoracic idiopathic scoliosis". J Bone Joint Surg Am. 65 (9): 1302–13. PMID 6654943.
- ↑ Pruijs JE, Hageman MA, Keessen W, van der Meer R, van Wieringen JC (1994). "Variation in Cobb angle measurements in scoliosis". Skeletal Radiol. 23 (7): 517–20. PMID 7824978.
- ↑ Beauchamp M, Labelle H, Grimard G, Stanciu C, Poitras B, Dansereau J (1993). "Diurnal variation of Cobb angle measurement in adolescent idiopathic scoliosis". Spine (Phila Pa 1976). 18 (12): 1581–3. PMID 8235834.
- ↑ Göçen S, Havitçioglu H (2001). "Effect of rotation on frontal plane deformity in idiopathic scoliosis". Orthopedics. 24 (3): 265–8. PMID 11300291.
- ↑ Lenke LG, Betz RR, Harms J, Bridwell KH, Clements DH, Lowe TG; et al. (2001). "Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis". J Bone Joint Surg Am. 83-A (8): 1169–81. PMID 11507125.
- ↑ Errico, Thomas (2009). Surgical management of spinal deformities. Philadelphia, PA: Saunders/Elsevier. ISBN 9781437719567.