Scoliosis and Spinal Deformity - Diagnosis to Treatment

Scoliosis is a complex, 3-dimensional disorder that affects the spine's structure and function. To understand how scoliosis can affect the spine as a whole, a review of spinal anatomy is needed. The following slides provide an illustrated overview of spinal anatomy.

Understanding anatomical planes is important because scoliosis is a 3-dimensional disorder affecting the coronal (or frontal), sagittal (or lateral), and axial (or transverse) planes. The coronal plane divides anterior and posterior; sagittal divides left and right; and, axial divides top from bottom and is at 90-degrees to each of the other planes.

Scoliosis was originally defined as a lateral curve in the frontal plane. The concept of force coupling broadened the understanding about how scoliotic curves alter the sagittal and axial planes. Force coupling is a force-combined motion along an axis. In scoliosis, force coupling contributes to rotation of the spinal column. As rotation occurs, all anatomical planes are altered.

Terms related to direction include: Anterior or ventral (toward the front); posterior or dorsal (toward the back); medial (toward the midline of the body; lateral (away from the midline of the body); proximal (toward a reference point, extremity); distal (away from a reference point, extremity); cephalad or cranial (toward the head); and, caudad or caudal (toward the tail); and, superior (upper or above); inferior (lower or below).

The functions of the vertebral column include: Protection, base for attachment, structural support, and flexibility and mobility.

The vertebral column protects the spinal cord and nerve roots; is a base of attachment for ligaments, tendons, and muscles; provides structural support, balance, connects the upper and lower body, and distributes weight; enables flexion, extension, side bending, and rotation; and the vertebral bodies store minerals and produces blood.

The 5 regions of the spine, starting at the base of the skull, are the cervical, thoracic, lumbar, sacrum, and coccyx. Scoliosis usually affects the thoracic and lumbar regions.

There are 7 cervical vertebrae (neck), 12 thoracic vertebrae (chest), 5 or 6 lumbar vertebrae (low back), 5 fused sacral vertebrae (pelvis), and 3 vertebrae in the coccyx (tailbone). Vertebrae and levels are abbreviated, such as L3 denotes the third lumbar vertebra.

Vertebrae are either typical or atypical. An atypical vertebra has no body or spinous process. Examples of atypical vertebrae are the atlas, axis, sacrum, and coccyx. Cervical, thoracic, and lumbar vertebrae are examples of typical vertebrae. These vertebral bodies vary in size and shape, as the next slides reveal.

An axial view of a cervical vertebra is illustrated. The cervical vertebrae are much smaller in size compared to thoracic and lumbar vertebrae. Note the vertebral body shape and size, neuroforaminal space throughwhich spinal nerves exit the spinal column, spinal cord canal, and foraminal passage for blood vessels.

Scoliosis mostly affects the thoracic spine. Illustrated is a thoracic vertebra in axial and lateral views. The axial view locates the vertebral body, spinous process, transverse facets, pedicle, spinal canal, lamina, superior facets, and foramen. These structures are apparent in the lateral view. The longer spinous process is typical of the thoracic vertebrae.

Illustrated is a posterior view of a normal thoracic spine and rib attachments. Unlike cervical or lumbar vertebrae, the thoracic vertebrae provide little flexibility because: (1) The thoracic vertebrae attach to the ribs and (2) the shape of the thoracic spinous processes.

The ribs articulate with the vertebral bodies and transverse processes by means of costovertebral joints (T2-T9). Rib attachment is an important consideration in thoracic deformity. Forced coupling almost always causes vertebral rotation within the scoliotic curve. Thoracic vertebral rotation causes rib displacement, thoracic asymmetry, and a rib hump deformity (discussed later).

Illustrated is an axial and lateral view of a lumbar vertebra. The structure is similar to the cervical and thoracic vertebrae; one exception is the lumbar vertebral bodies are larger. The lumbar intervertebral discs are also larger.

Normal and scoliotic spinal curves are either kyphotic or lordotic. Kyphotic curves are concave anteriorly and convex posteriorly. Lordotic curves are convex anteriorly and concave posteriorly. The degree of normal curvature varies by spinal region: Cervical lordosis is 20-40-degrees, thoracic kyphosis is 20-40-degrees, and lumbar lordosis is 40-60-degrees. The sacrum is fused in a kyphotic curve. Spinal curves are important for balance, flexibility, and stress and weight absorption, and distribution.

Ligaments and muscles support the spine and control movement. Illustrated are the following ligaments: Ligamentum flavum, facet capsulary, interspinous, supraspinous, intertransverse, posterior longitudinal, and anterior longitudinal.

Spinal muscles are categorized according to function such as flexion, extension, and rotation. Scoliosis, especially neuromuscular scoliosis, affects symmetry of the spine, rib cage, and pelvis causing trunk imbalance and deformity. Muscles important to spinal stabilization include the multifidus and longissimus muscles.

The multifidus muscle runs between the transverse and spinous processes. It stabilizes the joints at each segmental level, assists vertebrae to move, reduces joint structure degeneration, and is responsible for the extension and rotation of the vertebral column.

The longissimus muscle is made up of 3 sections: Cervicus (extends the cervical vertebrae), captitus (rotates the head), and thoracis (extension/lateral flexion of the vertebral column, rib rotation).

Other spinal structures include intervertebral discs, facet joints, spinal cord, nerve roots, and the vascular system.

Intervertebral discs are fibrocartilaginous structures attached by endplates (not depicted here) to the inferior and superior vertebrae. Endplates are the vertebral body's growth ring. These vascularized tissues are composed of cartilage and an inner bony layer. The location of the intervertebral discs and axial view is well-illustrated. The annulus fibrosis encloses the nucleus pulposus. Each fibrocartilaginous cushion absorbs and distributes pressure on the spine and allows some vertebral motion (e.g., extension/flexion). More motion is possible when several discs combine forces. However, in scoliosis, discs may not function normally for many reasons, including greater (and abnormal) mechanical stress due to vertebral displacement and rotation.

Facet joints, also termed zygapophyseal, or apophyseal joints, are synovial joints. Posterior to each vertebral body are 2 facet joints as illustrated in the image. Facet joints allow flexion/extension, twisting, and restrict some movement to stabilize the spine. Abnormal mechanical stress to the spine, such as caused by scoliosis, can cause joint inflammation leading to back and leg pain.

There is 31-pair of nerve roots branching off the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccyx. The spinal cord ends at L1 where the spinal nerves become the cauda equina within the spinal canal. The cauda equina is formed at the lower end of the spinal cord near L1. It is a bundle of lumbar, sacral, and coccygeal nerve roots that resemble a horse's tail. Cauda Equina Syndrome is a rare and serious disorder that occurs when nerve roots are compressed. The Syndrome may lead to bladder or bowel dysfunction and is considered a surgical emergency. (Neurological dysfunction may develop in disorders such as neuromuscular scoliosis and severe scoliotic deformity.)

Blood, plasma, and other vascular components nourish parts of the spine such as bones, spinal cord, neural structures, and muscles. The structures in red are arteries and veins are illustrated in blue. Important vascular structures include: (1) Carotid artery, (2) aortic arch, (3) thoracic aorta, (4) abdominal aorta, (5) iliac artery, (6) internal jugular vein, (7) superior vena cava, (8) inferior vena cava, and the (9) iliac vein.

Scoliosis is a side-to-side curve from the body's normal frontal axis. Scoliotic curves primarily develop in the thoracic or lumbar regions. Curves tend to be more flexible in young patients and more rigid in adults. Scoliosis is a complex 3-dimensional disorder, affecting the coronal, sagittal, and axial planes at multiple spinal levels.

In a normal spine, viewed on an AP X-ray, the spinous processes fall in a straight line from the cervical to the lumbar region. However, in scoliosis, the spinous processes move out of alignment because of abnormal side-to-side curvature and rotational changes. Structures moved from normal alignment are called displaced, such as vertebral displacement and rib displacement.

The body's effort to keep the skull aligned over the pelvis may cause major and minor curve development. Major curves (or curve) denote the greatest curve often accompanied by a minor curve. A minor curve (or curves) is compensatory, meaning it develops in the opposite direction above or below the major curve to maintain balance.

About 3 to 5 children out of 1,000 will develop spinal curves requiring treatment. Approximately 85% of all scoliosis is idiopathic (cause unknown). The 3 types of idiopathic scoliosis are infantile (birth to age 3), juvenile (3-9 years of age), and adolescent (approximately 10-18 years of age). Adolescent idiopathic scoliosis is the most common type representing more than 80% of surgical cases. Research continues to explore a genetic link in scoliosis.

Less than 1% of all idiopathic curves are infantile affecting children from birth to age 3. Infantile scoliosis usually affects boys and curves are often left-sided thoracic. Approximately 85% of these curves resolve with growth or spontaneously. About 15% rapidly progress to cause severe deformity, sometimes associated with neurological problems.

Approximately 15% of idiopathic curves are juvenile affecting children between the ages of 3 and 10 years. Girls are mostly affected by right-side thoracic curves. The risk for progression is high and patients with juvenile scoliosis are more likely to require surgery than patients with adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis is the most common type (more than 80%), mostly affects girls, and occurs between the ages of 10 and 17. Adolescent idiopathic scoliosis is usually painless. During puberty, when growth rate accelerates, patients with AIS are at highest risk for curve progression. It is not known why girls have a significantly higher risk for curve progression.

Congenital scolioisis is caused by the malformation of one or more vertebral segments. The malformation is caused by insult to the embryo between 6 and 8 weeks after gestation. Hemivertebra (half vertebra) is the most common type of malformation and may lead to severe scoliotic deformity. Spina bifida is an example of a formation failure involving the posterior spinal structures.

A block vertebra typifies segmentation failure. This occurs when 2 or more vertebrae fail to separate during embryonic development. The term unsegmented bar is also used to describe segmentation failure.

Neuromuscular scoliosis is associated with neuropathic disorders such as cerebral palsy and myopathic curves are associated with muscular dystrophy and polio. Spinal deformity is common and may be severe in some patients affecting life expectancy.

Scoliotic curves can be caused by other disorders such as systemic disorders, infections, trauma, or tumors. For example, systemic connective disorders are associated with Marfan's Syndrome and trauma can cause one or more spinal compression fractures. Marfan's Syndrome is a heritable connective tissue condition that may cause spinal ligaments to become loose leading to vertebral displacement. Spinal tumors, although rare, may cause lateral curvature to develop depending on the tumor's location.

Adult scoliosis is defined as affecting a person older than 18 years, skeletally mature, with a lateral spinal curve. Adult scoliosis can be idiopathic, or caused by degenerative disorders, trauma, or tumor.

Adult idiopathic scoliosis usually results from untreated, or a progression of adolescent idiopathic scoliosis. Patients age 40 and older are more apt to present with back pain as a primary complaint.

Degenerative scoliosis can be caused by degenerative disc disease, osteoporosis (related to spinal fracture), segmental instability, spinal stenosis, and vertebral compression fractures. This type of scoliosis can cause cardiopulmonary problems, back stiffness and pain, spinal instability, irregular gait, and/or nerve dysfunction or damage.

Spinal fracture or vertebral compression fracture typifies trauma. Spinal tumors, although rare, may cause lateral curvature to develop depending on the tumor's location.

Relevant to a scoliosis diagnosis is age-specific information about the patient's medical and family history, age at onset of puberty or menarche, and skeletal maturity. Since there may be a genetic component to scoliosis, it is important to obtain a family history. If other family members have or had scoliosis, it is of particular interest to the treating specialist.

The physical examination notes the patient's general health, cardiopulmonary function, bowel/bladder changes, and asymmetries in the shoulders, rib cage, waist, and pelvis. Children with severe thoracic scoliosis may exhibit shortness of breath. Adults may experience back pain, fatigue, and shortness of breath. Other tests during the exam may include:

The Adam's Forward Bending Test, which requires the patient to bend over at the waist, with arms hanging downward, to reveal a thoracic prominence called a rib hump. A rib hump may accompany thoracic scoliosis. As the rib cage rotates along the spine, the rib spread changes creating a rib hump. A Scoliometer is used to measure a rib hump.

Spinal palpation may reveal rib or muscle prominence on one side.

A plumb line is an undeviating vertical line, either imaginary or, such as a string from which a weight is suspended. In assessing scoliosis, such a plumb line, held posteriorly at C7, is allowed to hang below the buttocks. The line will fall straight between the buttocks if the spine is normal. However, with scoliosis, the line falls to the left or right of the spine.

Range of motion is observed during flexion/extension, lateral bending, and rotation movements.

A neurological examination assesses balance, reflexes, notes leg length discrepancy, and symptoms, such as pain (and pain pattern), numbness, paresthesias, sensory and motor function, muscle spasm, and weakness.

This standing posterior-anterior (PA) radiographic demonstrates scoliosis. Radiographs are used to diagnose scoliosis, measure curve magnitude (e.g., Cobb angle), and determine skeletal maturity (Risser sign). Standing, AP, lateral, and flexion/extension radiographs may be obtained. Certain patients may require CT or MRI imaging, such as adults, patients with congenital scoliosis, unusual curve patterns, and severe back pain. Sometimes a myelogram and CT scan is needed to examine the spinal canal and neural structures.

The Risser sign radiographically predicts skeletal maturity by grading ossification across the iliac crest.

Lateral left-right side bending films determine if curves are structural or non-structural. Structural curves are usually stiff or inflexible.

The Cobb angle and Lenke system use radiographs to measure curve size. The Lenke system classifies scoliotic curves.

Using the patient's AP radiograph, the Cobb angle method is used to measure curve magnitude in degrees. The Cobb angle is found by determining the superior and inferior vertebrae, followed by drawing intersecting perpendicular lines from the superior endplate of the top vertebra and the inferior endplate of the bottom vertebra and inferior surface of the inferior vertebra. The angle formed by the perpendicular lines is the Cobb angle.

The Lenke system uses a standing PA, lateral, and dual side bending radiographs. The Lenke system is comprehensive in that it considers scoliosis from multiple views and treats it as a multi-dimensional disorder. The benefit of the Lenke system is it more precisely identifies the levels to instrument and fuse. This system describes 6 curves: Main thoracic, double thoracic, double major, triple major, thoracolumbar/lumbar, and thoracolumbar/lumbar, main thoracic.

The goals of treatment for any type of scoliosis are the same: Obtain and maintain curve correction, stop curve progression (spinal fusion may be necessary), stabilize the spine, prevent lung compromise caused by abnormal spinal curves, reduce back pain, obtain acceptable cosmetic improvement.

Depending on the type of scoliosis, patient's age, skeletal maturity, curve progression and other factors, treatment options include: Observation, bracing, or surgery. Curves less than 15-20-degrees are observed for progression in skeletally immature patients. Guidelines for monitoring patients vary depending on the patient's age and curve classification. Skeletally immature patients require regular check-ups. Regular curve monitoring includes radiographs from which curve progression can be carefully watched.

Orthotic management (bracing) is common in children (skeletally immature, significant growth years remaining) diagnosed with adolescent idiopathic scoliosis with curves between 25-40-degrees.

Surgery may be recommended to stop curve progression, stabilize the spine, prevent or correct deformity, address cardiopulmonary problems, and reduce back pain. However, Adolescent Idiopathic Scoliosis is usually painless.

Nonoperative treatment may include heat therapy, pain medication, anti-inflammatory drugs, and physical therapy (posture, strengthening). Bracing is used to control pain and provide support and stability, not for deformity correction. Most adult patients do not need surgery.

In cases of adult degenerative scoliosis, surgery may be considered, although uncommon. Adults with curves greater than 45-degrees, curvature causing cardiopulmonary problems or neurologic complications, or failure of nonoperative therapies to control pain, may benefit from surgery.

In the early 1900's, scoliosis was believed to be caused by poor posture and was treated with bracing. During the last 40 years, there has been rapid progress in treatment options with the most major advances being in surgical options. Several surgeons pioneered new surgical techniques for correcting scoliosis and spinal deformity. Some are mentioned.

Doctor Paul Harrington started to treat progressive neuromuscular scoliosis relying on compression and distraction corrective techniques. Using facet screws, posterior hooks, and stainless steel rods, he corrected the position of the facets. Although short-term results were good, some long-term outcomes lacked deformity correction and implants loosened.

Harrington refined his technique using hooks at the cranial and caudal ends, and distraction to attach the rod and hooks on the concave side to correct the deformity. The procedure included bony fusion. Although good coronal correction could be achieved, sagittal alignment could not be effectively managed resulting in flat back syndrome. He further modified his technique to add construct stability by adding a small threaded rod to the curve's convex side and applying compression across multiple fixed points.

Doctor Eduardo Luque's principle of translation involved bringing the spine to a curved rod. He used sublaminar wires and a contoured rod with multiple points of fixation. Although overall surgical results were better than with the Harrington system, some sublaminar wires resulted in neurological complications.

Neither Harrington or Luque's techniques were able to provide correction in all planes.

The Galveston Method was developed by Dr. Allen and Dr. Ferguson. It involved a series of bends made to the rod allowing for insertion through the posterior column of bone in the ilium. Known today as the Luque-Galveston technique, it is used today to treat some cases of neuromuscular scoliosis.

Doctor Yves Cotrel and Dr. Jean Dubousset pioneered global derotation in the 1980s. The Cotrel/Dubousset fixation system combines hooks, curved rods, and bolts for segmental fixation and derotation for deformity correction. Although a notable improvement, derotation does not always correct the deformity and may create instability above and below the construct.

Cotrel/Dubousset also pioneered in situ rod bending. The spine is fixed to the rod and then the rod is bent. This technique is effective to correct lateral deformity, but is difficult over long constructs using titanium rods.

In 1986, Dr. Marc Asher introduced the translation/cantilever technique where the rod attachment uses a claw construct cephalad and bolts as an anchor caudally. The spine is translated to the rod using sublaminar wires. After the concave side of the deformity is addressed, a rod is affixed on the convex side. The claw creates compression on the convex side pulling lateral displacement into alignment. The distal rod end is brought toward the center line and anchored with pedicle screws. This technique is limited by its inability to correct rotational deformity.

In the 1990s, Dr. Harry Shufflebarger introduced Segmental Fixation. This comprehensive technique combined distraction, compression, and rotation at each vertebral level. Smaller rods and lower profile connectors are used. This complex technique requires a significant number of implants.

The techniques and implants discussed above all involve a posterior approach.

Going back to the 1970s, Dwyer addressed scoliotic deformity anteriorly by either stretching the concave side or shortening the convex side. His technique was improved with the development of Zielke instrumentation, which required placement of vertebral body screws more posteriorly. This allowed for more effective derotation and reduced iatrogenic kyphosis caused by the procedure.

The Kaneda system was the next generation incorporating two bicortical screws per vertebral body attached to two rods.

Advances in the surgical treatment of scoliosis and spinal deformity continue to be made. Several spine surgeons and device manufacturers continue to pioneer sophisticated implants and products specifically to treat deformity.

Preoperative planning includes a general medical clearance from the patient's pediatrician or primary care physician, additional imaging studies such as radiographs (PA, lateral left-right side bending), CT or MRI, and myelogram. Lateral left-right side bending X-rays demonstrate spinal flexibility and assists surgical planning by helping to determine which levels are to be fused (highest to lowest levels). Other tests may include a renal sonogram (e.g. congenital scoliosis), and/or echocardiogram (e.g. congenital scoliosis).

Surgical planning considers the patient's age and skeletal maturity, number of curves, curve magnitude, location, pattern, potential for progression, rotational displacement, rib cage volume, rib hump, bone quality, and coexisting arthritis, or degenerative disc disease.

Informed consent is part of preoperative planning which includes educating the patient about the risks, as well as the benefits, of scoliosis surgery. Several members of the surgical team speak with the patient before surgery, including the surgeon and anesthesiologist.

Steps are taken to reduce as many risks as possible, which may involve the patient making lifestyle changes such as smoking cessation to reduce risks associated with anesthesia and fusion. Although hypotensive anesthesia and cell saver reduces blood loss, the patient may consider autologous blood donation prior to surgery.

Other risk-reducing steps include: Compression stockings and wraps to lower the risk of blood clot formation and preoperative antibiotics to prevent infection. There is a low risk for instrumentation problems, such as implant breakage. Somatosensory evoked potentials (SSEPs) reduce the risk for neurologic injury during surgery, which, in most cases is small.

Scoliosis surgery may involve more than one procedure such as discectomy, osteotomy, and instrumentation and fusion. Discectomy and osteotomy may make curve reduction easier and improve spinal alignment. Instrumentation is internal fixation, such as screws, hooks and rods that holds the construct stable until a solid arthrodesis occurs. Bone graft facilitates arthrodesis. Graft may be harvested during surgery from local bone (such as a spinous process) or from the patient's iliac crest (a separate procedure). Allograft or bone substitutes may be used alone or to augment the patient's bone.

Surgery to treat scoliosis is performed either as an open approach or as a minimally invasive procedure. Anterior, posterior, and anterior-posterior are common approaches to the spine.

Open procedures are traditional and involve larger incisions and muscle stripping, which means a longer operative session, greater recuperative period, and substantial scars. Minimally invasive surgery is performed through several tiny percutaneous incisions (called portals) made lateral to the spine. Using endoscopic instruments, the surgeon performs the procedure, including instrumentation and fusion through the portals.

The posterior approach is the traditional approach for scoliosis surgery. A long incision is made along the back of the spine. Muscles are stripped away from bones to give the surgeon access to the operative field. Screws are affixed to the spine and rods are inserted to reduce abnormal spinal curvature. Bone graft is added to the construct to incite fusion.

An anterior release may be performed with a traditional posterior approach to treat severe deformity or rigid curves. Anterior release involves approaching the spine through an anterior open incision, or minimally invasively using an endoscope, and performing one or more discectomies. This procedure provides better curve reduction. Bone graft is added to the empty disc spaces to facilitate arthrodesis. Retrograde ejaculation and numbness are additional postoperative risks associated with anterior surgery.

A rib hump may accompany thoracic scoliosis. As the rib cage rotates along the spine, the rib spread changes creating a rib hump. Thoracoplasty treats rib deformity by resectioning, or shortening, rib segments. Thoracoplasty can be performed minimally invasive or as an open procedure (thoracotomy).

Postoperative care includes observing for signs of neurological deficit. Included are: Loss of muscle strength in the upper and lower extremities, and/or extremity and torso sensation; complaints of numbness, tingling, radiating pain, or heaviness in the extremities; or, urinary incontinence, bowel dysfunction.

Cardiopulmonary function is also observed. Use of Incentive Spirometry is highly encouraged. Lung expansion postoperatively is important especially in the hospitalized patient. Incentive spirometry exercises lungs and helps prevent lung infections such as pneumonia.

A Sequential Compression Device or anti-thrombolytic stockings are used to enhance blood circulation in the legs and to prevent deep vein thrombosis.

Patient-controlled analgesia is used the first few postoperative days for comfort and replaced by oral pain medication prior to discharge.

Physical therapists and nurses assist the patient in and out of bed. A walker or cane assists mobility and walking is gradually increased as tolerated. Some patients are discharged sooner than others. Generally, a patient is considered ready for discharge when they can eat a regular diet, urinate normally, walk, go up and down stairs, and have no fevers.

Some surgeons prescribe a brace for postoperative wear to keep the spine immobile. Although patients are encouraged to be safely active, restrictions include no bending, lifting, or twisting for the first 3 months after surgery.