The Cobb angle is a measurement of bending disorders of the vertebral column such as scoliosis and traumatic deformities.
The Cobb angle is a measurement of bending disorders of the vertebral column such as scoliosis and traumatic deformities.
It is defined as the greatest angle at a particular region of the vertebral column, when measured from the superior endplate of a superior vertebra to the inferior endplate of an inferior vertebra. [1] However, the endplates are generally parallel for each vertebra, so not all sources include usage of a superior versus inferior endplate in the definition. [2]
Unless otherwise specified it is generally presumed to refer to angles in the coronal plane, such as projectional radiography in posteroanterior view. In contrast, a sagittal Cobb angle is one measured in the sagittal plane such as on lateral radiographs. [3]
Cobb angles are preferably measured while standing, since laying down decreases Cobb angles by around 7–10°. [4]
It is a common measurement of scoliosis.
The Cobb angle is also the preferred method of measuring post-traumatic kyphosis in a recent meta-analysis of traumatic spine fracture classifications. [5]
| Severity | Cobb angle |
|---|---|
| Not scoliosis | <10° [6] |
| Mild scoliosis | 10–30° |
| Moderate scoliosis | 30–45° [7] |
| Severe scoliosis | >45° [7] |
Those with Cobb angle of more than 60° usually have respiratory complications. [7]
Scoliosis cases with Cobb angles between 40 and 50 degrees at skeletal maturity progress at an average of 10 to 15 degrees during a normal lifetime. Cobb angles of more than 50 degrees at skeletal maturity progress at about 1 to 2 degrees per year. [8]
The Cobb angle is named after the American orthopedic surgeon John Robert Cobb (1903–1967). It was originally used to measure coronal plane deformity on radiographs with antero-posterior projection for the classification of scoliosis. [9] It has subsequently been adapted to classify sagittal plane deformity, especially in the setting of traumatic thoracolumbar spine fractures.
Scoliosis is a condition in which a person's spine has a sideways curve. The curve is usually "S"- or "C"-shaped over three dimensions. In some, the degree of curve is stable, while in others, it increases over time. Mild scoliosis does not typically cause problems, but more severe cases can affect breathing and movement. Pain is usually present in adults, and can worsen with age. As the condition progresses, it may impact a person's life and hence, can also be considered a disability.
The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse process and by the absence of facets on the sides of the body. They are designated L1 to L5, starting at the top. The lumbar vertebrae help support the weight of the body, and permit movement.
Kyphosis is an abnormally excessive convex curvature of the spine as it occurs in the thoracic and sacral regions. Abnormal inward concave lordotic curving of the cervical and lumbar regions of the spine is called lordosis. It can result from degenerative disc disease; developmental abnormalities, most commonly Scheuermann's disease; Copenhagen disease, osteoporosis with compression fractures of the vertebra; multiple myeloma; or trauma. A normal thoracic spine extends from the 1st thoracic to the 12th thoracic vertebra and should have a slight kyphotic angle, ranging from 20° to 45°. When the "roundness" of the upper spine increases past 45° it is called kyphosis or "hyperkyphosis". Scheuermann's kyphosis is the most classic form of hyperkyphosis and is the result of wedged vertebrae that develop during adolescence. The cause is not currently known and the condition appears to be multifactorial and is seen more frequently in males than females.
Genu valgum, commonly called "knock-knee", is a condition in which the knees angle in and touch each other when the legs are straightened. Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs. The term originates from the Latin genu, 'knee', and valgus which means "bent outwards", but is also used to describe the distal portion of the knee joint which bends outwards and thus the proximal portion seems to be bent inwards.
In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.
The Harrington rod is a stainless steel surgical device. Historically, this rod was implanted along the spinal column to treat, among other conditions, a lateral or coronal-plane curvature of the spine, or scoliosis. Up to one million people had Harrington rods implanted for scoliosis between the early 1960s and the late 1990s.
The transverse plane is an anatomical plane that divides the body into superior and inferior sections. It is perpendicular to the coronal and sagittal planes.
A back brace is a device designed to limit the motion of the spine in cases of bone fracture or in post-operative spinal fusiona, as well as a preventative measure against some progressive conditions or to correct patient posture.
A burst fracture is a type of traumatic spinal injury in which a vertebra breaks from a high-energy axial load, with shards of vertebra penetrating surrounding tissues and sometimes the spinal canal. The burst fracture is categorized by the "severity of the deformity, the severity of (spinal) canal compromise, the degree of loss of vertebral body height, and the degree of neurologic deficit." Burst fractures are considered more severe than compression fractures because long-term neurological damage can follow. The neurologic deficits can reach their full extent immediately, or can progress for a prolonged time.
Congenital vertebral anomalies are a collection of malformations of the spine. Most, around 85%, are not clinically significant, but they can cause compression of the spinal cord by deforming the vertebral canal or causing instability. This condition occurs in the womb. Congenital vertebral anomalies include alterations of the shape and number of vertebrae.
Copenhagen disease, sometimes known as Copenhagen syndrome or progressive non-infectious anterior vertebral fusion (PAVF), is a unique spinal disorder with distinctive radiological features. This is a rare childhood disease of unknown cause, affecting females slightly more than males (60%). Prevalence is unknown, but there have been approximately 80–100 individuals with Copenhagen disease reported since 1949. However, there is still little known research due to the rarity of the disease.
Kyphoscoliosis describes an abnormal curvature of the spine in both the coronal and sagittal planes. It is a combination of kyphosis and scoliosis. This musculoskeletal disorder often leads to other issues in patients, such as under-ventilation of lungs, pulmonary hypertension, difficulty in performing day-to-day activities, psychological issues emanating from anxiety about acceptance among peers, especially in young patients. It can also be seen in syringomyelia, Friedreich's ataxia, spina bifida, kyphoscoliotic Ehlers–Danlos syndrome (kEDS), and Duchenne muscular dystrophy due to asymmetric weakening of the paraspinal muscles.
Scheuermann's disease is a self-limiting skeletal disorder of childhood. Scheuermann's disease describes a condition where the vertebrae grow unevenly with respect to the sagittal plane; that is, the posterior angle is often greater than the anterior. This uneven growth results in the signature "wedging" shape of the vertebrae, causing kyphosis. It is named after Danish surgeon Holger Scheuermann.
Atlanto-occipital dislocation, orthopedic decapitation, or internal decapitation describes ligamentous separation of the spinal column from the skull base. It is possible for a human to survive such an injury; however, 70% of cases result in immediate death. It should not be confused with atlanto-axial dislocation, which describes ligamentous separation between the first and second cervical vertebra.
A spinal fracture, also called a vertebral fracture or a broken back, is a fracture affecting the vertebrae of the spinal column. Most types of spinal fracture confer a significant risk of spinal cord injury. After the immediate trauma, there is a risk of spinal cord injury if the fracture is unstable, that is, likely to change alignment without internal or external fixation.
The neuromechanics of idiopathic scoliosis is about the changes in the bones, muscles and joints in cases of spinal deformity consisting of a lateral curvature scoliosis and a rotation of the vertebrae within the curve, that is not explained by either congenital vertebral abnormalities, or neuromuscular disorders such as muscular dystrophy. The idiopathic scoliosis accounts for 80–90% of scoliosis cases. Its pathogenesis is unknown. However, changes in the vestibular system, a lateral shift of the hand representation and abnormal variability of erector spinae motor map location in the motor cortex may be involved in this disease. A short spinal cord and associated nerve tensions has been proposed as a cause and model for idiopathic scoliosis. Besides idiopathic scoliosis being more frequent in certain families, it is suspected to be transmitted via autosomal dominant inheritance. Estrogens could also play a crucial part in the progression of idiopathic scoliosis through their roles in bone formation, growth, maturation and turnover. Finally, collagen, intervertebral disc and muscle abnormalities have been suggested as the cause in idiopathic scoliosis, although these are perhaps results rather than causes.
Each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species.
The management of scoliosis is complex and is determined primarily by the type of scoliosis encountered: syndromic, congenital, neuromuscular, or idiopathic. Treatment options for idiopathic scoliosis are determined in part by the severity of the curvature and skeletal maturity, which together help predict the likelihood of progression. Non-surgical treatment should be pro-active with intervention performed early as "Best results were obtained in 10-25 degrees scoliosis which is a good indication to start therapy before more structural changes within the spine establish." Treatment options have historically been categorized under the following types:
Adolescent idiopathic scoliosis is a rather common disorder in which the spine starts abnormally curving sideways (scoliosis) at the age of 10–18 years old. This disorder generally occurs during the growth spurt that happens right before and during adolescence. In some teens, the curvature is progressive, meaning that it gets worse over time, however this is rare, since it is more common for this variant of scoliosis to show itself as a mild curvature.
Spinal posture is the position of the spine in the human body. It is debated what the optimal spinal posture is, and whether poor spinal posture causes lower back pain.
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