Harrington rod

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Harrington rods used in spinal fusion Blausen 0446 HarringtonRods.png
Harrington rods used in spinal fusion

The Harrington rod (or Harrington implant) is a stainless steel surgical device. [1] 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.

Contents

History

The Harrington implant was developed in 1953 by Paul Harrington, a professor of orthopedic surgery at Baylor College of Medicine in Houston, Texas. [2]

Harrington rods were intended to provide a means to reduce the curvature and to provide more stability to a spinal fusion. Before the Harrington rod was invented, scoliosis patients had their spines fused without any instrumentation to support it; such fusions required many months in plaster casts, and large curvatures could progress despite fusion.

Purpose

Harrington rod instrumentation was used to treat instability and deformity of the spine. Instability occurs when the spine no longer maintains its normal shape during movement. Such instability results in nerve damage, spinal deformities, and disabling pain. Spinal deformities may be caused by birth defects, fractures, marfan syndrome, neurofibromatosis, neuromuscular diseases, severe injuries, and tumors. By far, the most common use for the Harrington rod was in the treatment of scoliosis, for which it was invented.

Description

The device itself was a stainless steel distraction rod fitted with hooks at both ends and a ratchet and was implanted through an extensive posterior spinal approach, the hooks being secured onto the vertebral laminae. It was used at the beginning without performing a spinal fusion but early results proved fusion as part of the procedure was mandatory, as movement of the unfused spine would cause the metal to fatigue and eventually break. The procedure required the use of a postoperative plaster cast or bracing until vertebral fusion had occurred.

Flatback syndrome

Flatback syndrome is a problem that develops in some patients treated with Harrington rod instrumentation, where the rod extends down into lower part of the lumbar spine. Because the Harrington cannot follow the natural lordosis of the lower back (i.e. the backwaist curve), the spine is straightened out into an unnatural position. At first, the unfused spinal segments compensate for the straightening effects, but eventually the discs degenerate and wear down. The patient then develops back pain, has difficulty standing upright, and experiences limitations when walking. Eventually, the problem requires surgery to realign the spine.

As exemplified by Pecina and Dapic in the European Spine Journal (February 2007), flatback syndrome is not inevitable and does not happen to every person with a low Harrington rod instrumented fusion there are many people who have had Harrington rods for decades with no adverse effects.

Related Research Articles

Scoliosis Medical condition of the spine

Scoliosis is a medical 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.

Kyphosis Medical condition

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; 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.

Laminectomy

A laminectomy is a surgical procedure that removes a portion of a vertebra called the lamina, which is the roof of the spinal canal. It is a major spine operation with residual scar tissue and may result in postlaminectomy syndrome. Depending on the problem, more conservative treatments may be viable.

Degenerative disc disease Medical condition

Degenerative disc disease (DDD) is a medical condition in which there are anatomic changes and a loss of function of varying degrees of one or more intervertebral discs of the spine of sufficient magnitude as to cause symptoms. The root cause is thought to be loss of soluble proteins within the fluid contained in the disc with resultant reduction of the oncotic pressure, which in turn causes loss of fluid volume. Normal downward forces cause the affected disc to lose height, and the distance between vertebrae is reduced. The anulus fibrosus, the rigid outer shell of a disc, also weakens. This loss of height causes laxity of the longitudinal ligaments, which may allow anterior, posterior, or lateral shifting of the vertebral bodies, causing facet joint malalignment and arthritis; scoliosis; cervical hyperlordosis; thoracic hyperkyphosis; lumbar hyperlordosis; narrowing of the space available for the spinal tract within the vertebra ; or narrowing of the space through which a spinal nerve exits with resultant inflammation and impingement of a spinal nerve, causing a radiculopathy.

Klippel–Feil syndrome Congenital condition characterised by fusion of two or more vertebrae in the neck

Klippel–Feil syndrome (KFS), also known as cervical vertebral fusion syndrome, is a rare congenital condition characterized by the abnormal fusion of any two of the seven bones in the neck. It results in a limited ability to move the neck and shortness of the neck, resulting in the appearance of a low hairline.

Back brace


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.

Spinal fusion Immobilization or ankylosis of two or more vertebrae by fusion of the vertebral bodies

Spinal fusion, also called spondylodesis or spondylosyndesis, is a neurosurgical or orthopedic surgical technique that joins two or more vertebrae. This procedure can be performed at any level in the spine and prevents any movement between the fused vertebrae. There are many types of spinal fusion and each technique involves using bone grafting—either from the patient (autograft), donor (allograft), or artificial bone substitutes—to help the bones heal together. Additional hardware is often used to hold the bones in place while the graft fuses the two vertebrae together. The placement of hardware can be guided by fluoroscopy, navigation systems, or robotics.

Anterior longitudinal ligament Ligament running down the front of the vertebral column

The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs on their ventral side. It may be partially to treat certain abnormal curvatures in the vertebral column, such as kyphosis.

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 has been reported approximately 80-100 individuals with Copenhagen disease since 1949. However, there is still little known research due to the rarity of the disease. The disease is so rare that the National Organization for Rare Diseases does not even mention Copenhagen disease in their database.

Kyphoscoliosis Medical condition

Kyphoscoliosis describes an abnormal curvature of the spine in both a coronal and sagittal plane. 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.

Scheuermanns disease Medical condition

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.

Milwaukee brace

The Milwaukee brace, also known as a cervico-thoraco-lumbo-sacral orthosis or CTLSO, is a back brace most often used in the treatment of spinal curvatures in children but also, more rarely, in adults to prevent collapse of the spine and associated pain and deformity. It is a full-torso brace that extends from the pelvis to the base of the skull. It was originally designed by Blount and Schmidt in 1946 for postoperative care when surgery required long periods of immobilization.

Minimally-invasive thoracic spinal fusion is one of the newest approaches to scoliosis surgery. Instead of a vertical scar down the back or horizontal from the middle of the chest to the center of the back, a rod is inserted through a series of small incisions on the side of the body. The spine is not exposed during the surgery; a small scope is used instead.

Vertebral fixation is an orthopedic surgical procedure in which two or more vertebrae are anchored to each other through a synthetic "vertebral fixation device", with the aim of reducing vertebral mobility and thus avoiding possible damage to the spinal cord and/or spinal roots.

Scoliosis Research Society (SRS) is a non-profit, professional, international organization, made up of physicians and allied health personnel, whose purpose is to "care for those with spinal deformity throughout life by patient care, education, research and patient advocacy." Founded in 1966 with 37 members, the SRS has grown to include over 1300 spinal deformity surgeons and allied health personnel in 41 countries, with a primary focus on providing continuing medical education for health care professionals and on funding/supporting research in spinal deformities. Among its founding members were Dr. Paul Randall Harrington, inventor of the Harrington Rod treatment for scoliosis, and Dr. David B. Levine, spine surgeon at Hospital for Special Surgery. Harrington later served as President from 1972 to 1973, and Levine was President of the Society from 1978 to 1979. Current membership primarily includes spinal deformity surgeons, as well as some researchers, physician assistants, and orthotists who are involved in research and treatment of spinal deformities. Strict membership criteria ensure that the individual SRS Fellows are dedicated to the highest standards of care for adult and pediatric spinal deformities, utilizing both non-operative and operative techniques.

Paul Randall Harrington American orthopedic surgeon

Paul Randall Harrington was an American orthopaedic surgeon. He is best known as the designer of the Harrington Rod, the first device for the straightening and immobilization of the spine inside the body. It entered common use in the early 1960s and remained the gold standard for scoliosis surgery until the late 1990s. During this period over one million people benefited from Harrington's procedure.

Neuromechanics of idiopathic scoliosis

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.

Vertebral osteomyelitis is a type of osteomyelitis that affects the vertebrae. It is a rare bone infection concentrated in the vertebral column. Cases of vertebral osteomyelitis are so rare that they constitute only 2%-4% of all bone infections. The infection can be classified as acute or chronic depending on the severity of the onset of the case, where acute patients often experience better outcomes than those living with the chronic symptoms that are characteristic of the disease. Although vertebral osteomyelitis is found in patients across a wide range of ages, the infection is commonly reported in young children and older adults. Vertebral osteomyelitis often attacks two vertebrae and the corresponding intervertebral disk, causing narrowing of the disc space between the vertebrae. The prognosis for the disease is dependent on where the infection is concentrated in the spine, the time between initial onset and treatment, and what approach is used to treat the disease.

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:

  1. Observation
  2. Bracing
  3. Specialized physical therapy
  4. Surgery

Anterior vertebral body tethering (AVBT) is a relatively new surgery for the treatment of scoliosis in pediatric patients. Left untreated, severe scoliosis can worsen and eventually affect a person's lungs and heart.

References

  1. "Harrington rod, a spinal instrument used in traditional scoliosis surgery - Information provided by Ann Arbor Spine Center - Southeast Michigan - Ypsilanti, Brighton, Chelsea, Novi, Ann Arbor". www.annarborspinecenter.com. Retrieved 2018-05-10.
  2. "Polio struck terror in Houston and across the nation". Houston Chronicle. Retrieved 2018-05-10.