The Harrington rod (or Harrington implant) is a

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

surgical device. Historically, this rod was implanted along the

spinal column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmen ...

to treat, among other conditions, a lateral or coronal-plane curvature of the spine, or

scoliosis Scoliosis (: scolioses) is a condition in which a person's Vertebral column, spine has an irregular curve in the coronal plane. The curve is usually S- or C-shaped over three dimensions. In some, the degree of curve is stable, while in others ...

. Up to one million people had Harrington rods implanted for scoliosis between the early 1960s and the late 1990s.

History

The Harrington implant was developed in 1953 by Paul Harrington, a professor of

orthopedic surgery Orthopedic surgery or orthopedics ( alternative spelling orthopaedics) is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...

Baylor College of Medicine The Baylor College of Medicine (BCM) is a private medical school in Houston, Texas, United States. Originally as the Baylor University College of Medicine from 1903 to 1969, the college became independent with the current name and has been se ...

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. Harrington had a keen interest in working with patients with neuromuscular scoliosis, particularly patients who had poliomyelitis. Harrington collaborated with an orthotist named Thorkild Engen to develop the Harrington Rod. 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. Harrington personally created and adjusted the rods from his previous patients, allowing him to refine the Harrington rods over time. He first presented the Harrington Rods at the American Academy of Orthopaedic Surgeons Annual Meeting in 1958, which was met with skepticism. He worked with Zimmer Manufacturing for production and sale of the Harrington rods in the 1960s. Harrington and his rods were featured on the cover of Time Magazine in 1962 which recognized his work and innovation.

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 A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

fractures Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

marfan syndrome Marfan syndrome (MFS) is a multi-systemic genetic disorder that affects the connective tissue. Those with the condition tend to be tall and thin, with dolichostenomelia, long arms, legs, Arachnodactyly, fingers, and toes. They also typically ha ...

neurofibromatosis Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, e ...

neuromuscular disease A neuromuscular disease is any disease affecting the peripheral nervous system (PNS), the neuromuscular junctions, or skeletal muscles, all of which are components of the motor unit. Damage to any of these structures can cause muscle atrophy and we ...

s, severe injuries, and

tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

. 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 Each vertebra (: vertebrae) 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 spina ...

laminae. It was used at the beginning without performing a

spinal fusion Spinal fusion, also called spondylodesis or spondylosyndesis, is a surgery performed by Orthopedic surgery#Practice, orthopaedic surgeons or neurosurgeons that joins two or more vertebrae. This procedure can be performed at any level in the spine ...

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 Lordosis is historically defined as an ''abnormal'' inward curvature of the lumbar spine. However, the terms ''lordosis'' and ''lordotic'' are also used to refer to the normal inward curvature of the lumbar and cervical vertebrae, cervical regio ...

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 fusionthere are many people who have had Harrington rods for decades with no adverse effects.

References

{{Reflist

External links

Medscape – Modern Posterior Thoracic Instrumentation

20-year follow-up of Harrington instrumentation in the treatment of severe Idiopathic Scoliosis
Pecina & Dapic, ''European Spine Journal'' Vol 16 No 2 Feb 2007 (subscription only) Orthopedic implants Orthopedic surgical procedures