Scoliosis, or curvature of the spine, affects 2 to 3 percent of the population in the United States, or about 6 million people, the A.D.A.M. Medical Encyclopedia reported in 2009. Scoliosis most often appears between ages 10 and 15 and affects about 10 percent of all adolescents, although only about 1 percent require treatment. Between 1964 and 2000, the standard treatment for scoliosis was fusion of the vertebrae in the curved part of the spine and placement of a steel rod, called a Harrington rod, which attached to the vertebrae to allow the fused spine to heal. Complications can occur after Harrington rod placement.
Normally, the lower part of the spine, called the lumbar spine, curves inward, a condition known as lordosis. Placement of a Harrington rod that extends to the lower spine can cause flat-back syndrome, in which the lumbar spine no longer curves inward but flattens or even bulges outward, a condition called lumbar kyphosis. About 40 percent of patients with Harrington rods develop flat-back syndrome, A.D.A.M. reports. Symptoms include back pain and an inability to stand up straight. People with flat-back syndrome may lean forward or lose hip flexibility. Surgery to repair flat-back syndrome is complex and symptoms may persist after surgery. Not placing rods in the lumbar spine and using segmented devices rather than a single rod has reduced the incidence in recent years, the National Scoliosis Foundation states.
Crankshaft phenomenon occurs in 33 percent of children who had Harrington rods placed when they were younger than 11 and still had immature skeletons, lead author Dr. Kimberly Kesling, of the Twin Cities Spine Center in Minneapolis, reported at the 2001 Scoliosis Research Society meeting. The front part of the spine continues to grow normally while the fused posterior spine doesn’t grow. The posterior spine becomes twisted and curves as the anterior portion grows. Fusing both the front and back spine in young children helps prevent crankshaft phenomenon.
Harrington rods are metal rods attached to bone with hooks and other metal devices. Rods can break; hooks and other metal pieces can migrate to other areas of the spine, causing nerve damage, back pain and, in the case of severe symptoms, lead to surgery to remove the damaged parts, Dr. Kazuko Shem, of the Santa Clara Valley Medical Center in San Jose, Calif., reported in the 2005 "Journal of Spinal Cord Medicine."
Infection can occur after placement of a Harrington rod. Inflammation can occur as a reaction to a foreign body in the spine, the Encyclopedia of Surgery reports.