The Effect of Harrington Rod Contouring on Lumbar Lordosis

Prevention and Management of Iatrogenic Flatback Deformity

“…The most common reported cause of flatback syndrome is the extension of distraction instrumentation into the lower lumbar spine or sacrum [4][5][6][7][8][9][10][14][15][16] . It has also been reported following the use of anterior thoracolumbar compression instrumentation without structural graft support, but this is a rare occurrence 17 .…”

“…For patients with scoliosis, obtaining normal postoperative sagittal balance may be more critical functionally than is restoring so-called normal thoracic kyphosis and lumbar lordosis. Caudally, the fusion should be stopped at or cephalad to L3 except when a more caudad level is absolutely required to prevent curve progression or decompensation [4][5][6][7][8] . In addition to decreasing the risk of postoperative loss of lumbar lordosis, saving caudad fusion segments in the lumbar spine may decrease the risks of pseudarthrosis and late low-back pain, retrolisthesis, and degeneration of adjacent segments caudad to the fusion mass 9,14,18,50,51 .…”

“…As noted, the primary cause of the vast majority of cases of iatrogenic flatback syndrome is loss of lumbar lordosis secondary to the use of distraction (Harrington) instrumentation in the lumbar spine [1][2][3][4][5][6][7][8][9][10][14][15][16] . Following the initial recognition of this complication, there were several attempts to modify the Harrington instrumentation, such as with the use of a Moe squared-end rod to prevent rotation following contouring, use of Harrington compression instrumentation on the convex side of scoliotic curves, and the "rod-long, fuse-short" 15 technique.…”

“…Following the initial recognition of this complication, there were several attempts to modify the Harrington instrumentation, such as with the use of a Moe squared-end rod to prevent rotation following contouring, use of Harrington compression instrumentation on the convex side of scoliotic curves, and the "rod-long, fuse-short" 15 technique. These modifications have been proven to be inadequate 4,5,10,15,56 . Therefore, the use of distraction instrumentation caudad to the level of L1 or L2 is still highly inadvisable, even with the implant modifications, as a result of the substantial risk of reducing the lumbar lordosis with variable production of a symptomatic flatback deformity.…”

“…Since then, flatback syndrome, which is also commonly known as fixed sagittal imbalance, has become a well-recognized entity. The etiology of flatback syndrome may be multifactorial, but the most common cause is iatrogenic loss of lumbar lordosis secondary to Harrington distraction instrumentation [4][5][6][7][8][9][10] . Farcy and Schwab 11,12 described a subgroup of similar patients who had what they termed "kyphotic decompensation syndrome" and "flat buttock syndrome," a fixed positive sagittal imbalance due to malalignment at the site of a spinal fusion to the sacrum performed with distraction instrumentation for etiologies other than scoliosis.…”