Flat back syndrome is loss of the normal inward curve of the low back, which shifts the trunk forward and makes it hard to stand upright without bending the knees or tiring the back muscles. The best-documented cause is older scoliosis fusion with Harrington distraction rods extended into the lower lumbar spine. In a series of 55 patients treated for flatback after fusion, 95 percent could not stand erect and 89 percent had back pain. Corrective surgery helped most, but 47 percent still leaned forward and 36 percent had moderate or severe pain at about six years.
I am Dr. Justin Dick at Clear Life Scoliosis and Chiropractic Center in Charlotte, NC. I see adults fused in the 1970s and 1980s who now struggle to stand tall. This post explains why it happens and what the evidence says about options.
Why Older Fusions Caused Flat Back
Harrington rods corrected the sideways curve by distraction, pushing the ends of the curve apart. When that distraction extended into the lumbar spine, it straightened the low back's natural inward curve. Aaro and Öhlén studied 96 patients after Harrington instrumentation and found that the more distal the lumbar fusion, the less lordosis and flexion remained and the more rigidity and pain patients reported. Potter, Lenke, and Kuklo identified Harrington distraction into the lower lumbar spine as the most common cause of iatrogenic flatback, with other causes including failure to restore lordosis during fusion, pseudarthrosis, kyphosis at the thoracolumbar junction, degeneration above or below a prior fusion, and hip flexion contractures.
Why Patients Lean Forward
When the low back loses its inward curve, the trunk tips forward over the pelvis. The patient compensates by tilting the pelvis back, bending the knees, and contracting the back muscles continuously, which is tiring and painful. Glassman and colleagues showed in 752 adults with spinal deformity that health scores worsened in a linear fashion as the head and trunk shifted forward of the pelvis, and that kyphosis in the lumbar region was poorly tolerated.
What Standing Films Show
Flat back is diagnosed on a standing full-length side-view radiograph that shows lumbar lordosis, pelvic tilt, and whether the head and trunk sit forward of the pelvis. The degree of compensation, such as pelvic retroversion and knee flexion, matters as much as the angle. A lying MRI cannot show it. Roussouly and colleagues showed that the expected lordosis depends on pelvic anatomy, so the measurement has to be read against the patient's pelvis.
Treatment
Lagrone and colleagues treated 55 patients with 66 extension osteotomies. Sixty percent had at least one complication, including pseudarthrosis, dural tear, hardware failure, and nerve injury. Most felt they benefited, but failure to restore balance was linked with pseudarthrosis and recurrent deformity. Potter and colleagues describe pedicle subtraction and Smith-Petersen osteotomies as the main surgical options, with generally improved balance, fair to good outcomes, high satisfaction, and moderately high complication rates. Non-surgical care does not restore lordosis across fused segments. It can address the mobile segments, hip flexibility, and trunk endurance, which may improve function. That is clinical reasoning; I found no trial of non-surgical care for iatrogenic flatback.
Is Flat Back Still a Risk Today?
Modern segmental instrumentation is designed to preserve or restore lordosis, and Potter and colleagues list avoiding distraction into the lower lumbar spine and positioning with the hips extended as prevention. The older series overstate the risk for a patient fused today, but degeneration next to a fusion can still change alignment over decades.
How Dr. Justin Dick Evaluates Flat Back at Clear Life
At our Charlotte office, patients with a prior fusion and forward lean get standing full-spine radiographs when clinically indicated, measurement of lordosis, pelvic parameters, and global balance, and an exam of the mobile segments and hips. Care focuses on what can move, and surgical opinion is recommended when imbalance is significant. Our page on care after spinal fusion describes the approach.
Comparison
| Topic | Finding | Source |
|---|---|---|
| Most common cause | Harrington distraction into lower lumbar spine | Potter 2004; Lagrone 1988 |
| Symptoms at presentation | 95% unable to stand erect; 89% back pain | Lagrone 1988, 55 patients |
| Lumbar motion after Harrington fusion | Lower fusion, less lordosis and flexion | Aaro and Öhlén 1983, 96 patients |
| Forward imbalance and health | Scores worsen linearly with forward shift | Glassman 2005, 752 adults |
| Osteotomy outcomes | 60% complications; 47% still leaned forward at 6 years | Lagrone 1988 |
Research and Evidence
Evidence tiering: Lagrone and Aaro and Öhlén are older case series, Glassman a retrospective analysis of a prospective database, Roussouly a radiographic study of volunteers, and Potter a narrative review. No randomized trial compares treatments for flat back syndrome. The role of non-surgical care is clinical reasoning.
My own published work includes sagittal alignment in older adults with scoliosis. The geriatric sagittal alignment case series, Radiographic Sagittal Alignment and Kinetic Chain Alterations in Geriatric Patients With Scoliosis: A Case Series(Cureus, 2026, PMID 42037873), describes two patients and is case-level evidence.
References
- Lagrone MO, Bradford DS, Moe JH, et al. Treatment of symptomatic flatback after spinal fusion. J Bone Joint Surg Am. 1988;70(4):569-80. PMID 3356724
- Potter BK, Lenke LG, Kuklo TR. Prevention and management of iatrogenic flatback deformity. J Bone Joint Surg Am. 2004;86(8):1793-808. doi:10.2106/00004623-200408000-00027
- Aaro S, Ohlén G. The effect of Harrington instrumentation on the sagittal configuration and mobility of the spine in scoliosis. Spine. 1983;8(6):570-5. doi:10.1097/00007632-198309000-00002
- Glassman SD, Bridwell K, Dimar JR, et al. The impact of positive sagittal balance in adult spinal deformity. Spine. 2005;30(18):2024-9. doi:10.1097/01.brs.0000179086.30449.96
- Roussouly P, Gollogly S, Berthonnaud E, Dimnet J. Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position. Spine. 2005;30(3):346-53. doi:10.1097/01.brs.0000152379.54463.65
- Whelan JP, Dick JM. Radiographic sagittal alignment and kinetic chain alterations in geriatric patients with scoliosis: a case series. Cureus. 2026;18(3):e105827. doi:10.7759/cureus.105827
Frequently Asked Questions
What is flat back syndrome?
Loss of the low back's normal inward curve, which shifts the trunk forward. Patients lean forward, bend their knees, and tire quickly when standing.
What causes flat back syndrome?
The most common cause is older Harrington distraction rods extended into the lower lumbar spine. Other causes include failure to restore lordosis, pseudarthrosis, and degeneration next to a fusion.
What are the symptoms of flat back syndrome?
In a series of 55 patients, 95 percent could not stand erect and 89 percent had back pain. Fatigue when standing and walking is common.
Can flat back syndrome be fixed?
Corrective osteotomy surgery can improve balance, but in one series 60 percent had complications and 47 percent still leaned forward about six years later.
Can I still get flat back after modern scoliosis surgery?
The risk is lower with modern instrumentation designed to preserve lordosis, but degeneration next to a fusion can change alignment. Dr. Justin Dick at Clear Life Scoliosis in Charlotte, NC monitors alignment above and below fusions.
Where can I get flat back evaluated in Charlotte, NC?
Clear Life Scoliosis and Chiropractic Center, 8814 Rachel Freeman Way, Suite 103, Charlotte, NC 28278, provides standing alignment evaluation with Dr. Justin Dick, DC. Call 980-368-0766.
Service Area
Clear Life Scoliosis and Chiropractic Center sees patients from Charlotte NC, Huntersville NC, Ballantyne NC, Matthews NC, Concord NC, Mooresville NC, Rock Hill SC, Fort Mill SC. Families from across the Charlotte region and the South Carolina border communities come to the Rachel Freeman Way office for radiographic scoliosis evaluation with Dr. Justin Dick.
Related Pages
- Scoliosis Care After Spinal Fusion
- Scoliosis Rods Long Term
- Can You Bend Your Back After Scoliosis Surgery
- Scoliosis Surgery Risks and Outcomes
- Scoliosis Biomechanics and Sagittal Alignment
- Scoliosis Treatment for Adults
- Kyphosis Treatment in Charlotte
- Kinetic Chain Dysfunction in Geriatric Scoliosis
- Scoliosis Second Opinion
- Dr. Justin Dick Research
Schedule an Evaluation in Charlotte
If you were fused years ago and now struggle to stand upright, standing films show what has changed. Dr. Justin Dick reviews them at our Charlotte office.
Dr. Justin M. Dick, DC
8814 Rachel Freeman Way, Suite 103, Charlotte, NC 28278
Phone: 980-368-0766 · Email: office@clearlifescoliosis.com
clearlifescoliosis.com · Book online
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