If you had scoliosis surgery between the 1960s and the early 1990s, there is a good chance you have a Harrington rod in your spine. For decades, it was the standard of care for scoliosis correction — a major advance when it was introduced, and a procedure that helped hundreds of thousands of patients. But the Harrington rod has a fundamental limitation that was not fully understood at the time, and many patients who had the surgery are now, decades later, living with complications that are directly related to how that hardware works.
If you are one of those patients — or a family member of one — this post is for you. Here is what a Harrington rod is, why complications develop, and what can be done about them.
The History: Why the Harrington Rod Was Revolutionary
Before Dr. Paul Harrington developed his rod system in the 1950s, scoliosis surgery was primitive and unreliable. The available techniques offered little correction and required months of postoperative casting. Harrington’s innovation — a single metal rod attached with hooks to the top and bottom of the curved segment, then lengthened to straighten the spine — was transformative for its time. For the first time, meaningful correction could be achieved and maintained. The Harrington rod became the dominant technique for scoliosis surgery for the next three decades.
It was, by any measure, a genuine advance in patient care. The patients who received it were well-served by the best available technology of their era. The problem emerged not from the surgery failing to do what it was designed to do — it largely succeeded — but from what it could not do.
The Core Problem: What the Harrington Rod Could Not Do
The Harrington rod corrected scoliosis by distracting (lengthening) the spine along its concave side — straightening the side-to-side curvature. This worked well for the coronal plane (the front view). What it could not do was maintain or restore the normal front-to-back curves of the spine.
The human spine is not meant to be straight from front to back. The lower back (lumbar spine) has a natural inward curve called lordosis. This curve is essential for balanced, upright posture. It positions the body’s center of gravity correctly over the pelvis and allows people to stand upright without excessive muscular effort.
The Harrington rod, by design, tended to straighten or flatten the lumbar spine as it distracted the scoliotic curve. The lordosis was lost or reduced. At the time of surgery, this was not recognized as a significant problem. Patients were young, their muscles were strong, and they could compensate. But compensation has limits — and over decades, those limits are reached.
Flatback Deformity: The Most Common Late Complication
The loss of lumbar lordosis after Harrington rod surgery leads, over time, to a condition called flatback deformity. As the name suggests, the lower back loses its normal curve and becomes flat — or in some cases, actually reverses into a kyphotic curve. Without normal lordosis, the body’s center of gravity shifts forward. To stay upright, a patient must constantly exert muscular effort to hold themselves up against gravity.
The result is exhausting. Patients with flatback deformity describe an inability to stand upright for more than a few minutes at a time. Walking becomes painful and tiring. They find themselves leaning forward progressively as the day goes on. Activities that most people take for granted — standing in line, walking through a grocery store, attending a social event — become significant challenges.
Flatback deformity typically begins to manifest in a patient’s 30s or 40s, often 20 or 30 years after the original surgery. It does not improve on its own. Without treatment, it tends to progress slowly but steadily.
Other Late Complications of Harrington Rod Surgery
Flatback deformity is the most common and most disabling late complication, but it is not the only one. Patients with Harrington rod instrumentation can also develop:
- Hardware failure — rod fracture, hook dislodgement, or wire breakage. The hardware was designed for the shorter life expectancy assumptions of an earlier era; many patients have now had their implants for 40 or 50 years.
- Pseudarthrosis — failure of the fusion to fully heal, creating a non-union within the fused segment. This causes pain, instability, and stress fractures of the hardware.
- Adjacent segment degeneration — the levels immediately above and below a long spinal fusion bear increased mechanical load. Over decades, this accelerated wear causes disc degeneration, stenosis, and nerve compression at adjacent levels.
- Neurological symptoms — new leg pain, numbness, weakness, or bladder changes arising from adjacent segment stenosis, hardware migration, or progressive deformity. These symptoms warrant prompt evaluation.
- Crankshaft phenomenon — in patients who had surgery before skeletal maturity, continued anterior spinal growth against a posterior fusion can cause progressive rotational deformity.
Why Modern Surgery Is Different
The limitations of the Harrington rod directly shaped the development of modern spinal instrumentation. Beginning in the 1980s and 1990s, segmental fixation systems using pedicle screws were introduced. Unlike a Harrington rod — which attached only at the top and bottom of the construct — pedicle screw systems attach to every vertebra in the fusion, providing three-dimensional control of each segment.
This three-dimensional control allows surgeons to correct not just the side-to-side curvature of scoliosis, but also to restore and maintain normal lumbar lordosis. Modern scoliosis surgery does not produce flatback deformity. The outcomes for patients treated today are fundamentally different from those treated in the Harrington era — not because surgeons are more skilled, but because the tools allow three-dimensional correction that was simply not achievable before.
What Revision Surgery Involves
Revision surgery for Harrington rod complications is among the most technically complex procedures in spine surgery. It typically involves:
- Removal of the old Harrington rod hardware — often deeply embedded in scar tissue after decades in place
- Osteotomy — a controlled cut through the fused bone to allow the spine to be repositioned. For flatback correction, this typically involves a pedicle subtraction osteotomy (PSO), which achieves 30–40 degrees of lordosis correction at a single level, or multiple Smith-Petersen osteotomies (SPOs) across several levels
- Reconstruction with modern instrumentation — replacement of the old hardware with a modern pedicle screw-rod construct that maintains the corrected alignment
- Extension of the fusion — in many cases, the fusion needs to be extended to include levels above or below the original construct, often including the pelvis, to achieve balanced alignment
This is major surgery. It requires an experienced team, a high-volume center with appropriate infrastructure, and a surgeon who performs these procedures regularly. The outcomes for appropriately selected patients, however, can be transformative. Many patients describe being able to stand upright without pain for the first time in years.
Should You Be Evaluated?
If you had Harrington rod surgery and are experiencing any of the following, a specialist evaluation is appropriate:
- Progressive difficulty standing upright or a feeling that you are leaning forward
- Worsening back pain, particularly with standing or walking
- New or worsening leg pain, numbness, or weakness
- Any changes in bladder or bowel function
- A noticeable change in your posture or the way you walk
- Pain at the site of the original hardware
You do not need to be in crisis to seek an evaluation. In fact, earlier evaluation generally means simpler treatment options and better outcomes. If you are managing day-to-day but noticing a slow decline in what you can do, that is the right time to be seen — not after years of further progression.
Even if you feel well, a baseline evaluation with full-length standing X-rays at a center experienced in Harrington rod complications can give you a clear picture of where your spine stands — and whether any intervention is likely to be needed in the future.
About Dr. Zeeshan Sardar
Dr. Sardar is Co-Chief of Spinal Deformity Surgery at NewYork-Presbyterian / Columbia University and specializes in complex revision spine surgery, Harrington rod revision, and adult spinal deformity reconstruction. He sees patients from across the United States and internationally. To schedule a consultation, call 212-932-5187 or visit the contact page.
This article is for educational purposes only and does not constitute individualized medical advice. Please consult a qualified spine specialist to discuss your specific condition.
Sardar Spine | NYC Spinal Deformity & Scoliosis Surgeon 