If you had surgery for scoliosis in the 1960s, 70s, or 80s, you almost certainly had a Harrington rod. At the time, it was a remarkable advance — the first instrumented system that could actually straighten a scoliosis curve and hold it in place while the spine fused. For many patients, it delivered real results and a meaningful improvement in their curve.
But decades later, a significant number of those same patients are experiencing problems they weren’t warned about — and many don’t know that what they’re experiencing has a name, a cause, and in many cases a surgical solution.
What the Harrington rod did — and what it didn’t
The Harrington rod worked by distraction: a metal rod was hooked to the spine at the top and bottom of the scoliosis curve, then lengthened to pull the curve straighter. It corrected the side-to-side curvature reasonably well by the standards of its time. What it didn’t do was maintain the normal front-to-back curves of the spine — particularly the inward curve of the lower back, called lumbar lordosis.
Modern spinal instrumentation uses multiple anchoring points along the entire curve and is designed to restore three-dimensional spinal alignment, including lordosis. Harrington rods were a single-rod system with no ability to do this. The result, in many patients, is that the scoliosis was corrected but the lumbar spine was left flat — or even reversed into slight kyphosis. At the time, this wasn’t fully understood. Now it is.
The most common late complication: flatback deformity
Flatback deformity is the loss of lumbar lordosis — and it is the single most common and most disabling late complication of Harrington rod surgery. When the lower spine is flat, the body’s center of gravity shifts forward. To avoid falling, patients must continuously compensate by bending their knees, thrusting their hips forward, and recruiting enormous muscular effort just to stay upright.
Early on, this compensation is manageable. Over years and decades, it becomes exhausting and then impossible. Patients describe it as follows: they can no longer stand upright without tremendous effort. Walking any distance becomes painful. Standing at a kitchen counter or a social event is agonizing. They lean forward when they walk, which people around them may notice before they do.
Flatback deformity typically begins to manifest in a patient’s 30s or 40s — well after the original surgery — and worsens slowly over time. Many patients assume this is simply aging. It is not. It is a mechanical consequence of the original instrumentation, and it is correctable.
Other late complications to know about
Hardware failure. The rod, hooks, and any supplemental wiring can fracture, dislodge, or loosen over decades. Hardware failure may cause a sudden change in symptoms — increased pain, a change in posture, or a palpable change under the skin. It is diagnosed on imaging and typically requires revision surgery.
Pseudarthrosis. Harrington rod fusions were performed with older bone grafting techniques that had lower fusion rates than modern methods. Some patients develop pseudarthrosis — a failure of the fusion to achieve solid bony union — that becomes symptomatic years later. CT scan is the most reliable way to diagnose it.
Adjacent segment degeneration. A long spinal fusion places increased mechanical stress on the discs and joints immediately above and below the fused segment. Over decades, this accelerated wear causes degeneration at adjacent levels that may produce new symptoms not present at the time of the original surgery.
Progressive curve. Some patients find that their scoliosis curve has progressed despite the fusion, either through pseudarthrosis, crankshaft phenomenon, or extension of the curve into unfused segments.
New neurological symptoms. Leg pain, numbness, weakness, or bladder changes in a patient with prior Harrington rod surgery warrant prompt evaluation. These symptoms can arise from adjacent segment stenosis, hardware migration, instability, or deformity progression causing nerve compression.
What a modern evaluation looks like
If you had Harrington rod surgery and are experiencing new or worsening symptoms — or simply want to understand the current state of your spine — a modern evaluation should include full-length standing X-rays to assess overall alignment and sagittal balance; CT scan to evaluate fusion integrity, hardware status, and bone quality; MRI to assess the discs, nerves, and cord above, below, and within the fused segment; and a detailed clinical examination by a surgeon familiar with late Harrington rod complications.
Can anything be done?
Yes — in many cases, significantly. Flatback deformity can be corrected with an osteotomy (a controlled cut through the fused bone) that restores lumbar lordosis and rebalances the spine. The most powerful single-level osteotomy — the pedicle subtraction osteotomy (PSO) — can provide 30–40 degrees of correction at one level. Adjacent segment problems can be addressed with revision decompression or extension of the fusion construct. Hardware failure can be revised with modern pedicle screw systems that provide far superior fixation.
These are not simple operations — they are among the most technically demanding procedures in spine surgery. But for appropriately selected patients, the functional gains can be dramatic. Many describe being able to stand upright without pain for the first time in years.
A note on age
Many patients with Harrington rods are now in their 60s, 70s, and even 80s. Age alone is not a contraindication to revision surgery. What matters is overall health, bone quality, functional status, and the extent of surgery required. A thorough pre-operative evaluation at a high-volume deformity center will give you the clearest picture of what is realistic for your situation.
If you have been told that nothing can be done, or that you are too old or too high-risk, a second opinion from a surgeon who specializes in this population is entirely appropriate.
Dr. Sardar is Co-Chief of Spinal Deformity Surgery at the Och Spine Hospital at NewYork-Presbyterian / Columbia University and specializes in the evaluation and revision of late Harrington rod complications. Telemedicine consultations are available for patients in NY, NJ, CT, FL, PA, MO, CA, and TX.
This post is for educational purposes only and does not constitute individualized medical advice. Please consult a qualified spine specialist to discuss your specific condition.