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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Orthopedic surgery

Surgical Interventions: Fusion and Tethering

At a Glance

Idiopathic scoliosis surgery is often discussed for curves around 45 to 50 degrees or more, but growth remaining, progression, balance, and personal goals also guide the decision. Fusion is more predictable; vertebral body tethering preserves motion but has higher risks of breakage and repeat surgery.

While many cases of scoliosis are managed with observation or bracing, surgery becomes a consideration when the curve reaches a size that is likely to continue progressing into adulthood [1].

The decision to have surgery is rarely an emergency. It is a shared decision made between you, your family, and your surgeon based on your curve size, your remaining growth, and your personal goals for the future [2][3]. Choosing observation at these thresholds is not automatically unsafe.

When is Surgery Recommended?

In the United States and Europe, the “surgical threshold” is generally a Cobb angle of 45 to 50 degrees or greater [1][4]. These are discussion ranges, not automatic rules. Decisions consider progression, balance, and goals.

  • Why 50 degrees? Research shows that curves smaller than 30 degrees at the end of growth rarely get worse, but curves that reach 50 degrees often continue to grow by about 1 degree per year throughout adulthood [5].
  • Skeletal Maturity Matters: If you have a 45-degree curve and are still Risser 0 (lots of growth left), the risk of the curve reaching 60 or 70 degrees is very high, making surgery a common discussion [6][3].

Posterior Spinal Fusion (PSF): The Gold Standard

For decades, Posterior Spinal Fusion has been the most common and predictable treatment for severe AIS [2].

  • The Procedure: The surgeon uses metal rods and screws to straighten the spine as much as safely possible. Small pieces of bone (bone graft) are placed along the spine; over several months, these pieces “fuse” the vertebrae together into a single, solid bone [2][7].
  • Predictability: PSF is highly effective. It typically corrects the curve by 60% to 70% and has a very low revision rate (the chance of needing a second surgery is about 6%, depending on the study and follow up duration) [7][8]. Important risks include infection, blood loss (possibly requiring transfusion), neurologic injury, nonunion, implant problems, adding-on, persistent pain, and reoperation.
  • The Trade-off: The fused part of your spine will no longer grow or bend. The number of levels fused and resulting flexibility depend on your curve. Most patients find they can still participate in most sports because the lower back (lumbar spine) is often left unfused to allow for bending and twisting [9][10].

Vertebral Body Tethering (VBT): The Motion-Preserving Option

Vertebral Body Tethering is a newer, “growth-friendly” alternative for patients who are still growing [11].

  • The Procedure: Instead of rods and fusion, the surgeon places screws into the side of the vertebrae and connects them with a strong, flexible cord (the tether) [12]. The tether is tightened to pull the curve straighter.
  • How it Works: As you grow, the tether holds back the “long” side of the curve while the “short” side continues to grow, allowing the spine to straighten itself naturally [13].
  • Eligibility: VBT is typically for patients aged 8 to 16 who are still Risser 0-2 (or Sanders 3-5) and have flexible curves between 35 and 60 degrees. Availability and regulatory status vary by country and center, and it has less long-term evidence than PSF [11][14].
  • The Risks: While VBT preserves motion, it is less predictable than fusion. Tether breakage is common, occurring in 21% to 45% of patients in some cohorts [13][15]. Tether breakage does not always require revision, but the revision rate is higher than fusion, with 14% to 24% of patients needing a second surgery to adjust the tether or convert to a fusion [16][15].

Recovery and Returning to Life

Modern “Enhanced Recovery” protocols have made the hospital stay much shorter than it used to be.

  • Hospital Stay: Most patients go home 3 to 5 days after surgery [17][18]. VBT patients often have a slightly shorter stay and may use fewer opioid pain medications than PSF patients [18][19].
  • Return to School: Many adolescents are ready to return to school (with a light backpack) in 3 to 4 weeks, though this varies by patient [9].
  • Return to Sports:
    • PSF: You can usually start light activity (walking) immediately. Non-contact sports often begin at 6 months, and most surgeons clear patients for all activities, including contact sports, by 12 months [9][20].
    • VBT: Because there is no bone fusion to wait for, the return to activity can be faster, though “collision” sports still require careful discussion with your surgeon [19][20]. Clearance for sports is strictly individualized.
  • Urgent Symptoms: You must contact your care team promptly if you develop a fever, wound drainage, new weakness, or breathing problems postoperatively.

Common questions in this guide

When is surgery usually considered for idiopathic scoliosis?
Surgery is commonly discussed when the curve measures about 45 to 50 degrees or more on an X-ray, particularly if it is progressing and the patient still has substantial growth remaining. The number is a discussion range, not an automatic rule; curve balance and personal goals also matter, and observation may still be reasonable.
How does posterior spinal fusion differ from vertebral body tethering?
Posterior spinal fusion uses rods, screws, and bone graft to permanently join selected vertebrae, so it usually offers more predictable correction but reduces motion in the fused part of the spine. Vertebral body tethering uses screws and a flexible cord in patients who are still growing to guide the spine toward a straighter position while preserving more motion, but its results are less predictable and repeat surgery is more common.
Could I be a candidate for vertebral body tethering?
Vertebral body tethering is generally considered for patients who are still growing, often ages 8 to 16, with a flexible curve measuring about 35 to 60 degrees. Growth-stage measures such as Risser 0-2 or Sanders 3-5 may be used, and eligibility, availability, and regulatory approval vary by country and treatment center.
How soon can I return to school and sports after scoliosis surgery?
Many patients leave the hospital 3 to 5 days after surgery and return to school in about 3 to 4 weeks with a light backpack, although recovery differs. After fusion, walking starts early, non-contact sports often resume around 6 months, and full activity may be allowed around 12 months; vertebral body tethering may allow a faster return, but sports clearance is individualized.
How often does the tether break after vertebral body tethering, and does it require another surgery?
Tether breakage has occurred in about 21% to 45% of patients in some study groups. A break does not always require treatment, but roughly 14% to 24% may need another operation to adjust the tether or change to a spinal fusion.
What warning signs should I report after scoliosis surgery?
Contact your surgical care team promptly for a fever, drainage from the wound, new weakness, or trouble breathing after surgery. These symptoms need timely assessment rather than waiting for a routine follow-up.
Is it unsafe to wait if my scoliosis curve is near the surgical range?
Not necessarily. Surgery is not usually an emergency, and observation can be reasonable at these thresholds, but curves around 50 degrees may continue progressing during adulthood. Discuss the monitoring plan and timing of treatment with your surgeon.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my current growth stage and curve pattern, am I a candidate for Vertebral Body Tethering (VBT), or is Posterior Spinal Fusion (PSF) the better option for me?
  2. 2.What is your personal success rate and revision rate for VBT, and how do you handle cases of tether breakage?
  3. 3.If I choose spinal fusion, how many levels of my spine will be fused, and how much flexibility will I likely lose in my daily activities and sports?
  4. 4.What does the typical recovery timeline look like at your hospital, and when can I realistically expect to return to school and competitive sports?
  5. 5.If we decide to wait and the curve reaches 55 or 60 degrees, does that make the surgery significantly more difficult or risky?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
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    Assessment and Management of Adolescent Idiopathic Scoliosis: From the Perspective of a Physiatrist.

    Su YC, Feng CK, Yang TF

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    Surgical versus non-surgical interventions in people with adolescent idiopathic scoliosis.

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    Vertebral body tethering: An alternative to posterior spinal fusion in idiopathic scoliosis?

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    Anterior vertebral body tethering for idiopathic scoliosis in growing children: A systematic review.

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    Vertebral Body Tethering in Skeletally Immature Patients: Results of a Prospective U.S. FDA Investigational Device Exemption Study.

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This page explains surgical options for idiopathic scoliosis for educational purposes and is not personal medical advice. Your spine surgeon and care team can assess your curve, growth, and goals to recommend the safest plan.

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