The Risser stage is a 0-to-5 scoring system that tells doctors how close an adolescent is to being done growing. It works by looking at a specific strip of bone along the top of the pelvis, called the iliac apophysis, on an X-ray. As a teenager matures, this bony cap gradually hardens and fuses to the pelvis in a predictable pattern. A Risser stage of 0 means no hardening has started, while a stage of 5 means the bone is fully fused and skeletal growth is essentially complete.
This system matters most in the treatment of adolescent scoliosis, where knowing how much growth remains directly shapes decisions about bracing, monitoring, and surgery.
How the Scoring Works
The iliac crest is the curved rim of bone you can feel at the top of your hip. During puberty, a thin cap of cartilage along this rim begins to harden (ossify) in a wave that starts near the front of the hip and moves toward the spine. Doctors track how far that wave has traveled to assign a stage.
In the system used in the United States, the crest is divided into four equal quarters:
- Stage 0: No ossification visible on X-ray. The child is still in early growth or approaching peak growth.
- Stage 1: Ossification covers the first 25% of the crest (the outer front portion).
- Stage 2: Ossification reaches 50%.
- Stage 3: Ossification reaches 75%.
- Stage 4: The bony cap covers 100% of the crest but has not yet fused to the pelvis beneath it.
- Stage 5: The cap has completely fused to the underlying bone. Growth is finished.
A different version, commonly used in France and other European countries, divides the crest into thirds instead of quarters for stages 1 through 3, with stage 4 marking the start of fusion. Because of this, the same X-ray can receive a higher Risser number under the U.S. system than the French system. In a comparison study of 148 patients where the two systems disagreed, the U.S. grade was higher in virtually every case. If you’re reading a scoliosis report, it’s worth knowing which version your doctor used.
Why It Matters for Scoliosis
A spinal curve is most likely to worsen during periods of rapid growth. The Risser stage gives doctors a rough gauge of how much growth is left and, by extension, how much risk there is that a curve will progress. The lower the Risser stage and the larger the existing curve, the greater the concern.
Bracing for scoliosis is typically recommended when a patient is between ages 10 and 14, has a curve between 25° and 40°, and is at Risser stage 0, 1, or 2. These are the stages where significant growth remains and a brace can still influence spinal alignment as the skeleton develops. In a large Italian cohort of over 3,500 adolescents with scoliosis, only 27% of those at Risser 0 had started menstruating, compared to 79% at Risser 1 and 97% by Risser 3. That steep climb illustrates how quickly the body matures through the early stages and why early intervention matters.
Bracing is generally discontinued around Risser stage 4, along with evidence that height has stopped increasing for at least six months. But Risser 4 is not the same as fully mature. Research shows that patients who were still at Risser 4 at the end of treatment were significantly more likely to see their curve progress by more than 5° compared to those who had reached Risser 5. In practical terms, your doctor may want to continue monitoring even after bracing ends if you haven’t reached full fusion.
Limitations of the Risser System
The Risser system is simple and easy to read on a standard spinal X-ray, which is a big part of why it’s been used since the 1950s. But it has a notable blind spot: Risser stage 0 covers a very wide window of development. A child at the very beginning of their growth spurt and one who is already past peak height velocity can both appear as Risser 0 on an X-ray.
When researchers compared the Risser system against hand X-ray methods (which look at bone development in the wrist and fingers), they found that Risser stage 0 corresponded to six different grades on the Sanders skeletal maturity scale, a much finer tool. This means Risser 0 can underestimate how mature a skeleton actually is. In girls, the risk of underestimating maturity was as high as 59% when relying on the Risser stage alone, but dropped to about 17% when doctors also checked hand bone development.
For boys, the problem was even more pronounced. Hand X-ray methods were significantly more effective at pinpointing peak growth in males than the Risser system. This is one reason many scoliosis specialists now use the Risser stage alongside other maturity markers rather than depending on it as the sole indicator.
How Risser Stage Relates to Puberty Milestones
Because the Risser system tracks bone development that happens during puberty, it roughly correlates with other physical milestones. In girls, the onset of menstruation is one of the most commonly referenced markers. Most girls are at Risser 0 or 1 when their first period arrives. By Risser 3, about 53% are already two or more years past that milestone, and by Risser 4, 87% are. Since significant spinal growth slows considerably about two years after the first period, these two markers together give a more reliable picture than either one alone.
Height is another useful cross-reference. Doctors often pair the Risser stage with height measurements taken over several visits. Once a patient shows no increase in height over six months and has reached Risser 4, the combination suggests the growth window has effectively closed. Peak height velocity, the fastest rate of growth during puberty, generally occurs around Risser 0 in both boys and girls, which is exactly why that stage represents the highest-risk period for curve progression.
What Your Risser Stage Means in Practice
If your child has been diagnosed with scoliosis, the Risser stage will likely appear on their radiology report and come up in treatment discussions. At stages 0 through 2, the focus is on active management: monitoring the curve closely (often every four to six months) and starting bracing if the curve crosses 25°. At stages 3 and 4, the conversation shifts toward whether bracing can be tapered and how stable the curve looks. At stage 5, skeletal growth is done, and the risk of further progression drops considerably, though curves above 40° to 45° at maturity can still slowly worsen over decades.
One important detail: curves that are already 45° or larger at the time bracing is stopped carry about five times the odds of progressing further compared to smaller curves. So the Risser stage tells you about growth, but the size of the curve at maturity is what most strongly predicts long-term behavior. Both numbers matter, and treatment decisions rely on the full picture rather than any single measurement.