Parents often first notice Blount's disease as a child's legs looking progressively more bow-legged, sometimes on one side more than the other, past the age when normal childhood bowing usually straightens out on its own. It is a genuine growth disorder of the shin bone — not just a cosmetic variation — and understanding what it is helps make sense of why timely evaluation matters.
What is Blount's disease?
Blount's disease is a growth disturbance affecting the growth plate at the top of the tibia (shin bone), on its inner side. Instead of growing evenly, that part of the growth plate slows down relative to the rest, causing the leg to progressively bow inward (a varus deformity) below the knee. It is distinct from the mild, symmetric bowing seen in many toddlers, which is a normal developmental stage that typically self-corrects by around age two to three.
Two patterns
- Infantile Blount's disease — appears in early childhood, often affects both legs, and tends to be identified when normal toddler bowing does not resolve as expected.
- Adolescent (or late-onset) Blount's disease — appears later, often in one leg, and is more frequently associated with higher body weight.
How is it diagnosed?
Diagnosis combines a clinical examination of the leg alignment and gait with standing X-rays of both legs, which show the characteristic changes at the growth plate and allow the degree of deformity to be measured accurately. This distinguishes true Blount's disease from physiological (normal) bowing, which has a different X-ray appearance and a different natural course.
How is it corrected?
Treatment is guided by the child's age, the severity of the deformity, and how the growth plate looks on imaging.
Bracing (selected early infantile cases)
In some younger children with milder, early-stage disease, a brace may be tried to influence growth while the growth plate still has significant remaining potential.
Guided growth (growth modulation)
In appropriate cases with growth remaining, a small implant can be placed across part of the growth plate to gradually guide the bone back towards a straighter alignment as the child continues to grow — a less invasive option that works with the child's own growth.
Corrective osteotomy
For more significant deformity, or when growth potential is limited, the bone is surgically cut and realigned (an osteotomy) and stabilised while it heals, correcting the deformity directly. This is a well-established technique for structural correction of the lower limb.
Q: Will the deformity come back?
Blount's disease can recur, particularly in infantile cases treated at a very young age, which is why planned follow-up through the remaining growth years matters — correction is not always a single, final event, and the plan is adjusted as the child grows.
Q: Is Blount's disease the parents' or child's fault?
No. It is a growth-plate condition; while higher body weight is an associated factor in adolescent Blount's, the disease itself is a structural growth issue, not something caused by how a child sits, sleeps, or walks.
Why it is easy to miss early on
The early stages of Blount's disease can look reassuringly similar to the normal bowing seen in almost every toddler learning to walk, which is exactly why some cases are picked up later than ideal — a family is told, correctly, that a two-year-old's mild bow-legs are usually nothing to worry about, and the follow-up needed to confirm that the bowing is actually resolving on schedule does not always happen. A simple rule of thumb: normal toddler bowing should be visibly improving by around age two to three; bowing that is static, worsening, or clearly asymmetric between the two legs at that stage deserves an X-ray rather than continued reassurance alone.
What a family can expect at the first visit
The initial assessment involves watching the child stand and walk, measuring the distance between the knees or ankles depending on the deformity pattern, and standing X-rays of both legs from hip to ankle. This single set of images usually gives a clear answer as to whether this is physiological bowing, early Blount's disease, or another cause of leg deformity, and it forms the baseline against which any future growth or treatment response is measured.
Persistent or worsening leg bowing past early toddlerhood, or bowing in only one leg, deserves a proper clinical and X-ray assessment rather than a wait-and-watch guess. This is an area of particular clinical interest, including published work on Blount's disease. Learn more about our approach to deformity correction, or book a consultation for your child.