Bowed legs

Bowed legs (genu varum) describe legs that curve outward at the knees, so that when a child or adult stands with the ankles together, the knees remain apart. It is very common and usually normal in babies and toddlers: many children are naturally bow-legged up to about the age of two or three, and the legs straighten by themselves as the child grows (often passing through a mild knock-kneed phase before settling). This physiological bowing is symmetrical, painless and gradually improves. The important thing is to distinguish it from bowing that signals a problem. The classic medical cause is rickets — softening of the growing bones from vitamin D deficiency (or, less often, low calcium or phosphate, or inherited phosphate disorders) — where the soft bones bend under the child's weight. Features that suggest rickets or another cause rather than normal bowing include bowing that is severe, worsening rather than improving, affects one leg much more than the other, persists beyond about age three, or comes with short stature, bone pain, delayed walking or other signs of rickets. Other, rarer causes include a growth-plate disorder (Blount's disease) and previous bone injury.

• Normal (physiological) bowing — common and self-correcting in babies and toddlers.
• Rickets — vitamin D deficiency softening the growing bones; the key medical cause.
• Low calcium or phosphate, or inherited phosphate disorders — as in some rickets.
• Blount's disease — a growth-plate disorder causing progressive bowing.
• Previous bone injury or growth-plate damage.
• In adults, longstanding conditions — osteoarthritis, old rickets, Paget's disease of bone.

For a young child with mild, symmetrical bowing that is improving, no tests are usually needed — it is a normal stage. Assessment and blood tests are directed at bowing that is marked, worsening, one-sided, persists beyond toddlerhood, or comes with other signs. Because rickets is the key treatable cause, the relevant blood tests are vitamin D, calcium, phosphate and alkaline phosphatase (typically raised in rickets), often with parathyroid hormone; X-rays of the knees confirm rickets or a growth-plate disorder. Mediora.AI can highlight the low vitamin D with raised alkaline phosphatase and altered calcium/phosphate that points to rickets, offering a treatable explanation for bowed legs; but the pattern and severity of the bowing determine the workup, so significant or worsening bowing in a child should be assessed by your doctor.