Knock Knee Deformity
Knock knee, medically called genu valgum, is a leg alignment where the knees turn inward and touch or knock together in a standing posture, while a gap of roughly 3–4 inches remains between the ankles — the legs form a rough letter X from hip to foot, the mirror opposite of bow legs, which form an O shape.
What Is Happening in the Leg
Normally the thigh bone (femur) and shin bone (tibia) meet at a slight, controlled angle at the knee. In knock knee, the femur slants inward more than it should, pulling the knee toward the body's midline, while the lower leg angles back outward to reach the ground — leaving the ankles apart even when the knees are pressed together.
Who Gets It, and Why It Matters
Mild knock knee is common and normal in young children as part of typical growth, and it usually self-corrects by around age 7–8, though it can persist into adolescence in some cases. When it does not resolve, the uneven angle changes how weight passes through the knee joint — the outer (lateral) side gets compressed and the inner (medial) side gets stretched, which over time can cause pain, accelerate wear on the joint's cartilage, make walking or climbing stairs uncomfortable, and produce an awkward, compensating gait.
Causes
Besides the normal growth phase in early childhood, knock knee can result from injury or infection near the growth plate, rickets, a deficiency of vitamin D or calcium, obesity (which places extra load on developing bones), and arthritis that erodes the joint surface unevenly.
Correctives
The correctives prescribed for knock knee combine simple physical activity with specific therapeutic postures:
- Horse riding, which naturally works the inner thigh muscles against an outward-pulling position
- Holding a pillow between the knees while standing erect, to retrain the legs toward a straighter alignment
- The yoga postures Padmasana and Gomukhasana
- Seated or lying leg raises to strengthen the muscles supporting proper knee alignment
- Walking callipers, used specifically before puberty while the bones are still developing
- Weight loss, where obesity is a contributing factor
Knock knee is not merely a cosmetic concern — left unaddressed, the uneven joint loading it causes can accelerate arthritis and produce chronic knee pain later in life. Because a mild version is genuinely normal in early childhood, the corrective approach differs by age: pre-puberty, walking callipers and postural correctives are the standard first response; a case that persists or is severe enough to affect gait or cause pain needs assessment beyond self-correction.