Knee angulation, a common concern for parents

A common concern for parents is the alignment of their children’s legs when viewed from the front. This alignment presents different types within the normality, finding us with:

  • Bowed legs, called genu varum. It occurs when the knees are separated and the ankles are together.
  • Straight
  • X-shaped, called genu valgum. When the knees come together and the ankles separate.

This alignment changes as the child grows: from birth to 18 months – 2 years old it is normal to observe a genu varum. From this age onwards, the lower limbs align until a genu valgum appears, which increases progressively until 3 – 4 years of age. Subsequently it is reduced again until 7 – 9 years old when the child already presents the form that will be maintained for the rest of the life.

At the end of this evolutionary process, the common situation is a slight genu valgum, although its presence or a moderate genu valgum is also normal. What is essential is not the aesthetics, whether the shape of the legs is more or less pleasing, but the consequences that this shape may have on the knees in the future. As long as the shape of the legs allows the transmission of weight from the hip to the ankle and passes centrally through the knee, the alignment is correct. If this load transmission takes place outside or inside the knee, the alignment is not correct.

On occasion, misalignment may be caused by pathologies such as Blount’s disease, metabolic diseases, bone dysplasia, sequelae of fractures or infections.

In order for the specialist in paediatric traumatology to assess whether the alignment is correct or not and whether it may be due to a pathology, a physical examination of the child is generally sufficient. It is essential to take into account the alignment that corresponds to each age.
Alterations should be suspected if genu varum persists beyond 3 years of age and is progressive, genu valgum with ankle separation greater than 9 cm after 8 – 10 years of age, or if there is asymmetry between both legs. If there is a clinical possibility of improper alignment, radiographs are taken.

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In most cases, therefore, the evolution throughout the first years of life leads to a normal alignment, so that no treatment is necessary other than periodic observation. In addition, the use of orthopedic devices, insoles, etc. does not alter this evolution. In cases where there is the presence of a pathology causing the deformity or where the varus or valgus exceeds normal values, the recommended treatment is usually surgery.

If the child has already reached the end of development it is necessary to perform corrective osteotomies, that is, to cut the bone to modify its alignment. This is an aggressive surgery and may present complications. However, if the child still has enough growth left, what we call “guided growth” can be performed, a simple technique that guides the growth of the bone so that it progressively corrects its alignment.

So before resorting to unnecessary and ineffective treatments, parents should consult their pediatrician or a specialist in pediatric orthopedics. Most likely, the child will not need any treatment, but if treatment is required, it is important that the child has not finished growing so that it can be corrected as easily as possible.