What is it?

W-sitting involves your child sitting on the floor with their hips and knees bent, legs apart, and hips rotated inwardly, forming a ‘W’ (see picture) (1). In this position, the legs are creating a wide base of support and providing increased stability.

There is a lot of contradicting information on W-sitting. It has been thought that W-sit is a harmful position for your child to be in and could lead to orthopedic complications such as femoral anteversion –an inward rotation of the thigh bone that can cause the knee and foot to also rotate inwards (2)- or developmental hip dysplasia –a condition where an infant’s hip joint is not formed properly (3). Let’s take a closer look at what the research has to say about this…

Femoral anteversion is formed during fetal development in the womb. Most children are born with some degree of it and it gradually decreases as they age (2). Femoral anteversion becomes an issue when the rotation is significantly more than the typical amount (2). Based on this information, W-sit likely does not cause femoral anteversion, but may be a sign that it is present. In 2020, a study looked at the frequency of hip dysplasia (using x-rays) in W-sitters compared to non-W-sitters and found that there was no association between W-sitting and developmental hip dysplasia (4). This further demonstrates that W-sit does not cause developmental hip dysplasia.

Overall, W-sit may not cause orthopedic conditions such as hip dysplasia or femoral anteversion, but rather be a sign that these conditions are already present.

What does this mean?

W-sit is a common position for young children that they will likely grow out of as they get older. However, if your child only uses W-sit, it may be a sign of an underlying issue such as reduced core strength, tight hip muscles, low muscle tone, and/or high muscle tone. If you are noticing W-sit in addition to pain, gross motor delays, in-toeing, or trips/falls, it might be worthwhile to have them assessed by a pediatric physiotherapist.

By: Maddie Fyfe, Registered Physiotherapist

 

Resources

  1. Honig EL, Haeberle HS, Kehoe CM, Dodwell ER. Pediatric orthopedic mythbusters: the truth about flexible flatfeet, tibial and femoral torsion, W-sitting, and idiopathic toe-walking. Current Opinion in Pediatrics. 2021 Feb 1;33(1):105-13.
  2. Femoral anteversion [Internet]. Johns Hopkins Medicine. [cited 2022Jan27]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/femoral-anteversion
  3. Developmental Dysplasia of the Hip [Internet]. Johns Hopkins Medicine. [cited 2022Jan27]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/developmental-dysplasia-of-the-hip
  4. Rethlefsen SA, Mueske NM, Nazareth A, Abousamra O, Wren TA, Kay RM, Goldstein RY. Hip dysplasia is not more common in W-Sitters. Clinical Pediatrics. 2020 Oct;59(12):1074-9.