The effects of abnormal sitting and sleeping positions on young children
Dr Anthony Duffin
(PhD in Biostructural Research)
Children spend a lot of time playing inside, watching television, playing with computer games and a myriad of other toys that are easier to enjoy if they are able to utilise a floor space directly in front of them. They commonly frog sit or sit on their feet so they can play without reaching over their legs and feet.
They have greater flexibility than adults and can comfortably sit in these positions for extended periods, but both postures can interfere with the natural development of the bones in the leg and thigh. The abnormal bone and soft tissue changes which result from these sitting positions can be detected in children as young as 18 months and, if not treated, these changes can persist for their entire life.
The photo below shows a child frog sitting.
Habitual frog sitters are very comfortable and relaxed in this position but abnormal changes are occurring around their hips and legs. In very young children the bones, ligaments and tendons are soft and flexible; they can change shape very quickly and easily. In the frog position the leg acts as a giant lever, forcing the hip to turn in much further than normal. This stretches the ligaments around the hip joint causing an extremely high range of inward motion. The further the child’s feet are away from their bottom the greater the strain on the hip. An average adult’s hip will have approximately 40 degrees of inward and outward rotation. Frog sitters will often have normal outward rotation (40 degrees) but may have up to 100 degrees of inward rotation. This creates an imbalance when the child walks, their knees may face towards each other, they may be pigeon toed and often their feet will flatten.
That’s not the only change that occurs in children who frog-sit. Just as the leg acts as a lever turning the hips inward, the foot acts as a lever turning the leg bone outwards. This results in a very high range of outward twist in the ligaments around the knee and the leg bones (tibia and fibular). At birth the leg bones have virtually no twist but as we grow they twist out around 15-20 degrees, eventually making the feet turn slightly out when we walk, this is a normal development. This twist can be increased up to 40 degrees in frog sitters.
So now we have a combination of high inward twist in the hip and outward twist in the leg. As you can imagine, this places a great deal of strain on the knee and the foot. Interestingly these children don’t seem to have many problems with their hips and they may not develop pain from these changes for many years. However their gross motor skills may be adversely affected, making them slower than other children and / or tire more rapidly than you’d expect.
The photo below is of a child sitting on her feet.
This is not a problem if the heels are touching each other but if you look carefully you will notice the child’s feet have rolled onto their sides. Again the foot acts as a lever but in this case it forces the leg bones and ligaments in the knees to turn inwards without affecting the hips.
Children who sit this way may walk with their feet turned in (pidgeon-toed). They may fall frequently or have poor gross motor skills. They literally trip over their own feet. In some children the body will compensate by adjusting the way they walk to turn their hips out and prevent the intoe. This change in hip motion stops any obvious signs of walking problems but it may lead to knee problems later in life.
The structural changes which occur in children who sit on their feet are exactly the opposite of frog sitting children. The frog sitters have in-turned hips and out-turned legs, children who sit on their feet will have out-turned hips and in-turned legs.
Of cause sitting positions are not the only cause of hip and leg problems. Sleeping on their tummy, abnormal intrauterine positions and genetics may also play strong roles in changing the rotation of the hips and legs.
If you are concerned about your child stop them from sitting abnormally. This can be very difficult and frustrating for a parent, particularly if the child has been sitting abnormally for a long time. Sitting them at a small table to play rather than on the floor may help but make sure they don’t sit on their feet on the chair.
Parents should encourage their children to sit with their feet in front or cross legged from the time they start to sit. They should also stop the child from sleeping on their tummy. Very young babies should be moved into different positions - on their back and either side to prevent flattening of the head by staying in one position for too long.
If you are still concerned about your child you should have them assessed by a podiatrist who is experienced in paediatrics. There are some simple exercises which can improve the twist in the leg and hip but the older the child, the more difficult these problems are to correct. So don’t wait.