There are a group of infants who, once they are able to sit., will start to scoot either backwards or forwards on the their buttock. 

The infant may sit with one leg bent forwards, foot on the floor and push on the opposite arm. Infants who move like this always sit with the same foot in front. 

Other infants sit with the hips widely abducted, knees flexed and thighs touching the floor. They move forwards by vigorously rocking the pelvis forwards and backwards and bouncing on their buttocks. This action requires strong trunk (core) muscle strength.

The two YouTube video clips clearly show how infants combine LE and pelvic movements to propel themselves. Both these infants move in a fairly symmetrical manner.  

Why do some infants scoot?
You may have noticed that the infants in the video clips both sit with a large range of hip abduction and lateral rotation. Such excessive hip ROM is usually associated with generalized joint hypermobility, but may also be a late outcome of the hip posture adopted by preterm infants. 

The most common reason for the extra mobility in the hips is generalized joint hypermobility, but it is also seen in infants who were born preterm. 

Joint hypermobility: loose joints with some tight muscles 

Most often infants who have excessive outward rotation of the hips, also have restricted extensibility of the muscular and fascial structures that cross over the lateral aspect of the hips, including the iliotibial band. This restricts hip adduction when the hips are in extension or in flexion.

This tendency to abduct the hips can be seen in prone and when the infant kneels. 

Because infants born preterm tend to lie with their hips laterally rotated and thighs flat on the cot mattress, they are also at risk of developing tightness in the hip abductor muscles and associated fascial structures. 

The restricted adduction of the hips affects the infants ability to push up into prone kneeling. More about the requirements for prone kneeling (all fours).

Can sit. Will move. 
By the age of 10 -12 months active infants are not happy staying put in one place - they want to get moving. Infants who are crawling do not have a problem getting where they want to be - they are able to flip from sitting onto their hands and knees and off they go. 

Infants who are not yet crawling do not have this option. However, with determined and repeated efforts to reach desired toys and people that are out of reach, they quickly discover that by moving their pelvis and legs they can swivel around and move forwards. 

A comprehensive plan of action for infants who scoot 
Start by broadening the intervention focus

Physical therapy intervention for infants who scoot on their buttocks needs to address all aspects of the infant's development rather than narrowly focusing on getting the infant to stop scooting and start crawling, which is usually a losing battle. 

1  Use active mobilization to address the restricted hip adduction
This should be done both in sitting and kneeling. Read more 

2 Promote active sitting and transitions to kneeling

Active sitting with reaching in all directions and transitioning to kneeling are important for the development of an active range of movement in the trunk and the hips. 

A low foam step will often facilitate the transition from sitting to prone kneeling 

      z

3  Practice prone with chest supported on a low step

Infants who scoot on their buttocks are often very resistant to being in prone and have not learned to push up on the UEs.  This means that they do not develop the strength in the UE extensors needed for crawling. 

They will often tolerate activities in prone when the chest is supported on a foam step. 

4  Train kneeling at a step 
Once an infant has learned to scoot and can get where they want to be, they are generally not interested in learning to crawl.

However, since crawling is an important activity for infants in terms of flexibility, upper extremity (UE) strength and as a precursor to clambering, it is important  to work on training activities that encourage kneeling with weight on the arms and actively, and independently transitioning to kneeling, usually from sitting. More ideas for training kneeling

5 Practice crawling up and over 
Once the infant has learned to kneel facing a step, encourage her to clamber up onto the step, starting with a low step and increasing the height over time.

Create low barriers for the infant to get over. Pillows also challenges the infant to crawl. 

6 Start working on standing with support
If the infant has not yet started to pull up into standing and has poor  balance in supported standing, it is important to start working on these skills. This is particularly important if the infant is reluctant to take weight on the LEs. 

Practicing standing up from sitting on a step is a good way to get infants to take weight on the LE's .

The height of the support surface can be adapted to allow the infant to stand safely while exploring taking weight on the LE's, adjusting the amount of extension in the knees and shifting weight in different directions. Read more Guide to Training Standing with Support 

TOMT Training Guides 
For ideas and instructions for training infant gross motor skills