About the children who provide the illustrations for this section

Will - born full term with typical development. 

Will does everything on time and in the right way. 

Roan who was born at 35 weeks

She had some initial feeding problems and spent  a lot of time sleeping on her daddy's  tummy in the first few months.

Roan was very happy to engage in stretching activities and worked hard at gaining the strength she needed for crawling and standing up. She crawled at 12 months and walked at 16 months. 

Toesies who was born at 35 weeks 

He was a  little fellow (2 kg) but was kangarood from day 1, which gave him a good start in life. 

Toesies has hypermobile elbows and developed a fair degree of tightness in his hip abductor muscles. He was also very feisty and strongly resisted my efforts to mobilise tight muscles. 

Toesies crawled at 15 months and walked at 20 months. 

Typical development and and muscle extensibility

Typically, full term newborn infants assume a flexed position of the upper and lower extremities when lying supine.

• The hip joints cannot be fully extended (termed physiological flexion contracture of the newborn) and hip external rotation is greater than internal rotation. 
• The knee joints also lacks full extension. 
• The upper extremities (UE) are held close to the trunk with the elbows flexed. 

Active movements of the LE's increases the ROM of the hips and knees

Over the first six months the range of hip extension/adduction increases as the infant  actively extends the hips in supine and prone.

This imposes an active stretch on the flexor muscles and strengthens the extensors in the shortened range. 

​Hypermobile and pre-term infants have a different experience

Newborn infants with increased connective tissue compliance associated with joint hypermobility do not have the same degree of resistance to full extension of the hip muscles. 

At birth they lie with the UE and LE's in more extension and lateral rotation. The same pattern is seen in preterm infants who have not been exposed to the confined uterine space during the last weeks of pregnancy. 

Below you see Toesies at 2 weeks lying with the thighs flat on the mattress, despite the fact that he was usually supported by bolsters on either side when he was supine. 

​Hypermobile infants sit with the hips in wide abduction 

The trunk also tends to be flexed. 

The habitual abducted  posture of the hips means that the infant tends to have restricted hip adduction in flexion and extension. 

The restricted hip adduction influences development of hip extension in prone

Toesies aged 11 months does not like being prone. Notice the wide abduction and poor extension of the hips in this position. 

Compare this with the hip extension / adduction seen in Will aged 7 months. 

 

 

This is Roan at 10 months.

Notice the hyperextension in the elbows, the hyperextension of the spine and lack of active extension in the hips.

Pushing up into prone kneeling is difficult from this position. 

     Here you see how Roan's movements are constrained by the wide abduction of her hips when she tries to get into prone kneeling, as well as when she kneels at a low block. 

 Infants with joint hypermobility also tend to stand with their hips very wide apart and often locked into extension.

  Sitting down without flexing the knees is a typical pattern seen in children who lock their knees into extension. 

    As a result the child does not develop the strength needed for graded flexion of the knees needed for sitting down. 

Suggestions for reflection and updating assumptions 

Take time to observe the video clip of infants on the move and identify the many times when they engage muscles in isometric contraction in the lengthened range. 

If available, review video clips of children with JH when they were infants.