If a child is not walking yet, then this is usually caused by a problem in balance, muscle coordination, spasticity, or leg alignment. Each of these reasons should be looked into closely so the problem can be addressed and fixed. 7 to 12 years
“By the time a child reaches this age  the rate of physical improvement has leveled off in areas such as balance and coordination, and its a good idea to refocus the child’s attention away from additional physical improvement and toward intellectual learning.”  During this time period a child should lean away from physical therapy and do more outdoor or social exercises such as sports and adaptive P.E. Usually by age 8-10 a child has reached maximum walking ability. This will usually decrease a little when a child hits puberty and gains height and weight because walking becomes harder during this changing period. Any significant problems in walking should be addressed with surgery at this stage. 13 to 18 years
“During this time period of a child’s development, a major issue is separating from the family.”  Parents should learn how to cope with their child growing up and give them more freedom and independence. Teenagers need to make their own decisions and learn from them. One way to do this is for parents to compromise and let the child make smaller decisions so they feel important. Parents should also understand that their child may regress in walking some from increase in height and weight.
Mecasermin, sold under the brand name Increlex, also known as recombinant human insulin-like growth factor-1 (rhIGF-1), is a recombinant form of human insulin-like growth factor 1 (IGF-I) which is used in the long-term treatment of growth failure and short stature in children with severe primary IGF-I deficiency, for instance due to growth hormone deficiency or Laron syndrome (growth hormone insensitivity).Mecasermin has a biological half-life of about 5.8 hours in children with severe primary IGF-1 deficiency.A related medication is mecasermin rinfabate (brand name Iplex), which is a combination of mecasermin (rhIGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and insulin-like growth factor binding protein acid labile subunit (IGFALS) as a ternary complex. The complex serves to prolong the action of mecasermin in the human body; the half-life of mecasermin when provided as this complex is 13.4 hours in individuals with severe primary IGF-1 deficiency. References
External links
"Mecasermin". Drug Information Portal. U.S. National Library of Medicine.