Development of the infant muscular system
The normal infant follows a patterned progression for the acquisition of autonomous and independent gait.
The infant controls his/her head until the 3rd month, leans on the prone position (tummy time) in the 4th month, can sit alone at 6-8 months, get up in the upright position at 8-10 months and performs the first autonomous steps from 12-15 months.
Four-leg baby movement (Quadrupedalism)
The evolution of the movement of babies on the floor is noteworthy. They begin to change position as they turn from supine to prone position and vice versa, they continue with a steady movement on the buttocks first backwards and then forwards and end with a four-legged movement (crawling).
The movement of babies on all fours is observed in 80% of cases. There is a family predisposition observed; when one child does not crawl, most likely the other child will not do it.
The four-legged movement pattern coordinates the cross movements between the arm and the leg on the opposite side. This movement is achieved by infants from the 9th – 10th month and is an indication of normal motor development.
The upright support
At the beginning of the upright standing, at the frontal level, the baby has the lower limbs in bow position, namely the knees have no contact in the midline. The feet, in support position, are in contact at the inner edge of the foot, with the sole of the foot at an outward turn towards the hips.
The bow position remains until the age of 18-24 months and is gradually corrected. At the age of 3, the knees come in the opposite position, in knock-knees, namely the knees are in contact and the tibias have a gap.
The normal femoral tibial angle at the frontal level, in the upright position, is restored at the age of 5-6 years and obtains the normal values, which is 5-8m in boys and 5-11m in girls.
Independent gait begins after the 1st year, with a wider support base, an outwards turn of the lower extremities, with small quick steps and without bending the knees. Gradually the knees begin to bend from 16-18 months and overcome obstacles during walking.
By what age should the baby start walking?
If the baby does not walk until 16-18 months, the presence of a pathological cause for the delay of walking should be examined. When walking has not been achieved by 2 years, the cause of the delay must be found.
In infants with a history of uncomplicated pregnancy and childbirth, with normal motor development regarding the stages of movement, a common cause for delayed gait up to 18-20 months is the associated family predisposition.
In the family history of the infant’s parents or siblings, there is a clear indication that the father or brother took the first steps at 18 months and the further course of gait developed normally. However, when the 18 months pass, an examination must be made to rule out any pathological cause.
Causes of delayed gait
There is a great variety of diseases associated with the delay in the infant’s.
- Hip Dislocation
- Cerebral palsy
- Neuromuscular disorders
- Spinal cord conditions
- Floppy Child
- Developmental dysplasia of the hip
- Familial Predisposition
- Deviations from the mean range
Diseases of the nervous system affecting the brain or the spinal cord must be ruled out. The use of modern technology and examination with ultrasound, computed tomography or magnetic resonance imaging and the recording of nerve potential help to identify possible damage.
Muscular disorders with genetic predisposition are tested by laboratory investigations.
The examination of the hypotonic infant or toddler, as we characterize the child with a delay in motor development, is a diagnostic maze, as sometimes it is very difficult to make an accurate diagnosis.
Examination of the musculoskeletal system
Examination of the musculoskeletal system is indicated in infants whose neurological control is normal.
The presence of dysplasia or dislocation of the hip, a condition in which the head of the femur is not properly articulated in the pelvis, is a common cause of delayed onset of gait. It usually affects girls, with a hip projection and possibly a positive family history of hip dislocation.
Although nowadays the early diagnosis of the disease allows treatment of the hip dysplasia, sometimes when the condition has progressed to early diagnosis, delayed onset of gait may be one of the first points to diagnose it especially when it is bilateral.
Severe deformities of the spine, lower extremities as well as differences in the length of the lower extremities are rare causes for delayed onset of gait.
The approach of the floppy child, namely an infant or toddler who has a time delay in motor development but shows normal findings in the examination, is done with the help of physiotherapy, systematic monitoring and re-examinations. Most infants develop normally, but in a small number during the tests are diagnosed with the condition.
One group of infants who need special monitoring to start walking are those born prematurely. There are many accompanying factors that affect the overall development, such as duration of pregnancy, multiple pregnancies, weight of the newborn at birth and problems associated with hospitalization. These babies need regular monitoring and often additional physiotherapy support.
We have to monitor the motor development and observe for the autonomous gait to become normal gait.
Delayed gait is sometimes due to mild forms of diplopic or hemiplegic nervous system involvement.