P2

Chapter III.  Lower Extremity
	The human being has developed the most elaborate weight 
bearing mechanism, in bipedal locomotion, on a very narrow 
weight-bearing base between the feet. This is all due to 
development of the musculo-skeletal system, integrated with the 
neuro-cerebral system. In cerebral palsy, due to disturbed 
neuro-cerebral and musculo-skeletal systems, bipedal locomotion is 
inhibited. So, it is essential to analyze normal and abnormal 
musculo-skeletal mechanisms in each part of the lower extremity 
and apply these acquired informations for achieving a near normal 
condition.

1. Weight Bearing Mechanism
Propulsive mechanism of the lower extremity
	The most primitive mechanism of the lower extremity is the 
propulsive mechanism of the body. In the developmental process, 
initially the limb-buds originate and gradually develop. In the lower 
extremity, the thigh, calf and foot are formed along with joints, 
such as the hips, knee and ankle. The thigh is connected to the 
pelvis by the hip joint. Due to these joints, flexible movements of 
the limb have become possible. Originally, the activities of the 
lower limbs were a propelling activities, with flexion and 
extension movements used mostly in the water and in waterfront. 
This propelling mechanism is observed, in various phases of 
locomotion (see Part I).

Development of weight bearing mechanism
	The lower extremity, which initially worked as a propelling 
organ, has gradually developed an antigravity mechanism, through 
periods of quadrupedal locomotion of the mammals till finally a 
bipedal locomotion was established with highly matured antigravity 
stability. Each part of the lower extremity had developed 
specifically to enable the human being to move with the bipedal 
locomotion. These propelling and weight-bearing mechanisms are 
discussed in detail at each joint of hip, knee, and foot and ankle.

Fig. 101A. 5-year-old girl, spastic diplegia 
Before OSSCS

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