Excision of the head of the radius in a child should not be done because :
Complications of radial head excision in children :

Proximal migration of radius with inferior radio - ulnar (distal radio - ulnar) joint instability.
Postero-lateral instability.
Cubitus valgus deformity.
It produces instability of elbow joint
It leads to secondary osteoarthritis of elbow
It causes subluxation of inferior radio-ulnar joint
It causes myositis ossificans