"Trendelenburg sign" isn't positive in damage of the following nerve
High-Yield Explanation
Causes of positive trendelenberg test: *There are three fundamental causes: 1) Paralysis of the abductor muscles *eg. Polio *Paralysis of superior gluteral nerve 2) Marked approximation of the inseion of the abductor muscle to their origin by upward displacement of the greater trochanter; so that muscles are slack. *eg. Severe coxa vara *Dislocation of hip 3) Absence of stable fulcrum & lever arm about which the abductor muscles can act *Neck femur fracture *Dislocation of hip :Ref: Maheshwari 4th/e p.348