Final answer:
Russell's traction is prescribed to reduce or realign a fracture site in a child with a lower leg fracture.
Step-by-step explanation:
The primary action of Russell's traction, which is prescribed for a child with a lower leg fracture, is to reduce or realign a fracture site. It uses pulleys and ropes to apply a consistent and steady force to the fracture, helping to bring the broken bones back into alignment and promote healing. It is not primarily used to relieve pain, provide restraint, or limit movement.