**Core Concept**
Russell traction is a type of skeletal traction used to manage femoral shaft fractures. It involves the application of a specific type of traction to the lower extremity to stabilize and align the fracture. This method is particularly useful in pediatric patients due to the unique anatomical and physiological characteristics of their bones.

**Why the Correct Answer is Right**
In pediatric patients, the epiphyseal plates are still open, allowing for more plastic deformation and remodeling of the bone. Russell traction takes advantage of this property to align and stabilize the fracture without the need for immediate surgical intervention. The traction is applied to the lower extremity, typically with a combination of a Russell or Thomas splint, to counteract the muscular forces that can cause malalignment. This approach allows for the bone to heal in a more anatomically correct position, reducing the risk of complications.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Russell traction is not typically used in adults, as their bones are less likely to remodel and more prone to malunion.
**Option B:** This option is incorrect because Pavlik harness is used for treatment of developmental dysplasia of the hip, not femoral shaft fractures.
**Option C:** This option is incorrect because Hip spica cast is used for treatment of hip fractures, not femoral shaft fractures.

**Clinical Pearl / High-Yield Fact**
In pediatric patients, the use of skeletal traction for femoral shaft fractures is often preferred over surgical intervention due to the lower risk of complications and the potential for bone remodeling.

**Correct Answer:** C.