**Core Concept**
Non-union of a femoral shaft fracture is a challenging condition that requires a thorough understanding of the underlying pathophysiology and the principles of fracture management. The treatment of non-union often involves a combination of surgical techniques aimed at promoting bone healing and stabilizing the fracture.

**Why the Correct Answer is Right**
Bone grafting with internal fixation using a Kuntscher nail (K-Nail) is a widely accepted treatment for non-union of the femoral shaft. The K-Nail provides stable internal fixation, allowing for compression and promotion of bone healing. Bone grafting supplements the defect in bone, providing a scaffold for new bone formation. This combination of internal fixation and bone grafting enhances the chances of successful union and restores the mechanical integrity of the femur.

**Why Each Wrong Option is Incorrect**
**Option A:** Open reduction with external fixation is not the preferred treatment for non-union of the femoral shaft, as it may not provide sufficient stability for bone healing.

**Option B:** Excision of the bone is not a viable option for non-union of the femoral shaft, as it would result in significant loss of bone stock and compromise the function of the lower limb.

**Clinical Pearl / High-Yield Fact**
When treating non-union of the femoral shaft, it is essential to assess the quality and quantity of the bone stock, as well as the presence of any associated vascular or soft tissue injuries. A thorough preoperative evaluation is crucial for planning the most appropriate treatment strategy.

**✓ Correct Answer: C. Bone grafting with internal fixation with K-Nail**