**Core Concept**
The intramedullary 'K' nail is a type of internal fixation device used in orthopedic surgery to stabilize and align long bone fractures, particularly in the femur and tibia. The 'K' nail is a type of locked intramedullary nail, which relies on the mechanical properties of the bone and the nail to provide stability.

**Why the Correct Answer is Right**
The 'K' nail works by being inserted into the medullary cavity of the bone and then locked into place using a locking screw or a locking plate. This provides compression and stability to the fracture site, allowing for early mobilization and healing. The intramedullary canal of the bone serves as a guide for the insertion of the nail, and the locked design ensures that the nail remains in place and does not migrate over time.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the 'K' nail does not work by relying on external fixation pins or screws to hold it in place. Instead, it uses a locked design to provide stability.
**Option B:** This option is incorrect because the 'K' nail is not a type of external fixation device, such as a plate or a rod, that is attached to the outside of the bone.
**Option C:** This option is incorrect because the 'K' nail does not work by relying on tension band principles to provide stability.

**Clinical Pearl / High-Yield Fact**
It is essential to choose the correct size and type of intramedullary nail for the patient, taking into account the diameter of the medullary canal, the type of fracture, and the patient's overall health.

**Correct Answer:** C.