**Core Concept**
Pathological fractures occur when a bone is weakened by disease, such as metastatic cancer, osteoporosis, or bone cysts, leading to a fracture that would not normally occur. The goal of treatment is to stabilize the fracture, alleviate pain, and prevent further bone damage.

**Why the Correct Answer is Right**
The treatment of choice in pathological fractures is internal fixation, which involves using surgical implants, such as plates, screws, or rods, to stabilize the bone and maintain its alignment. This approach allows for early mobilization, reduces the risk of further bone damage, and helps to alleviate pain. Internal fixation is often used in conjunction with other treatments, such as chemotherapy or radiation therapy, to address the underlying cause of the fracture.

**Why Each Wrong Option is Incorrect**
**Option A:** External fixation is a temporary solution used in cases where the soft tissues are severely damaged or in emergency situations, but it is not the treatment of choice for pathological fractures.
**Option B:** Arthroplasty is a surgical procedure that involves replacing a joint with an artificial one, which is not typically indicated for pathological fractures.
**Option C:** Conservative management, such as bed rest and pain management, may be used in the initial stages of treatment, but it is not sufficient to address the underlying bone weakness and may lead to further complications.

**Clinical Pearl / High-Yield Fact**
It is essential to identify the underlying cause of the fracture, as treating the bone weakness is crucial to preventing further fractures and improving patient outcomes.

**Correct Answer:** C.