**Core Concept**
The management of open fractures involves a combination of immediate and definitive care to prevent infection and promote healing. The primary goal is to remove all non-viable tissue and debris from the wound, followed by stabilization of the fracture to maintain alignment and promote healing.

**Why the Correct Answer is Right**
Debridement is the initial step in managing open fractures. It involves the removal of all non-viable tissue, including dead bone, muscle, and skin, to prevent infection and promote healing. This is typically performed in the operating room under sterile conditions. The goal of debridement is to create a clean environment for the wound to heal, which is essential for preventing infection and promoting the growth of new tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** Tourniquet is not used in the treatment of open fractures. While a tourniquet may be used to control bleeding, it is not a treatment for the fracture itself and can actually increase the risk of infection by compromising blood flow to the affected area.

**Option B:** Internal fixation is a definitive treatment for fractures but is not typically performed immediately in the case of an open fracture. Internal fixation may be delayed until the wound has been treated and stabilized.

**Option C:** While debridement is the correct answer, the other options are not entirely incorrect. External fixation (Option D) may be used as a temporary measure to stabilize the fracture and promote healing, especially in cases where internal fixation is not feasible. However, it is not the primary treatment for open fractures.

**Clinical Pearl / High-Yield Fact**
In the management of open fractures, the "Dirty little secret" is that the wound should be left open to allow for drainage and promote healing, rather than being closed immediately. This allows for the removal of any remaining debris or infection and promotes the growth of new tissue.

**Correct Answer: C. Debridement**