**Core Concept**
The immediate treatment of unstable tibial plateau fracture involves stabilizing the fracture to prevent further instability, articular surface damage, and potential neurovascular compromise. This is typically achieved through emergency surgical intervention, aiming to restore anatomical alignment and reduce the risk of complications.

**Why the Correct Answer is Right**
The correct answer involves emergency surgical intervention, specifically **arthroscopic-assisted reduction and internal fixation** or **open reduction and internal fixation (ORIF)**. This approach allows for precise reduction of the articular surface, restoration of the joint's congruity, and stabilization of the fracture using plates, screws, or other implants. The primary goal is to prevent further instability and potential neurovascular compromise, which can lead to severe consequences, including compartment syndrome, nerve damage, or vascular injury.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because conservative management, such as **immobilization and bed rest**, is not suitable for unstable tibial plateau fractures, as it may lead to further instability and joint damage.

**Option B:** This option is incorrect because **traction** alone is insufficient for stabilizing unstable tibial plateau fractures, as it may not adequately address the articular surface damage and may lead to further instability.

**Option C:** This option is incorrect because **arthrodesis** (fusion of the joint) is a definitive treatment option for certain cases of tibial plateau fractures, but it is not the immediate treatment of choice for unstable fractures, as it may lead to loss of joint mobility and function.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize the importance of rapid and accurate diagnosis, as well as timely surgical intervention, in the management of unstable tibial plateau fractures to prevent potential complications and optimize patient outcomes.

**Correct Answer: D. Arthroscopic-assisted reduction and internal fixation or open reduction and internal fixation (ORIF).**