**Core Concept:** Osteomyelitis is a type of bone infection caused by bacterial invasion and subsequent inflammation. The question is asking about the initial stage where the infection begins. Osteomyelitis can be classified into two types: acute and chronic. In acute osteomyelitis, the infection starts from hematogenous spread, while in chronic osteomyelitis, it typically originates from adjacent soft tissue infections or trauma.

**Why the Correct Answer is Right:** In the context of the question, osteomyelitis begins as an inflammation of the bone due to acute onset. This type of osteomyelitis typically develops from hematogenous spread, where bacteria enter the bloodstream and reach the bone through the blood vessels. The correct answer is not about the overall classification but focuses on the initial stage of the acute form.

**Why Each Wrong Option is Incorrect:**
A. Osteomyelitis begins as an inflammation of the soft tissue (wrong, as this refers to chronic osteomyelitis, which has a different pathogenesis).
B. Osteomyelitis begins as an inflammation of the joint (wrong, as this refers to a different type of infection, not osteomyelitis).
C. Osteomyelitis begins as an inflammation of the skin (wrong, as this refers to a different type of infection, not osteomyelitis).
D. Osteomyelitis begins as an inflammation of the blood vessels (incorrect, as the correct answer discusses the initial stage of acute osteomyelitis, not the blood vessels).

**Clinical Pearl / High-Yield Fact:** Understanding the pathogenesis of osteomyelitis is crucial in making an accurate diagnosis and treatment plan. Acute osteomyelitis typically starts as an inflammation of the bone through hematogenous spread, and understanding this concept helps in differentiating it from other types of bone infections and infections involving adjacent tissues.