**Core Concept**
Perthes disease, also known as Legg-Calve-Perthes disease, is a childhood hip disorder characterized by the temporary loss of blood supply to the femoral head, leading to its necrosis and deformation. This condition primarily affects children between the ages of 4 and 10, with a slight male predominance.

**Why the Correct Answer is Right**
The exact cause of Perthes disease is unknown, but it is believed to result from a combination of genetic and environmental factors. The condition is thought to occur when there is an interruption in the blood supply to the femoral head, leading to ischemia and subsequent necrosis of the bone tissue. This can be due to various factors, including trauma, infection, or vascular anomalies. The affected bone undergoes a process of collapse and deformation, resulting in the characteristic symptoms of the disease.

**Why Each Wrong Option is Incorrect**
**Option A:** Perthes disease primarily affects infants and toddlers, which is incorrect.
Perthes disease typically affects children between the ages of 4 and 10, not infants and toddlers.

**Option B:** Perthes disease is a common condition in adults, which is incorrect.
Perthes disease is a childhood hip disorder and is relatively rare in adults.

**Option C:** Perthes disease primarily affects the tibia, which is incorrect.
Perthes disease primarily affects the femoral head, not the tibia.

**Option D:** Perthes disease is caused by a bacterial infection, which is incorrect.
The exact cause of Perthes disease is unknown, but it is not believed to be caused by a bacterial infection.

**Clinical Pearl / High-Yield Fact**
Perthes disease can be a challenging diagnosis, and it is essential to consider the condition in the differential diagnosis of hip pain in children. A thorough history, physical examination, and imaging studies, such as X-rays and MRI, are necessary to establish the diagnosis.

**Correct Answer:** D. Perthes disease affects children between the ages of 4 and 10.