Kohler’s disease is due to osteonecrosis of:
**Core Concept**
Kohler's disease is a rare bone disorder characterized by osteonecrosis, specifically affecting the navicular bone in the foot. This condition results from a disruption in the blood supply to the bone, leading to bone cell death and potential collapse of the navicular bone.
**Why the Correct Answer is Right**
Kohler's disease is caused by osteonecrosis of the navicular bone, which is a result of avascular necrosis. Avascular necrosis occurs when there is a loss of blood supply to the bone, leading to cell death and structural collapse. The navicular bone is particularly susceptible to avascular necrosis due to its unique blood supply and anatomy.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Kohler's disease specifically affects the navicular bone, not the calcaneus or talus. The calcaneus and talus are also susceptible to osteonecrosis, but this is a different condition.
* **Option B:** This option is incorrect because Kohler's disease is not caused by osteoporosis or osteopenia. While osteoporosis and osteopenia can increase the risk of fractures and osteonecrosis, they are distinct conditions from Kohler's disease.
* **Option C:** This option is incorrect because Kohler's disease is not caused by a tumor or infection. While tumors and infections can cause bone damage and osteonecrosis, they are not the underlying cause of Kohler's disease.
**Clinical Pearl / High-Yield Fact**
Kohler's disease typically presents in children and adolescents, and early diagnosis is crucial to prevent long-term damage to the navicular bone. A high index of suspicion and prompt imaging studies are essential in diagnosing this condition.
**Correct Answer:** D.