**Core Concept**
Freiberg's disease is a rare, painful condition affecting the foot, specifically the metatarsal bones. It is characterized by ischemic necrosis of the metatarsal head, leading to joint pain and deformity. This condition is often seen in young adults and is thought to be caused by a combination of factors, including trauma, vascular compromise, and genetic predisposition.

**Why the Correct Answer is Right**
Freiberg's disease occurs due to ischemic necrosis of the metatarsal head, which is likely caused by the interruption of blood supply to the affected bone. This can be triggered by a sudden increase in activity or trauma, leading to damage to the blood vessels that supply the metatarsal head. The lack of blood supply results in ischemia, which can progress to necrosis and eventual collapse of the bone.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a recognized cause of Freiberg's disease. While osteochondritis dissecans can cause similar symptoms, it is a distinct condition characterized by the separation of cartilage from the underlying bone, rather than ischemic necrosis.

**Option B:** This option is incorrect because Kienbock's disease affects the lunate bone in the wrist, not the metatarsal bones in the foot. Kienbock's disease is a similar condition to Freiberg's disease, but it affects a different bone and is characterized by ischemic necrosis of the lunate.

**Option C:** This option is not a recognized cause of Freiberg's disease. While osteomyelitis can cause bone pain and deformity, it is an infectious condition that is typically caused by bacteria, rather than ischemic necrosis.

**Clinical Pearl / High-Yield Fact**
To remember the key features of Freiberg's disease, use the mnemonic "F.R.I.E.B.E.R.G.S." which stands for "Foot pain, Recurring, Ischemic, Erosion, Bone collapse, Early, Recurrence, Gait symptoms". This mnemonic can help you recall the common symptoms and complications of Freiberg's disease.

**Correct Answer: D.**