Ankle Sprain: This is often the most common cause of chronic ankle pain, especially if the patient has a history of ankle injuries. Normal X-rays do not rule out ligamentous injuries or chronic instability.

Tendinopathy (Achilles or Peroneal): Chronic overuse or repetitive strain can lead to tendon inflammation and pain. Normal X-rays are expected in tendinopathy, as the condition primarily affects soft tissues.
Ankle Impingement: This can be anterior or posterior and is often related to chronic inflammation or scar tissue formation, which may not be visible on X-rays.
Osteochondral Lesions of the Talus: Although X-rays might be normal, these lesions can be a cause of chronic ankle pain, especially if they involve the cartilage and underlying bone.

Osteoid Osteoma: A small, benign bone tumor that can cause severe pain, often worse at night and relieved by NSAIDs. X-rays might be normal if the tumor is small or in an early stage.
Infection (Osteomyelitis or Septic Arthritis): Chronic infection can present with normal X-rays in the early stages. A high index of suspicion is necessary, especially in patients with risk factors such as diabetes or immunocompromised states.
Tumor (Benign or Malignant): Although rare, bone or soft tissue tumors can cause chronic pain. Early detection is crucial for treatment and prognosis.

Chronic Regional Pain Syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity, which can follow an injury. The diagnosis is clinical, and X-rays are typically normal.
Nerve Entrapment (e.g., Sural or Peroneal Nerve): Nerve compression or irritation can cause chronic pain and might not be evident on X-rays.
Inflammatory Arthropathy (e.g., Rheumatoid Arthritis, Psoriatic Arthritis): These conditions can cause chronic ankle pain and may have normal X-rays in the early stages, with changes becoming apparent later in the disease process.