What does a normal ankle x-ray (x-ray) result indicate?

Normal Ankle X-ray Findings

A normal ankle x-ray shows intact bones with proper alignment, no fractures, normal joint spaces, and absence of soft tissue abnormalities, indicating proper ankle anatomy and function. 1

Standard Radiographic Views

A complete ankle x-ray examination typically includes three standard views:

• Anteroposterior (AP) view: Shows the tibia, fibula, talus, and their articulations from front to back
• Lateral view: Shows the ankle joint from the side, visualizing the relationship between the tibia, fibula, talus, and calcaneus
• Mortise view: An AP view with 15-20° internal rotation that best demonstrates the ankle mortise (joint space between the tibia, fibula, and talus)

Research suggests that the lateral and mortise views alone may be sufficient for fracture diagnosis in many cases, potentially reducing radiation exposure 2.

Normal Radiographic Findings

Osseous Structures

• Tibia and fibula: Intact cortical margins with normal density
• Talus: Normal contour and density, properly seated in the ankle mortise
• Calcaneus: Normal trabecular pattern and density
• Navicular and other tarsal bones: Normal position and density

Joint Spaces

• Ankle mortise: Uniform joint space between the tibia, fibula, and talus
• Subtalar joint: Normal alignment between talus and calcaneus
• No joint effusion: Absence of increased fluid in joint spaces

Soft Tissues

• Normal soft tissue density: No significant swelling
• No calcifications: Absence of abnormal calcifications in tendons or ligaments
• No foreign bodies: No radio-opaque foreign materials

What Normal X-rays Don't Show

It's important to understand that normal radiographs have limitations:

• Ligamentous injuries: X-rays cannot directly visualize ligaments; 15% of ligamentous injuries (including sprains and tears) at the syndesmosis show no fracture on radiography 1
• Cartilage abnormalities: Up to 41% of osteochondral lesions may be missed on standard radiographs 1
• Bone contusions: Not visible on x-rays but may be present with normal radiographs
• Early stress injuries: May not be apparent on initial x-rays

When Further Imaging Is Needed Despite Normal X-rays

If clinical suspicion remains high despite normal radiographs, additional imaging may be warranted:

• MRI: Most sensitive for occult fractures, bone marrow edema, and soft tissue injuries 1
• CT: Better for detailed bone assessment, especially for talar fractures or subtalar joint injuries 1
• Weight-bearing radiographs: May detect dynamic abnormalities not apparent on standard views, such as joint malalignment or subluxation 1

Clinical Implications of Normal X-rays

A normal ankle x-ray in the setting of trauma suggests:

• Absence of fracture: No visible bone discontinuity
• Normal alignment: Proper positioning of ankle bones
• Stable joint: No dislocation or subluxation

However, soft tissue injuries may still be present and should be considered based on clinical findings, especially with persistent pain despite normal radiographs.

Common Pitfalls in Interpretation

• Overlooking subtle fractures: Particularly in the lateral process of the talus or posterior malleolus
• Missing osteochondral lesions: May require MRI for definitive diagnosis
• Failing to consider ligamentous injuries: Normal x-rays do not rule out significant soft tissue damage
• Not obtaining proper views: Inadequate technique can miss important findings

Remember that clinical correlation is essential, as normal radiographs do not exclude all pathology, particularly in patients with persistent symptoms.