Components of an Ankle X-ray Report
A comprehensive ankle x-ray report should include three standard views: anteroposterior (AP), lateral, and mortise views, with specific attention to osseous structures, joint spaces, alignment, and any abnormalities. 1, 2
Standard Views Required
- Anteroposterior (AP) view: Evaluates the tibiotalar joint and overall alignment
- Lateral view: Assesses the talus, calcaneus, and subtalar joint relationships
- Mortise view: Obtained by internally rotating the foot 15-20 degrees, specifically evaluates the ankle mortise and syndesmosis
Ideally, these should be weight-bearing (standing) radiographs when possible, as they better demonstrate dynamic abnormalities such as joint malalignment or subluxation that may not be apparent on non-weight-bearing images. 2
Essential Elements to Include in the Report
1. Osseous Structures Assessment
- Tibia (distal portion)
- Fibula (distal portion)
- Talus
- Calcaneus (if visible)
- Navicular (if visible)
- Presence/absence of fractures, avulsions, or ossific fragments
- Bone density and trabecular pattern
- Presence of periosteal reaction or osteophytes
2. Joint Space Evaluation
- Tibiotalar joint space width and uniformity
- Medial clear space measurement
- Lateral clear space
- Syndesmotic space (tibiofibular clear space)
- Evidence of joint effusion (visible in anterior ankle joint recess)
3. Alignment Analysis
- Ankle mortise integrity
- Talar tilt
- Tibiofibular relationship
- Subtalar alignment (if visible)
4. Soft Tissue Assessment
- Presence/absence of soft tissue swelling
- Joint effusion
- Calcifications in soft tissues
- Abnormal radiolucencies
5. Pathological Findings (if present)
- Osteoarthritis changes (joint space narrowing, subchondral sclerosis, osteophytes)
- Osteochondral lesions
- Stress fractures or insufficiency fractures
- Loose bodies
- Evidence of prior trauma or surgical hardware
Practical Considerations
When interpreting ankle radiographs, the American College of Radiology recommends a systematic approach that can identify common etiologies of ankle pain including osteoarthritis, osteochondral injury, tendon abnormalities, ligament abnormalities, instability, and impingement. 1
For suspected Charcot neuro-osteoarthropathy in diabetic patients, bilateral plain x-rays are recommended with the same three standard projections (AP, lateral, mortise). 1
While some research has suggested that two views (lateral and mortise) may be sufficient for fracture diagnosis 3, current guidelines still recommend all three standard views for comprehensive assessment. 1, 2
Common Pitfalls to Avoid
- Failing to identify subtle fractures, particularly avulsion fractures at ligament attachments
- Missing osteochondral lesions of the talus
- Overlooking syndesmotic injuries
- Not commenting on joint effusions which may indicate ligamentous injury
- Inadequate assessment of alignment relationships
- Not comparing with the contralateral side when available
By following this structured approach to ankle x-ray reporting, clinicians can ensure comprehensive evaluation that guides appropriate management decisions for patients with ankle pathology.