What should I assess on a heel X‑ray in an adult with acute heel trauma or chronic heel pain, and when is additional imaging (CT or MRI) indicated?

Heel X-ray Assessment and Advanced Imaging Indications

For acute heel trauma, obtain standard three-view foot radiographs (AP, oblique, lateral) plus an axial calcaneal view, and proceed directly to CT for complex calcaneal fractures requiring surgical planning or when radiographs show intra-articular involvement. 1, 2

Initial Radiographic Assessment

Standard Views for Acute Trauma

• Obtain a four-view series: anteroposterior, oblique, lateral, and axial calcaneal views 1, 2
• The axial calcaneal view is critical because it increases specificity for diagnosing calcaneal fractures and sensitivity for distinguishing intra-articular involvement 1, 2
• Standard radiographs achieve 99% sensitivity for detecting foot fractures when properly obtained 1, 2

Weight-Bearing Views

• Always obtain weight-bearing radiographs when the patient can tolerate standing, as non-weight-bearing films miss subtle malalignment and joint instability 2, 3
• This is particularly crucial for suspected midfoot injuries that may accompany heel trauma 2, 3

Key Structures to Assess on Heel Radiographs

Calcaneus:

• Böhler's angle and Gissane's angle for calcaneal body fractures 1
• Posterior facet involvement and subtalar joint alignment 1
• Calcaneal tuberosity fractures and avulsion injuries 1
• Varus/valgus malalignment of the heel (standard radiographs underestimate varus deformity by up to 40% in severe cases) 4

Talus:

• Lateral process fractures (snowboarder's fracture) 1
• Talar body and dome fractures 1
• Osteochondral lesions of the talus 1

Subtalar joint:

• Joint space narrowing or widening 1
• Associated fracture-dislocations 1

Soft tissues:

• Retrocalcaneal bursa swelling 5
• Achilles tendon calcification or avulsion 5
• Plantar fascia thickness (>4mm suggests plantar fasciitis) 2

When CT is Indicated

Immediate CT (First-Line After Radiographs)

• Any calcaneal fracture visible on radiographs requires CT to determine extent, displacement, comminution, intra-articular extension, and surgical planning 1
• High-energy trauma or polytrauma patients (approximately 25% of fractures are missed on radiographs alone in these cases) 3, 6
• Complex fractures involving the subtalar joint 1
• Posterior malleolar fractures and posterior pilon variants (50% and 20% frequency respectively in calcaneal trauma) 1
• Suspected talar fractures, where radiograph sensitivity is only 78% 6

CT Advantages Over Radiographs

• CT is superior for detecting nondisplaced fractures and subtle osseous injuries 3
• Demonstrates the full extent of osseous injury and associated fractures 3
• Essential for preoperative planning in displaced intra-articular calcaneus fractures 1, 4

When MRI is Indicated

MRI After Negative Radiographs with Persistent Pain

• Persistent heel pain 1-3 weeks after trauma with negative radiographs warrants MRI to detect occult fractures, bone contusions, and stress injuries 1, 2
• Suspected osteochondral lesions of the talus (70% of ankle fractures result in cartilage injury) 1
• Evaluation of Achilles tendon tears or plantar fascia ruptures not adequately assessed by radiographs 3
• Suspected osteonecrosis of the talus (MRI is highly accurate for this complication) 1

MRI Advantages

• MRI detects bone marrow edema and stress reactions invisible on radiographs 2, 3
• Superior for soft-tissue evaluation including tendons, ligaments, and the plantar fascia 3
• Excellent for evaluating osteomyelitis in diabetic patients (77-100% sensitivity, 80-100% specificity) 3

Chronic Heel Pain Assessment

Initial Imaging

• Weight-bearing radiographs are first-line for chronic heel pain 2
• Weight-bearing views combined with plantar fascia thickness assessment achieve 85% sensitivity and 95% specificity for plantar fasciitis 2
• Look for heel spurs, stress fractures, and bone condensation patterns 7

Advanced Imaging for Chronic Pain

• Bone scan has 100% sensitivity and negative predictive value for ruling out stress fractures when radiographs are negative 2
• MRI is preferred when soft-tissue pathology (plantar fasciitis, Achilles tendinopathy, bursitis) is suspected 3, 5
• Ultrasound can evaluate plantar fascia thickness and Achilles tendon pathology with excellent spatial resolution for superficial structures 5

Critical Pitfalls to Avoid

• Never rely on standard radiographs alone for calcaneal fractures requiring surgery—CT is mandatory for operative planning 1, 3
• Do not skip the axial calcaneal view, as it significantly improves fracture detection and characterization 1, 2
• Radiograph sensitivity for midfoot fractures is only 25-33%, so maintain high suspicion for associated injuries 6
• In diabetic patients with neuropathy, patients may walk despite fractures—image more liberally regardless of pain level 1, 3
• Standard radiographs underestimate varus heel deformity, particularly in severe cases (measuring only 18° when actual deformity is 30°) 4
• Do not use CT or MRI as first-line imaging when standard radiographs are appropriate 1