What symptom would a patient with ankle pain exhibit if it were a stress or occult fracture?

Clinical Presentation of Stress or Occult Ankle Fractures

A patient with a stress or occult ankle fracture typically presents with persistent, localized pain over the affected bone that worsens with activity and improves with rest, along with point tenderness and sometimes swelling, but often has normal initial radiographs. 1

Key Clinical Features

Pain Characteristics

• Insidious onset of activity-related pain that progressively worsens if the patient continues exercising 2, 3
• Pain becomes more severe or occurs earlier during activity as the fracture progresses 3
• Persistent pain for more than 1 week despite initial negative radiographs is highly suggestive 1
• Symptoms are typically mild at rest but increase significantly with walking and training 4

Physical Examination Findings

• Localized bony tenderness is the most obvious and consistent finding on examination 2, 3
• Point tenderness directly over the specific bone (malleoli, talus, or calcaneus) 1
• Ankle effusion may be present, particularly with medial malleolar stress fractures 5
• Occasionally, redness, swelling, or periosteal thickening at the fracture site 3
• Absence of diffuse tenderness helps distinguish from medial tibial stress syndrome (shin splints) 2

Critical Distinguishing Features by Location

Medial Malleolar Stress Fractures (High-Risk)

• Chronic or subacute pain over the medial malleolus with ankle effusion 5
• History of running activity at time of injury or activities that aggravate the pain 5
• May be associated with lateral ankle instability from prior sprains 4
• Frequently normal on initial radiographs because the medial malleolus consists mainly of cancellous bone 4, 6

Lateral Process of Talus ("Snowboarder's Fracture")

• Swelling inferior to the lateral malleolus in appropriate clinical setting 1
• Overlooked on routine radiographs 40-50% of the time 1
• Often misdiagnosed as lateral ankle sprain 1

Calcaneal Stress Fractures

• Initial radiographs have only 87% sensitivity compared to CT 1, 7
• Particularly difficult to detect when involving the posterior facet 1, 7

Important Clinical Pitfalls

Patients with Neuropathy

• May have no pain or point tenderness despite fracture presence 1
• Can walk without discomfort due to poor pain proprioception 1
• Requires high index of suspicion and lower threshold for imaging 1

Athletes and Active Individuals

• History of recent increase in activity or repeated activity with limited rest 2
• Previous ankle sprains may predispose to stress fractures from altered biomechanics 4
• Early diagnosis is critical for return to sport planning 4, 5

When Occult Fracture Should Be Suspected

Persistent pain beyond 1 week with negative initial radiographs warrants advanced imaging (MRI or CT) to evaluate for:

• Radiographically occult fracture 1
• Bone contusion 1
• Subtle cartilage injury 1
• Soft-tissue injury 1

High-Risk Stress Fracture Locations Requiring Heightened Suspicion

• Anterior tibial cortex 6
• Medial malleolus 6
• Navicular 6
• Base of second metatarsal 6
• Proximal fifth metatarsal 6
• Talus 6

These locations are prone to delayed union or nonunion and require early definitive diagnosis 6.

Diagnostic Approach for Suspected Occult Fractures

MRI without IV contrast is the most sensitive next study after negative radiographs for detecting occult fractures with associated bone marrow edema patterns 1. MRI demonstrates:

• Bone marrow edema at fracture site 1
• Periosteal edema 3
• Actual fracture line 3
• Associated soft-tissue injuries 1

CT without IV contrast is useful when MRI is unavailable or contraindicated, particularly for:

• Talar fractures (lateral process or comminuted body/dome) 1
• Subtalar joint fractures 1
• Posterior malleolar fractures 1
• Demonstrating fractures in one-third of cases with joint effusion but negative radiographs 1

Bone scan shows increased uptake at the fracture site but is less commonly used, as it doesn't visualize the fracture itself and has lower specificity than MRI 2, 5.