What is the best X-ray view for a patient with a history of gouty arthritis, obesity, and hypertension, who has developed an oozing wound on the ankle after 1 week of treatment with coamoxiclav (amoxicillin/clavulanic acid)?

Recommended X-ray Views for Ankle with Oozing Wound Post-Antibiotic Treatment

For this patient with an oozing ankle wound after one week of coamoxiclav treatment, order standard three-view ankle radiographs (anteroposterior, lateral, and mortise views) as the initial imaging study to evaluate for underlying osteomyelitis, and consider adding an axial Harris-Beath view if calcaneal involvement is suspected. 1, 2

Standard Radiographic Protocol

The three standard views are essential and should include:

• Anteroposterior (AP) view - evaluates the tibiotalar joint and distal tibia/fibula 1
• Lateral view - assesses anterior and posterior ankle structures and alignment 1
• Mortise view - critical for evaluating the ankle mortise and detecting subtle fractures or joint space abnormalities 1

These three views should extend to include the base of the fifth metatarsal bone distal to the tuberosity 1. This standard protocol has 92-99% sensitivity for detecting ankle pathology 1.

Weight-Bearing vs Non-Weight-Bearing Considerations

• Weight-bearing radiographs are preferred when clinically feasible, as they provide important information about joint stability and alignment that may not be apparent on non-weight-bearing films 1, 2, 3
• However, given this patient has an oozing wound with likely pain and possible infection, non-weight-bearing views are acceptable and appropriate for initial evaluation 1
• A medial clear space of <4 mm on weight-bearing films confirms ankle stability if this becomes relevant 1

Special Considerations for This Clinical Scenario

Suspected Osteomyelitis Evaluation

Given the oozing wound and history of gouty arthritis (which can mimic infection), radiographs serve as the essential first-line imaging:

• Plain radiographs can demonstrate bone destruction, periosteal reaction, trabecular coarsening, cortical erosions, and soft-tissue swelling associated with osteomyelitis 1
• Radiographs are neither sensitive nor specific for early infection - they may appear normal in acute osteomyelitis or show only subtle changes 1
• Classic radiographic changes of osteomyelitis include cortical erosion, periosteal reaction, and mixed lucency and sclerosis 1

Additional View for Heel/Calcaneal Pathology

If the oozing wound involves the heel region or if gouty tophi are suspected in the calcaneus:

• Add an axial Harris-Beath view, which is optimal for evaluating calcifications and pathology in the heel 2
• This view is particularly valuable for determining intra-articular extent of calcaneal abnormalities 2

Bilateral Imaging Consideration

For patients with diabetes or suspected Charcot neuro-osteoarthropathy (relevant given obesity and hypertension history):

• Obtain bilateral weight-bearing plain X-rays if the patient can tolerate this, as temperature and structural differences between feet aid diagnosis 3
• Look for joint malalignment, subluxation, and fracture displacement that suggest Charcot arthropathy 3

Algorithm for Next Steps Based on Initial Radiograph Results

If Radiographs Show Classic Osteomyelitis Changes:

• Treat for presumptive osteomyelitis after obtaining appropriate specimens for culture 1
• Consider bone biopsy if the etiologic agent or antibiotic susceptibilities are unpredictable 1

If Radiographs Are Normal or Equivocal:

• Treat the soft-tissue infection for 2 weeks, then repeat plain radiographs 2-4 weeks later to look for interval development of bony changes 1
• If clinical suspicion for osteomyelitis remains high despite normal radiographs, MRI is the preferred next imaging study 1, 2
• MRI has high sensitivity and specificity for acute osteomyelitis, and a negative MRI effectively excludes the diagnosis 1

If Radiographs Show Findings Consistent But Not Characteristic of Osteomyelitis:

Three options exist 1:

1. Obtain MRI (preferred) or nuclear medicine scan with leukocyte/immunoglobulin techniques 1
2. Provide empirical antibiotic therapy for 2-4 weeks then repeat radiographs to assess for progression 1
3. Perform bone biopsy (percutaneous under fluoroscopic or CT guidance) if diagnosis remains in doubt or for mid/hind-foot lesions 1

Critical Pitfalls to Avoid

• Do not rely solely on radiographs to exclude osteomyelitis - they have low sensitivity for early infection and may remain normal for 10-14 days after onset 1
• Do not order CT or MRI as the initial study - plain radiographs must come first per established protocols 1
• Do not assume gouty tophi exclude infection - these patients are at risk for both conditions simultaneously, and tophi can become secondarily infected 4, 5
• Avoid manipulating the ankle prior to radiographs unless there is neurovascular deficit or critical skin injury, as this may complicate management 1

Context-Specific Considerations for This Patient

Given the history of gouty arthritis:

• Radiographs may show chronic changes from gout including joint space narrowing, erosions with overhanging edges, and soft-tissue masses (tophi) 4, 6
• These chronic gouty changes can be difficult to distinguish from osteomyelitis on plain films alone 1
• The oozing wound could represent an ulcerated tophus rather than primary infection 5, 7

The failure to improve after one week of coamoxiclav suggests:

• Possible underlying osteomyelitis requiring longer treatment duration 1
• Inadequate antibiotic coverage (consider culture-directed therapy) 1
• Non-infectious process such as gouty flare with ulcerated tophus 5