Initial Imaging for Post-Total Ankle Arthroplasty with Sudden Severe Pain
Obtain standard three-view ankle radiographs immediately: anteroposterior (AP), lateral, and mortise views, ensuring the entire prosthesis is included in the imaging field.
Recommended Radiographic Protocol
While the provided evidence primarily addresses total knee arthroplasty and acute ankle trauma rather than post-TAA complications, the fundamental imaging principles for arthroplasty complications remain consistent across joints.
Standard Views Required
- Three orthogonal views are essential: AP, lateral, and mortise projections should be obtained to evaluate the prosthetic components and surrounding bone 1.
- Include the entire prosthesis in all views to assess component position, alignment, and periprosthetic bone 1.
- Weight-bearing films are preferred if the patient can tolerate them, as they provide critical information about component stability and alignment 1.
What Radiographs Can Detect
Plain radiographs effectively demonstrate:
- Periprosthetic fractures (a critical cause of sudden severe pain post-arthroplasty) 1
- Component loosening evidenced by periprosthetic lucency, subsidence, or change in component position 1
- Hardware malalignment or failure 1
- Osteolysis around components 1
- Heterotopic bone formation 1
- Joint effusion and soft-tissue swelling 1
When Advanced Imaging Is Needed
CT Indications
- If radiographs show subtle findings requiring further characterization, CT without contrast should be obtained 2.
- CT detects more and larger periprosthetic osteolytic lesions than radiographs around ankle prostheses and is recommended for patients with suspected or known periprosthetic lucencies 2.
- Complex fracture patterns or polytrauma situations warrant CT for surgical planning 1.
MRI Indications
- When radiographs and CT are negative but pain persists, MRI with metal artifact reduction sequences is highly accurate for identifying occult complications 3.
- MRI excels at detecting: bone resorption, osteolysis, infection, osseous stress reactions, nondisplaced fractures, polyethylene damage, nerve injuries, and tendon/ligament tears 3.
Critical Pitfalls to Avoid
- Do not delay imaging in the setting of sudden severe pain post-arthroplasty—this presentation demands urgent evaluation for periprosthetic fracture or acute component failure 1.
- Do not skip weight-bearing views unless contraindicated, as non-weight-bearing films may miss instability 1.
- Radiographs underestimate osteolysis: if lucencies are visible on plain films, strongly consider CT for complete assessment 2.
- Infection cannot be reliably distinguished from aseptic loosening on radiographs alone—if infection is suspected clinically, proceed with joint aspiration and laboratory workup in addition to imaging 1.