Evaluation and Management of New Onset Right Knee to Ankle Pain
Initial Clinical Assessment
Begin with plain radiographs of both the knee and ankle as your initial imaging study, guided by clinical examination findings and the Ottawa Ankle Rules for the ankle component. 1
Key Clinical Examination Elements
For the ankle component, apply the Ottawa Ankle Rules to determine imaging necessity 1:
- Point tenderness over the medial malleolus, posterior edge or inferior tip of lateral malleolus, talus, or calcaneus 2, 1
- Inability to bear weight immediately after injury or inability to walk four steps 2, 1
- If Ottawa Ankle Rules are positive, obtain ankle radiographs (92-99% sensitivity for fractures) 2, 1
- If Ottawa Ankle Rules are negative and patient can ambulate, no initial imaging is needed 2
For the knee component, assess for 3:
- Acute trauma with severe pain, swelling, instability, or inability to bear weight (requires urgent evaluation) 3
- Age-related patterns: patellofemoral pain in younger active patients (<40 years), osteoarthritis in patients ≥45 years 4
- Mechanical symptoms: locking, catching, or giving way suggesting meniscal or ligamentous injury 4
- Joint line tenderness (83% sensitivity and specificity for meniscal tears) 4
Standard Radiographic Protocol
For ankle: Obtain three standard views (anteroposterior, lateral, and mortise) including the base of the fifth metatarsal 2, 1
For knee: Plain radiographs are indicated for chronic pain (>6 weeks) or acute traumatic pain meeting evidence-based criteria 3, 5
Advanced Imaging Based on Initial Results
If Radiographs Are Negative But Pain Persists
For ankle pain persisting >1 week with negative radiographs:
- Order MRI without IV contrast as the next study 2, 1
- MRI has 93-96% sensitivity and 100% specificity for detecting ligament injuries and occult fractures 1
- MRI effectively identifies radiographically occult fractures, bone contusions, cartilage injuries, and soft-tissue pathology 2
- CT without IV contrast is an alternative if MRI is contraindicated, particularly for detecting occult fractures 2
For knee pain with negative radiographs:
- MRI is indicated when surgery is being considered or when pain persists despite adequate conservative treatment 3
- MRI is particularly useful for evaluating cartilage, menisci, and cruciate/collateral ligaments 5
Special Clinical Scenarios
If multiple sites of degenerative joint disease are present:
- Consider image-guided anesthetic injection (fluoroscopy, CT, or ultrasound-guided) to identify the specific pain source and aid surgical planning 2
If osteochondral lesion is suspected with normal radiographs:
- MRI without IV contrast should be the definitive next study 2
- MRI has 96% sensitivity for osteochondral abnormalities and 97% sensitivity for determining lesion instability 2
If tendon abnormality is suspected:
- Either MRI without IV contrast or ultrasound are appropriate options 2
- Ultrasound has higher resolution for peripheral structures and allows dynamic evaluation 2
For patients with peripheral neuropathy or neurologic disorders:
- Radiographs remain the initial study even without typical pain patterns, as these patients may have fractures without pain or point tenderness due to poor proprioception 2, 1
Common Pitfalls to Avoid
Do not order foot radiographs in addition to ankle radiographs in the presence of inversion injury or ankle fracture—studies show no additional foot fractures beyond the fifth metatarsal base are detected 2
Avoid manipulation of the ankle prior to radiographs unless there is neurovascular deficit or critical skin injury, to prevent complications 2
Do not routinely use MRI, CT, bone scan, or ultrasound as first-line imaging for acute ankle trauma when Ottawa Ankle Rules can be applied 2
Reserve MRI for knee evaluation until conservative treatment has been attempted or surgery is being considered, rather than ordering it immediately 3
Weight-bearing radiographs provide critical information about ankle stability, particularly for malleolar fractures—obtain when possible 2