What is the appropriate workup for a patient with knee pain and leg pain who has a history of Open Reduction Internal Fixation (ORIF) due to a fracture?

Workup of Knee and Leg Pain in Patient with Prior ORIF

Begin with standard radiographs of the knee (anteroposterior, lateral, and tangential patellar views) as the initial imaging study, and if these are normal or show only joint effusion but pain persists, proceed directly to MRI without IV contrast to evaluate for hardware complications, post-traumatic arthritis, and soft tissue pathology. 1

Initial Imaging Approach

• Obtain three-view knee radiographs including anteroposterior, lateral, and tangential patellar views of the affected knee 1
• Radiographs serve as the mandatory first-line imaging to assess for:
  • Hardware position and integrity
  • Post-traumatic osteoarthritis
  • Loose bodies
  • Signs of prior osseous injury (fracture malunion, hardware loosening) 1
  • Joint effusion 1

When Radiographs Are Normal or Show Only Effusion

MRI without IV contrast is the next indicated examination when initial radiographs are normal or reveal only a joint effusion but pain persists 1

MRI provides critical information about:

• Hardware-related complications: Soft tissue irritation, synovitis, or effusion related to implants 1
• Bone marrow lesions (BML): New or increasing BMLs are associated with increased knee pain and may indicate subchondral insufficiency fractures 1
• Meniscal pathology: Though meniscal tears are common incidental findings in patients over 45 years, MRI can identify symptomatic tears 1
• Articular cartilage damage: Subchondral cysts and cartilage abnormalities are easily detected 1
• Popliteal cysts: MRI accurately depicts presence or rupture of popliteal cysts 2
• Post-traumatic arthrofibrosis: A known complication after ORIF 3

Critical Differential Diagnoses to Exclude

Referred Pain from Hip

• Obtain hip radiographs if knee radiographs are unremarkable and there is clinical evidence of hip pathology 1, 2
• Hip pathology commonly refers pain to the thigh, knee, or buttock 1

Referred Pain from Lumbar Spine

• Consider lumbar spine radiographs if knee radiographs are unremarkable and there is clinical concern for lumbar spine pathology 1, 2
• Complete thorough clinical examination including lumbar spine assessment before attributing all symptoms to knee pathology 2

Hardware-Specific Considerations

Given the history of ORIF, specific attention should be directed to:

• Hardware-related pain: Occurs in approximately 23-31% of patients after ORIF of lower extremity fractures 4
• Symptomatic hardware: Look for pain overlying hardware on examination, as this correlates with poorer functional outcomes 4
• Post-traumatic arthritis: A known complication after ORIF that develops over time 3
• Infection: Though typically presents acutely, low-grade infection can cause chronic pain 3

Common Pitfalls to Avoid

• Do not perform premature MRI: Approximately 20% of patients with chronic knee pain undergo MRI without recent radiographs within the prior year 1, 2
• Do not overlook referred pain: Always assess hip and lumbar spine clinically before attributing all symptoms to knee pathology 2
• Do not assume all imaging findings are symptomatic: Meniscal tears are present in the majority of people over 70 years of age asymptomatically 1, 2
• Do not ignore bilateral findings: In patients over 70 years, bilateral structural abnormalities can be present with primarily unilateral symptoms 1, 2

Additional Imaging Considerations

If Radiographs Show Signs of Prior Osseous Injury

• MRI without IV contrast is usually appropriate to evaluate the medial patellofemoral ligament, cartilage injury extent, and identify loose bodies 1
• MRI can assess menisci effectively if radiograph suggests prior ligamentous injury 1

If Joint Effusion Is Present

• Consider ultrasound or fluoroscopy-guided aspiration if there is concern for crystal disease or infection 1
• Synovial fluid analysis can differentiate inflammatory from mechanical causes 1

CT Imaging Role

• CT without IV contrast may be indicated to evaluate patellofemoral anatomy if there is concern for maltracking or to confirm hardware position 1
• CT is not routinely the first-line study but can complement MRI findings 1