What is the appropriate evaluation and management for a patient with a three‑month history of knee pain, audible clicking on ambulation, and a small joint effusion on plain radiography without osseous abnormality?

Evaluation and Management of Chronic Knee Pain with Clicking and Small Effusion

MRI without IV contrast is the appropriate next imaging study for this patient with 3 months of knee pain, clicking, and a small effusion on radiographs without osseous pathology. 1

Immediate Next Steps

Order MRI of the knee without intravenous contrast to evaluate for:

• Meniscal tears (the most likely cause of mechanical clicking in this clinical scenario) 1
• Cartilage pathology including chondral defects or early osteochondritis dissecans 1
• Ligamentous injuries that may not be apparent on plain films 1
• Synovial pathology including plicae, which can cause clicking and effusion 1
• Bone marrow edema or occult stress injuries not visible on radiographs 1

The American College of Radiology explicitly states that when initial radiographs are normal or demonstrate only a joint effusion but pain persists, MRI is the appropriate next imaging study 1, 2. This patient's 3-month duration qualifies as chronic pain, and the clicking strongly suggests internal derangement requiring soft-tissue evaluation that only MRI can provide 1.

Why MRI Is Indicated Here

The combination of clicking plus effusion without fracture creates a high pretest probability for meniscal pathology 3. Research demonstrates that meniscal tears are specifically associated with mechanical symptoms like clicking 3, and MRI is highly accurate (86-100% sensitivity) for detecting meniscal and cartilage abnormalities 1.

Do not delay MRI in this scenario. The ACR guidelines note that approximately 20% of patients inappropriately receive MRI without recent radiographs 1, 4, but this patient has already completed appropriate initial radiographic evaluation 1, 4. Waiting longer risks progression of a repairable meniscal tear to an irreparable degenerative tear 1.

Key Clinical Correlations to Document

Before ordering MRI, exclude referred pain sources:

• Hip pathology frequently refers pain to the knee; ask about groin pain, hip range of motion limitations 1, 5, 4
• Lumbar radiculopathy can mimic knee pain; inquire about back pain, radicular symptoms 1, 4

If hip or spine symptoms are present, consider radiographs of those regions before knee MRI 1, 4.

What the MRI Will Clarify

MRI without contrast is specifically indicated to evaluate 1:

• Meniscal morphology and tears (medial meniscus tears cause medial clicking; lateral tears cause lateral clicking) 1, 3
• Articular cartilage integrity including focal defects or early degenerative changes 1
• Ligament integrity (ACL, PCL, collateral ligaments) 1
• Bone marrow signal to detect occult fractures, bone marrow edema syndrome, or early osteonecrosis 1, 6
• Synovial pathology including plicae, loose bodies, or synovitis 1

Alternative Imaging Considerations (Usually Not Appropriate)

Ultrasound is not useful as a comprehensive examination in this scenario 1. While ultrasound can confirm effusion and guide aspiration 1, it cannot adequately evaluate menisci or intra-articular structures causing clicking 1.

CT or CT arthrography may be considered if MRI is contraindicated (pacemaker, severe claustrophobia), but has lower soft-tissue resolution 1.

Aspiration is not indicated unless there is concern for infection (fever, erythema, warmth) or crystal disease (acute inflammatory presentation) 1, 5. A small chronic effusion in the setting of mechanical symptoms does not require aspiration 1.

Common Pitfalls to Avoid

• Do not attribute clicking to "normal joint sounds" in the presence of effusion and 3 months of pain; this combination indicates structural pathology requiring imaging 1, 3
• Do not order MRI with IV contrast as a first study; contrast is reserved for suspected infection, tumor, or inflammatory arthropathy, none of which are suggested by this presentation 1
• Do not order bone scan, which has low specificity and poor anatomic resolution compared to MRI 1
• Recognize that effusion alone is nonspecific; it may reflect meniscal tear, cartilage injury, synovitis, or ligament injury—all of which require MRI for differentiation 1, 7

Management Pending MRI Results

While awaiting MRI (typically scheduled within 1-2 weeks for non-urgent cases):

• Activity modification: avoid deep squatting, pivoting, or activities that provoke clicking 1
• NSAIDs for symptomatic relief if not contraindicated 1
• Physical therapy may begin with focus on quadriceps strengthening and range of motion, but definitive treatment awaits MRI diagnosis 1

The MRI findings will determine whether the patient requires orthopedic referral for arthroscopy (repairable meniscal tear, loose body, unstable osteochondritis dissecans) versus conservative management (degenerative meniscal changes, mild chondromalacia). 1