What is the next step in treating a patient with knee pain and instability, who has been established on physical therapy (PT) and nonsteroidal anti-inflammatory drugs (NSAIDs) for analgesia, with an MRI showing a small popliteal cyst and chondral fissuring, but no internal derangement of the knee?

Management of Knee Pain with Popliteal Cyst and Chondral Fissuring

For a patient with knee pain and instability who has been using PT and NSAIDs, with MRI showing a small popliteal cyst and chondral fissuring but no internal derangement, continue conservative management with physical therapy focusing on quadriceps strengthening while optimizing pain control with NSAIDs and considering targeted interventions for the popliteal cyst if symptoms persist.

Assessment of Current Findings

The MRI findings reveal two key issues:

1. Small popliteal cyst (Baker's cyst): A fluid-filled sac in the popliteal fossa that may contribute to posterior knee discomfort
2. Chondral fissuring on the medial side: Early cartilage damage that can cause pain and potentially progress to osteoarthritis

The absence of internal derangement (no meniscal or ligamentous tears) is important, as it guides treatment toward non-surgical approaches.

Optimized Conservative Management

Physical Therapy Enhancement

• Quadriceps strengthening: Prioritize exercises specifically targeting quadriceps muscles to improve knee stability 1, 2
• Hamstring strengthening: Add complementary exercises to balance muscle groups around the knee
• Neuromuscular education: Include proprioceptive training to improve joint stability 2
• Low-impact aerobic activities: Incorporate swimming or stationary cycling to maintain fitness without joint stress

Pain Management Optimization

• NSAIDs: Continue current NSAID therapy if effective and well-tolerated 1
• Acetaminophen: Consider as first-line alternative if NSAIDs cause GI issues 1
• Topical NSAIDs: Consider as an alternative for patients ≥75 years or those with GI concerns 1

Supportive Measures

• Assistive devices: Consider walking aids if instability persists 2
• Knee bracing: A stabilizing brace may help with reported instability 2
• Weight management: If patient is overweight, counsel regarding weight loss to reduce knee load 1, 2

Targeted Interventions for Popliteal Cyst

If the popliteal cyst is symptomatic and conservative measures fail:

1. Ultrasound-guided aspiration and corticosteroid injection: Consider if the cyst is causing significant discomfort 1, 3

   • Ultrasound is as accurate as MRI for evaluating popliteal cysts 1
   • Most cysts respond to intra-articular corticosteroid injections 3

2. Arthroscopic treatment: Rarely necessary but may be considered if the cyst remains symptomatic despite conservative management 4

Management of Chondral Fissuring

For the chondral fissuring on the medial side:

1. Continue physical therapy: Focus on exercises that strengthen muscles supporting the medial compartment
2. Consider medially wedged insoles: May help redistribute forces away from the medial compartment if symptoms persist 1

Monitoring and Follow-up

1. Re-evaluate in 6-8 weeks: Assess response to optimized conservative management
2. Consider repeat imaging only if symptoms worsen: Additional MRI is not necessary unless there is clinical deterioration

When to Consider More Aggressive Intervention

Consider referral to orthopedic surgery if:

• Persistent mechanical symptoms: Locking or catching despite 6-12 weeks of conservative management 2
• Progressive instability: Not responding to physical therapy and bracing
• Popliteal cyst complications: Such as rupture or compression of neurovascular structures 5

Common Pitfalls to Avoid

1. Overreliance on imaging findings: MRI findings must correlate with clinical symptoms; many popliteal cysts are asymptomatic 3
2. Premature surgical intervention: Most popliteal cysts and early chondral lesions respond to conservative management
3. Inadequate physical therapy: Ensure PT is specifically targeting quadriceps strengthening and knee stability
4. Missing underlying pathology: Though no internal derangement was found, continued instability warrants reassessment

By following this approach, most patients with these findings will experience improvement in both pain and function without requiring surgical intervention.