M23.012 Cystic meniscus, anterior horn of medial meniscus, left knee

Name of the Condition

• Cystic meniscus, anterior horn of medial meniscus, left knee

Summary

A cystic meniscus, anterior horn of medial meniscus, left knee, is a condition where a fluid-filled sac forms in the anterior horn of the medial meniscus, a C-shaped cartilage structure in the left knee that cushions and stabilizes the joint. This can lead to pain, swelling, and restricted knee movement.

Causes

Cystic meniscus often develops due to degenerative changes or tears within the meniscus itself. It may also result from repetitive stress or injury to the knee joint, which can trigger fluid accumulation in the meniscal tissue.

Risk Factors

• Active participation in sports involving repetitive knee motions (e.g., soccer, basketball)
• Aging, which contributes to degenerative changes
• Previous knee injuries
• Genetic predisposition to joint abnormalities

Symptoms

• Pain or tenderness in the affected knee
• Swelling or a palpable lump on the inner side of the knee
• Limited range of motion
• Clicking or locking sensation during knee movement

Diagnosis

Diagnosis typically involves a physical examination and patient history, followed by imaging tests such as MRI or ultrasound to visualize the meniscal cyst. Arthroscopy may be used in some cases to confirm the diagnosis and assess the extent of the condition.

Treatment Options

• Rest and physical therapy to strengthen surrounding muscles and improve flexibility
• Aspiration of the cyst to reduce swelling
• Surgical intervention, such as meniscectomy or cyst decompression, if conservative measures fail

Prognosis and Follow-Up

Prognosis depends on the severity of the cyst and associated meniscal damage. Most patients improve with conservative treatment, but recovery may take several weeks to months. Follow-up care often includes monitoring for recurrence and gradual return to activity.

Complications

• Persistent pain or instability
• Recurrence of the cyst
• Meniscal tear progression
• Knee joint degeneration over time

Lifestyle & Prevention

• Avoid high-impact activities that stress the knee
• Maintain a healthy weight to reduce joint load
• Use proper form during exercise or sports
• Strengthen knee muscles through targeted exercises

When to Seek Professional Help

Seek medical attention if you experience severe knee pain, sudden swelling, inability to bear weight, or locking of the knee joint.

Tips for Medical Coders

Document the specific location (anterior horn of medial meniscus) and laterality (left knee) to support accurate coding. Ensure clinical notes specify the cystic nature and affected knee side for proper code assignment.