M23.02 Cystic meniscus, posterior horn of medial meniscus

Name of the Condition

• Cystic meniscus, posterior horn of medial meniscus

Summary

A cystic meniscus, posterior horn of medial meniscus, is a condition where a fluid-filled sac forms in the posterior horn of the medial meniscus, a C-shaped cartilage structure in the 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
• Progression to meniscal tear or osteoarthritis
• Limited mobility if left untreated

Lifestyle & Prevention

• Avoid repetitive 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 physical therapy

When to Seek Professional Help

Seek medical attention if you experience sudden, severe knee pain, inability to bear weight, or signs of infection (e.g., redness, fever). Persistent symptoms despite rest or worsening swelling also warrant evaluation.

Tips for Medical Coders

Document the specific location (posterior horn of medial meniscus) and any associated findings, such as meniscal tears or joint effusion, to support accurate coding. Ensure clinical documentation aligns with the ICD-10-CM code M23.02 and reflects the anatomical specificity of the condition.