M23.029 Cystic meniscus, posterior horn of medial meniscus, unspecified knee

Name of the Condition

• Cystic meniscus, posterior horn of medial meniscus, unspecified knee

Summary

A cystic meniscus, posterior horn of medial meniscus, unspecified knee, 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
• Medications (e.g., NSAIDs) to reduce pain and inflammation
• Corticosteroid injections for symptom relief
• Surgical intervention (e.g., arthroscopic cyst decompression or meniscectomy) for persistent or severe cases

Prognosis and Follow-Up

Prognosis depends on the size of the cyst, associated meniscal damage, and treatment response. Most patients experience symptom improvement with conservative management, though some may require surgery. Follow-up care includes monitoring for recurrence and gradual return to activity as tolerated.

Complications

• Persistent pain or instability if left untreated
• Increased risk of meniscal tears or joint degeneration
• Limited mobility affecting daily activities

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 surrounding muscles (e.g., quadriceps, hamstrings) to support the knee

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 swelling, locking, or worsening symptoms also warrant evaluation.

Tips for Medical Coders

Document the specific knee affected (right/left/unspecified) and the meniscal location (posterior horn of medial meniscus) to ensure accurate coding. Include details on cyst size, associated meniscal tears, or surgical interventions if applicable. Verify laterality and anatomical specificity to align with ICD-10-CM guidelines.