M71.069 Abscess of bursa, unspecified knee

Name of the Condition

• Abscess of bursa, unspecified knee

Summary

An abscess of the bursa, unspecified knee is a localized collection of pus within the bursa of the knee, a small fluid-filled sac that reduces friction between tissues. This condition typically causes pain, swelling, and warmth at the affected site. The unspecified knee designation indicates the abscess is localized to the bursa in the knee region without specifying left or right.

Causes

Abscesses of the knee bursa usually result from bacterial infection, often introduced through direct trauma, skin breakdown, or spread from adjacent tissues. Staphylococcus aureus is a common causative organism. Non-infectious causes, such as foreign body reaction or sterile inflammation, are less frequent.

Risk Factors

• Recent injury or surgery near the knee bursa
• Skin infections or open wounds in the knee area
• Immunocompromised states (e.g., diabetes, HIV)
• Chronic inflammatory conditions (e.g., rheumatoid arthritis)
• Repetitive motion or pressure on the knee bursa

Symptoms

• Localized pain, tenderness, or throbbing in the knee
• Swelling, redness, or warmth over the bursa
• Limited range of motion in the knee joint
• Possible fever or systemic signs if infection spreads
• Pus drainage if the abscess ruptures

Diagnosis

Diagnosis involves a physical examination to assess bursal swelling, warmth, and tenderness. Imaging (e.g., ultrasound) may confirm the presence of fluid or pus. Aspiration of the bursa may be performed to identify the causative organism and guide treatment.

Treatment Options

Treatment typically includes antibiotic therapy for bacterial infections, often targeted at Staphylococcus aureus. Drainage of the abscess may be necessary for larger or persistent collections. Rest, elevation, and pain management support recovery. Severe cases may require surgical intervention.

Prognosis and Follow-Up

With appropriate treatment, most knee bursal abscesses resolve without long-term complications. Follow-up ensures infection clearance and monitors for recurrence. Persistent symptoms or complications may require additional imaging or drainage.

Complications

Untreated abscesses can lead to spread of infection, sepsis, or damage to surrounding tissues. Chronic inflammation or scarring may result in persistent pain or limited mobility.

Lifestyle & Prevention

Avoid trauma or excessive pressure on the knee. Maintain skin integrity and promptly treat wounds or infections. Manage chronic conditions like diabetes to reduce infection risk.

When to Seek Professional Help

Seek care if symptoms worsen, fever develops, or pus drainage occurs. Prompt evaluation is necessary for severe pain, swelling, or signs of systemic infection.

Tips for Medical Coders

Document the knee involvement as unspecified when left or right is not documented. Ensure clinical correlation with physical exam findings, imaging, or aspiration results to support the diagnosis.