M20.022 Boutonniere deformity of left finger(s)

Name of the Condition

• Boutonniere deformity of left finger(s)
• ICD-10-CM Code: M20.022

Summary

Boutonniere deformity of the left finger(s) is a structural abnormality characterized by flexion at the proximal interphalangeal (PIP) joint and hyperextension at the distal interphalangeal (DIP) joint, resulting in a "buttonhole" appearance. This deformity can impair hand function, particularly in gripping or fine motor tasks, and may cause pain or stiffness.

Causes

The deformity typically results from disruption of the central slip of the extensor tendon at the PIP joint. Common causes include trauma (e.g., a direct blow or laceration), inflammatory conditions (e.g., rheumatoid arthritis), or chronic overuse that weakens tendon integrity. In some cases, it may develop secondary to untreated injuries or degenerative changes.

Risk Factors

• History of finger trauma or injury
• Chronic inflammatory conditions (e.g., rheumatoid arthritis)
• Occupational or recreational activities involving repetitive hand use
• Age-related tendon degeneration
• Previous tendon or joint damage in the left finger(s)

Symptoms

• Flexion at the PIP joint with hyperextension at the DIP joint
• Visible "buttonhole" appearance of the affected left finger(s)
• Pain, swelling, or tenderness over the PIP joint
• Reduced range of motion or stiffness in the left finger(s)
• Difficulty gripping objects or performing fine motor tasks

Diagnosis

Diagnosis involves a physical examination to assess finger alignment, range of motion, and tenderness. Imaging studies, such as X-rays, may be used to evaluate bone structure and joint integrity. Patient history, including injury or disease onset, helps guide evaluation.

Treatment Options

Treatment depends on severity and may include splinting to correct alignment, physical therapy to restore function, or surgical intervention for severe cases. Pain management and activity modification are often part of the plan.

Prognosis and Follow-Up

Prognosis varies based on the cause and timeliness of treatment. Early intervention may improve outcomes, while chronic or untreated cases may lead to permanent deformity. Follow-up care focuses on monitoring function and adjusting treatment as needed.

Complications

Potential complications include permanent joint stiffness, chronic pain, reduced grip strength, or progression to other deformities. Untreated cases may also increase the risk of secondary injuries.

Lifestyle & Prevention

• Avoid repetitive or forceful hand movements that strain the fingers.
• Use protective gear during activities with a high risk of finger injury.
• Manage underlying conditions (e.g., arthritis) to reduce tendon stress.
• Perform hand exercises to maintain flexibility and strength.

When to Seek Professional Help

Seek care if you notice a "buttonhole" appearance, persistent pain, or difficulty moving the left finger(s). Early evaluation can prevent worsening deformity and improve treatment outcomes.

Tips for Medical Coders

Document the specific location (left finger(s)) and confirm the presence of the characteristic PIP flexion and DIP hyperextension. Ensure clinical notes support the diagnosis and specify whether the deformity is acute or chronic for accurate coding.