M20.012 Mallet finger of left finger(s)

Name of the Condition

• Mallet finger of left finger(s)
• ICD-10-CM Code: M20.012

Summary

Mallet finger of left finger(s) is a condition where the distal interphalangeal (DIP) joint of one or more left fingers cannot be actively extended due to injury or damage to the extensor tendon. This results in a drooping fingertip and may impair grip or fine motor function.

Causes

Mallet finger typically occurs when the extensor tendon at the DIP joint is torn or stretched, often from a sudden forceful flexion injury. Common mechanisms include a direct blow to the fingertip or a laceration that severs the tendon. In some cases, the injury may involve a small avulsion fracture of the bone where the tendon attaches.

Risk Factors

• Participation in sports or activities with high risk of finger trauma (e.g., basketball, volleyball)
• Occupational tasks requiring repetitive or forceful finger use
• History of prior finger injuries or tendon damage
• Age-related tendon degeneration, which may increase susceptibility to injury

Symptoms

• Inability to actively straighten the fingertip at the DIP joint
• Visible drooping of the fingertip when attempting to extend the finger
• Pain, swelling, or tenderness over the DIP joint
• Bruising or discoloration around the injured area
• Reduced grip strength or difficulty 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 the severity of the injury. Mild cases may be managed with splinting to immobilize the DIP joint in extension for several weeks. Severe cases, including those with avulsion fractures, may require surgical repair of the tendon or fracture. Physical therapy may be recommended to restore function after healing.

Prognosis and Follow-Up

With proper treatment, most patients recover full function. However, delayed or inadequate treatment can lead to chronic stiffness or deformity. Follow-up appointments are important to monitor healing and adjust treatment as needed. Long-term outcomes are generally favorable if the injury is addressed promptly.

Complications

• Chronic stiffness or limited range of motion in the DIP joint
• Persistent drooping of the fingertip (swan neck deformity)
• Development of arthritis in the affected joint over time
• Reduced grip strength or functional impairment

Lifestyle & Prevention

• Use protective gear during high-risk activities (e.g., sports)
• Avoid forceful finger flexion or direct trauma to the fingertips
• Maintain finger strength and flexibility through regular exercise
• Seek prompt medical attention for finger injuries to prevent complications

When to Seek Professional Help

Consult a healthcare provider if you experience:

• Sudden inability to extend a fingertip after injury
• Persistent pain, swelling, or deformity in a finger
• Difficulty performing daily tasks due to finger weakness or drooping
• Signs of infection (e.g., redness, warmth, pus) at the injury site

Tips for Medical Coders

Document the specific finger(s) affected (left) and confirm the diagnosis aligns with the clinical presentation of mallet finger. Ensure the injury mechanism (e.g., trauma, laceration) and any associated fractures are clearly recorded to support code assignment. Verify that the code M20.012 is used only for left-sided involvement, as specified.