I49.9 - Cardiac arrhythmia, unspecified

Clinical Definition

A sprain of the medial collateral ligament of knee is a stretching or tearing of the thick band of tissue on the inside of the knee that connects the femur to the tibia, providing medial stability to the knee joint.

Documentation Requirements

• Laterality (right, left, or bilateral)

• Severity/Grade (1, 2, or 3)

• Acuity (acute, chronic, or acute-on-chronic)

• Initial vs. subsequent encounter

• Healing status (routine, delayed, nonunion)

• Any associated injuries

• Mechanism of injury (sports, fall, direct trauma)

Common Synonyms

• MCL sprain

• Inner knee ligament injury

• Medial knee sprain

• "Inside knee strain"

Coding Conflicts

Excludes1:

• Old disruption of MCL ligament (M23.52)

• Dislocation of knee (S83.1-)

Excludes2:

• Lateral collateral ligament sprain (S83.42-)

• Multiple ligament sprains (S83.57)

Scribing.io Automation

The AI scribe automatically identifies:

• Directional terms ("medial," "inner side")

• Physical exam findings ("valgus stress test positive")

• Anatomical references ("MCL," "tibial collateral ligament")

• Imaging results mentioning "MCL" or "medial collateral"
  These are flagged for review and mapped to appropriate MCL sprain documentation requirements.