A person with a knee sprain has a stretched or torn one or more ligaments in the knee. Ligaments are strong fibrous bands that hold the bones in place during movement. Sprains occur when the joint moves beyond the normal range of motion.

Knee sprains may cause injury to the:

• Lateral collateral ligament:
• Stabilizes the knee from stress applied to the sides of the knee
• Medial collateral ligament:
• Stabilizes the knee from stress applied to the sides of the knee
• Posterior cruciate ligament:
• Stabilizes the knee from stress applied to the front or back of the knee
• Anterior cruciate ligament:
• Stabilizes the knee from stress applied to the front or back of the knee