Tendons are strong bands of fibrous tissue attaching muscles to bones. The most critical tendon in the straightening function for the knee is the quadriceps tendon. The four quadriceps muscles meet above the patella to form the quadriceps tendon. Working together, the quadriceps muscles, quadriceps tendon, and patellar tendon form a pulley mechanism to straighten the knee.

Tears to the quadriceps tendon are uncommon. Quadriceps tendon tears can be partial or complete. Small tears cause pain and limit mobility. A complete tear is disabling. When a complete quadriceps tendon tear occurs, the muscle is no longer anchored to the kneecap.

Though uncommon, when quadricep tendon injuries occur, they frequently require surgery and subsequent physical therapy (PT). Quadricep tendon injuries usually result from middle-aged people engaged in activities like running or sports that involve jumping. Other causes include falls, direct force to the front of the knee, and lacerations.

Signs and Symptoms

• Tearing or popping sensation
• Pain and swelling
• Limited ability to straighten the knee and difficulty walking
• Indentation at the top of the kneecap
• Bruising
• Tenderness
• Cramping