The knee extensor mechanism includes:

• Quadriceps Tendon: Connects the quadriceps muscle to the top of the kneecap.
• Patellar Tendon: Connects the bottom of the kneecap to the shinbone (tibia).
• Quadriceps Muscle Group: The muscles on the front of the thigh.
• Patella (Kneecap): The bone that sits in front of the knee joint.

These parts work together to straighten the knee and keep it stable, allowing you to walk and move without the knee giving out.

A quadriceps tendon rupture occurs when the quadriceps tendon tears off or near the top of the kneecap, either completely or partially. This injury affects the tendon that helps you straighten your knee. With a ruptured tendon, you may have trouble straightening your leg, walking, running, or jumping.

• Sudden, Powerful Movements: Such as a fall, jumping, landing, or sudden stops.
• Chronic Overuse: Repeated stress or strain over time, especially in older people.

• Severe pain in the front of the knee, often above or around the kneecap.
• Swelling of the knee.
• Difficulty straightening the knee or lifting your leg.
• Trouble bearing weight on the leg.
• A noticeable gap or dent just above the kneecap.
• The kneecap might move down lower than it normally sits (patella baja).

To diagnose a quadriceps tendon injury, doctors usually perform:

1. Physical Examination: Checking for gaps or dents in the tendon above the kneecap, testing your ability to straighten your leg, and seeing if you can hold it straight.
2. X-rays: To rule out fractures and check if the kneecap has moved lower than usual.
3. MRI: To see the extent of the tendon injury and check for any other damage to ligaments, menisci, or cartilage.