Patellar Tendon Tears

The patellar tendon is a thick, strong band of tissue that connects the bottom of the kneecap (patella) to the shinbone (tibia). It works with the quadriceps muscles at the front of the thigh to help straighten the leg, allowing you to walk, run, jump, and climb stairs. When this tendon is partially or completely torn, it disrupts this connection and makes it difficult or even impossible to extend the knee.

A partial tear means only some of the tendon fibers have been damaged, while a complete tear occurs when the tendon is fully detached from the kneecap or shinbone. Complete tears are typically more severe and require prompt medical attention.

Patellar tendon tears most often result from a sudden, forceful load on the knee. This usually happens when the knee is bent and then forced straight, such as when landing from a jump, missing a step, or pushing off forcefully during sports. Athletes in sports like basketball, soccer, or track and field are particularly at risk.

In other cases, the tendon may weaken over time due to overuse, chronic inflammation, or degenerative changes, which make it more prone to injury even during everyday movements. Patients with preexisting conditions that affect tendon strength, such as tendinitis, diabetes, or chronic kidney disease, may also be more susceptible.

Trauma, such as a direct blow to the knee, or prior knee surgery can also contribute to patellar tendon tears. In some cases, the tendon may tear from the bottom of the kneecap, while in others, it can rupture closer to where it attaches to the shinbone.

When a patellar tendon tear occurs, symptoms typically appear suddenly and can be quite severe. Common signs include:

• A sudden, sharp pain at the front of the knee
• A popping or snapping sensation at the time of injury
• Swelling and bruising around the knee within hours
• A visible indentation just below the kneecap where the tendon has torn
• Inability to straighten the knee or lift the leg against gravity
• The kneecap moving higher than normal (in complete tears)
• Difficulty walking or bearing weight on the affected leg

For partial tears, pain and weakness may be present, but the patient may still be able to move the knee, but with discomfort. In complete tears, the leg often cannot be straightened at all, and the knee may buckle when attempting to stand or walk.

A patellar tendon tear can occur in anyone, but certain factors make this injury more likely:

• High-impact sports that involve jumping, running, or quick directional changes increase the likelihood of a tear.
• Long-term inflammation or degeneration of the tendon weakens the tissue and raises the risk of rupture.
• Previous knee surgery such as total knee replacement or prior tendon repairs can sometimes weaken the tendon’s attachment.
• Repeated local corticosteroid injections near the knee can cause tendons to lose strength and elasticity.
• Diseases that affect circulation, healing, or tissue quality—like diabetes, lupus, or rheumatoid arthritis—can increase risk.
• Middle-aged adults who engage in occasional but intense activity (so-called “weekend warriors”) may have higher risk because of decreased tendon flexibility with age.

Diagnosis begins with a physical examination, during which an orthopedic specialist like Dr. Collon will evaluate swelling, tenderness, and the position of the kneecap. He will test the ability to extend the knee or lift the leg while lying down provides critical clues about the severity of the injury.

Imaging tests confirm the diagnosis. X-rays can reveal whether the kneecap has shifted out of position, while ultrasound or MRI scans provide detailed images of the tendon to assess the extent of the tear. These tools help determine whether the injury is partial or complete and guide treatment planning.