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Patellar Tendon Tears

What is the patellar tendon?

The patellar tendon is a strong fibrous structure located at the front of the knee joint, connecting the patella (kneecap) to the tibia (shinbone). It plays a crucial role in the extension of the knee, allowing for movements such as running, jumping, and squatting. Comprised primarily of dense collagen fibers, the patellar tendon withstands significant forces during weight-bearing activities and provides stability to the knee joint. Injuries to the patellar tendon, such as tears or ruptures, can result from sudden, forceful contractions of the quadriceps muscles or chronic overuse, leading to pain, swelling, and functional limitations.

What are the causes of patellar tendon rupture?

Patellar tendon rupture often occurs due to sudden, forceful contraction of the quadriceps muscles against a fully extended knee, commonly during activities such as jumping, landing, or sudden stops. This force can exceed the tensile strength of the tendon, leading to partial or complete tearing. The risk of patellar tendon rupture is higher in individuals with preexisting tendon weakness or degeneration, chronic tendonitis (tendinopathy), previous knee surgery, or systemic conditions such as diabetes or rheumatoid arthritis. Additionally, steroid use, certain medications, and anatomical factors such as patella alta (high-riding patella) or abnormal patellar alignment may increase the risk of tendon rupture.

What are the symptoms?

The symptoms of a patellar tendon rupture typically include a sudden, sharp pain in the front of the knee, often accompanied by a popping or tearing sensation at the time of injury. Patients may experience swelling, bruising, and difficulty bearing weight on the affected leg, as well as an inability to straighten the knee or perform activities such as walking, climbing stairs, or jumping. In cases of partial tears, symptoms may be less severe, with mild pain and functional limitations.

How is it diagnosed?

Diagnosing a patellar tendon rupture usually involves a combination of medical history, physical examination, and imaging studies. During the physical examination, Dr. Shane J. Nho will assess the appearance and function of the knee, looking for signs of swelling, bruising, and loss of knee extension strength. Special tests such as the patellar apprehension test or the patellar tap test may be performed to assess for tendon integrity and stability. Imaging studies such as X-rays, ultrasound, or magnetic resonance imaging (MRI) are typically ordered to confirm the diagnosis, evaluate the extent of the tear, and assess for associated injuries such as patellar fractures or cartilage damage.

At a Glance

Dr. Shane Nho

  • Board-certified, fellowship-trained orthopedic surgeon
  • Team Physician for Chicago Bulls, White Sox, Steel
  • Performs more than 700 procedures each year
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