Quadriceps & Patellar Tendon Tear
What Is a Quadriceps or Patellar Tendon Tear?
The quadriceps tendon and patellar tendon work together as the knee’s “extensor mechanism” — the connected chain of tissue that allows you to straighten your knee. The quadriceps tendon connects the large thigh muscle to the top of the kneecap, while the patellar tendon connects the bottom of the kneecap to the shinbone. A tear in either tendon disrupts this chain, making it difficult or impossible to actively straighten the leg, since the muscle can no longer transmit its force down to the shinbone.
What Causes a Quadriceps or Patellar Tendon Tear?
- A sudden, forceful contraction of the quadriceps muscle against resistance — such as landing awkwardly from a jump or stumbling while carrying weight
- A direct blow or fall onto a bent knee
- Chronic tendon degeneration, which can weaken the tendon over time and make it more prone to tearing, even with a relatively minor incident
- Certain medical conditions and medications, including chronic kidney disease and fluoroquinolone antibiotics, which have been associated with a higher risk of tendon rupture
- Anabolic steroid use, in some cases
Quadriceps tendon tears tend to occur more often in older patients, while patellar tendon tears are somewhat more common in younger, more athletic patients — though both can occur at any age.
What Are the Symptoms of a Quadriceps & Patellar Tendon Tear?
- A sudden, sharp pain at the top or bottom of the kneecap at the moment of injury
- An audible pop or tearing sensation
- Rapid swelling and bruising
- Inability to straighten the leg or perform a straight-leg raise
- A palpable gap or defect above or below the kneecap
- The kneecap may sit noticeably higher or lower than normal, depending on which tendon is torn
Can You Tell a Torn Tendon From a Broken Kneecap?
The symptoms can look remarkably similar, since both injuries disrupt the same extensor mechanism and cause an inability to straighten the leg. One helpful distinguishing clue on exam is the position of the kneecap: with a quadriceps tendon tear, the kneecap often sits lower than normal, while with a patellar tendon tear, it tends to ride higher than normal, since the opposing tendon is still pulling on it unopposed. A careful physical exam combined with an X-ray or MRI is used to confirm exactly which structure is torn — the kneecap bone itself, or one of the two tendons attached to it.
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Treatment Options for Quadriceps & Patellar Tendon Tears
Partial tears, where the patient can still actively straighten the leg (even if painful and weak), may be treated nonsurgically with a period of bracing in full extension, followed by a gradual, supervised return to bending the knee and progressive strengthening.
Complete tears almost always require surgery, since a fully torn tendon cannot heal back together on its own once the ends have pulled apart. Surgical repair involves reattaching the torn tendon back to the kneecap using strong sutures, often passed through small tunnels drilled in the bone, restoring the connection needed to actively straighten the knee. Repair is generally most successful when performed within the first couple of weeks after injury, since a tendon that has retracted and scarred for an extended period becomes progressively more difficult to fully restore to its original length.
Following surgery, recovery involves an initial period of bracing with the knee locked straight, followed by a gradual, carefully staged return of motion and strength over several months, since the repaired tendon needs significant time to heal securely before it can tolerate the full forces of walking, stairs, and higher-impact activity.
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Dr. Palsis specializes in the treatment of knee, shoulder, and sports injuries.