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Quadriceps/Patellar Tendon Rupture

What is the quadriceps tendon?


The quadriceps tendon is the strong, thick tendon that inserts on the top of the

patella (knee cap). The quadriceps tendon is a coming together of the four muscles

(the “quad”) that extend the knee.  The four muscles (vastus medialis, vastus

intermedius, vastus lateralis and rectus femoris) work together to extend the knee

and leg.  The quadriceps tendon is important because if it is injured then you will

not be able to extend your knee, which impacts your ability to stand, walk, run or

perform most activities involving the lower leg.


What is the patella tendon?


The patellar tendon is the terminal extension of the quadriceps muscle in the leg.  The patella lies within the quadriceps tendon.  The quadriceps tendon becomes thicker and narrower as it crosses the kneecap to the tibia (shin bone) becoming the patellar tendon.  The patellar tendon functions like the quadriceps tendon, allowing someone to straighten their leg, which is a function needed for most lower extremity activities.


How do you tear your quadriceps or patella tendon?


The quadriceps tendon is injured most commonly from a forced eccentric contraction

(contracting while lengthening muscle) against an outside force.  A quadriceps tendon

rupture occurs relatively infrequently and usually occurs in people older than 40 years. 

It can happen during high-energy trauma, such as motor vehicle accidents, during

sporting activities, or during low energy injuries such as falls from a standing position,

especially if the knee gets bent behind you.


Generally, “normal” patellar tendons do not rupture.  Usually, there is some underlying degeneration prior to a rupture.  The usual mechanism of injury is a quick contraction of the quadriceps when the knee is in a flexed position, like jumping or running up stairs.

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to learn more about knee injuries,
disorders and treatment options
Quadriceps tendon tear

What are some risk factors for a quadriceps or patella tendon tear?


Generally, there are very few risk factors.  Most quadriceps tendon ruptures are the result of either direct or indirect trauma. There are some medical problems that can increase a person’s risk, including renal (kidney) disease, rheumatoid arthritis, chronic steroid use and diabetes mellitus. However, even in patients with these disorders, the incidence of quadriceps tendon ruptures is still very low.


A patellar tendon rupture occurs more commonly in people age 40 and younger.  Any condition that affects the integrity of tendons or ligaments can increase the risk for rupture, such as diabetes mellitus, anabolic steroid use, systemic lupus, and chronic corticosteroid use.

How do I know I tore my quadriceps or patella tendon?


Most people with a quadriceps tendon rupture will have acute, significant pain and disability in the affected leg.  There will usually be pain in the knee or just above the knee, and often times a palpable defect where the tendon is torn.  If it is a complete rupture, you will be unable to extend your knee and will have a difficult time walking on the affected leg.  If it is a partial tear, you may still be able to extend your knee, but you will have significant weakness when compared to the other leg.


If you torn your patellar tendon, you will have immediate pain and swelling in the knee.  Some people may feel a “rip” or “tearing” sensation.  You will likely be unable to walk.  On examination, there will be a palpable defect and an inability to straighten your leg.

Do I definitely need surgery?


There are two types of tendon ruptures: partial and complete tears.


Partial tears can sometimes be treated non-operatively, usually if you can still lift your leg up on your own.  Treatment will consist of a brace to hold the knee straight for a few weeks followed by physical therapy to regain motion and strength.  Normally, you can resume normal activities after approximately 3-6 months, after you have regained full range of motion and normal strength.


Complete tears, or partial tears when someone unable to lift their leg, are always in need of surgery.  Without surgery, you will be unable to extend your knee and have significant long-term disability.  Surgery is typically recommended within a few days to one week after the injury.


Typically, surgery involves making an incision on the front of the knee.  Strong sutures are placed into the tendon and anchored or tied to the patella.  Surgery generally takes 1-2 hours, and you will be placed in a splint or brace with crutches to hold the knee straight while the tendon is healing. 


What is the recovery after surgery?


Surgery is usually done as a same-day surgery, meaning you can go home the same day.  After surgery, you will start gentle range of motion exercises with a physical therapist.  You will slowly regain full range of motion of the knee over 6-8 weeks.  You may be able to bear weight on the leg, but always with the brace fixed in the straight position for the first 6-8 weeks, until you gain enough motion and the repair has time to heal.  Typically, the brace is discontinued 8 weeks from surgery.  Full recovery with return to running and sports can take 4-6 months depending on your specific tear and recovery.



What can I expect long-term after a tendon tear and surgery?


Tendon repairs have good long-term success.  Most people will be able to return to work and sports after the appropriate rehabilitation.  It is important to follow the prescribed physical therapy to ensure a good outcome.  The most common complication after surgical repair is loss of motion in the knee.  Re-tear of the tendon after surgical repair is rare unless something unexpected or traumatic occurs (i.e. a fall during the early post-operative phase).

Will I need X-rays or MRI?


Initially, you will likely need a plain radiograph or X-Ray.  An x-ray will help evaluate for associated injury, like a fracture. 


If it is a complete quadriceps tendon rupture, the x-ray may reveal a kneecap that is lower than normal because the tendon is no longer holding the patella up.  If it is a complete patellar tendon rupture, the kneecap may be higher than normal on x-ray because the quadriceps tendon is pulling the kneecap up without any resistance. 


Further imaging with an MRI to evaluate the integrity of the tendon and distinguish between a complete and partial tear.

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